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1. Numerical Weather Forecasts at Kilometer Scale in the French Alps: Evaluation and Application for Snowpack Modeling

Author

Eric Bazile, Matthieu Lafaysse, Yann Seity, Ingrid Dombrowski-Etchevers, Louis Quéno, and Vincent Vionnet

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, Cloud cover, 0208 environmental biotechnology, Flood forecasting, Mesoscale meteorology, Weather forecasting, Terrain, 02 engineering and technology, Snowpack, Snow, computer.software_genre, 01 natural sciences, Wind speed, 020801 environmental engineering, Climatology, Environmental science, computer, 0105 earth and related environmental sciences
Abstract

Numerical weather prediction (NWP) systems operating at kilometer scale in mountainous terrain offer appealing prospects for forecasting the state of snowpack in support of avalanche hazard warning, water resources assessment, and flood forecasting. In this study, daily forecasts of the NWP system Applications of Research to Operations at Mesoscale (AROME) at 2.5-km grid spacing over the French Alps were considered for four consecutive winters (from 2010/11 to 2013/14). AROME forecasts were first evaluated against ground-based measurements of air temperature, humidity, wind speed, incoming radiation, and precipitation. This evaluation shows a cold bias at high altitude partially related to an underestimation of cloud cover influencing incoming radiative fluxes. AROME seasonal snowfall was also compared against output from the Système d’Analyse Fournissant des Renseignements Atmosphériques à la Neige (SAFRAN) specially developed for alpine terrain. This comparison reveals that there are regions of significant difference between the two, especially at high elevation, and possible causes for these differences are discussed. Finally, AROME forecasts and SAFRAN reanalysis have been used to drive the snowpack model Surface Externalisée (SURFEX)/Crocus (SC) and to simulate the snowpack evolution over a 2.5-km grid covering the French Alps during four winters. When evaluated at the experimental site of Col de Porte, both simulations show good agreement with measurements of snow depth and snow water equivalent. At the scale of the French Alps, AROME-SC exhibits an overall positive bias, with the largest positive bias found in the northern and central French Alps. This study constitutes the first step toward the development of a distributed snowpack forecasting system using AROME.

Published
2016
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2. Improvement of the forecast of convective activity from the AROME-France system

Author

Julien Léger, Didier Ricard, Pierre Brousseau, and Yann Seity

Subjects
Convection, Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, Climatology, 0208 environmental biotechnology, Environmental science, 02 engineering and technology, 01 natural sciences, 020801 environmental engineering, 0105 earth and related environmental sciences
Published
2016
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3. The ALADIN System and its canonical model configurations AROME CY41T1 and ALARO CY40T1

Author

F. Bouyssel, Patricia Pottier, Neva Pristov, Radmila Brožková, Oldřich Španiel, Alain Joly, Yong Wang, Rafiq Hamdi, Petra Smolíková, J. Mašek, Eric Bazile, Bogdan Bochenek, Martina Tudor, Daan Degrauwe, Ryad El Khatib, Maria Derkova, Claude Fischer, Pierre Bénard, Christoph Wittmann, Piet Termonia, and Yann Seity

Subjects
Engineering, 010504 meteorology & atmospheric sciences, Relation (database), Meteorology, 0208 environmental biotechnology, Weather forecasting, 02 engineering and technology, computer.software_genre, 01 natural sciences, Global model, Data assimilation, Canonical model, GENERAL-CIRCULATION MODEL, 0105 earth and related environmental sciences, TURBULENCE CLOSURE MODELS, COEFFICIENTS SEMIIMPLICIT SCHEMES, business.industry, ALADIN System, NWP model, Limited area model, lcsh:QE1-996.5, LIMITED-AREA MODEL, NUMERICAL WEATHER-PREDICTION, SHALLOW-WATER EQUATIONS, Numerical weather prediction, 020801 environmental engineering, lcsh:Geology, ECMWF FORECAST MODEL, Earth and Environmental Sciences, General Circulation Model, FULLY ELASTIC SYSTEM, CONSERVATIVE THERMODYNAMIC EQUATIONS, business, computer, HIGH-RESOLUTION
Abstract

