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1. Variability and trends of carbon parameters at a time series in the eastern tropical Atlantic

Author: Nathalie Lefèvre, Doris Veleda, Moacyr Araujo, and Guy Caniaux
Subjects: fugacity of CO2, ocean acidification, time series, eastern tropical Atlantic, Meteorology. Climatology, QC851-999
Abstract: Hourly fCO2 is recorded at a time series at the PIRATA buoy located at 6°S 10°W in the eastern tropical Atlantic since June 2006. This site is located south and west of the seasonal Atlantic cold tongue and is affected by its propagation from June to September. Using an alkalinity–salinity relationship determined for the eastern tropical Atlantic and the observed fCO2, pH and the inorganic carbon concentration are calculated. The time series is investigated to explore the intraseasonal, seasonal and interannual timescales for these parameters, and to detect any long-term trends. At intraseasonal timescales, fCO2 and pH are strongly correlated. On seasonal timescales, the correlation still holds between fCO2 and pH and their variations are in agreement with those of sea surface salinity. At interannual timescales, some important differences appear in 2011–2012: lower fCO2 and fluxes are observed from September to December 2011 and are explained by higher advection of salty waters at the mooring, in agreement with the wind. In early 2012, the anomaly is still present and associated with lower sea surface temperatures. No significant long-term trend is detected over the period 2006–2013 on CO2 and any other physical parameter. However, as atmospheric fCO2 is increasing over time, the outgassing of CO2 is reduced over the period 2006–2013 as the flux is mainly controlled by the difference of fCO2 between the ocean and the atmosphere. A longer time series is required to determine if any significant trend exists in this region.
Published: 2016
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2. Amazon Plume Salinity Response to Ocean Teleconnections

Author: Pedro Tyaquiçã, Doris Veleda, Nathalie Lefèvre, Moacyr Araujo, Carlos Noriega, Guy Caniaux, Jacques Servain, and Thiago Silva
Subjects: El Niño, sea surface temperature, rainfall, sea surface salinity, Amazon River plume, Science, General. Including nature conservation, geographical distribution, QH1-199.5
Abstract: Pacific and Atlantic sea surface temperature (SST) variability strongly influences rainfall changes in the Amazon River basin, which impacts on the river discharge and consequently the sea surface salinity (SSS) in the Amazon plume. An Empirical Orthogonal Function (EOF) analysis was performed using 46 years of SST, rainfall, and SSS datasets, in order to establish the relationship between these variables. The first three modes of SST/rainfall explained 87.83% of the total covariance. Pacific and Atlantic SSTs led Amazon basin rainfall events by 4 months. The resultant SSS in the western tropical North Atlantic (WTNA) lagged behind basin rainfall by 3 months, with 75.04% of the total covariance corresponding to the first four EOF modes. The first EOF mode indicated a strong SSS pattern along the coast that was connected to negative rainfall anomalies covering the Amazon basin, linked to El Niño events. A second pattern also presented positive SSS anomalies, when the rainfall was predominantly over the northwestern part of the Amazon basin, with low rainfall around the Amazon River mouth. The pattern with negative SSS anomalies in the WTNA was associated with the fourth mode, when positive rainfall anomalies were concentrated in the northwest part of South America. The spatial rainfall structure of this fourth mode was associated with the spatial rainfall distribution found in the third EOF mode of SST vs. rainfall, which was a response to La Niña Modoki events. A statistical analysis for the 46 year period and monthly anomaly composites for 2008 and 2009 indicated that La Niña Modoki events can be used for the prediction of low SSS patterns in the WNTA.
Published: 2017
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3. SST Indexes in the Tropical South Atlantic for Forecasting Rainy Seasons in Northeast Brazil

Author: Gbèkpo Aubains Hounsou-Gbo, Jacques Servain, Moacyr Araujo, Guy Caniaux, Bernard Bourlès, Diogenes Fontenele, and Eduardo Sávio P. R. Martins
Subjects: Brazilian Northeast, rainfall, predictability, tropical Atlantic, Meteorology. Climatology, QC851-999
Abstract: May-to-July and February-to-April represent peak rainy seasons in two sub-regions of Northeast Brazil (NEB): Eastern NEB and Northern NEB respectively. In this paper, we identify key oceanic indexes in the tropical South Atlantic for driving these two rainy seasons. In Eastern NEB, the May-to-July rainfall anomalies present a positive relationship with the previous boreal winter sea surface temperature anomalies (SSTA) in the southeast tropical Atlantic (20°−10° S; 10° W−5° E). This positive relationship, which spread westward along the southern branch of the South Equatorial Current, is associated with northwesterly surface wind anomalies. A warmer sea surface temperature in the southwestern Atlantic warm pool increases the moisture flux convergence, as well as its ascending motion and, hence, the rainfall along the adjacent coastal region. For the Northern NEB, another positive relationship is observed between the February-to-April rainfall anomalies and the SSTA of the previous boreal summer in the Atlantic Niño region (3° S−3° N; 20° W−0°). The negative remote relationship noticeable between the Northern NEB rainfall and the concomitant Pacific Niño/Niña follows cold/warm events occurring during the previous boreal summer in the eastern equatorial Atlantic. The southeastern tropical Atlantic and Atlantic Niño SSTA indexes may, then, be useful to predict seasonal rainfall over the Eastern and Northern NEB, respectively, for about a 6 month leading period. The ability of both southeastern tropical Atlantic and Atlantic Niño SSTA indexes to forecast the Eastern and Northern NEB rainfall, with about a 6 month lead time, is improved when these indexes are respectively combined with the Niño3 (5° S−5° N; 150°−90° W) and the northeast subtropical Atlantic (20° N−35° N, 45° W−20° W), mainly from the 1970’s climate shift.
Published: 2019
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4. Modeling the intense 2012-2013 dense water formation event in the northwestern Mediterranean Sea: Evaluation with an ensemble simulation approach

Author: Louis Marie Prieur, Samuel Somot, Claude Estournel, Guy Caniaux, Marine Herrmann, Robin Waldman, Anthony Bosse, Loïc Houpert, Pierre Testor, and Florence Sevault
Subjects: Mediterranean climate, Water mass, Isopycnal, 010504 meteorology & atmospheric sciences, 010505 oceanography, Magnitude (mathematics), Oceanography, 01 natural sciences, Geophysics, Mediterranean sea, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, Climatology, Earth and Planetary Sciences (miscellaneous), Bathymetry, Thermohaline circulation, 14. Life underwater, Mixing (physics), Geology, 0105 earth and related environmental sciences
Abstract: The northwestern Mediterranean Sea is a well-observed ocean deep convection site. Winter 2012–2013 was an intense and intensely documented dense water formation (DWF) event. We evaluate this DWF event in an ensemble configuration of the regional ocean model NEMOMED12. We then assess for the first time the impact of ocean intrinsic variability on DWF with a novel perturbed initial state ensemble method. Finally, we identify the main physical mechanisms driving water mass transformations. NEMOMED12 reproduces accurately the deep convection chronology between late January and March, its location off the Gulf of Lions although with a southward shift and its magnitude. It fails to reproduce the Western Mediterranean Deep Waters salinification and warming, consistently with too strong a surface heat loss. The Ocean Intrinsic Variability modulates half of the DWF area, especially in the open-sea where the bathymetry slope is low. It modulates marginally (3–5%) the integrated DWF rate, but its increase with time suggests its impact could be larger at interannual timescales. We conclude that ensemble frameworks are necessary to evaluate accurately numerical simulations of DWF. Each phase of DWF has distinct diapycnal and thermohaline regimes: during preconditioning, the Mediterranean thermohaline circulation is driven by exchanges with the Algerian basin. During the intense mixing phase, surface heat fluxes trigger deep convection and internal mixing largely determines the resulting deep water properties. During restratification, lateral exchanges and internal mixing are enhanced. Finally, isopycnal mixing was shown to play a large role in water mass transformations during the preconditioning and restratification phases.
Published: 2017

5. A PV-approach for dense water formation along fronts: Application to the Northwestern Mediterranean

Author: Hervé Giordani, Cindy Lebeaupin-Brossier, Fabien Léger, and Guy Caniaux
Subjects: geography, Pycnocline, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, 010505 oceanography, Baroclinity, Diabatic, Front (oceanography), Forcing (mathematics), Oceanography, 01 natural sciences, Geophysics, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, Ocean gyre, Potential vorticity, Climatology, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, Geology, Geostrophic wind, 0105 earth and related environmental sciences
Abstract: The mechanisms of dense water formation (σ >29.0 kg m−3) at work in the baroclinic cyclonic gyre of the North-Western Mediterranean basin are investigated through a PV-budget (PV: Potential Vorticity). The PV-budget is diagnosed from an eddy-resolving (1/36°) ocean simulation driven in surface by hourly air-sea fluxes provided by a non-hydrostatic atmospheric model at 2.5km-resolution. The PV-budget is controlled by the diabatic, frictional and advective PV-fluxes. Around the gyre the surface diabatic PV-flux dominates the PV-destruction, except along the northern branch of the North Current where the surface frictional PV-flux is strongly negative. In this region, the bathymetry stabilizes the front and maintains the current northerly in the same direction as the dominant northerly wind. This configuration leads to optimal wind-current interactions and explains the preponderance of frictional PV-destruction on diabatic PV-destruction. This mechanical forcing drives a cross-front ageostrophic circulation which subducts surface low-PV waters destroyed by wind on the dense side of the front and obducts high-PV waters from the pycnocline on the light side of the front. The horizontal PV-advections associated with the geostrophic cyclonic gyre and turbulent entrainment at the pycnocline also contribute to the PV-refueling in the frontal region. The surface non-advective PV-flux involves energy exchanges down to −1400 W m−2 in the frontal zone: this flux is 3.5 times stronger than atmospheric buoyancy flux. These energy exchanges quantify the coupling effects between the surface atmospheric forcing with the oceanic frontal structures at submesoscale. This article is protected by copyright. All rights reserved.
Published: 2017

6. Oceanic Indices for Forecasting Seasonal Rainfall over the Northern Part of Brazilian Northeast

Author: Jacques Servain, Gbèkpo Aubains Hounsou-Gbo, Eduardo Sávio Passos Rodrigues Martins, Moacyr Araujo, Guy Caniaux, Bernard Bourlès, Universidade Federal de Pelotas = Federal University of Pelotas (UFPel), Processus de la variabilité climatique tropicale et impacts (PARVATI), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratório de Oceanografia Física Estuarina e Costeira, Depto. Oceanografia, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
Subjects: Climate events, VARIATION SAISONNIERE, 010504 meteorology & atmospheric sciences, Barrier Layer Thickness, 0208 environmental biotechnology, Temperature salinity diagrams, Wind stress, Floresta Amazônica, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Seasonal Rainfall, 02 engineering and technology, 01 natural sciences, Atmosphere, Latent heat, INTERACTION OCEAN ATMOSPHERE, 14. Life underwater, Energy exchange, 0105 earth and related environmental sciences, Brasil-Nordeste, TEMPERATURE DE SURFACE, ZONE DE CONVERGENCE TROPICALE, 020801 environmental engineering, VARIATION INTERANNUELLE, Oceanic Heat Content, Brazilian Northeast, Psychiatry and Mental health, Sea surface temperature, 13. Climate action, PLUIE, ANOMALIE, Climatology, TENSION DU VENT, Environmental science, Ocean heat content
Abstract: International audience; A relationship between oceanic conditions in the northwestern equatorial Atlantic (NWEA) and the seasonal rainfall over the northern part of Brazilian Northeast (NNEB) allows large climate events to be forecasted with a delay of a few months. Observed sea surface variables (sea surface temperature, wind stress and latent heat flux) and reanalyzed temperature and salinity profiles at depths of 0 - 150 m are used during 1974-2008. Perturbations in the Wind-Evaporation-SST mechanism over the NWEA during the last months of the year and the first months of the following year are of primary importance in evaluating the risk that strong climate events will affect the subsequent seasonal rainfall (in March-April) over the NNEB. Especially interesting are the Barrier Layer Thickness (BLT) and Ocean Heat Content (OHC) in the NWEA region from August-September through the subsequent months, during which a slow and steady evolution is apparent, with the highest signal occurring in October-November. Through their relationship with the local surface dynamic conditions, such BLT and OHC perturbations during the last months of the year can be used as a valuable indicator for forecasting wet or dry events over the NNEB during the subsequent rainfall season. A proposal is discussed to deploy additional temperature/conducti- vity sensors down to a depth of 140 m at three PIRATA moorings located in the NWEA region. That will be necessary if the BLT and other parameters of energy exchange between the ocean and atmosphere are to be estimated in real time and with a sufficiently high vertical resolution.
Published: 2016

7. Seasonal and Interannual Mixed-Layer Heat Budget Variability in the Western Tropical Atlantic From Argo Floats (2007-2012)

Author: Guy Caniaux, Miguel B. Araújo, A. V. Nogueira Neto, and Hervé Giordani
Subjects: Heat budget, mixed-layer heat budget, 010504 meteorology & atmospheric sciences, 010505 oceanography, Mixed layer, tropical Atlantic, Tropical Atlantic, Oceanography, 01 natural sciences, Sea surface temperature, Geophysics, sea surface temperature, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Argo floats, Environmental science, 14. Life underwater, Argo, 0105 earth and related environmental sciences
Abstract: Oceanic and atmospheric processes were investigated in order to explore the causes of seasonal and interannual variability of sea surface temperatures (SST) in the western tropical Atlantic (WTA; 20 degrees S-20 degrees N, 15 degrees W-60 degrees W). A mixed-layer (ML) heat budget was performed by using Argo profiles and supplementary data sets based on satellite and atmospheric products during the period 2007-2012. The WTA is divided into four boxes which represent the main temporal and spatial heterogeneities of this region. An analysis of error of each term pointed out that the mean net surface heat fluxes are systematically underestimated by 20 W m(-2). A correction of this term provides realistic estimates of the vertical mixing which was obtained as residual term. In agreement with previous studies, the results show that surface flux is the most important process that governs the seasonal cycle of the heat content. Changes in shortwave radiation and latent heat fluxes dictate the oceanic response to the meridional migration of the ITCZ. Along the equator, surface fluxes modulate the annual cycle of ML temperature, but are strongly balanced by horizontal advection. The entrainment term proves a small contribution to the cooling of the ML. On an interannual time scale, the strong positive (negative) SST anomalies observed in 2010 (2012) were generated during the previous winter in both years, mainly north of 10 degrees N, during which the wind anomalies were at the origin of intense heat loss anomalies. Horizontal advection may contributes to the maintaining of these SST anomalies in the equatorial zone and south Atlantic.
Published: 2018

