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107. Turbulence anisotropy carried by streaks in the neutral atmospheric surface layer

Author

Dubos, Thomas, Drobinski, Philippe, and Carlotti, Pierre

Subjects
Anisotropy -- Measurement, Turbulence -- Observations, Planetary boundary layer -- Observations, Atmospheric research, Earth sciences, Science and technology
Abstract

The authors investigate the relationships between coherent structures and turbulence anisotropy in the neutral planetary boundary layer by means of empirical orthogonal function (EOF) analysis of large-eddy simulation (LES) data. The simulated flow contains near-surface transient streaks. The EOF analysis extracts the most energetic patterns from the velocity fluctuations based on their second-order spatial correlations. The scale and direction of streaks obtained from a level-by-level analysis of the LES flow field do correspond to that of the EOFs. It is found that two characteristics of the turbulence anisotropy depend on whether or not the velocity fluctuations with a given horizontal wave vector present distinct patterns: (i) the vertical extent up to which the turbulent kinetic energy (TKE) is concentrated and (ii) the ratio of the vertical TKE [E.sub.v] to the horizontal TKE [E.sub.H]. Although still present in the complete signal, this anisotropy is strongly emphasized when the signal is projected onto the EOF structures. Hence the coherent structures do indeed carry more anisotropy than the remaining turbulent fluctuations. Furthermore, at horizontal wave vectors where energetic patterns are dominant, the ratio [E.sub.v]/[E.sub.H] takes values close to 0.2, representative of the ratio [E.sub.v]/[E.sub.H] based on the total LES flow and on in situ measurements.

Published
2008

110. First Mediterranean Assessment Report – Chapter 3.3: Resources – Energy transition

Author

Drobinski, Philippe, Azzopardi, Brian, Allal, Houda Ben Janet, Bouchet, Vincent, Civel, Edouard, Creti, Anna, Duic, Neven, Fylaktos, Nestor, Mutale, Joseph, Pariente-David, Silvia, Ravetz, Joe, Taliotis, Constantinos, Vautard, Robert, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-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), Malta College of Arts, Science and Technology, Partenaires INRAE, Mediterranean Energy Observatory (OME), Paris, France, École polytechnique (i3-CRG), Palaiseau, France, Ecole Polytechnique, Palaiseau, France, Climate Economics Chair, Economics of Gas Chair, Paris Dauphine University, Paris, France, Faculty of Mechanical Engineering and Naval Architecture [Zagreb], University of Zagreb, The Cyprus Institute, Nicosia, Cyprus, University of Manchester [Manchester], International Energy Consultant, Marseille, France, Manchester Urban Institute, Manchester, United Kingdom, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), 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), Union for the Mediterranean (UfM) thanks to the financial support from the Swedish International Development Cooperation Agency (SIDA), United Nations Environment Programme / Mediterranean Action, Plan Bleu (Regional Activity Center of UNEP/MAP), Ministry of Foreign Affairs and Cooperation of the Principality of Monaco, [Cramer W, Guiot J, and Marini K (eds.)]

Subjects
Mitigation, Mediterranean Region, [SDE]Environmental Sciences, Climate change, Adaptation, Energy transition
Abstract

International audience

Published
2020

111. MedECC 2020 Summary for Policymakers. Climate and Environmental Change in the Mediterranean Basin – Current Situation and Risks for the Future. First Mediterranean Assessment Report

Author

Cramer, Wolfgang, Guiot, Joël, Marini, Katarzyna, Azzopardi, Brian, Balzan, Mario V, Semia Cherif, Doblas-Miranda, Enrique, Santos, Maria Dos, Drobinski, Philippe, Fader, Marianela, Hassoun, Abed El Rahman, Giupponi, Carlo, Koubi, Vassiliki, Lange, Manfred, Lionello, Piero, Llassat, Maria Carmen, Moncada, Stefano, Mrabet, Rachid, Paz, Shlomit, Savé, Robert, Snoussi, Maria, Toreti, Andrea, Vafeidis, Athanasios T., Xoplaki, Elena, Cramer Wolfgang, Guiot Joël, Marini Katarzyna, and MedECC