The ALADIN System is a numerical weather prediction system (NWP) developed by the international ALADIN consortium for operational weather forecasting and research purposes. It is based on a code that is shared with the global model IFS of the ECMWF and the ARPEGE model of Météo-France. Today, this system can be used to provide a multitude of high-resolution limited-area model (LAM) configurations. A few configurations are thoroughly validated and prepared to be used for the operational weather forecasting in the 16 Partner Institutes of this consortium. These configurations are called the ALADIN Canonical Model Configurations (CMCs). There are currently three CMCs: the ALADIN baseline-CMC, the AROME CMC and the ALARO CMC. Other configurations are possible for research, such as process studies and climate simulations. The purpose of this paper is (i) to define the ALADIN System in relation to the global counterparts IFS and ARPEGE, (ii) to explain the notion of the CMCs and to document their most recent versions, and (iii) to illustrate the process of the validation and the porting of these configurations to the operational forecast suites of the Partner Institutes of the ALADIN consortium. This paper is restricted to the forecast model only; data assimilation techniques and postprocessing techniques are part of the ALADIN System but they are not discussed here.

Published
2018
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4. High-resolution simulation of a major West African dust-storm: comparison with observations and investigation of dust impact

Author

Pierre Tulet, Jean-Philippe Lafore, C. Kocha, and Yann Seity

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Subsidence (atmosphere), Storm, 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, African easterly jet, Cold front, 13. Climate action, Anticyclone, Dust storm, Potential vorticity, Climatology, Extratropical cyclone, Environmental science, 0105 earth and related environmental sciences
Abstract

This study focuses on the radiative impacts of dust on the thermodynamics and dynamics of a major Saharan dust-storm that occurred between 7 and 15 March 2006. The implementation of a dust module within the convective-scale operational model AROME permitted a 10-day simulation at high resolution (5 km) over a large domain (6.5-30°N; 3°W-33°E). The model is able to represent most of the life cycle of this dust-storm and of the principal dust sources. According to the comparison with a complete and comprehensive set of measurements obtained within the framework of the AMMA field campaign in 2006, the simulation succeeds in representing the main thermodynamic and radiative features of the storm both qualitatively and quantitatively. As compared with a simulation without the dust, the coupling with the dust module provides signatures of the storm that are in better agreement with radiation and temperature observations. The intense heating in the core of the dust plume (more than 2°C) resulted in a large vertical dipole of potential vorticity anomaly with higher values at low levels and weaker values at mid levels, either in the lower and the upper part of the dust plume respectively. This shows that the coupling with dust reinforces the intensity of the cold extratropical outbreak with more ascent at the cold front, more cyclonic convergence near the surface, and more anticyclonic divergence aloft. Also, the subsidence is increased at the rear of the outbreak with more northerly winds. A major result is the acceleration of the easterly along-front flow (∼3 m s−1) at low levels and in the African Easterly Jet, increasing the emission of dust and its westward long-range transport. Copyright © 2011 Royal Meteorological Society

Published
2011
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5. Initiation of deep convection at marginal instability in an ensemble of mesoscale models: a case-study from COPS

Author

Jan Handwerker, Daniel J. Kirshbaum, Hans-Stefan Bauer, J. Trentmann, Alan M. Blyth, Kirsty Hanley, Ralph Burton, Stephen Mobbs, Alan Gadian, Evelyne Richard, Jean-Pierre Chaboureau, Christian Barthlott, Bastian Kern, Thomas Schwitalla, Cyrille Flamant, Christian Keil, and Yann Seity

Subjects
Convection, 021110 strategic, defence & security studies, Atmospheric Science, Convective inhibition, 010504 meteorology & atmospheric sciences, Meteorology, Planetary boundary layer, 0211 other engineering and technologies, Mesoscale meteorology, Orography, 02 engineering and technology, Forcing (mathematics), 01 natural sciences, Convective available potential energy, Free convective layer, Physics::Fluid Dynamics, 13. Climate action, Climatology, Physics::Atmospheric and Oceanic Physics, Geology, 0105 earth and related environmental sciences
Abstract

The present study investigates the initiation of precipitating deep convection in an ensemble of convection-resolving mesoscale models. Results of eight different model runs from five non-hydrostatic models are compared for a case of the Convective and Orographically-induced Precipitation Study (COPS). An isolated convective cell initiated east of the Black Forest crest in southwest Germany, although convective available potential energy was only moderate and convective inhibition was high. Measurements revealed that, due to the absence of synoptic forcing, convection was initiated by local processes related to the orography. In particular, the lifting by low-level convergence in the planetary boundary layer is assumed to be the dominant process on that day. The models used different configurations as well as different initial and boundary conditions. By comparing the different model performance with each other and with measurements, the processes which need to be well represented to initiate convection at the right place and time are discussed. Besides an accurate specification of the thermodynamic and kinematic fields, the results highlight the role of boundary-layer convergence features for quantitative precipitation forecasts in mountainous terrain.