8. Main processes of the Atlantic cold tongue interannual variability

Author: Hervé Giordani, Yann Planton, Aurore Voldoire, Guy Caniaux, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), and Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, Vertical mixing, 010504 meteorology & atmospheric sciences, Wind stress, Stratification (water), 01 natural sciences, symbols.namesake, Interannual variability, Downwelling, 14. Life underwater, Mixed-layer heat budget, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Equatorial Atlantic, 010505 oceanography, Advection, Oceanic mixed-layer processes, Rossby wave, Ocean general circulation model, Sea surface temperature, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, symbols, Atlantic cold tongue, Kelvin wave, Geology
Abstract: The interannual variability of the Atlantic cold tongue (ACT) is studied by means of a mixed-layer heat budget analysis. A method to classify extreme cold and warm ACT events is proposed and applied to ten various analysis and reanalysis products. This classification allows five cold and five warm ACT events to be selected over the period 1982-2007. Cold (warm) ACT events are defined by the presence of negative (positive) sea surface temperature (SST) anomalies at the center of the equatorial Atlantic in late boreal spring, preceded by negative (positive) zonal wind stress anomalies in the western equatorial Atlantic. An ocean general circulation model capable of reconstructing the interannual variability of the ACT correctly is used to demonstrate that cold ACT events develop rapidly from May to June mainly due to intense cooling by vertical mixing and horizontal advection. The simulated cooling at the center of the basin is the result of the combined effects of non-local and local processes. The non-local process is an upwelling associated with an eastward-propagating Kelvin wave, which makes the mixed-layer more shallow and preconditions the upper layers to be cooled by an intense heat loss at the base of the mixed-layer, which is amplified by a stronger local injection of energy from the atmosphere. The early cooling by vertical mixing in March is also shown to be a good predictor of June cooling. In July, horizontal advection starts to warm the mixed-layer abnormally and damps SST anomalies. The advection anomalies, which result from changes in the horizontal temperature gradient, are associated in some cases with the propagation of Rossby waves along the equator. During warm ACT events, processes are reversed, generating positive SST anomalies: a downwelling Kelvin wave triggers stratification anomalies and mixed-layer depth anomalies, amplified by a weaker injection of energy from the atmosphere in May-June. In July, warm ACT events are abnormally cooled due to negative horizontal advection anomalies resulting from processes similar to those that occur during cold ACT events. This additional cooling process extends the period of cooling of the ACT, reducing SST anomalies.
Published: 2018

9. Gyre-scale deep convection in the subpolar North Atlantic Ocean during winter 2014-2015

Author: Guy Caniaux, Virginie Thierry, Herlé Mercier, Anne Piron, Laboratoire d'Océanographie Physique et Spatiale (LOPS), and Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, Convection, 010504 meteorology & atmospheric sciences, mixed layer depth, Mixed layer, Structural basin, 01 natural sciences, Atmosphere, Ocean gyre, preconditioning, 14. Life underwater, Argo, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, North Atlantic ocean, 010604 marine biology & hydrobiology, air-sea forcing, deep convection, Oceanography, Geophysics, 13. Climate action, [SDU]Sciences of the Universe [physics], Climatology, Deep ocean water, General Earth and Planetary Sciences, Thermocline, Geology
Abstract: International audience; Using Argo floats, we show that a major deep convective activity occurred simultaneously in the Labrador Sea (LAB), south of Cape Farewell (SCF), and the Irminger Sea (IRM) during winter 2014-2015. Convection was driven by exceptional heat loss to the atmosphere (up to 50% higher than the climatological mean). This is the first observation of deep convection over such a widespread area. Mixed layer depths exceptionally reached 1700 m in SCF and 1400 m in IRM. The deep thermocline density gradient limited the mixed layer deepening in the Labrador Sea to 1800 m. Potential densities of deep waters were similar in the three basins (27.73-27.74 kg m-3) but warmer by 0.3°C and saltier by 0.04 in IRM than in LAB and SCF, meaning that each basin formed locally its own deep water. The cold anomaly that developed recently in the North Atlantic Ocean favored and was enhanced by this exceptional convection.
Published: 2017

10. An inverse method to derive surface fluxes from the closure of oceanic heat and water budgets: Application to the north-western Mediterranean Sea

Author: Guy Caniaux, Jean-Luc Redelsperger, Hervé Giordani, Louis Marie Prieur, Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie de Villefranche (LOV), Observatoire océanologique de Villefranche-sur-mer (OOVM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Surface (mathematics), 010504 meteorology & atmospheric sciences, 010505 oceanography, Closure (topology), Oceanography, 01 natural sciences, Geophysics, Mediterranean sea, Space and Planetary Science, Geochemistry and Petrology, Climatology, Earth and Planetary Sciences (miscellaneous), Environmental science, Inverse method, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences
Abstract: International audience; The large amount of data collected during DeWEX, MOOSE, and HyMeX campaigns in the north-western Mediterranean in 2012-2013 allowed to implement an inverse method to solve the difficult problem of heat and water budget closure. The inverse method is based on the simulation of the observed heat and water budgets, strongly constrained by observations collected during the campaigns and on the deduction of adjusted surface fluxes. The inverse method uses a genetic algorithm that generates 50,000 simulations of a single-column model and optimizes some adjustable coefficients introduced in the surface fluxes. Finally, the single-column model forced by the adjusted fluxes during 1 year and over a test area of about 300 x 300 km(2) simulates the daily mean satellite bulk SST with an accuracy/uncertainty of 0.0110.072 degrees C, as well as daily mean SSS and residual buoyancy series deduced from wintertime analyses with an accuracy of 0.0110.008 and 0.030.012 m(2) s(-2), respectively. The adjusted fluxes close the annual heat and rescaled water budgets by less than 5 W m(-2). To our knowledge, this is the first time that such a flux data set is produced. It can thus be considered as a reference for the north-western Mediterranean and be used for estimating other flux data sets, for forcing regional models and for process studies. Compared with the adjusted fluxes, some operational numerical weather prediction models (ARPEGE, NCEP, ERA-INTERIM, ECMWF, and AROME), often used to force oceanic models, were evaluated: they are unable to retrieve the mean annual patterns and values.
Published: 2017

11. Lagrangian sources of frontogenesis in the equatorial Atlantic front

Author: Hervé Giordani and Guy Caniaux
Subjects: Atmospheric Science, Front (oceanography), Wind stress, Forcing (mathematics), Tropical Atlantic, Monsoon, Sea surface temperature, Atlantic Equatorial mode, Frontogenesis, Climatology, Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Physics::Atmospheric and Oceanic Physics, Geology
Abstract: Estimating the processes that control the north equatorial sea surface temperature (SST)-front on the northern edge of the cold tongue in the tropical Atlantic is a key issue for understanding the dynamics of the oceanic equatorial Atlantic and the West African Monsoon. Diagnosis of the frontogenetic forcings on a realistic high-resolution simulation was used to identify the processes involved in the formation and evolution of the equatorial SST-front. The turbulent forcing associated with the mixed-layer turbulent heat flux was found to be systematically frontolytic while the dynamic forcing associated with currents was found to be frontogenetic for the equatorial SST-front. Nevertheless, the low-frequency component of the turbulent forcing was frontogenetic and initiated the SST-front which was then amplified and maintained by the leading dynamic forcing. This forcing was mainly driven by the meridional convergence of the northern South Equatorial Current (nSEC) and the Guinea Current, which points out the essential role played by the circulation in the equatorial SST-front evolution. The quasi-biweekly variability of the equatorial SST-front and its forcings were found to be more strongly coupled to the wind energy flux (WEF) than to the surface wind stress. In fact the WEF controlled the convergence/divergence of the nSEC and Guinea Current and thus the meridional component of the leading dynamic forcing. The WEF explains the equatorial SST-front development better than the wind does because it is a coupled ocean-atmosphere process.
Published: 2014

12. Are atmospheric biases responsible for the tropical Atlantic SST biases in the CNRM-CM5 coupled model?

Author: Aurore Voldoire, Guy Caniaux, M. Claudon, Hervé Giordani, and Romain Roehrig
Subjects: Atmospheric Science, Wind power, business.industry, Equator, Flux, Tropical Atlantic, Atmospheric sciences, Annual cycle, Atlantic Equatorial mode, Heat flux, Climatology, Environmental science, Climate model, business
Abstract: In this study, the CNRM-CM5 model is shown to simulate too warm SSTs in the tropical Atlantic as most state-of-the-art CMIP5 models. The warm bias develops within 1 or 2 months in decadal experiments initialised in January using an observationally derived state. To better quantify the role of the atmospheric biases in initiating this warm SST bias, several sensitivity experiments have been performed. In a first set of experiments, the surface solar net heat flux sent to the ocean model is academically corrected over the southeastern tropical Atlantic Ocean. This correction locally reduces the warm SST bias by more than 50 % with some remote impacts over equatorial regions. In contrast, the solar heat flux correction has locally little impact on the spring cooling. A second set of experiments quantifies the role of surface winds, using a nudging technique. When applied in a narrow equatorial region, the wind correction mainly improves the SST annual cycle amplitude along the Equator. It promotes not only the spring cooling along the Equator in preconditioning the mixed-layer depth but also in the southeastern Atlantic along the African coast. These local and remote effects are attributed to the more realistic representation of the oceanic equatorial circulation, driven by corrected winds. These results are consistent with those reported by Wahl et al. (Clim Dyn 36:891–906, 2011) in a very similar study with the Kiel Climate Model. The solar and wind biases have comparable effects in their study, although the importance of off-equatorial winds is less clear in our study. Diagnosing the wind energy flux provides a physical understanding of the equatorial region. When combining the corrections of both the equatorial wind and the southeastern solar heat flux, no obvious feedback between them is evidenced. The present study also emphasizes the need to consider two time-scales, the annual mean and the seasonal cycle, as well as two regions, the equatorial and the southeastern Atlantic regions, to comprehensively address the Atlantic SST bias. As pointed out in Richter (Clim Dyn, doi: 10.1007/s00382-012-1624-5 , 2013), the need to improve the atmospheric component of the CNRM-CM model is emphasized, even though strong positive coupling feedbacks are highlighted.
Published: 2014

13. Intraseasonal mixed‐layer heat budget in the equatorial Atlantic during the cold tongue development in 2006

Author: Aurore Voldoire, Guy Caniaux, and Hervé Giordani
Subjects: Advection, Mixed layer, Tropical instability waves, Mesoscale meteorology, Stratification (water), Zonal and meridional, Oceanography, Sea surface temperature, Geophysics, Heat flux, Space and Planetary Science, Geochemistry and Petrology, Climatology, Earth and Planetary Sciences (miscellaneous), Physics::Atmospheric and Oceanic Physics, Geology
Abstract: [1] Estimating the mixed-layer heat budget is a key issue for understanding the cold tongue development in the eastern equatorial Atlantic. A high-resolution ocean regional model is used to diagnose the mixed-layer heat budget online during the EGEE-3 experiment from May to August 2006. The heat budget shows the major role of the horizontal advection and turbulent mixing in the mixed-layer temperature balance in the cold tongue. The surface net heat flux and entrainment processes play a minor role. The equatorial cooling is mainly induced by low-frequency advection, which is balanced by high-frequency zonal and meridional advections. The high-frequency advections are organized in patterns along the northern edge of the cold tongue, where they are associated with strong sea surface temperature gradients and well-developed tropical instability waves in the western Atlantic. Special attention is paid to the wind energy flux, which controls horizontal advection and turbulent mixing. We suggest that the wind energy flux drives the vertical velocity, which in turn adjusts the mixed-layer depth, its stratification, and the vertical shear of the horizontal current. Although vertical advection is not essential in providing cold water in the Atlantic cold tongue, it is shown that the vertical velocity plays a central role in preconditioning the mixed layer and maximizes the turbulent mixing.
Published: 2013

14. Argo float observations of basin-scale deep convection in the Irminger sea during winter 2011-2012

Author: Virginie Thierry, Herlé Mercier, Guy Caniaux, and Anne Piron
Subjects: Convection, 010504 meteorology & atmospheric sciences, Greenland Tip Jet, 010505 oceanography, Mixed layer, Air-sea interactions, Stratification (water), Labrador Sea Water, Aquatic Science, Structural basin, Oceanography, 01 natural sciences, Water column, Heat flux, 13. Climate action, Irminger Sea, 14. Life underwater, Mixed layer dynamics, Argo, Geology, Deep convection, 0105 earth and related environmental sciences, Argo data
Abstract: Analysis of Argo data obtained during winter 2011–2012 revealed the presence over the Irminger Basin of an exceptionally large number of profiles (41) with mixed layer depths (MLD) exceeding 700 m, which was deep enough to reach the pool of the intermediate Labrador Sea Water located in the Irminger Sea. Four of these profiles exhibited an MLD of 1000 m, which was the maximum value observed for the winter in question. The Argo sampling in the Irminger Sea during that winter, which was 3 to 4 times greater than for the preceding winters, enabled the different phases of the mixed layer deepening down to 1000 m, together with their spatial extents, to be observed for the first time. Two intense convective periods occurred: in late January south of Cape Farewell and in late February-early March east of Greenland. A final deepening period was observed in mid-March, during which the deepest mixed layers were observed. This long deepening period occurred in large regional areas and was followed by a rapid restratification phase. The temporal evolution of oxygen profiles from one Argo float testifies to the local and rapid ventilation of the mixed layer by the deep convection. A mixed layer heat budget along the trajectories of the 4 floats that sampled the deepest mixed layers showed that heat loss at the air-sea interface was mainly responsible for heat content variations in the mixed layer. Greenland Tip Jets were of primary importance for the development of deep convection in the Irminger Sea in the winter of 2011–2012. They enhanced the winter heat loss and two long (more than 24 hours), intense late events close together in time pushed the mixed layer deepening down to 1000 m. Net air-sea fluxes, the number of Greenland Tip Jets, the stratification of the water column, the NAO index and the Ekman-induced heat flux are pertinent indicators to assess conditions that are favorable for the development of deep convection in the Irminger Sea. By considering each of those indicators, it was concluded that the 2011-2012 event was not significantly different from the three other documented occurrences of deep convection in the Irminger Sea.
Published: 2016