Subjects
Mediterranean, climate, environment, change, risks, science policy interface, scientific assessment
Abstract

The First Mediterranean Assessment Report (MAR1) prepared by the independent network of Mediterranean Experts on Climate and environmental Change (MedECC) founded in 2015 was published in November 2020. MAR1 assesses the best available scientific knowledge on climate and environmental change and associated risks in the Mediterranean Basin in order to render it accessible to policymakers, stakeholders and citizens. The report includes a Summary for Policymakers (SPM), which comprises the key messages of the MAR1. The report has been written by 190 scientists from 25 countries, all contributing in individual capacity and without financial compensation. The UNEP/MAP – Barcelona Convention Secretariat, through its Plan Bleu Regional Activity Center, and the Secretariat of the Union for the Mediterranean work in partnership to support MedECC, and to contribute to establish a sound and transparent scientific assessment process., Preferred citation: MedECC 2020 Summary for Policymakers. In: Climate and Environmental Change in the Mediterranean Basin – Current Situation and Risks for the Future. First Mediterranean Assessment Report [Cramer W, Guiot J, Marini K (eds.)] Union for the Mediterranean, Plan Bleu, UNEP/MAP, Marseille, France, pp 11-40, doi:10.5281/zenodo.5513887.

Published
2020
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113. Climate and environmental change in the Mediterranean Basin - current situation and risks for the future. First Mediterranean assessment report union for the Mediterranean

Author

Cramer, Wolfgang, Guiot, Joël, Marini, Katarzyna, Azzopardi, Brian, Balzan, Mario V., Cherif, Semia, Doblas-Miranda, Enrique, Dos Santos, Maria, Drobinski, Philippe, Fader, Marianela, Hassoun, Abed El Rahman, Giupponi, Carlo, Koubi, Vassiliki, Lange, Manfred, Lionello, Piero, Llasat, Maria Carmen, Moncada, Stefano, Mrabet, Rachid, Paz, Shlomit, Savé, Robert, Snoussi, Maria, Toreti, Andrea, Vafeidis, Athanasios T., and Xoplaki, Elena

Subjects
Global environmental change, Climatic changes -- Mediterranean Region, Sustainable development -- Mediterranean Region
Abstract

Virtually all sub-regions of the Mediterranean Basin, on land and in the sea, are impacted by recent anthropogenic changes in the environment. The main drivers of change include climate (temperature, precipitation, atmospheric circulation, extreme events, sea-level rise, sea water temperature, salinity and acidification), population increase, pollution, unsustainable land and sea use practices and non-indigenous species. In most areas, both natural ecosystems and human livelihoods are affected. Due to global and regional trends in the drivers, impacts will be exacerbated in the coming decades, especially if global warming exceeds 1.5 to 2°C above the pre-industrial level. Significantly enhanced efforts are needed in order to adapt to inevitable changes, mitigate change drivers and increase resilience. Due to anthropogenic emissions of greenhouse gases, climate is changing in the Mediterranean Basin, historically and projected by climate models, faster than global trends. Annual mean temperatures on land and sea across the Mediterranean Basin are 1.5°C higher than during pre-industrial times and they are projected to rise until 2100 by an additional 3.8 to 6.5°C for a high greenhouse gas concentration scenario (RCP8.5) and 0.5 to 2.0°C for a scenario compatible with the long-term goal of the UNFCCC Paris Agreement to keep the global temperature well below +2°C above the pre-industrial level (RCP2.6). On land and in the sea, heat waves will intensify in duration and peak temperatures. Despite strong regional variations, summer rainfall will likely be reduced by 10 to 30% in some regions, increasing existing water shortages, desertification and decreasing agricultural productivity., peer-reviewed

Published
2020

116. Numerical and experimental investigation of the neutral atmospheric surface layer

Author

Drobinski, Philippe, Carlotti, Pierre, Redelsperger, Jean-Luc, Banta, Robert M., Masson, Valery, and Newsom, Rob K.