Published
2011
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6. Boundary-layer turbulent processes and mesoscale variability represented by Numerical Weather Prediction models during the BLLAST campaign

Author

Guylaine Canut, Fabienne Lohou, Fleur Couvreux, Yann Seity, Erik Nilsson, Eric Bazile, Marie Lothon, and Françoise Guichard

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, Advection, Cloud cover, 0208 environmental biotechnology, Meteorologi och atmosfärforskning, Mesoscale meteorology, 02 engineering and technology, Sensible heat, Atmospheric sciences, 01 natural sciences, lcsh:QC1-999, 020801 environmental engineering, lcsh:Chemistry, Boundary layer, lcsh:QD1-999, Meteorology and Atmospheric Sciences, Latent heat, Turbulence kinetic energy, Environmental science, Spatial variability, lcsh:Physics, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences
Abstract

This study evaluates the ability of three operational models, AROME, ARPEGE and ECMWF, to predict the boundary-layer turbulent processes and mesoscale variability observed during the Boundary Layer Late-Afternoon and Sunset Turbulence (BLLAST) field campaign. AROME is a 2.5 km limited area non-hydrostatic model operated over France, ARPEGE a global model with a 10 km grid-size over France and ECMWF a global model with a 16 km grid-size. We analyze the representation of the vertical profiles of temperature and humidity and the time evolution of near surface atmospheric variables as well as the radiative and turbulent fluxes for a total of 12 24h-long Intensive Observing Periods. Special attention is paid to the evolution of the turbulent kinetic energy that was sampled by a combination of independent instruments. For the first time, this variable, which is a central variable in the turbulence scheme used in AROME and ARPEGE, is evaluated with observations. In general, the 24h-forecasts succeed in reproducing the variability from one day to the other in term of cloud cover, temperature, boundary-layer depth. However, they exhibit some systematic biases, in particular a cold bias within the daytime boundary layer for all models. An overestimation of the sensible heat flux is noted for two points in ARPEGE, partly related to an inaccurate simplification of surface characteristics and over-predominance of forests. AROME shows a moist bias within the daytime boundary layer, consistently with overestimated latent heat fluxes. ECMWF presents a dry bias at 2 m above surface and also overestimates the sensible heat flux. The high-resolution model AROME better resolves the vertical structures, in particular the strong daytime inversion and the evening thin stable boundary layer. This model is also capable to capture the peculiar observed features, such as the orographically-driven subsidence and a well-defined maximum in water vapor mixing ratio in the upper part of the residual layer that arises during the evening due to mesoscale advection. The mesoscale variability is analyzed and the order of magnitude is also well reproduced in AROME. AROME provides a good simulation of the diurnal variability of the turbulent kinetic energy while ARPEGE shows a right order of magnitude.

Published
2016
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7. The SURFEXv7.2 land and ocean surface platform for coupled or offline simulation of Earth surface variables and fluxes

Author

Matthieu Lafaysse, G. Tanguy, Aurore Voldoire, Aaron Boone, A.-L. Gibelin, F. Bouyssel, Pierre Tulet, M. Mokhtari, Ramdane Alkama, Christine Delire, Dominique Carrer, Antoinette Alias, Florence Habets, C. Lebeaupin Brossier, Rui Salgado, F. Taillefer, Stéphanie Faroux, S. Donier, Sophie Belamari, K. Essaouini, Aude Lemonsu, Eric Brun, Bertrand Decharme, Pierre Brousseau, Béatrice Vincendon, G. Pigeon, Hervé Giordani, Jean-Christophe Calvet, Alina Barbu, P. Le Moigne, Vincent Vionnet, Sébastien Lafont, Jean-François Mahfouf, Yann Seity, S. Morin, G. Kerdraon, M. Jidane, P. Marguinaud, Ekaterina Kourzeneva, Valéry Masson, Eric Martin, 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), Centre national de recherches météorologiques [Casablanca] (CNRM), Maroc Météo, Structure et fonctionnement des systèmes hydriques continentaux (SISYPHE), Université Pierre et Marie Curie - Paris 6 (UPMC)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Mines Paris - PSL (École nationale supérieure des mines de Paris), Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Russian Sate Hydrometeorological University, Finnish Meteorological Institute (FMI), HMCI, 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 des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Office National de la Météorologie [Algeria] (ONM), Centro de Geofisica de Évora (CGE), Universidade de Évora, Laboratoire de l'Atmosphère et des Cyclones (LACy), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (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), Université Pierre et Marie Curie - Paris 6 (UPMC)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-MINES ParisTech - École nationale supérieure des mines de Paris, Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Météo France