15. Variability and trends of carbon parameters at a time series in the eastern tropical Atlantic

Author: Doris Veleda, Nathalie Lefèvre, Moacyr Araujo, Guy Caniaux, Austral, Boréal et Carbone (ABC), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Universidade Federal de Pernambuco [Recife] (UFPE), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, fugacity of CO2, Atmospheric Science, 010504 meteorology & atmospheric sciences, ocean acidification, Tropical Atlantic, lcsh:QC851-999, [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology, 01 natural sciences, eastern tropical Atlantic, time-series, Atmosphere, Total inorganic carbon, Fugacity, 14. Life underwater, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Buoy, Advection, 010604 marine biology & hydrobiology, Anomaly (natural sciences), Ocean acidification, 13. Climate action, Climatology, Environmental science, lcsh:Meteorology. Climatology, time series
Abstract: Hourly f CO 2 is recorded at a time series at the PIRATA buoy located at 6°S 10°W in the eastern tropical Atlantic since June 2006. This site is located south and west of the seasonal Atlantic cold tongue and is affected by its propagation from June to September. Using an alkalinity–salinity relationship determined for the eastern tropical Atlantic and the observed f CO 2 , pH and the inorganic carbon concentration are calculated. The time series is investigated to explore the intraseasonal, seasonal and interannual timescales for these parameters, and to detect any long-term trends. At intraseasonal timescales, f CO 2 and pH are strongly correlated. On seasonal timescales, the correlation still holds between f CO 2 and pH and their variations are in agreement with those of sea surface salinity. At interannual timescales, some important differences appear in 2011–2012: lower f CO 2 and fluxes are observed from September to December 2011 and are explained by higher advection of salty waters at the mooring, in agreement with the wind. In early 2012, the anomaly is still present and associated with lower sea surface temperatures. No significant long-term trend is detected over the period 2006–2013 on CO 2 and any other physical parameter. However, as atmospheric f CO 2 is increasing over time, the outgassing of CO 2 is reduced over the period 2006–2013 as the flux is mainly controlled by the difference of f CO 2 between the ocean and the atmosphere. A longer time series is required to determine if any significant trend exists in this region. Keywords: fugacity of CO 2 , ocean acidification, time series, eastern tropical Atlantic (Published: 10 May 2016) Citation: Tellus B 2016, 68, 30305, http://dx.doi.org/10.3402/tellusb.v68.30305
Published: 2016

16. Using Scintillometry to Estimate Sensible Heat Fluxes over Water: First Insights

Author: Annie Fiandrino, Gilles Bouhours, O. Traulle, Sophie Belamari, D. Legain, Eric Moulin, Marie-Noëlle Bouin, Joël Barrié, Guy Caniaux, and Franck Lagarde
Subjects: Atmospheric Science, Scintillation, Sensible heat flux, Source area, 010504 meteorology & atmospheric sciences, Monin–Obukhov similarity theory, Meteorology, Footprint, Eddy covariance, Air-sea fluxes, Large aperture, Sensible heat, Atmospheric sciences, 01 natural sciences, 010305 fluids & plasmas, law.invention, Scintillometer, law, 0103 physical sciences, Environmental science, Monin-Obukhov similarity theory, Scintillometry, Similarity theory, 0105 earth and related environmental sciences
Abstract: An extra large aperture scintillometer (XLAS) was used over several months across the Thau Lagoon (South of France) to retrieve one-wavelength scintillation and, thence, sensible heat flux. We present the experiment with the XLAS, an eddy-covariance station and meteorological stations measuring on or near the Thau Lagoon. Changes implemented to adapt the scintillometry processing schemes to the above water conditions are presented together with a full error budget, including sensitivity tests to the relevant parameters of the scintillometer processing scheme. The XLAS error budget amounts to 16% (systematic part) +/- 50% (random part). Sensible heat fluxes obtained using the XLAS under unstable atmospheric conditions are then compared to eddy-covariance estimates used as a reference. The scintillometry technique proved to perform satisfactorily in such a watery environment. Some discrepancies observed between the XLAS and eddy-covariance measurements were investigated according to the lagoon fraction of the source area, to discriminate whether they were related to deviations from the Monin-Obukhov similarity theory or to different atmospheric conditions at the respective instrument locations. Local atmospheric conditions agreed well with the Monin-Obukhov similarity theory, especially measurements with source areas largely composed of the lagoon surface. Retaining only the measurements with almost only the lagoon surface in the source area improved the agreement between the XLAS and eddy-covariance measurements. The remaining discrepancies are interpreted as being due to significant location differences between the two instruments, resulting in different atmospheric conditions, and to size differences in the source areas.
Published: 2012

17. Diagnosing vertical motion in the Equatorial Atlantic

Author: Guy Caniaux and Hervé Giordani
Subjects: Momentum flux, Curl (mathematics), Turbulence, Geophysics, Oceanography, Vertical motion, Physics::Geophysics, Climatology, Vortex stretching, Physics::Space Physics, Upwelling, Surface layer, Vertical velocity, Physics::Atmospheric and Oceanic Physics, Geology
Abstract: Estimating the vertical velocity (w) in the oceanic upper-layers is a key issue for understanding the cold tongue development in the Eastern Equatorial Atlantic. In this methodological paper, we develop an expanded and general formulation of the vertical velocity equation based on the primitive equation (PE) system, in order to gain new insight into the physical processes responsible for the Equatorial and Angola upwellings. This approach is more accurate for describing the real ocean than simpler considerations based on just the wind-driven patterns of surface layer divergence. The w-sources/forcings are derived from the PE w-equation and diagnosed from a realistic ocean simulation of the Equatorial Atlantic. Sources of w are numerous and express the high complexity of terms related to the turbulent momentum flux, to the circulation and to the mass fields, some of them depending explicitly on w and others not. The equatorial upwelling is found to be mainly induced by the (i) the zonal turbulent momentum flux, (ii) the curl of turbulent momentum flux and (iii) the imbalance between the circulation and the pressure fields. The Angola upwelling in the eastern part of the basin is controlled by strong curl of turbulent momentum flux. A strong cross-regulation is evidenced between the w-forcings independent of w and dependent on w, which suggests an equatorial balanced-dynamics. The w-forcing depending on w represents the negative feedback of the ocean to the w-forcing independent of w: in the equatorial band, this adjustment is led by non-linear processes and by vortex stretching outside.
Published: 2011

18. Numerical investigation of an oceanic resonant regime induced by hurricane winds

Author: Guillaume Samson, Hervé Giordani, Frank Roux, Guy Caniaux, Laboratoire de l'Atmosphère et des Cyclones (LACy), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Météo France, Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'aérologie (LAERO), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées
Subjects: Oceanic mixed layer, 010504 meteorology & atmospheric sciences, Meteorology, Mixed layer, Air-sea interactions, Wind stress, Energy flux, Flux, Oceanography, Atmospheric sciences, Kinetic energy, 01 natural sciences, Resonant regime, Meteorology/Climatology, Entrainment parameterization, Wind profile power law, Geophysics/Geodesy, 14. Life underwater, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, Hurricane propagation speed, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Fluids, Momentum (technical analysis), 010505 oceanography, Near-inertial currents, Storm, upwelling, Environmental Monitoring/Analysis, 13. Climate action, Geology
Abstract: International audience; The oceanic mixed layer (OML) response to an idealized hurricane with different propagation speeds is investigated using a two-layer reduced gravity ocean model. First, the model performances are examined with respect to available observations relative to Hurricane Frances (2004). Then, 11 idealized simulations are performed with a Holland (Mon Weather Rev 108(8):1212-1218, 1980) symmetric wind profile as surface forcing with storm propagation speeds ranging from 2 to 12 m s−1. By varying this parameter, the phasing between atmospheric and oceanic scales is modified. Consequently, it leads to different momentum exchanges between the hurricane and the OML and to various oceanic responses. The present study determines how OML momentum and heat budgets depend on this parameter. The kinetic energy flux due to surface wind stress is found to strongly depend on the propagation speed and on the cross-track distance from the hurricane center. A resonant regime between surface winds and near-inertial currents is clearly identified. This regime maximizes locally the energy flux into the OML. For fast-moving hurricanes (\textgreater6 m s−1), the ratio of kinetic energy converted into turbulence depends only on the wind stress energy input. For slow-moving hurricanes (\textless6 m s−1), the upwelling induced by current divergence enhances this conversion by shallowing the OML depth. Regarding the thermodynamic response, two regimes are identified with respect to the propagation speed. For slow-moving hurricanes, the upwelling combined with a sharp temperature gradient at the OML base formed in the leading part of the storm maximizes the oceanic heat loss. For fast propagation speeds, the resonance mechanism sets up the cold wake on the right side of the hurricane track. These results suggest that the propagation speed is a parameter as important as the surface wind speed to accurately describe the oceanic response to a moving hurricane.
Published: 2009

19. IDENTIFICATION DE TENDANCES RÉCENTES ET RUPTURES D'HOMOGÉNÉITE DES TEMPÉRATURES : EXEMPLE EN AFRIQUE DE L'OUEST ET SUR LE GOLFE DE GUINÉE

Author: Sandra ROME, Guy Caniaux, Justine Ringard, Bastien Dieppois, Arona Diedhiou, Laboratoire d'étude des transferts en hydrologie et environnement (LTHE), Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Université de Guyane (UG), Coventry University, Université de Liège, Laboratoire de Climatologie et Topoclimatologie, Michel ERPICUM, ANR-13-SENV-0007,ACASIS,Alerte aux Canicules Au Sahel et à leurs Impacts sur la Santé(2013), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])
Subjects: trends, [SHS.ENVIR]Humanities and Social Sciences/Environmental studies, West Africa, Temperature, discontinuities, [SHS.GEO]Humanities and Social Sciences/Geography, climate warming
Abstract: International audience; In the present context of environmental and climatic change, any trend in meteorological parameters, especially in temperature,is often discussed. This work aims to evaluate long term temperature trends and break points at two weather stations in WestAfrica (Niamey / Niger and Abidjan / Ivory Coast) and for sea surface temperatures (SSTs) in the Gulf of Guinea. The objective is to examine whether the model predictions of the fifth IPCC assessment report (2013) are consistent with observations and if the evolution of meridian thermal gradients will impact the West African monsoon in a context of global atmospheric and oceanic warming. Various heterogeneities are detected in the series: thermal break points are clearly identified in Niamey and Abidjan, in 1983 and 1986, respectively. After the mid-1980s, annual temperature anomalies show significant warming trends while equatorial Atlantic SST does not present any significant break point. It is however found that the large scale contrast of temperatures between the ocean and the continent represented by the series have increased by 0.07°C per decade during the last 30 years.; – Dans le contexte actuel de changements climatiques et environnementaux, la tendance des paramètres météorologiques, notamment celle de la température, est souvent discutée. Ce travail propose d'évaluer les tendances et les ruptures d'homogénéités des températures de deux stations météorologiques d'Afrique de l'Ouest (Niamey/ Niger ; Abidjan/ Côte d'Ivoire) et des données in-situ de températures de surface océanique (SST) dans le Golfe de Guinée. L'objectif est d'examiner si les prédictions fournies par les modèles du 5 ème rapport d'évaluation du GIEC (2013) produisent des tendances cohérentes avec les observations et si les gradients nord-sud des températures montrent une évolution susceptible de modifier la mousson sur l'Afrique de l'Ouest. Les résultats mettent en évidence, de manière robuste, différentes ruptures d'homogénéités : une rupture thermique est identifiée en 1983 à Niamey et en 1986 à Abidjan, dates à partir desquelles les températures moyennes subissent un réchauffement accentué. Aucune rupture n'affecte la SST sur la période considérée. Parallèlement, les contrastes océan-continent de large échelle représentés par ces séries indiquent un accroissement de 0.07°C par décennie sur les 30 dernières années. Mots-clés : Température, tendance, rupture, réchauffement climatique, Afrique de l'Ouest. Abstract – Identification of recent temperature breaks and trends: example in West Africa and in the Gulf of Guinea. In the present context of environmental and climatic change, any trend in meteorological parameters, especially in temperature, is often discussed. This work aims to evaluate long term temperature trends and break points at two weather stations in West Africa (Niamey / Niger and Abidjan / Ivory Coast) and for sea surface temperatures (SSTs) in the Gulf of Guinea. The objective is to examine whether the model predictions of the fifth IPCC assessment report (2013) are consistent with observations and if the evolution of meridian thermal gradients will impact the West African monsoon in a context of global atmospheric and oceanic warming. Various heterogeneities are detected in the series: thermal break points are clearly identified in Niamey and Abidjan, in 1983 and 1986, respectively. After the mid-1980s, annual temperature anomalies show significant warming trends while equatorial Atlantic SST does not present any significant break point. It is however found that the large scale contrast of temperatures between the ocean and the continent represented by the series have increased by 0.07°C per decade during the last 30 years.
Published: 2015