Subjects
Eddies -- Research, Atmospheric turbulence -- Research, Winds -- Speed, Winds -- Spectra, Winds -- Research, Earth sciences, Science and technology
Abstract

This study combines the experimental measurements with large-eddy simulation (LES) data of a neutral planetary boundary layer (PBL) documented by a 60-m lower instrumented with eight sonic anemometers, and a high-resolution Doppler lidar during the 1999 Cooperative Atmospheric and Surface Exchange Study (CASES-99) experiment. The target of the paper is (i) to investigate the multiscale nature of the turbulent eddies in the surface layer (SL), (ii) to explain the existence of a -1 power law in the velocity fluctuation spectra, and (iii) to investigate the different nature of turbulence in the two sublayers within the SL, which are the eddy surface layer (ESL; lower sublayer of the SL lying between the surface and about 20-m height) and the shear surface layer (SSL; lying between the ESL top and the SL top). The sonic anemometers and Doppler lidar prove to be proper instruments for LES validation, and in particular, the Doppler lidar because of its ability to map near-surface eddies. This study shows the different nature of turbulence in the ESL and the SSL in terms of organized eddies, velocity fluctuation spectra, and second-order moment statistics. If quantitative agreement is found in the SSL between the LES and the measurements, only qualitative similarity is found in the ESL due to the subgrid-scale model, indicating that the LES captures part of the physics of the ESL. The LES helps explain the origin of the -1 power-law spectral subrange evidence in the velocity fluctuation spectra computed in the SL using the CASES-99 dataset: strong interaction between the mean flow and the fluctuating vorticities is found in the SL, and turbulent production is found to be larger than turbulent energy transfer for [k.sub.1]z> 1 ([k.sub.1] being the longitudinal wavenumber and z the height), which is the condition of the -1 power-law existence.

Published
2007

125. The structure of the near-neutral atmospheric surface layer

Author

Drobinski, Philippe, Carlotti, Pierre, Newsom, Rob K., Banta, Robert M., Foster, Ralph C., and Redelsperger, Jean-Luc

Subjects
Earth sciences, Science and technology
Abstract

Recent observational data (turbulence variables by sonic anemometers and three-dimensional flow pattern by Doppler lidar), obtained during the Cooperative Atmosphere Surface Exchange Study field campaign in October 1999 (CASES-99), show evidence of a layered structure of the near-neutral surface layer: (i) the eddy surface layer (ESL), which is the lower sublayer where blocking of impinging eddies is the dominating mechanism; and (ii) the shear surface layer (SSL), which is an intermediate sublayer, where shear affects the isotropy of turbulence. The origin of the eddies impinging from aloft (probably from the SSL) down to the ESL is preliminarily addressed in this study, since the Doppler lidar data show evidence of linearly organized eddies embedded in the surface layer (i.e., about 100-m vertical extent) and horizontally spaced by about 300 m. This is consistent with theories predicting that the primary mechanism of eddy motion in high Reynolds number wall layers is 'top-down.' The layered structure of the surface layer also has a visible effect on vertical profiles of vertical velocity variance (bar.[w.sup.2]) and momentum transport. In the ESL, (bar.[w.sup.2]) scales as [z.sup.2/3] while it is constant or slightly decreases within the SSL. Concerning momentum transport, ejections contribute identically to the momentum flux as do sweeps in the ESL, whereas in the SSL, ejections give about 50% higher relative contribution.

Published
2004

128. Effectiveness of simultaneous independent realizations at low carrier-to-noise ratio to improve heterodyne Doppler lidar performance. II. experimental results

Author

Guerit, Gaspard, Drobinski, Philippe, Augere, Beatrice, and Flamant, Pierre H.

Subjects
Optical radar -- Evaluation, Optical radar -- Usage, Doppler radar -- Evaluation, Doppler radar -- Usage, Astronomy, Physics
Abstract

A 1.55-[micro]m continuous-wave heterodyne Doppler lidar (HDL) with three receiver-detector units is used to validate experimentally the findings presented in the Guerit et al. companion paper [Appl. Opt. 41, 2232 (2002)] on the effectiveness of independent realizations to improve HDL performance (velocity or power estimates or both) at a low carrier-to-noise ratio (CNR). In fact, noise has a detrimental effect on the accumulation techniques, so in the Guerit et al. companion paper, the chances of getting 'heavy' speckles in HDL signals from many receiver-detector units on a single- or several-shot basis are investigated theoretically and numerically with the Zrnic HDL model. The experimental results enable us to conclude there is a very good agreement (better than 95%) between the performance computed from actual HDL data and from the theoretical predictions. OCIS codes: 010.3640, 040.2840, 030.1640, 040.3780.