Subjects
surface flux, model validation, food.ingredient, Meteorology, 010504 meteorology & atmospheric sciences, water flow, Mesoscale meteorology, 0207 environmental engineering, heat flux, 02 engineering and technology, Scientific modelling, 01 natural sciences, food, Range (statistics), 020701 environmental engineering, climate modeling, 0105 earth and related environmental sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Sea salt, lcsh:QE1-996.5, Mode (statistics), carbon dioxide, Numerical weather prediction, Snow, lcsh:Geology, Environmental science, Climate model, sea surface, numerical model, sea salt
Abstract

SURFEX is a new externalized land and ocean surface platform that describes the surface fluxes and the evolution of four types of surfaces: nature, town, inland water and ocean. It is mostly based on pre-existing, well-validated scientific models that are continuously improved. The motivation for the building of SURFEX is to use strictly identical scientific models in a high range of applications in order to mutualise the research and development efforts. SURFEX can be run in offline mode (0-D or 2-D runs) or in coupled mode (from mesoscale models to numerical weather prediction and climate models). An assimilation mode is included for numerical weather prediction and monitoring. In addition to momentum, heat and water fluxes, SURFEX is able to simulate fluxes of carbon dioxide, chemical species, continental aerosols, sea salt and snow particles. The main principles of the organisation of the surface are described first. Then, a survey is made of the scientific module (including the coupling strategy). Finally, the main applications of the code are summarised. The validation work undertaken shows that replacing the pre-existing surface models by SURFEX in these applications is usually associated with improved skill, as the numerous scientific developments contained in this community code are used to good advantage.

Published
2013
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8. Snow/atmosphere coupled simulation at Dome C, Antarctica

Author

Yann Seity, Vincent Guidard, Aaron Boone, Patrick Le Moigne, Eric Bazile, Eric Brun, Ghislain Picard, Laurent Arnaud, Christophe Genthon, Florence Rabier, Delphine Six, Vincent Vionnet, A. Bouchard, 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), CLIPS, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - 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 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)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - 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 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), UCAR subcontract 20020793, Concordiasi, CALVA, COMBINE, European Project, 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)-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)-Centre National de la Recherche Scientifique (CNRS)-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)-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)-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), 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)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), and 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)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010506 paleontology, 010504 meteorology & atmospheric sciences, Forcing (mathematics), Snowpack, Atmospheric sciences, Snow, 01 natural sciences, Atmosphere, Dome (geology), Data assimilation, Amplitude, 13. Climate action, Climatology, Polar, [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

Using a snow/atmosphere coupled model, the evolution of the surface and near-surface snow temperature is modeled at Dome C, Antarctica, during the period 20–30 January 2010. Firstly, the detailed multilayer snow model Crocus is run in stand-alone mode, with meteorological input forcing data provided by local meteorological observations. The snow model is able to simulate the evolution of surface temperature with good accuracy. It reproduces the observed downward propagation of the diurnal heatwave into the upper 50 cm of the snowpack reasonably well. Secondly, a fully coupled 3-D snow/atmosphere simulation is performed with the AROME regional meteorological model, for which the standard single-layer snow parameterization is replaced by Crocus. In spite of a poor simulation of clouds, the surface and near-surface snow temperatures are correctly simulated, showing neither significant bias nor drifts during the simulation period. The model reproduces particularly well the average decrease of the diurnal amplitude of air temperature from the surface to the top of the 45 m instrumented tower. This study highlights the potential of snow/atmosphere coupled models over the Antarctic plateau and the need to improve cloud microphysics and data assimilation over polar regions.