20. Advanced insights into sources of vertical velocity in the ocean

Author: Louis Marie Prieur, Hervé Giordani, Guy Caniaux, Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie de Villefranche (LOV), Observatoire océanologique de Villefranche-sur-mer (OOVM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Météo France-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Momentum (technical analysis), Buoyancy, 010504 meteorology & atmospheric sciences, 010505 oceanography, Turbulence, Front (oceanography), Forcing (mathematics), Geophysics, engineering.material, Oceanography, 01 natural sciences, Physics::Geophysics, Physics::Fluid Dynamics, Ocean dynamics, Eddy, 13. Climate action, Ekman transport, engineering, 14. Life underwater, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences
Abstract: Estimating vertical velocity in the oceanic upper layers is a key issue for understanding ocean dynamics and the transport of biogeochemical elements. This paper aims to identify the physical sources of vertical velocity associated with sub-mesoscale dynamics (fronts, eddies) and mixed-layer depth (MLD) structures, using (a) an ocean adaptation of the generalized Q-vector form of the omega-equation deduced from a primitive equation system which takes into account the turbulent buoyancy and momentum fluxes and (b) an application of this diagnostic method for an ocean simulation of the Programme Ocean Multidisciplinaire Meso Echelle (POMME) field experiment in the North-Eastern Atlantic. The approach indicates that w-sources can play a significant role in the ocean dynamics and strongly depend on the dynamical structure (anticyclonic eddy, front, MLD, etc.). Our results stress the important contribution of the ageostrophic forcing, even under quasi-geostrophic conditions. The turbulent w-forcing was split into two components associated with the spatial variability of (a) the buoyancy and momentum (Ekman pumping) surface fluxes and (b) the MLD. Process (b) represents the trapping of the buoyancy and momentum surface energy into the MLD structure and is identified as an atmosphere/oceanic mixed-layer coupling. The momentum-trapping process is 10 to 100 times stronger than the Ekman pumping and is at least 1,000 times stronger than the buoyancy w-sources. When this decomposition is applied to a filamentary mixed-layer structure simulated during the POMME experiment, we find that the associated vertical velocity is created by trapping the surface wind-stress energy into this structure and not by Ekman pumping.
Published: 2006

21. Air–sea exchanges in the equatorial area from the EQUALANT99 dataset: Bulk parametrizations of turbulent fluxes corrected for airflow distortion

Author: P. Durand, S. Planton, Guy Caniaux, A. Butet, and Aurore Brut
Subjects: Atmospheric Science, Boundary layer, Meteorology, Drag, Turbulence, Latent heat, Airflow, Eddy covariance, Environmental science, Mechanics, Sensible heat, Physics::Atmospheric and Oceanic Physics, Wind speed
Abstract: Turbulent fluxes of momentum, sensible heat and water vapour were calculated using both the eddy covariance (EC) and the inertial dissipation (ID) methods applied to data collected on board the research vessel La Thalassa during 40 days of the EQUALANT99 oceanographic campaign. The aim of this experiment was to establish accurate parametrizations of air–sea fluxes for the equatorial Atlantic area from a large dataset. However, the accuracy of turbulent fluxes measured aboard ships is strongly affected by the distortion of airflow patterns generated by obstacles such as the ship and mast. For the EQUALANT99 experiment, the effects of airflow distortion were estimated using physical simulations in a water channel. To reproduce the conditions of the campaign, a neutral boundary layer was simulated in the water channel and a detailed model of the ship La Thalassa was built. Correction coefficients for the mean wind speed were evaluated from these physical simulations. They show a dependence on both the azimuth angle of the flow (i.e. the horizontal direction of the flow with respect to the ship's longitudinal axis) and the angle of incidence of the wind. The correction for airflow distortion was applied to the measured wind speed and also included in the flux computation using the ID method. Compared with earlier studies which applied a single correction per flux sample, it appears that our results for the corrected transfer coefficients present greater dependence on neutral wind speed than the previous parametrizations; the method also shows encouraging results, with a decrease in the scatter of the transfer coefficients parametrization. However, the distortion could not be corrected for in the fluxes calculated using the EC method, because this technique integrates a wide range of turbulence scales for which the airflow distortion cannot be simulated in a water channel. Fluxes computed using the ID and EC methods are presented and compared in order to determine which method, in the configuration of the EQUALANT99 experiment, provides the best resulting transfer coefficients. According to the results, fluxes of momentum and latent heat computed by ID were better for deriving the drag and humidity coefficients. The EC method seemed better adapted to calculate sensible-heat fluxes than the ID method, although a high scatter remained on the Stanton neutral number. Copyright © 2005 Royal Meteorological Society
Published: 2005

22. Statistical analysis of the volcanic eruption frequency in the azores islands : a contribution to risk assessment

Author: Guy Caniaux
Subjects: geography, geography.geographical_feature_category, Vulcanian eruption, Geology, Poisson distribution, symbols.namesake, Volcano, Archipelago, symbols, Period (geology), Stratovolcano, Statistical analysis, Physical geography, Seismology
Abstract: The datations of the last eruptive events which have occurred on 13 active volcanic complexes of the Azores are presented. By supposing that these events follow a statistical Poisson distribution, we estimate the occurrence period of these events, as well as the eruption probabilities for the next 300 years. Pico Mountain, Região dos Picos (São Miguel Island), the stratovolcano of Sete Cidades (São Miguel Island), the linear volcanic complexes of São Roque – Piedade (Pico Island) and of Capelo (Faial Island) must be considered as the most active volcanoes of the archipelago. The eruption styles of next eruptions are also specified.
Published: 2005

23. Evaluation of the ERA-40 air–sea surface heat flux spin-up

Author: S. Planton, Hervé Giordani, S. Ramos Buarque, and Guy Caniaux
Subjects: Atmospheric Science, Meteorology, Geology, Atmospheric model, Sensible heat, Oceanography, Atmospheric sciences, Radiative flux, Flux (metallurgy), ERA-40, Latent heat, Heat transfer, Radiative transfer, Environmental science, Computers in Earth Sciences, Physics::Atmospheric and Oceanic Physics
Abstract: Ocean models depend strongly on surface fluxes. When computed from atmospheric models, fluxes are affected by spin-up, i.e. they increase (or decrease) with forecast length. Such behavior may bias ocean models. The European Centre for Medium Range Forecasts (ECMWF) 40-year re-analysis (ERA-40) has been used to quantify short-range spin-ups of radiative and turbulent heat fluxes. Fluxes are compared as differences between two runs with the same initialization time. This method allows flux analysis over short-range forecasts as a function of distance from the initialization time. Results indicate that (i) latent heat flux spin-up increases with time but levels off after 24 h; (ii) sensible and radiative flux spin-ups remain constant after 6 h; (iii) regional spin-up of turbulent fluxes are systematic and can be larger than 30% for sensible heat but never exceeds 15% for latent heat; (iv) spin-up depends upon the season. The same analysis has been carried out with the ECMWF 15-year re-analysis (ERA-15); spin-ups in ERA-40 have been generally smaller than those in ERA-15.
Published: 2004

24. Toward a Better Determination of Turbulent Air–Sea Fluxes from Several Experiments

Author: Danièle Hauser, G. Lachaud, Denis Bourras, Laurence Eymard, Serge Planton, P. Durand, Alain Weill, Hervé Giordani, P. Nacass, Aurore Brut, Guy Caniaux, Hélène Dupuis, Rodrigo Pedreros, G. Bouhours, Sophie Cloché, A. Butet, Christophe Guérin, Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Météo-France, Météo-France Direction Interrégionale Sud-Est (DIRSE), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche et d'Application en Traitement de l'Image et du Signal (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Département de Géologie et d'Océanographie [Talence] (DGO), Université Sciences et Technologies - Bordeaux 1 (UB), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Météo-France [Paris], Météo France, Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Supérieure Chimie Physique Électronique de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1, Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), and Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Atmospheric Science, Meteorology, business.industry, Turbulence, Airflow, Mesoscale meteorology, Sea state, Computational fluid dynamics, Atmosphere, 13. Climate action, Latent heat, Environmental science, Satellite, 14. Life underwater, business, Physics::Atmospheric and Oceanic Physics
Abstract: International audience; An accurate determination of turbulent exchanges between the ocean and the atmosphere is a prerequisite to identify and assess the mechanisms of interaction that control part of the variability in the two media over a wide range of spatial and temporal scales. An extended dataset for estimating air-sea fluxes (representing nearly 5700 h of turbulence measurements) has been collected since 1992 during six dedicated experiments performed in the Atlantic Ocean and the Mediterranean Sea. This paper presents the methodology used through the successive experiments to progress in this field. The major developments concern (i) flux instrumentation, with the deployment of a microwave refractometer to get the latent heat flux in most meteorological conditions; (ii) the analysis of airflow distortion effects around the ship structure and sensors through both computational fluid dynamics and physical simulations in a water tank, then the derivation of correction for these effects; (iii) the application of both inertial dissipation and eddy-correlation methods from the various experiments, allowing the authors to assess and discuss flux-determination methods on ships, and particularly bulk parameterization; (iv) the validation and analysis of mesoscale surface flux fields from models and satellites by using ship data, showing some deficiencies in operational model fields from ECMWF, the need of high-quality fluxes to interpret ocean-atmosphere exchanges, and the potential advantage of satellite retrieval methods. Further analysis of these datasets is being performed in a unique database (the ALBATROS project, open to the international scientific community). It will include refinement of airflow distortion correction and reprocessing of earlier datasets, the investigation of fluxes under specific conditions (low wind), and the effect of sea state among others. It will also contribute to further validation and improvements of satellite retrievals in various climatic/meteorological conditions.
Published: 2003

25. Tropical Atlantic variability and climate

Author: Guy Caniaux, Jacques Servain, Michael J. McPhaden, Moacyr Araujo, Yves K. Kouadio, Johns, W.E. (ed.), Brandt, P. (ed.), Chang, P. (ed.), Processus de la variabilité climatique tropicale et impacts (PARVATI), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), NOAA Pacific Marine Environmental Laboratory [Seattle] (PMEL), National Oceanic and Atmospheric Administration (NOAA), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636))
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, VENT, Wind stress, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Tropical Atlantic, 010502 geochemistry & geophysics, 01 natural sciences, Atlantic Equatorial mode, Atlantic multidecadal oscillation, ANOMALIE DE TEMPERATURE, 14. Life underwater, Hadley cell, INTERACTION OCEAN ATMOSPHERE, ComputingMilieux_MISCELLANEOUS, FLUX THERMIQUE, 0105 earth and related environmental sciences, TEMPERATURE DE SURFACE, Intertropical Convergence Zone, FORCING, Sea surface temperature, CIRCULATION OCEANIQUE, 13. Climate action, CLIMAT, Climatology, CHANGEMENT CLIMATIQUE, NIVEAU MARIN, Environmental science, Ocean heat content, VARIATION PLURIANNUELLE
Abstract: A homogeneous monthly data set of sea surface temperature (SST) and pseudo wind stress based on in situ observations is used to investigate the climatic trends over the tropical Atlantic during the last five decades (1964–2012). After a decrease of SST by about 1 °C during 1964–1975, most apparent in the northern tropical region, the entire tropical basin warmed up. That warming was the most substantial (>1 °C) in the eastern tropical ocean and in the longitudinal band of the intertropical convergence zone. Surprisingly, the trade wind system also strengthened over the peirod 1964–2012. Complementary information extracted from other observational data sources confirms the simultaneity of SST warming and the strengthening of the surface winds. Examining data sets of surface heat flux during the last few decades for the same region, we find that the SST warming was not a consequence of atmospheric heat flux forcing. Conversely, we suggest that long-term SST warming drives changes in atmosphere parameters at the sea surface, most notably an increase in latent heat flux, and that an acceleration of the hydrological cycle induces a strengthening of the trade winds and an acceleration of the Hadley circulation. These trends are also accompanied by rising sea levels and upper ocean heat content over similar multi-decadal time scales in the tropical Atlantic. Though more work is needed to fully understand these long term trends, especially what happens from the mid-1970’s, it is likely that changes in ocean circulation involving some combination of the Atlantic meridional overtuning circulation and the subtropical cells are required to explain the observations.
Published: 2014

26. Surface heat budget in an oceanic simulation using data from Tropical Ocean-Global Atmosphere Coupled Ocean-Atmosphere Response Experiment

Author: Marcelo Dourado and Guy Caniaux
Subjects: Atmospheric Science, Ecology, Mixed layer, Advection, Ocean current, Paleontology, Soil Science, Forestry, Ocean general circulation model, Aquatic Science, Oceanography, Atmosphere, Geophysics, Heat flux, Space and Planetary Science, Geochemistry and Petrology, Latent heat, Climatology, Heat transfer, Earth and Planetary Sciences (miscellaneous), Environmental science, Physics::Atmospheric and Oceanic Physics, Earth-Surface Processes, Water Science and Technology
Abstract: A three-dimensional regional ocean model is used to investigate the response of the upper ocean to different atmospheric weather events encountered during the Tropical Ocean-Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (COARE). The basic model is a version of the ocean general circulation model developed at the Laboratoire d'Oceanographie Dynamique et de Climatologie in Paris and includes open lateral boundaries and a 1.5 level order turbulence closure scheme. The horizontal grid spacing is 0.1° in longitude and 0.08° in latitude. There are 29 vertical levels, with a resolution of 5 m near the top. The surface atmospheric forcing used comes from a combination of European Centre for Medium-Range Weather Forecasts model output and estimates from bulk parameterization. The data set collected during the Intensive Observation Period enables a detailed initialization of the model. The analyses of the model output show that most features are in good agreement with the observations. During westerly wind bursts the mixed layer heat budget is negative (−83 W m−2) over a larger part of the COARE domain mainly because of the strong latent heat flux and weak solar radiation. Strong inhomogeneities due to local importance of horizontal advection contrast with relative homogeneous net heat flux. In this period all terms of the heat balance are active in the oceanic mixing layer. During the calm period the budget is weakly positive (15 W m−2) but still remains patchy because of the contribution of horizontal advection.
Published: 2001