Published
2002

129. Effectiveness of simultaneous independent realizations at low carrier-to-noise ratio to improve heterodyne Doppler lidar performance. I. Theory and numerical simulations

Author

Guerit, Gaspard, Drobinski, Philippe, Flamant, Pierre H., and Cariou, Jean-Pierre

Subjects
Optics -- Research, Optical radar -- Research, Astronomy, Physics
Abstract

It is shown that the performance of heterodyne Doppler lidar (HDL) can be improved by (i) at least one good realization for every single shot or (ii) several simultaneous good realizations for accumulation. Until now, several simultaneous independent realizations at high carrier-to-noise ratio (CNR) have been considered. At low CNR, noise may have a detrimental effect on the accumulation techniques. We determine the chances of getting 'heavy' speckles in HDL signals from many receiver--detector units on a single-shot basis and several good realizations on a single-shot basis, which is required for an effective accumulation. The use of multiple receiver--detector units at low CNR is worthwhile in contexts such as space lidar, where optimized treatment is at a premium. We conclude on the effectiveness of many receiver--detector units in parallel in order to achieve simultaneous independent realizations at low CNR to improve the performance of HDL on a statistical basis. OCIS codes: 010.3640, 040.2840, 030.1640, 040.3780.

Published
2002

136. Refractive-index structure parameter in the planetary boundary layer: comparison of measurements taken with a 10.6 micro-m coherent lidar, a 0.9 micro-m scintillometer, and in situ sensors

Author

Drobinski, Philippe, Dabas, Alain M., Delville, Patricia, Flamant, Pierre H., Pelon, Jacques, and Hardesty, R. Michael

Subjects
Planetary boundary layer -- Measurement, Atmospheric turbulence -- Measurement, Refractive index -- Models, Optical measurements -- Models, Astronomy, Physics
Abstract

An optical technique is described that determines the path-averaged value of a refractive-index structure parameter at 10.6 [[micro]meter] by use of a pulsed coherent C[O.sub.2] lidar in direct detection and hard-target returns. The lidar measurements are compared with measurements taken by a 0.9-[[micro]meter] scintillometer and temperature probe (with humidity corrections). The experimental results show good agreement for [[C.sub.n].sup.2] [greater than or equal to] [10.sup.-14] [m.sup.-2/3]. With respect to practical applications the new technique permits [[C.sub.n].sup.2] lidar measurements in a neutral meteorological situation to an unstably stratified convective boundary layer over long ranges (1 km or more).

Published
1999

139. Cyclone generation Algorithm including a THERmodynamic module for Integrated National damage Assessment (CATHERINA 1.0) compatible with CMIP climate data.

Author

Le Guenedal, Théo, Drobinski, Philippe, and Tankov, Peter

Subjects
*TROPICAL cyclones, *CYCLONES, *ATMOSPHERIC models, *NATURAL disasters, *ALGORITHMS, TROPICAL climate
Abstract

Tropical cyclones are responsible for a large share of global damage resulting from natural disasters and estimating cyclone-related damage at a national level is a challenge attracting growing interest in the context of climate change. The global climate models, whose outputs are available from the Coupled Model Intercomparison Project (CMIP), do not resolve tropical cyclones. The Cyclone generation Algorithm including a THERmodynamic module for Integrated National damage Assessment (CATHERINA) presented in this paper, couples statistical and thermodynamic relationships to generate synthetic tracks sensitive to local climate conditions and estimates the damage induced by tropical cyclones at a national level. The framework is designed to be compatible with CMIP models data offering a simple solution to resolve tropical cyclones in climate projections. We illustrate it by producing damage projections in Representative Concentration Pathways (RCP) at the global level and for individual countries. The algorithm contains a module to correct biases in climate models based on the distributions of the climate variables in the reanalyses. [ABSTRACT FROM AUTHOR]

Published
2021
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140. Aerosol indirect effects on summer precipitation in a regional climate model for the Euro-Mediterranean region