Published
2012
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9. Influence of high-resolution wind forcing on hydrodynamic modeling of the Gulf of Lions

Author

Yann Seity, Anne Molcard, Amandine Schaeffer, Pierre Garreau, Philippe Fraunié, Laboratoire de sondages électromagnétiques de l'environnement terrestre (LSEET), and Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS)

Subjects
CURRENTS, 010504 meteorology & atmospheric sciences, Wind stress curl, CALIFORNIA, Mesoscale meteorology, EDDY KINETIC-ENERGY, Oceanography, 01 natural sciences, CONTINENTAL-SHELF, Mediterranean sea, STRATIFICATION, Coastal modeling, MM5, 14. Life underwater, FORECASTING SYSTEM, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric models, Upwelling, OCEAN CIRCULATION, 010505 oceanography, WESTERN MEDITERRANEAN SEA, Inertial wave, VARIABILITY, 13. Climate action, Climatology, Temporal resolution, Gulf of Lions, High resolution atmospheric forcing, COASTAL OCEAN, Geology
Abstract

The impact of the choice of high-resolution atmospheric forcing on ocean summertime circulation in the Gulf of Lions (GoL; Mediterranean Sea) is evaluated using three different datasets: AROME (2.5 km, 1 h), ALADIN (9.5 km, 3 h), and MM5 (9 km, 3 h). A short-term ocean simulation covering a 3-month summer period was performed on a 400-m configuration of the GoL. The main regional features of both wind and oceanic dynamics were well-reproduced by all three atmospheric models. Yet, at smaller scales and for specific hydrodynamic processes, some differences became apparent. Inertial oscillations and mesoscale variability were accentuated when high-resolution forcing was used. Sensitivity tests suggest a predominant role for spatial rather than temporal resolution of wind. The determinant influence of wind stress curl was evidenced, both in the representation of a mesoscale eddy structure and in the generation of a specific upwelling cell in the north-western part of the gulf.

Published
2010

10. La campagne Cops : genèse et cycle de vie de la convection en région montagneuse

Author

Evelyne Richard, Yann Seity, G. Pigeon, Y. Pointin, Frédéric Tridon, Ch. Kottmeier, P. Di Girolamo, Juan Cuesta, Ulrich Corsmeier, J. van Baelen, S. Argence, Volker Wulfmeyer, Cédric Champollion, Jean-Pierre Chaboureau, Pierre Bosser, Frédéric Masson, P. Limnaios, François Bouttier, Christian Barthlott, Andreas Behrendt, Joel Arnault, Pierre Brousseau, C. Flamant, Martin Hagen, 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, TROPO - 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), Laboratoire de météorologie physique (LaMP), Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS), Géosciences Montpellier, Université des Antilles et de la Guyane (UAG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institute for Meteorology and Climate Research (IMK), Karlsruhe Institute of Technology (KIT), Institut für Physik und Meteorologie [Stuttgart] (IPM), Universität Hohenheim, LAboratoire de Recherche en Géodésie (LAREG), Ecole nationale des sciences géographiques (ENSG), Institut géographique national [IGN] (IGN)-Institut géographique national [IGN] (IGN), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (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), Dipartimento di Ingegneria e Fisica dell'Ambiente [Potenza] (Difa), Università degli studi della Basilicata [Potenza] (UNIBAS), DLR Institut für Physik der Atmosphäre (IPA), Deutsches Zentrum für Luft- und Raumfahrt [Oberpfaffenhofen-Wessling] (DLR), Météo-France [Paris], Météo France, Ecole et Observatoire des Sciences de la Terre (EOST), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), ANR, Cnes, programme Lefe/Idao de l’Insu et de Météo- France, Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-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)-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), 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 Blaise Pascal - Clermont-Ferrand 2 (UBP)-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)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), 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), Météo-France, and Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], 010504 meteorology & atmospheric sciences, 010501 environmental sciences, [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology, 01 natural sciences, 0105 earth and related environmental sciences
Abstract