27. Sensitivity of Cyclogenesis to Sea Surface Temperature in the Northwestern Atlantic

Author: Hervé Giordani and Guy Caniaux
Subjects: Atmospheric Science, Buoyancy, Planetary boundary layer, Thermal wind, engineering.material, Sea surface temperature, Cold front, Climatology, Cyclogenesis, Atmospheric instability, engineering, Cyclone, Physics::Atmospheric and Oceanic Physics, Geology
Abstract: During the Intensive Observation Period 15 (13‐15 February 1997) of the FASTEX Experiment, a major cyclone crossed the Atlantic Ocean from the Newfoundland Basin to southern Iceland. Its surface low center deepened by 17 hPa in 7 h when the perturbation crossed the North Atlantic Current (NAC) from cold (38C) to warm water (158C). To elucidate the role of sea surface temperature (SST) and air‐sea fluxes in the dynamics of oceanic cyclones, three nonhydrostatic mesoscale simulations were performed. The first one is a control experiment with a realistic SST field describing in detail the oceanic front associated with the NAC system. The two following simulations are sensitivity experiments where the SST front is removed: the first one uses a uniformly cold SST equal to 38C and the second one uses a uniformly warm SST equal to 158C. The frontogenetic function and the vertical velocity sources in the lower-atmospheric layers of the three simulations were diagnosed. In the control simulation, the surface heat fluxes were found to be negative in the perturbation warm sector and positive in the region behind the cold front. As reported by numerous authors, this pattern of surface heating and cooling did not intensify the cyclone, except in the occlusion when the phasing with the SST front occurs. This configuration enhances the horizontal gradient of surface buoyancy flux across the occlusion, which increases the buoyancy flux source of vertical velocity ( w). When the SST front is removed, the surface heat fluxes are strongly affected in magnitude and in spatial variability. The marine atmospheric boundary layer (MABL) stability, the convective activity, the warm advection in the core of the wave, and the heating depth are strongly affected by the different surface flux fields. There are several consequences: (i) the uniform SSTs tend to decrease the cold front intensity of the wave, (ii) a weaker buoyancy flux source of vertical velocity is found above a uniform cold SST across the occlusion in comparison with the control case, and (iii) surprisingly, a weaker w buoyancy flux source is also found above a uniform warm SST because of a higher heating depth. Vertical velocity depends not only on the buoyancy flux forcing but also on the thermal wind, the turbulent momentum, and the thermal wind imbalance forcings. The thermal wind forcing and the thermal wind imbalance forcing were the most sensitive to the SST compared to the turbulent momentum forcing. This result means that (i) the feed back of the ageostrophic circulation induced by the surface is greater on the kinematic forcings than on the turbulent forcings and (ii) the turbulent momentum forcing does not play a crucial role in cyclogenesis. Above a uniform warm SST, the strongest intensity of the occlusion is due to the strongest w thermal wind forcing and w thermal wind imbalance forcing in the MABL, in spite of a weaker w buoyancy flux forcing than in the control case. This result is explained by the convective activity that increases the low-level convergence and vorticity spinup. This point means that latent heat release and baroclinicity are in tight interaction. In the first 12 h and at the scale of the simulation domain, the three cyclones evolve similarly, but at a small scale their internal structures diverge strongly and rapidly. The scale at which the surface turbulent fluxes act on the dynamics of marine cyclones is therefore important. Finally, the cyclone simulated in the warm SST case developed more rapidly than those simulated in the real and the cold SST cases. This behavior is attributed to the strong positive surface heat fluxes because they preconditioned the MABL by moistening and heating the low levels during the incipient stage of the cyclone development.
Published: 2001

28. FASTEX IOP17 cyclone: Introductory synoptic study with field data

Author: Patrick Mascart, Patrick Santurette, Philippe Arbogast, Jean-Pierre Cammas, Guy Caniaux, Alain Joly, Béatrice Pouponneau, Isabelle Mallet, and Gérald Desroziers
Subjects: Atmospheric Science, Meteorology, Baroclinity, Climatology, Synoptic scale meteorology, Field data, Mesoscale meteorology, Extratropical cyclone, Cyclone, Outflow, Geology
Abstract: This paper introduces the study of the early development phase of the IOP17 frontal cyclone of the FASTEX field experiment (Fronts and Atlantic Storm-Track EXperiment). With the support of observations from FASTEX observing platforms a synoptic description highlights the development of mesoscale features of interest in the operational Meteo-France ARPEGE (Action de Recherche Petite Echelle Grand Echelle) analysis cycle, i.e. cloud head, dry wedge and upper-level jet outflow. A discussion attempts to isolate two significant differences of the present cyclone life cycle compared with previous well-known conceptual models of maritime cyclone life cycles: (i) the indirect role of an upper-level precursor in triggering the surface low; (ii) the existence of a diabatic regime taking over from the baroclinic development to sustain the deepening rate of the cyclone. These two mechanisms are the subject of two companion papers.
Published: 1999

29. Overview of the field phase of the fronts and Atlantic Storm-Track EXperiment (FASTEX) project

Author: Robert Gall, Alain Joly, Y. Lemaǐtre, James A. Moore, Patrick Mascart, Chris Snyder, François Lalaurette, Dave Jorgensen, Melvyn A. Shapiro, Zoltan Toth, P. Ola G. Persson, Kerry Emanuel, Jean-Pierre Cammas, Richard Dirks, Roger M. Wakimoto, Keith A. Browning, Frank Roux, Rolf H. Langland, P. Bessemoulin, Guy Caniaux, Laurence Eymard, Peter H. Hildebrand, Jean-Pierre Chalon, Tim Hewson, and S. A. Clough
Subjects: Atmospheric Science, Meteorology, Doppler radar, Mesoscale meteorology, law.invention, law, Climatology, Middle latitudes, Cyclogenesis, Extratropical cyclone, Environmental science, Storm track, Predictability, Dropsonde
Abstract: Summary The eld phase of the FASTEX project took place between 5 January and 27 February 1997 with the deployment of a unique set of observing facilities across the North-Atlantic. The major objective was to document the life-cycle of a representative set of mid-latitude cyclones. Other objectives were to test the practical feasibility of iadaptivei observations with a view to improving the prediction of these same cyclones and to document the internal structure of the associated cloud systems using combined airborne Doppler radars and dropsondes. Another goal of FASTEX was to measure air-sea exchange parameters under conditions of strong winds with high seas. These objectives were successfully achieved. Intensive Observation Periods were conducted on 19 occasions. High-resolution vertical proles through the same cyclones at three dierent stages of their life-cycle have been obtained on more than 10 occasions. Calculation of areas where observations were needed to keep the growth of forecast error under control was undertaken using dierent techniques, and ights were planned and executed in these areas on time. Combined dropsonde and Doppler radar observations of cloud systems are available for 10 cases. A unique air-sea turbulent exchange dataset has been obtained.
Published: 1999

30. Assimilation of satellite altimeter data in a primitive-equation model of the Azores–Madeira region

Author: Guy Caniaux, Pierre De Mey, and M. Gavart
Subjects: Atmospheric Science, Isopycnal, Meteorology, Mesoscale meteorology, Wind stress, Geology, Oceanography, Data assimilation, Satellite, Altimeter, Computers in Earth Sciences, Projection (set theory), Interpolation
Abstract: The aim of this study is to implement satellite altimetric assimilation into a high-resolution primitive-equation ocean model and check the validity and sensitivity of the results. Beyond this paper, the remote objective is to get a dynamical tool capable of simulating the surface ocean processes linked to the air–sea interactions as well as to perform mesoscale ocean forecasting. For computational cost and practical reasons, this study takes place in a 1000 by 1000 sq km open domain of the Canary basin. The assimilation experiments are carried out with the combined TOPEX/POSEIDON and ERS-1 data sets between June 1993 and December 1993. The space–time domain overlaps with in situ data collected during the SEMAPHORE experiment and thus enables an objective validation of the results. A special boundary treatment is applied to the model by creating a surrounding recirculating area separated from the interior by a buffer zone. The altimetric assimilation is done by implementing a reduced-order optimal interpolation algorithm with a special vertical projection of the surface model/data misfits. We perform a first experiment with a vertical projection onto an isopycnal EOF representing the Azores Current vertical variability. An objective validation of the model's velocities with Lagrangian float data shows good results (the correlation is 0.715 at 150 dbar). The question of the sensitivity to the vertical projection is addressed by performing similar experiments using a method for lifting/lowering of the water column, and using an EOF in Z -coordinates. Some comparisons with in situ temperature data do not show any significant difference between the three projections, after five months of assimilation. However, in order to preserve the large-scale water characteristics, we felt that the isopycnal projection was a more physically consistent choice. Then, the complementary character of the two satellites is assessed with two additional experiments which use each altimeter data sets separately. There is an evidence of the benefit of combining the two data sets. Otherwise, an experiment assimilating long-wavelength bias-corrected CLS altimetric maps every 10 days exhibits the best correlation scores and emphasizes the importance of reducing the orbit error and biases in the altimetric data sets. The surface layers of the model are forced using realistic daily wind stress values computed from ECMWF analyses. Although we resolve small space and time scales, in our limited domain the wind stress does not significantly influence the quality of the results obtained with the altimetric assimilation. Finally, the relative effects of the data selection procedure and of the integration times (cycle lengths) is explored by performing data window experiments. A value of 10 days seems to be the most satisfactory cycle length.
Published: 1999

31. A three-dimensional ocean mesoscale simulation using data from the SEMAPHORE experiment: Mixed layer heat budget

Author: Serge Planton and Guy Caniaux
Subjects: Atmospheric Science, Ecology, Meteorology, Mixed layer, Ocean current, Mesoscale meteorology, Paleontology, Soil Science, Forestry, Ocean general circulation model, Forcing (mathematics), Aquatic Science, Oceanography, Latitude, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Heat transfer, Earth and Planetary Sciences (miscellaneous), Longitude, Geology, Earth-Surface Processes, Water Science and Technology
Abstract: A primitive equation model is used to simulate the mesoscale circulation associated with a portion of the Azores Front investigated during the intensive observation period (IOP) of the Structure des Echanges Mer-Atmosphere, Proprietes des Heterogeneites Oceaniques: Recherche Experimentale (SEMAPHORE) experiment in fall 1993. The model is a mesoscale version of the ocean general circulation model (OGCM) developed at the Laboratoire d'Oceanographie Dynamique et de Climatologie (LODYC) in Paris and includes open lateral boundaries, a 1.5-level-order turbulence closure scheme, and fine mesh resolution (0.11° for latitude and 0.09° for longitude). The atmospheric forcing is provided by satellite data for the solar and infrared fluxes and by analyzed (or reanalyzed for the wind) atmospheric data from the European Centre for Medium-Range Weather Forecasts (ECMWF) forecast model. The extended data set collected during the IOP of SEMAPHORE enables a detailed initialization of the model, a coupling with the rest of the basin through time dependent open boundaries, and a model/data comparison for validation. The analysis of model outputs indicates that most features are in good agreement with independent available observations. The surface front evolution is subject to an intense deformation different from that of the deep front system, which evolves only weakly. An estimate of the upper layer heat budget is performed during the 22 days of the integration of the model. Each term of this budget is analyzed according to various atmospheric events that occurred during the experiment, such as the passage of a strong storm. This facilitates extended estimates of mixed layer or relevant surface processes beyond those which are obtainable directly from observations. Surface fluxes represent 54% of the heat loss in the mixed layer and 70% in the top 100-m layer, while vertical transport at the mixed layer bottom accounts for 31% and three-dimensional processes account for 14%.
Published: 1998

32. Increased CO2 outgassing in February-May 2010 in the tropical Atlantic following the 2009 Pacific El Nino

Author: Nathalie Lefèvre, Serge Janicot, Guy Caniaux, Abdou Karim Gueye, Échanges dans la couche de surface : des pôles aux tropiques (SURF), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Variabilité climatique tropicale et globale (VARCLIM), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), and Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, fugacity of CO2, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], tropical Atlantic, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Oceanography, 01 natural sciences, Atlantic Equatorial mode, Geochemistry and Petrology, Atlantic multidecadal oscillation, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, 0105 earth and related environmental sciences, 010604 marine biology & hydrobiology, Intertropical Convergence Zone, North Atlantic Deep Water, Western Hemisphere Warm Pool, Sea surface temperature, Geophysics, Tropical cyclogenesis, 13. Climate action, Space and Planetary Science, North Atlantic oscillation, Climatology, Geology
Abstract: International audience; The fugacity of CO2 (fCO2) has been measured underway during the voyages of a merchant ship sailing from France to Brazil since 2008. High fCO2 values are observed in 2010, between approximately 8°S and 8°N, and are particularly pronounced in boreal spring. These high values are explained by the anomalous situation occurring in the tropical Atlantic in 2010 after the 2009 El Niño in the Pacific. The weakening of the trade winds during the El Niño event contributes to an increase of sea surface temperatures in the tropical Atlantic and a northward shift of the intertropical convergence zone. The anomalous position of the intertropical convergence zone is accompanied by reduced precipitation in boreal spring and hence a higher than usual sea surface salinity. The year 2010 is also characterized by a strong positive Atlantic multidecadal oscillation index and a negative North Atlantic oscillation index that contribute to the tropical Atlantic warming. Positive anomalies of both surface temperature and salinity cause an increase of surface CO2, leading to a stronger outgassing of CO2 in 2010 compared with 2009 and 2011. The main factor responsible for the CO2 anomalies is the Pacific El Niño teleconnection. The Atlantic multidecadal oscillation index also contributes in the northern hemisphere, and the role of the North Atlantic oscillation is negligible.
Published: 2013