Author

Da Silva, Nicolas, Mailler, Sylvain, Drobinski, Philippe, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-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), and École des Ponts ParisTech (ENPC)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology
Abstract

Aerosols affect atmospheric dynamics through their direct and semi-direct effects as well as through their effects on cloud microphysics (indirect effects). The present study investigates the indirect effects of aerosols on summer precipitation in the Euro-Mediterranean region, which is located at the crossroads of air masses carrying both natural and anthropogenic aerosols. While it is difficult to disentangle the indirect effects of aerosols from the direct and semi-direct effects in reality, a numerical sensitivity experiment is carried out using the Weather Research and Forecasting (WRF) model, which allows us to isolate indirect effects, all other effects being equal. The Mediterranean hydrological cycle has often been studied using regional climate model (RCM) simulations with parameterized convection, which is the approach we adopt in the present study. For this purpose, the Thompson aerosol-aware microphysics scheme is used in a pair of simulations run at 50 km resolution with extremely high and low aerosol concentrations. An additional pair of simulations has been performed at a convection-permitting resolution (3.3 km) to examine these effects without the use of parameterized convection. While the reduced radiative flux due to the direct effects of the aerosols is already known to reduce precipitation amounts, there is still no general agreement on the sign and magnitude of the aerosol indirect forcing effect on precipitation, with various processes competing with each other. Although some processes tend to enhance precipitation amounts, some others tend to reduce them. In these simulations, increased aerosol loads lead to weaker precipitation in the parameterized (low-resolution) configuration. The fact that a similar result is obtained for a selected area in the convection-permitting (high-resolution) configuration allows for physical interpretations. By examining the key variables in the model outputs, we propose a causal chain that links the aerosol effects on microphysics to their simulated effect on precipitation, essentially through reduction of the radiative heating of the surface and corresponding reductions of surface temperature, resulting in increased atmospheric stability in the presence of high aerosol loads. Keywords. Atmospheric composition and structure (aerosols and particles)

Published
2019

142. E4CLIM 1.0: The Energy for a Climate Integrated Model: Description and Application to Italy

Author

Tantet, Alexis, Concettini, Silvia, d'Ambrosio, Claudia, Thomopulos, Dimitri, Tankov, Peter, St��fanon, Marc, Drobinski, Philippe, Badosa, Jordi, Cr��ti, Anna, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-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), Département de Mécanique de l'École polytechnique (X-DEP-MECA), École polytechnique (X), EconomiX, Université Paris Nanterre (UPN)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche juridique interdisciplinaire (IRJI), Université de Tours (UT), Département d'Économie de l'École Polytechnique (X-DEP-ECO), Centre de Géopolitique de l’Energie et des Matières Premières (LEDA-CGEMP), Laboratoire d'Economie de Dauphine (LEDa), Institut de Recherche pour le Développement (IRD)-Université Paris Dauphine-PSL, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Paris Dauphine-PSL, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'informatique de l'École polytechnique [Palaiseau] (LIX), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche en Économie et Statistique (CREST), Ecole Nationale de la Statistique et de l'Analyse de l'Information [Bruz] (ENSAI)-École polytechnique (X)-École Nationale de la Statistique et de l'Administration Économique (ENSAE Paris)-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)-École normale supérieure - Paris (ENS-PSL), Université de Tours, Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Paris Dauphine-PSL, and Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)

Subjects
FOS: Computer and information sciences, climate variability, Control and Optimization, 010504 meteorology & atmospheric sciences, Computer science, 020209 energy, Energy Engineering and Power Technology, 02 engineering and technology, 01 natural sciences, 7. Clean energy, Statistics - Applications, lcsh:Technology, Robustness (computer science), 0202 electrical engineering, electronic engineering, information engineering, [INFO]Computer Science [cs], Applications (stat.AP), Electrical and Electronic Engineering, Engineering (miscellaneous), 0105 earth and related environmental sciences, [STAT.AP]Statistics [stat]/Applications [stat.AP], Renewable Energy, Sustainability and the Environment, business.industry, lcsh:T, [SPI.NRJ]Engineering Sciences [physics]/Electric power, Energy mix, Environmental economics, sensitivity, renewable energy, Renewable energy, energy mix, mean-variance, 13. Climate action, Software deployment, business, Energy (miscellaneous)
Abstract