International audience; The Convective and Orographically- induced Precipitation Study (COPS) is a coordinated international project, comprised of an observational field campaign and a research programme aiming to advance the quality of fore- casts of orographically-induced pre- cipitation by four-dimensional obser- vations and modelling of its life cycle. The COPS field campaign took place during June-July-August 2007 over eastern France and south-western Germany. Its main objective was to provide an unprecedented comprehen- sive set of in situ and remotely-sensed meteorological observations of the entire depth of the troposphere. After a short overview of the project, the paper focuses on the French contribution to the COPS field phase, describes the experimental setup and highlights some key observations.; L’étude des précipitations convectives induites par l’orographie (Cops selon l’acronyme anglais) est un projet inter- national coordonné qui comprend une campagne d’observations de terrain et un programme scientifique et qui vise à améliorer la qualité des prévisions des précipitations orographiques convectives à la fois par l’observation quadridimensionnelle et la modélisa- tion de leur cycle de vie. La campagne de terrain s’est déroulée en juin-juillet- août 2007 sur l’est de la France et le sud-ouest de l’Allemagne. Son objectif majeur était de fournir un jeu d’obser- vations météorologiques, in situ et à distance, aussi complet que possible et sur toute la profondeur de la colonne troposphérique.Après une brève revue d’ensemble du projet, l’article se concentre sur la contribution française à la campagne Cops, décrit le dispositif expérimental mis en œuvre et met en valeur quelques observations clés.

Published
2009
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11. Semi-Lagrangian advection scheme with controlled damping: An alternative to nonlinear horizontal diffusion in a numerical weather prediction model

Author

Pierre Bénard, Yann Seity, Filip Váňa, André Simon, Jean-François Geleyn, Czech Hydrometeorological Institute (CHMI), Slovak Hydrometeorological Institute, Slovak Hydrometeorological Institute (SHMU), 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
Scheme (programming language), [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Atmospheric Science, 010504 meteorology & atmospheric sciences, Advection, [MATH.MATH-CV]Mathematics [math]/Complex Variables [math.CV], [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology, 010502 geochemistry & geophysics, Numerical weather prediction, 01 natural sciences, Stability (probability), Interpolation, Nonlinear system, Flow (mathematics), Calculus, Applied mathematics, Diffusion (business), Numerical diffusion, computer, Aladin, 0105 earth and related environmental sciences, Mathematics, computer.programming_language
Abstract

International audience; This paper proposes a nonlinear horizontal diffusion scheme for models using semi-Lagrangian formulations. The scheme is made flow dependent and not entirely linked to the model levels. As an extension, the implementation of the scheme to the model Aladin is given. The damping abilities of interpolation are used for the diffusion filtering. The aim is to provide a horizontal diffusion scheme of similar stability and computational efficiency as the existing linear spectral diffusion scheme in Aladin. Preserving such qualities, the new scheme brings beneficial new skills to the model. The differences between the performances of the two diffusion schemes are examined and discussed. Finally, some interesting case-studies simulated with both horizontal diffusion schemes are presented.Copyright © 2008 Royal Meteorological Society

Published
2008
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12. Cloud-to-ground lightning activity in hail-bearing storms

Author

Yann Seity, Serge Soula, H. Sauvageot, and Laurent Féral

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, Soil Science, Aquatic Science, 010502 geochemistry & geophysics, Oceanography, Radar reflectivity, 01 natural sciences, Cloud to ground, law.invention, Geochemistry and Petrology, law, Earth and Planetary Sciences (miscellaneous), Precipitation, Radar, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Ecology, Paleontology, Peak current, Forestry, Storm, Reflectivity, Wavelength, Geophysics, 13. Climate action, Space and Planetary Science, Environmental science
Abstract

[1] The cloud-to-ground lightning flash (CG) produced by several apparent hailstorms are analyzed in different locations of southern Europe. The hail detection is performed via four different analysis techniques: radar reflectivity factor estimation, radar echo shape analysis, polarimetric hydrometeor identification, and reflectivity difference between radars with different wavelengths. The CG parameters considered are the flash rate and density, the flash polarity, the multiplicity, and the peak current. Some of the observed storms exhibit hail-bearing cell features, while others exhibit heavy precipitation rates without any apparent hail production. One of the hailstorms can be classified as severe because reported hailstorm diameters reach 39 mm. The CG lightning characteristics of both types of storms are compared. The CG rates corresponding to all hail-bearing storms are singularly lower than those of rain-only storms, typically by a factor 5. So, the CG rate of the hail-bearing storms considered does not exceed 2 min−1 while it can reach about 12 min−1 for heavy rain-bearing storms. Moreover, some of them can produce especially high positive CG proportions associated with negative CGs with low values of peak current and multiplicity. This last observation suggests that the negative charge available for CG flashes is weak within the cloud when positive CG flashes are dominant. In order to interpret the low CG rates observed in the case of hail-bearing storms several interpretations are discussed, but it would be necessary to know the intracloud flash activity in such cases of storms in order to enrich the discussion.