33. Long-term heat exchanges over a Mediterranean lagoon

Author: Marie-Noëlle Bouin, D. Legain, O. Traulle, Guy Caniaux, and Patrick Le Moigne
Subjects: Atmospheric Science, Ecology, Evaporation, Eddy covariance, Paleontology, Soil Science, Forestry, Aquatic Science, Sensible heat, Oceanography, Wind speed, Atmosphere, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Climatology, Latent heat, Heat transfer, Earth and Planetary Sciences (miscellaneous), Environmental science, Relative humidity, Earth-Surface Processes, Water Science and Technology
Abstract: [1] Heat exchanges between a medium-sized Mediterranean lagoon and the atmosphere are investigated at various time scales using long-term observations including 9 months of eddy covariance measurements. Turbulent heat fluxes are assessed using both eddy covariance and aerodynamic methods with a relative accuracy estimated at 15%. At time scales ranging from the diurnal to the seasonal cycle, heat exchanges appear to be dominated by evaporation, and most of the heat release of the lagoon occurs on time scales between 2 and 20 days. Seasonal variations are mainly due to the effects of net radiation and air temperature, while daily and short-term fluctuations of the sensible heat flux are influenced by air temperature and wind. In the short term, low relative humidity is more efficient than high wind speeds to produce strong peaks of evaporation (latent heat flux more than 350 W m−2). Episodes of Tramontane, a regional orography-induced wind, are shown to be responsible for 84% of the cooling of the lagoon surface (for cooling of more than 0.5°C) and for 70% of the heat loss due to evaporation. Short-term heat transfers between the lagoon and the atmosphere are largely punctuated by the two regional winds. The Tramontane generates pulses of evaporation lasting 1 to 4 days, while Marin episodes result in very low or negative latent heat fluxes and negative sensible heat fluxes corresponding to heat transfer from the atmosphere to the lagoon.
Published: 2012

34. Origin, formation and variability of the Subpolar Mode Water located over the Reykjanes Ridge

Author: Virginie Thierry, Herlé Mercier, E. de Boisséson, Guy Caniaux, and Damien Desbruyères
Subjects: Convection, Atmospheric Science, 010504 meteorology & atmospheric sciences, Mixed layer, Soil Science, Subtropics, Aquatic Science, Structural basin, Oceanography, 01 natural sciences, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Ecology, 010505 oceanography, Paleontology, Forestry, Current (stream), Geophysics, 13. Climate action, Space and Planetary Science, Ridge (meteorology), Mode water, Geology, Lagrangian analysis
Abstract: The origin and formation of the Subpolar Mode Water (SPMW) located over the Reykjanes Ridge in the North-Atlantic Ocean and the variability of its properties over the period 1966-2004 are investigated through the use of a global eddy-permitting (1/4 degrees) ocean/sea-ice model and a Lagrangian analysis tool. The SPMW is fed by subtropical and subpolar waters advected by the branches of the North-Atlantic Current. The SPMW acquires its properties when its source waters enter the winter mixed layer in the Iceland Basin. The SPMW temperature variability is mainly explained by variations of the relative contributions of the subtropical and subpolar water transports to the total transport. Compared to the 1966-2004 mean, lower (higher) subtropical water relative transport contribution leads to colder (warmer) SPMW in the early 1990s (in the late 1960s and late 1990s). The intensity of the winter convection in the Iceland basin also influences the SPMW temperature through the amount of relatively cold intermediate waters of subtropical origin integrated in the SPMW layer. Strong convection partly explains the cold SPMW of the early 1990s. The large increase in the SPMW temperature in the late 1990s is due to both a decrease in the winter convection and an increase in the relative transport of the subtropical waters.
Published: 2012

35. A Numerical Study of the Stratiform Region of a Fast-Moving Squall Line. Part II: Relationship between Mass, Pressure, and Momentum Fields

Author: Jean-Philippe Lafore, Jean-Luc Redelsperger, and Guy Caniaux
Subjects: Atmospheric Science, Mesoscale convective system, Meteorology, Front (oceanography), Geophysics, Surface pressure, Mesohigh, law.invention, Squall, law, Hydrostatic equilibrium, Squall line, Geology, Pressure gradient
Abstract: In a companion paper, a two-dimensional simulation of a fast-moving tropical squall line was successfully compared to observations performed during the COPT81 experiment over West Africa. The full ice phase parameterization is shown to be crucial in the simulation of trailing anvil precipitation. Different diagnostic tools are applied to the simulated fields to further our understanding of the scale interactions within a squall line-type mesoscale convective system. The pressure organization is characterized by two marked features important for explaining the inner circulation: first, a front-to-rear midlevel pressure gradient and, second. the surface pressure mesohigh extending from the gust front to the rear of the most active part of the trailing stratiform region. Based on the hydrostatic approximation, an original method of decomposition of the pressure field is proposed, whereby dynamical and buoyant contributions depend only on the horizontal and vertical, respectively. The mean pressure i...
Published: 1995

36. DMS dynamics in the most oligotrophic subtropical zones of the global ocean

Author: Alessandro Tagliabue, SÃ©verine Alvain, Laurent Bopp, Julia Uitz, Louis Marie Prieur, Patrick Brockmann, Nobue Kasamatsu, Mitsuo Fukuchi, Italo Masotti, Hubert Loisel, CÃ©dric Fichot, Sauveur Belviso, Guy Caniaux, JosÃ©phine Ras, David Dessailly, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ICOS-RAMCES (ICOS-RAMCES), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modélisation du climat (CLIM), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut national des sciences de l'Univers (INSU - CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie de Villefranche (LOV), Observatoire océanologique de Villefranche-sur-mer (OOVM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord])
Subjects: 0106 biological sciences, Chlorophyll a, 010504 meteorology & atmospheric sciences, 010604 marine biology & hydrobiology, Biogeochemistry, Context (language use), Subtropics, 15. Life on land, 01 natural sciences, chemistry.chemical_compound, Oceanography, Nutrient, chemistry, 13. Climate action, Phytoplankton, Environmental Chemistry, Environmental science, Sargasso sea, Ecosystem, 14. Life underwater, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology
Abstract: The influences of physico-chemical and biological processes on dimethylsulfide (DMS) dynamics in the most oligotrophic subtropical zones of the global ocean were investigated. As metrics for the dynamics of DMS and the so-called ‘summer DMS paradox’ of elevated summer concentrations when surface chlorophyll a (Chl) and particulate organic carbon (POC) levels are lowest, we used the DMS-to-Chl and DMS-to-POC ratios in the context of three independent and complementary approaches. Firstly, field observations of environmental variables (such as the solar radiation dose, phosphorus limitation of phytoplankton and bacterial growth) were used alongside discrete DMS, Chl and POC estimates extracted from global climatologies (i.e., a ‘station based’ approach). We then used monthly climatological data for DMS, Chl, and POC averaged over the biogeographic province wherein a given oligotrophic subtropical zone resides (i.e., a ‘province based’ approach). Finally we employed sensitivity experiments with a new DMS module coupled to the ocean general circulation and biogeochemistry model PISCES to examine the influence of various processes in governing DMS dynamics in oligotrophic regions (i.e., a ‘model based’ approach). We find that the ‘station based’ and ‘province based’ approaches yield markedly different results. Interestingly, the ‘province based’ approach suggests the presence of a ‘summer DMS paradox’ in most all of the oligotrophic regions we studied. In contrast, the ‘station based’ approach suggests that the ‘summer DMS paradox’ is only present in the Sargasso Sea and eastern Mediterranean. Overall, we found the regional differences in the absolute and relative concentrations of DMS between 5 of the most oligotrophic regions of the world’s oceans were better accounted for by their nutrient dynamics (specifically phosphorus limitation) than by physical factors often invoked, e.g., the solar radiation dose. Our ‘model based’ experiments suggest that it is the limitation of phytoplankton/bacterial production and bacterial consumption of DMS by pervasive phosphorus limitation that is responsible for the ‘summer DMS paradox’.
Published: 2012

37. A Numerical Study of the Stratiform Region of a Fast-Moving Squall Line. Part I: General Description and Water and Heat Budgets

Author: Jean-Luc Redelsperger, Guy Caniaux, and Jean-Philippe Lafore
Subjects: Atmospheric Science, Circulation (fluid dynamics), Computer simulation, Convection zone, Meteorology, Atmospheric circulation, Flow (psychology), Transition zone, Precipitation, Squall line, Geology
Abstract: A two-dimensional nonhydrostatic cloud model is applied to the simulation of a tropical squall line that occurred on 23 June during the COPT 81 experiment. Owing to the use of an ice parameterization scheme, the simulation reproduces many interesting features of the stratiform part observed with Doppler radars. In particular, this includes the dynamical, thermodynamical, and microphysical structures of the stratiform part. Different parts are clearly identified from the simulation and observations: a leading convective zone 40-km wide with large precipitation; a developed stratiform zone stretching over 150 km with moderate precipitation; between these two regions, a transition zone 20-km wide giving only light precipitation; and a forward anvil near 12 km. The mean horizontal circulation is characterized by two mean flows: the front-to-rear flow that represents upward and rearward injection of boundary-layer air and the underlying rear-to-front flow. The simulated vertical velocity, except in th...
Published: 1994

38. Coupling between the Atlantic cold tongue and the West African monsoon in boreal spring and summer

Author: Françoise Guichard, Hervé Giordani, Jean-Luc Redelsperger, Guy Caniaux, Erica Key, and Malick Wade
Subjects: Convection, Atmospheric Science, Ecology, Equator, Paleontology, Soil Science, Wind stress, Forestry, Aquatic Science, Oceanography, Monsoon, Wind speed, Sea surface temperature, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Anticyclone, Climatology, Earth and Planetary Sciences (miscellaneous), Upwelling, Geology, Earth-Surface Processes, Water Science and Technology
Abstract: [1] The formation of the Atlantic cold tongue (ACT) is the dominant seasonal sea surface temperature signal in the eastern equatorial Atlantic (EEA). A comprehensive analysis of variability in its spatial extent, temperature, and onset is presented. Then, the physical mechanisms which initiate ACT onset, as well as the feedbacks from the ACT to the maritime boundary layer, and how the ACT influences the onset of the West African monsoon (WAM) are discussed. We argue that in the EEA, the air-sea coupling between the ACT and WAM occurs in two phases. From March to mid-June, the ACT results from the intensification of the southeastern trades associated with the St. Helena anticyclone. Steering of surface winds by the basin shape of the EEA imparts optimal wind stress for generating the maximum upwelling south of the equator. During the second phase (mid-June–August), wind speeds north of the equator increase as a result of the northward progression of the intensifying trades and as a result of significant surface heat flux gradients produced by the differential cooling between the ACT and the tropical waters circulating in the Gulf of Guinea (GG). It is anticipated that the atmospheric divergence induced at low levels north of the equator reduces convection over the GG and that increased northward winds shift convection over land. Correlations between the ACT and the WAM onset dates over the last 26 years (1982–2007) measure as much as 0.8. This suggests that the ACT plays a key role in the WAM onset.
Published: 2011

39. Monsoon Multidisciplinary Analysis (AMMA) : an integrated project for understanding of the West African climate system and its human dimension

Author: G. de Coëtlogon, Romain Roehrig, Sally L. Lavender, Bernard Fontaine, Flore Mounier, Romain Marteau, Christopher M. Taylor, Christophe Lavaysse, Serge Janicot, Guy Caniaux, Fabrice Chauvin, George N. Kiladis, Stéphanie Leroux, Jean-Philippe Lafore, Benjamin Sultan, Nathalie Philippon, Nicholas M. J. Hall, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques ( LOCEAN ), Muséum National d'Histoire Naturelle ( MNHN ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Groupe d'étude de l'atmosphère météorologique ( CNRM-GAME ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Météo France-Centre National de la Recherche Scientifique ( CNRS ), ESTER - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales ( LATMOS ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Centre de Recherches de Climatologie ( CRC ), Université de Bourgogne ( UB ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire d'études en Géophysique et océanographie spatiales ( LEGOS ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Centre National d'Etudes Spatiales ( CNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), NOAA Earth System Research Laboratory ( ESRL ), National Oceanic and Atmospheric Administration ( NOAA ), Department of Atmospheric and Oceanic Sciences [Montreal], McGill University, School of Environmental Sciences [Norwich], University of East Anglia [Norwich] ( UEA ), Centre for Ecology and Hydrology [Wallingford] ( CEH ), Natural Environment Research Council ( NERC ), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherches de Climatologie (CRC), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), NOAA Earth System Research Laboratory (ESRL), National Oceanic and Atmospheric Administration (NOAA), Department of Atmospheric and Oceanic Sciences [Montréal], McGill University = Université McGill [Montréal, Canada], University of East Anglia [Norwich] (UEA), Centre for Ecology and Hydrology [Wallingford] (CEH), Natural Environment Research Council (NERC), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, 0207 environmental engineering, 02 engineering and technology, [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology, Intraseasonal variability, Monsoon, Atmospheric sciences, 01 natural sciences, West africa, West African monsoon, predictability, Monsoon onset, monsoon onset, Crop yield, Precipitation, Predictability, 020701 environmental engineering, 0105 earth and related environmental sciences, intraseasonal variability, [ SDU.STU.ME ] Sciences of the Universe [physics]/Earth Sciences/Meteorology, crop yield, Scale (music), West african, 13. Climate action, Climatology, Environmental science, Atmospheric dynamics
Abstract: International audience; The intraseasonal time scale is critical in West Africa where resources are highly rainfall dependent. Three main modes of variability have been identified, two with a mean periodicity of 15 days and one with a mean periodicity around 40 days. These modes have a regional scale and can strongly influence precipitation and convective activity. They are mainly controlled by atmospheric dynamics and land-surface interactions. They can also modulate the very specific phase of the African summer monsoon onset. A better knowledge of the mechanisms controlling this scale is necessary to improve its predictability.
Published: 2011