Published
2004
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13. The convective storm system during IOP 2a of MAP: Cloud-to-ground lightning flash production in relation to dynamics and microphysics

Author

Serge Soula, Yann Seity, Pierre Tabary, Georges Scialom, 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, 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), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), 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
Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, 0207 environmental engineering, Mesoscale meteorology, 02 engineering and technology, [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology, 01 natural sciences, law.invention, symbols.namesake, law, Storm microphysics and dynamics, Radar, 020701 environmental engineering, 0105 earth and related environmental sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Severe weather, Microphysics, Mesoscale Alpine Programme, Lightning, 13. Climate action, Convective storm detection, symbols, Environmental science, Doppler effect, Graupel
Abstract

This paper presents a study about correlation between cloud-to-ground lightning  ash (CG) activity, and the dynamics and microphysics of thunderclouds. Data collected during Intense Observation Period (MAP IOP) 2a of the Mesoscale Alpine Programme Special Observing Period (SOP) over the Lago Maggiore Target Area (LMTA) in northern Italy are used. IOP 2a was the most electrically active period during the SOP, representing 75% of the total CG activity. Thunderclouds were strongly vertically developed (the 30 dBZ echo tops were sometimes higher than 12 km) and produced large amounts of rainfall and some hail. Doppler and polarimetric radar data allow us to retrieve the three-dimensional wind and radar-reflectivity fields from two synchronous Doppler radars, and particle-type fields in the thunderclouds from the S-Pol polarimetric radar. Both polarities of CGs are distinguished. Temporal and spatial relationships from the global activity over the LMTA are first studied. Then, the temporal correlation between CG rates and dynamics or microphysics for five individual cells is considered. A very strong correlation is observed between CG and the presence of a mixture of graupel and hail, which strongly supports a non-inductive charging mechanism. CG impacts seem to be located underneath large radar-reflectivity values and around the maximum vertical velocities. Two individual cells are studied in more detail, in order to better understand their different electrical behaviours: the first produced mainly negative CGs, and the second produced 61% positive CGs in the second phase of its lifetime. The association of positive CGs with severe weather and especially with the presence of hail is observed.

Published
2003
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14. Extreme rainfall in Mediterranean France during the fall: added value of the CNRM-AROME Convection-Permitting Regional Climate Model

Author

Cécile Caillaud, Quentin Fumière, Samuel Somot, Olivier Laurantin, Yann Seity, Michel Déqué, O. Nuissier, Antoinette Alias, 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
Convection, Mediterranean climate, Atmospheric Science, Convection-Permitting Regional Climate Model, 010504 meteorology & atmospheric sciences, uc(cnrm-arome), Added value, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Forcing (mathematics), 010502 geochemistry & geophysics, 01 natural sciences, uc(aladin-c)limate, Heavy precipitating events, uc(comephore), 13. Climate action, [SDU]Sciences of the Universe [physics], Climatology, Environmental science, Common spatial pattern, Climate model, Precipitation, Scale (map), 0105 earth and related environmental sciences
Abstract

International audience; South-East France is a region often affected by heavy precipitating events the characteristics of which are likely to be significantly impacted in the future climate. In this study, uc(cnrm-arome), a Convection-Permitting Regional Climate Model with a 2.5 km horizontal resolution is compared to its forcing model, the Regional Climate Model uc(aladin-c)limate at a horizontal resolution of 12.5 km, self-driven by the uc(era-i)nterim reanalysis. An hourly observation dataset with a resolution of 1 km, uc(comephore), is used in order to assess simulated surface precipitation from a seasonal to hourly scale. The representation of the spatial pattern of fall precipitation climatology is improved by uc(cnrm-arome). It also shows a clear added value with respect to uc(aladin-c)limate through the improvement of the localization and intensity of extreme rainfall on a daily and hourly time scale on both fine and coarse spatial scales (2.5, 12.5 and 50 km). uc(cnrm-arome) in particular is able to simulate intense rainfall on lowlands and makes sub-daily rainfall events more intense than uc(aladin-c)limate. uc(cnrm-arome) still underestimates very extreme precipitation from above 30 mm/h or 230 mm/day.

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