40. A one-dimensional modeling study of the diurnal cycle in the equatorial Atlantic at the PIRATA buoys during the EGEE-3 campaign

Author: Rebecca Hummels, Malick Wade, Marcus Dengler, Yves duPenhoat, Guy Caniaux, Hervé Giordani, Echanges Côte-Large (ECOLA), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Convection, ATLANTIC, Buoyancy, 010504 meteorology & atmospheric sciences, LAYER HEAT-BUDGET, Mixed layer, TROPICAL, Wind stress, cold tongue, engineering.material, Oceanography, 01 natural sciences, PACIFIC WARM POOL, TURBULENCE MARINE, Diurnal cycle, PIRATA buoys, 14. Life underwater, WIND STRESS, 0105 earth and related environmental sciences, TEMPERATURE DE SURFACE, Equatorial Atlantic, Buoy, 010505 oceanography, Oceanic mixed-layer processes, COURANT DE CONVECTION, UPPER OCEAN, Western Hemisphere Warm Pool, One-dimensional model, Turbulence, Sea surface temperature, CIRCULATION OCEANIQUE, 13. Climate action, Climatology, FACTEUR CLIMATIQUE, SEA-SURFACE TEMPERATURE, engineering, CYCLE DIURNE, Environmental science, SHEAR-FLOW, INTRASEASONAL VARIABILITY, ENERGIE CINETIQUE, VARIATION JOURNALIERE, MIXED-LAYER, KINETIC-ENERGY
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METEOR SOC, V133, P117, DOI 10.1002/qj.4 Woolnough SJ, 2000, J CLIMATE, V13, P2086, DOI 10.1175/1520-0442(2000)0132.0.CO;2 Yu LS, 2006, J CLIMATE, V19, P6153, DOI 10.1175/JCLI3970.1 Wade, Malick Caniaux, Guy duPenhoat, Yves Dengler, Marcus Giordani, Herve Hummels, Rebecca Dengler, Marcus/A-7327-2014 Dengler, Marcus/0000-0001-5993-9088 AMMA; European Community This study was supported by the AMMA project. Based on a French initiative, AMMA was built by an international scientific group and is currently funded by a large number of agencies, including those in France, the UK, the US, and Africa. It has been the beneficiary of a major financial contribution from the European Community's Sixth Framework Research Program. Detailed information on scientific coordination and funding is available on the AMMA International web site http://www.amma-international.org. We thank Bernard Bourles, the chief scientist of the EGEE program, and all the persons who acquired and prepared the data used in this study as well as the Captain of the RN L'Atalante and his crew for their help during the EGEE-3 cruise. We warmly thank Dr. Gregory Foltz and an anonymous reviewer for their pertinent and useful comments and remarks. 8 SPRINGER HEIDELBERG HEIDELBERG OCEAN DYNAM; A one-dimensional model is used to analyze, at the local scale, the response of the equatorial Atlantic Ocean under different meteorological conditions. The study was performed at the location of three moored buoys of the Pilot Research Moored Array in the Tropical Atlantic located at 10 degrees W, 0 degrees N; 10 degrees W, 6 degrees S; and 10 degrees W, 10 degrees S. During the EGEE-3 (Etude de la circulation oceanique et de sa variabilite dans le Golfe de Guinee) campaign of May-June 2006, each buoy was visited for maintenance during 2 days. On board the ship, high-resolution atmospheric parameters were collected, as were profiles of temperature, salinity, and current. These data are used here to initialize, force, and validate a one-dimensional model in order to study the diurnal oceanic mixed-layer variability. It is shown that the diurnal variability of the sea surface temperatures is mainly driven by the solar heat flux. The diurnal response of the near-surface temperatures to daytime heating and nighttime cooling has an amplitude of a few tenths of degree. The computed diurnal heat budget experiences a net warming tendency of 31 and 27 Wm(-2) at 0 degrees N and 10 degrees S, respectively, and a cooling tendency of 122 Wm(-2) at 6 degrees S. Both observed and simulated mixed-layer depths experience a jump between the nighttime convection phase and the well-stabilized diurnal water column. Its amplitude changes dramatically depending on the meteorological conditions occurring at the stations and reaches its maximum amplitude (similar to 50 m) at 100 degrees S. At 6 degrees and 10 degrees S, the presence of barrier layers is observed, a feature that is clearer at 10 degrees S. Simulated turbulent kinetic energy (11(E) dissipation rates, compared to independent microstructure measurements, show that the model tracks their diurnal evolution reasonably well. It is also shown that the shear and buoyancy productions and the vertical diffusion of TKE all contribute to the supply of TKE, but the buoyancy production is the main source of TKE during the period of the simulation.
Published: 2011

41. Variability of the mixed layer heat budget in the eastern equatorial Atlantic during 2005-2007 as inferred using Argo floats

Author: Yves du Penhoat, Malick Wade, Guy Caniaux, Laboratoire de Physique de l'Atmosphère et de l'Océan Siméon Fongang (LPAO-SF), École Supérieure Polytechnique de Dakar (ESP), Université Cheikh Anta Diop [Dakar, Sénégal] (UCAD)-Université Cheikh Anta Diop [Dakar, Sénégal] (UCAD), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Echanges Côte-Large (ECOLA), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
Subjects: CURRENTS, Atmospheric Science, 010504 meteorology & atmospheric sciences, WEST-AFRICAN, Mixed layer, TROPICAL INSTABILITY WAVES, Equator, CIRCULATION, Soil Science, Aquatic Science, Oceanography, Monsoon, 01 natural sciences, 010305 fluids & plasmas, Atlantic Equatorial mode, Geochemistry and Petrology, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), PACIFIC-OCEAN, 14. Life underwater, Argo, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, ANNUAL CYCLE, Ecology, Tropical instability waves, Paleontology, Forestry, Prediction and Research Moored Array in the Atlantic, MONSOON, SEASONAL-VARIATIONS, Sea surface temperature, Geophysics, 13. Climate action, Space and Planetary Science, Climatology, SEA-SURFACE TEMPERATURE, SHIP DRIFTS, INTERANNUAL VARIABILITY, Geology
Abstract: We examine the variability of the sea surface temperatures in the eastern equatorial Atlantic during 2005-2007 by using Argo profiling floats, Prediction and Research Moored Array in the Atlantic buoys and satellite, in situ, and atmospheric data sets. The eastern equatorial Atlantic, characterized by shallow mixed layers all yearlong, is divided into nine boxes of nearly equal surface area, with respect to the dynamics and thermodynamics in this region. Monthly mixed layer heat budgets are computed in each box from 10 day Argo profiles. In all the boxes, the net surface heat flux is one of the main causes of the seasonal evolution of sea surface temperatures for the 3 studied years. The amount of short-wave radiation penetrating through the base of the mixed layer and horizontal heat advection may locally contribute to the temperature variability, while entrainment has a weaker contribution. To balance the heat budget, a residual term exists which includes all processes that cannot be calculated with observations as well as the possible errors in the other terms. This residual is more intense in the cold tongue and the northern region and exhibits a clear seasonal cycle, with minimum (negative) values in boreal summer and maximum values in winter. This residual compares well with available observations of vertical turbulent mixing collected during Etude de la Circulation Oceanique et des Echanges Ocean-Atmosphere dans le Golfe de Guinee campaigns (2005-2007) in the eastern equatorial Atlantic. When assuming that the residual is mostly associated with vertical turbulent mixing, it can be conjectured that turbulent mixing is a significant cooling source in the cold tongue and north of the equator.
Published: 2011

42. Monsoon Multidisciplinary Analysis (AMMA) : an integrated project for understanding of the West African climate system and its human dimension

Author: Hervé Giordani, Andreas Funk, Verena Hormann, Peter Brandt, Frédéric Marin, Marcus Dengler, Guy Caniaux, Alban Lazar, Bernard Bourlès, Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Océan du Large et Variabilité Climatique (OLVAC), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL)
Subjects: Convection, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, 010504 meteorology & atmospheric sciences, 010505 oceanography, cold tongue, Monsoon, 01 natural sciences, Ocean dynamics, Sea surface temperature, West African monsoon, Oceanography, Atlantic Equatorial mode, Boreal, 13. Climate action, Anticyclone, Climatology, Thermocline, equatorial Atlantic, Geology, 0105 earth and related environmental sciences
Abstract: Zonal wind anomalies in the western equatorial Atlantic during late boreal winter to early summer precondition boreal summer cold/warm events in the eastern equatorial Atlantic (EEA) that manifest in a strong interannual Atlantic cold tongue (ACT) variability. Local intraseasonal wind fluctuations, linked to the St. Helena anticyclone, contribute to the variability of cold tongue onset and strength, particularly during years with preconditioned shallow thermoclines. The impact of cold tongue sea surface temperature (SST) anomalies on the wind field in the Gulf of Guinea is assessed. It contributes to the northward migration of humidity and convection and possibly the West African monsoon (WAM) jump. Copyright @ 2010 Royal Meteorological Society
Published: 2011

43. A 3D mesoscale simulation of the ocean using data from the ATHENA 88 field experiment

Author: H. Roquet, Serge Planton, and Guy Caniaux
Subjects: Meteorology, Advection, Turbulence, Mixed layer, Mesoscale meteorology, Aquatic Science, Classification of discontinuities, Oceanography, Closure (computer programming), Bathythermograph, Physics::Atmospheric and Oceanic Physics, Ecology, Evolution, Behavior and Systematics, Geology, Geostrophic wind
Abstract: A mesoscale version of the OGCM developed at the LODYC (Laboratoire d'Oceanographie Dynamique et de Climatologie) has been used to simulate a rectangular domain in the North-east Atlantic ocean. It includes open lateral boundaries, a level 1.5 turbulence closure scheme, a fine horizontal and vertical mesh, a surface turbulent fluxes parameterization and its initialized with observed data. The simulation uses the extended mesoscale data set collected during the ATHENA 88 experiment, including three hydrological surveys, a satellite data set for the solar fluxes and the analysed data issued from atmospheric forecast models for the atmospheric forcing. The model is initialized by an optimal interpolation of XBT and CTD data collected during the first survey and by the geostrophic approximation for the flow field. The comparison of the model results with the observations and the analyses deduced from other surveys reveals that the model is able to reproduce most of the mesoscale features in the deep ocean and in the mixed layer. Some disagreement concerning the location of a warm salty eddy entering the simulation domain from the South may be due to uncertainties in the lateral boundary conditions or due to the lack of topography in the model. Near surface heat and TKE balances indicate that mixed-layer processes are essentially three-dimensional, and that advection cannot be neglected in this part of the ocean. Under the influence of atmospheric forcing, the model is also able to produce discontinuities not included in the initial state under the influence of atmospheric forcing. The analysis of a near surface thermal front generated by the model emphasizes the need to use high-frequency atmospheric forcing, in particular for the wind, in order to reproduce such transient features.
Published: 1993

44. Mixed layer heat budget in the Iceland Basin from Argo

Author: Virginie Thierry, Herlé Mercier, E. de Boisséson, Guy Caniaux, Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), IFREMER, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Mixed layer, Soil Science, Aquatic Science, Oceanography, 01 natural sciences, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Diffusion (business), Argo, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Ecology, 010505 oceanography, Advection, Paleontology, Sampling (statistics), Forestry, Geophysics, 13. Climate action, Space and Planetary Science, Climatology, Heat transfer, Mode water, Environmental science, Geostrophic wind
Abstract: International audience; The mixed layer processes that govern the mode water properties in the Iceland Basin are quantified through a mixed layer heat budget from Argo data collected over 2001-2007. This budget includes the mixed layer heat content variation, the surface heat fluxes, and the Ekman contribution to advection. The geostrophic advection cannot be directly estimated from Argo data but, following previous works, an ad hoc procedure is implemented to take it into account. The resulting annual budget is closed within the error bar but this closure hides some compensation between the summer and the winter residuals (−16 ± 9 W m−2 and 21 ± 26 W m−2, respectively). A similar heat budget built by using colocated Argo floats in the 1/4° DRAKKAR ORCA025‐G70fo simulation over 2001-2007 shows seasonal patterns similar to the Argo‐based budget. An Eulerian model‐based heat budget in the Iceland Basin shows that the mixed layer heat content variation is driven by the air‐sea fluxes, the advection, and the vertical diffusion. The indirect estimate of the latter in a new Argo‐based budget leads to a summer residual of 2 ± 11 W m−2 and to an unchanged winter residual. The summer and winter standard errors of the Argo‐based budget (11 and 26 W m‐2, respectively) reflect the limited sampling of the Iceland Basin by Argo floats. Sensitivity experiments show that such errors would be reduced by a denser Argo sampling.
Published: 2010

45. Mesoscale and diel to monthly variability of CO2 and carbon fluxes at the ocean surface in the northeastern Atlantic

Author: Jacqueline Boutin, Liliane Merlivat, Guy Caniaux, Melchor González Dávila, Gilles Reverdin, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Facultad de Ciencias del Mar (FCM), University of Las Palmas de Gran Canaria (ULPGC), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Mixed layer, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Mesoscale meteorology, Soil Science, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Aquatic Science, Oceanography, 01 natural sciences, chemistry.chemical_compound, Geochemistry and Petrology, Dissolved organic carbon, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, Diel vertical migration, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Oceanography: Biological and Chemical: Biogeochemical cycles processes and modeling (0412 0414 0793 1615 4912), Oceanography: Biological and Chemical: Carbon cycling (0428), Ecology, Buoy, 010505 oceanography, Paleontology, Forestry, Salinity, Geophysics, chemistry, Oceanography: General: Physical and biogeochemical interactions, 13. Climate action, Space and Planetary Science, Carbon dioxide, Biogeosciences: Diel seasonal and annual cycles (4227), Environmental science, Mode water, Biogeosciences: Carbon cycling (4806)
Abstract: International audience; Four CARIOCA Lagrangian buoys were deployed in the northeast Atlantic Ocean as part of the Programme Océan Multidisciplinaire Méso Echelle (POMME) dedicated to the study of the role of mesoscale eddies in biological production, the carbon budget, and the subduction of mode waters. An extensive set of hourly surface measurements of temperature, salinity, and carbon dioxide fugacity (fCO2) was collected from February to August 2001. The high-frequency spatial and temporal variability observed in surface fCO2 and in the derived dissolved inorganic carbon (DIC) concentrations suggests that abrupt changes of the carbon variables are being generated along frontal patterns and filaments by submesoscale and mesoscale eddy-eddy interactions, especially in winter. On the basis of a 1-D model of the diurnal mixed layer along the buoy trajectory, we show that under certain conditions the diel cycle of DIC is driven by the daily cycle of photosynthesis and metabolic CO2 release at the ocean surface. This information is quantitatively used to derive in-situ primary production, carbon gross, and net community production. The analysis of 107 observed diel cycles of DIC shows that episodic biological production processes are triggered by the mesoscale activity of surface eddies. Over the sampled period, the POMME area is a sink for atmospheric CO2 with an estimated flux of -4 mmol m-2 day-1. The calculated amount of anthropogenic carbon transported into the ocean interior by subduction of subpolar mode water is equal to 2.8 1013 gC yr-1.
Published: 2009

46. Turbulent air-sea fluxes in the Gulf of Guinea during the AMMA experiment

Author: B. Sinardet, Bruno Piguet, Joël Barrié, O. Traulle, F. Boutet, Alain Weill, François Baudin, S. Letourneur, Denis Bourras, Erica L. Key, D. Legain, Bernard Bourlès, Gilles Bouhours, Laurence Eymard, Guy Caniaux, Christophe Berthod, Jean-Paul Vinson, Aurélien Clemençon, ESTER - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Institut Pierre-Simon-Laplace (IPSL), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences de l'Univers (INSU/SPU), Centre National de la Recherche Scientifique (CNRS), Rosenstiel School of Marine and Atmospheric Science (RSMAS), University of Miami [Coral Gables], Laboratoire Interdisciplinaire Carnot de Bourgogne (LICB), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Division technique INSU/SDU (DTI), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Laboratoire Atmosphères, Milieux, Observations Spatiales ( LATMOS ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Groupe d'étude de l'atmosphère météorologique ( CNRM-GAME ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Météo France-Centre National de la Recherche Scientifique ( CNRS ), Institut Pierre-Simon-Laplace ( IPSL ), École normale supérieure - Paris ( ENS Paris ) -Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Centre National d'Etudes Spatiales ( CNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques ( LOCEAN ), Muséum National d'Histoire Naturelle ( MNHN ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire d'études en Géophysique et océanographie spatiales ( LEGOS ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Centre National d'Etudes Spatiales ( CNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Institut National des Sciences de l'Univers ( INSU/SPU ), Centre National de la Recherche Scientifique ( CNRS ), Rosenstiel School of Marine and Atmospheric Science ( RSMAS ), Laboratoire Interdisciplinaire Carnot de Bourgogne ( LICB ), Université de Bourgogne ( UB ) -Centre National de la Recherche Scientifique ( CNRS ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Centre d'étude des environnements terrestre et planétaires ( CETP ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies ( FEMTO-ST ), Université de Technologie de Belfort-Montbeliard ( UTBM ) -Ecole Nationale Supérieure de Mécanique et des Microtechniques ( ENSMM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Division technique INSU/SDU ( DTI ), and Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS )
Subjects: [ SDU.OCEAN ] Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, Eddy covariance, Soil Science, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Tourbillon, Aquatic Science, Oceanography, Monsoon, 01 natural sciences, Physics::Fluid Dynamics, Flux (metallurgy), [ PHYS.PHYS.PHYS-GEO-PH ] Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Ecology, 010505 oceanography, Turbulence, Paleontology, Forestry, Aerodynamics, Geophysics, [ PHYS.PHYS.PHYS-AO-PH ] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Space and Planetary Science, Environmental science, Spectral method, Parametrization
Abstract: International audience; Turbulent fluxes at the air‐sea interface were estimated in the framework of the African Monsoon Multidisciplinary Analysis (AMMA) international program. A specific flux measurement mast was designed so as to minimize aerodynamic flow distortion and vibrations. The mast was installed on the research vessel Atalante that cruised in the Gulf of Guinea during the onset of the African monsoon, in June-July 2006. Turbulent fluxes were calculated with an eddy covariance method and with a spectral method. Calculation of eddy correlation fluxes required a correction of flow distortion at turbulent scales, which was performed with a new statistical technique. Application of the spectral flux calculation method revealed that an imbalance term was required, in agreement with results from earlier experiments, and indicated that the value of the Kolmogorov constant (0.55) should not be modified. Bulk exchange coefficients calculated are in good agreement with earlier parameterizations in medium wind conditions.
Published: 2009

47. Why Were Sea Surface Temperatures so Different in the Eastern Equatorial Atlantic in June 2005 and 2006?

Author: Yves Gouriou, Frédéric Marin, Erica L. Key, Bernard Bourlès, Hervé Giordani, Guy Caniaux, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Instrumentation, Moyens analytiques, Observatoires en Géophysique et Océanographie (IMAGO), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
Subjects: Cold tongue, 010504 meteorology & atmospheric sciences, 010505 oceanography, Equator, Wind stress, Tropical Atlantic, Oceanography, Spatial distribution, 01 natural sciences, Trade wind, Sea surface temperature, Atlantic Equatorial mode, 13. Climate action, Climatology, Geology, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences
Abstract: A comparison of June 2005 and June 2006 sea surface temperatures in the eastern equatorial Atlantic exhibits large variability in the properties of the equatorial cold tongue, with far colder temperatures in 2005 than in 2006. This difference is found to result mainly from a time shift in the development of the cold tongue between the two years. Easterlies were observed to be stronger in the western tropical Atlantic in April–May 2005 than in April–May 2006, and these winds favorably preconditioned oceanic subsurface conditions in the eastern Atlantic. However, it is also shown that a stronger than usual intraseasonal intensification of the southeastern trades was responsible for the rapid and early intense cooling of the sea surface temperatures in mid-May 2005 over a broad region extending from 20°W to the African coast and from 6°S to the equator. This particular event underscores the ability of local intraseasonal wind stress variability in the Gulf of Guinea to initiate the cold tongue season and thus to dramatically impact the SST in the eastern equatorial Atlantic. Such intraseasonal wind intensifications are of potential importance for year-to-year variability in the onset of the African monsoon.
Published: 2009

48. Large-scale overview of the summer monsoon over West Africa during the AMMA field experiment in 2006

Author: Mireille Tomasini, Flore Mounier, Thierry Lebel, Acmad forecasters team, Abdou Ali, Claire E. Reeves, A. Ulanovsky, Guy Caniaux, Benjamin Sultan, Christophe Lavaysse, Nicole Asencio, Laurent Kergoat, Serge Janicot, Hans Schlager, Rémy Roca, Chris D. Thorncroft, Gareth James Berry, Olivier Bock, Philippe Nédélec, P. de Rosnay, Fabrizio Ravegnani, Jean-Luc Redelsperger, Fabrice Chauvin, Bernard Bourlès, A. Deme, Jean-Philippe Lafore, Béatrice Marticorena, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Earth and Atmospheric Sciences [Albany], University at Albany [SUNY], State University of New York (SUNY)-State University of New York (SUNY), Laboratoire d'étude des transferts en hydrologie et environnement (LTHE), Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Service d'aéronomie (SA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Centre d'études spatiales de la biosphère (CESBIO), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'aérologie (LAERO), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Istituto di Scienze dell'Atmosfera e del Clima (ISAC), Consiglio Nazionale delle Ricerche [Roma] (CNR), School of Environmental Sciences [Norwich], University of East Anglia [Norwich] (UEA), Institut fuer Physik der Atmosphaere, Central Aerological Observatory (CAO), Russian Federal Service for Hydrometeorology and Environmental Monitoring (Roshydromet), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN), Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'aérologie (LA), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)
Subjects: Wet season, Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, Atmospheric circulation, [SDE.MCG]Environmental Sciences/Global Changes, 0207 environmental engineering, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 02 engineering and technology, precipitation, Monsoon, 01 natural sciences, West African monsoon, Earth and Planetary Sciences (miscellaneous), meteorology and atmospheric dynamics, East Asian Monsoon, Precipitation, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, 020701 environmental engineering, lcsh:Science, mesocale convective system, 0105 earth and related environmental sciences, 2. Zero hunger, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:QC801-809, Atmosphärische Spurenstoffe, Geology, Astronomy and Astrophysics, climatology, Annual cycle, 6. Clean water, lcsh:QC1-999, Water resources, lcsh:Geophysics. Cosmic physics, Space and Planetary Science, Climatology, tropical meteorology, Environmental science, lcsh:Q, Tropical cyclone, aircraft measurements, lcsh:Physics
Abstract: The AMMA (African Monsoon Multidisciplinary Analysis) program is dedicated to providing a better understanding of the West African monsoon and its influence on the physical, chemical and biological environment regionally and globally, as well as relating variability of this monsoon system to issues of health, water resources, food security and demography for West African nations. Within this framework, an intensive field campaign took place during the summer of 2006 to better document specific processes and weather systems at various key stages of this monsoon season. This campaign was embedded within a longer observation period that documented the annual cycle of surface and atmospheric conditions between 2005 and 2007. The present paper provides a large and regional scale overview of the 2006 summer monsoon season, that includes consideration of of the convective activity, mean atmospheric circulation and synoptic/intraseasonal weather systems, oceanic and land surface conditions, continental hydrology, dust concentration and ozone distribution. The 2006 African summer monsoon was a near-normal rainy season except for a large-scale rainfall excess north of 15° N. This monsoon season was also characterized by a 10-day delayed onset compared to climatology, with convection becoming developed only after 10 July. This onset delay impacted the continental hydrology, soil moisture and vegetation dynamics as well as dust emission. More details of some less-well-known atmospheric features in the African monsoon at intraseasonal and synoptic scales are provided in order to promote future research in these areas.
Published: 2008

49. A high-resolution simulation of the ocean during the POMME experiment: Mesoscale variability and near surface processes

Author: Gilles Reverdin, Guy Caniaux, Louis Marie Prieur, Marina Lévy, A. Paci, Hervé Giordani, Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Mixed layer, Temperature salinity diagrams, Mesoscale meteorology, Soil Science, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Aquatic Science, Oceanography, 01 natural sciences, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Ecology, 010505 oceanography, Advection, Paleontology, Forestry, Ocean general circulation model, Ocean dynamics, Geophysics, Eddy, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Climatology, Mode water, Geology
Abstract: International audience; This article is the second part of a modeling study of upper ocean mesoscale physical processes in an area of the northeast Atlantic that was extensively sampled during the Programme Océan Multidisciplinaire Méso-Echelle (POMME experiment, October 2000-September 2001). The model is a high-resolution regional version of the ocean general circulation model OPA integrated from February to May 2001. The mesoscale upper ocean dynamics has been carefully validated in a first paper (Paci et al., 2005). In the present article, the simulation is used to analyze the contribution of mesoscale eddies to the mixed layer processes during the period that controls the annual subduction rate and the characteristics of the subducted water. Mesoscale eddies account for a significant part of the mixed layer heat, salt, and water budgets through mesoscale and submesoscale structures acting on the horizontal advective terms. They represent respectively 52% and 66% of the horizontal advection of temperature and salinity and 70% of the lateral induction. They also induce an earlier and more intense restratification. The domain-averaged detrainment appears to be reduced by more than 15% by mesoscale eddies and reaches about 0.8 Sv. However, these eddies increase the density of the detrained water. Some dense water, likely to be involved in the formation of subpolar mode water, is detrained by them in a way that maximizes its chance to be effectively subducted in the area.
Published: 2007

50. A Nonlinear Statistical Model of Turbulent air-sea Fluxes

Author: Guy Caniaux, Denis Bourras, Gilles Reverdin, Sophie Belamari, Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, Momentum (technical analysis), Air-sea interaction, 010504 meteorology & atmospheric sciences, Meteorology, 010505 oceanography, Turbulence, Nonlinear model, Astrophysics::High Energy Astrophysical Phenomena, [SDE.MCG]Environmental Sciences/Global Changes, Statistics, Eddy covariance, Wind stress, Statistical model, Mechanics, Sensible heat, 01 natural sciences, Flux (metallurgy), Fluxes, Latent heat, Environmental science, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Algorithms, 0105 earth and related environmental sciences
Abstract: Most of the bulk algorithms used to calculate turbulent air–sea fluxes of momentum and heat are iterative algorithms whose convergence is slow and not always achieved. To avoid these drawbacks that are critical when large datasets must be processed, a statistical model of bulk air–sea fluxes based on artificial neural networks was developed. It was found that classical bulk algorithms were slower than the statistical model, by a factor of 1.75–7 depending on the bulk algorithm selected for the comparison. A set of 12 global analyses of an operational meteorological model as well as in situ data corresponding to equatorial and midlatitude conditions were used to assess the accuracy of the proposed model. The wind stress, latent, and sensible heat fluxes calculated with neural networks have acceptable biases with respect to bulk fluxes, between 0.4% and 1% depending on the flux magnitudes. Moreover, the rms deviation between bulk fluxes and neural network flux estimates is only 0.003 N m−2 for the momentum flux, 0.5 W m−2 for the sensible heat flux, and 1.8 W m−2 for the latent heat flux, at global scale, which is small compared with the natural variability of these quantities or the expected error.
Published: 2007

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