We develop an open-source Python software integrating flexibility needs from Variable Renewable Energies (VREs) in the development of regional energy mixes. It provides a flexible and extensible tool to researchers/engineers, and for education/outreach. It aims at evaluating and optimizing energy deployment strategies with higher shares of VRE, assessing the impact of new technologies and of climate variability and conducting sensitivity studies. Specifically, to limit the algorithm’s complexity, we avoid solving a full-mix cost-minimization problem by taking the mean and variance of the renewable production−demand ratio as proxies to balance services. Second, observations of VRE technologies being typically too short or nonexistent, the hourly demand and production are estimated from climate time series and fitted to available observations. We illustrate e4clim’s potential with an optimal recommissioning-study of the 2015 Italian PV-wind mix testing different climate data sources and strategies and assessing the impact of climate variability and the robustness of the results.

Published
2019

143. Process-based evaluation of the VALUE perfect predictor experiment of statistical downscaling methods

Author

Soares, Pedro M. M., Maraun, Douglas, Brands, Swen, Jury, Martin, Gutiérrez, José M., San-Martín, Daniel, Hertig, Elke, Belušić Vozila, A., Cardoso, Rita M., Kotlarski, Sven, Drobinski, Philippe, Obermann-Hellhund, A., Soares, Pedro M. M., Maraun, Douglas, Brands, Swen, Jury, Martin, Gutiérrez, José M., San-Martín, Daniel, Hertig, Elke, Belušić Vozila, A., Cardoso, Rita M., Kotlarski, Sven, Drobinski, Philippe, and Obermann-Hellhund, A.

Abstract

Statistical downscaling methods (SDMs) are techniques used to downscale and/or bias-correct climate model results to regional or local scales. The European network VALUE developed a framework to evaluate and inter-compare SDMs. One of VALUE's experiments is the perfect predictor experiment that uses reanalysis predictors to isolate downscaling skill. Most evaluation papers for SDMs employ simple statistical diagnostics and do not follow a process-based rationale. Thus, in this paper, a process-based evaluation has been conducted for the more than 40 participating model output statistics (MOS, mostly bias correction) and perfect prognosis (PP) methods, for temperature and precipitation at 86 weather stations across Europe. The SDMs are analysed following the so-called “regime-oriented” technique, focussing on relevant features of the atmospheric circulation at large to local scales. These features comprise the North Atlantic Oscillation, blocking and selected Lamb weather types and at local scales the bora wind and the western Iberian coastal-low level jet. The representation of the local weather response to the selected features depends strongly on the method class. As expected, MOS is unable to generate process sensitivity when it is not simulated by the predictors (ERA-Interim). Moreover, MOS often suffers from an inflation effect when a predictor is used for more than one station. The PP performance is very diverse and depends strongly on the implementation. Although conditioned on predictors that typically describe the large-scale circulation, PP often fails in capturing the process sensitivity correctly. Stochastic generalized linear models supported by well-chosen predictors show improved skill to represent the sensitivities.

Published
2019

145. Untangling the Mistral and seasonal atmospheric forcing driving deep convection in the Gulf of Lion: 2012-2013.

Author

Keller Jr, Douglas, Givon, Yonatan, Pennel, Romain, Raveh-Rubin, Shira, and Drobinski, Philippe

Subjects
SEASONS, AUTUMNAL equinox, VERNAL equinox, HEAT flux
Abstract

Deep convection in the Gulf of Lion is believed to be primarily driven by the Mistral winds. However, our findings show that the seasonal atmospheric change provides roughly 2/3 of the buoyancy loss required for deep convection to occur, for the 2012 to 2013 year, with the Mistral supplying the final 1/3. Two NEMOMED12 ocean simulations of the Mediterranean Sea were run for the Aug. 1st, 2012 to July 31st, 2013 year, forced with two sets of atmospheric forcing data from a RegIPSL coupled run within the Med-CORDEX framework. One set of atmospheric forcing data was left unmodified, while the other was filtered to remove the signal of the Mistral. The Control simulation featured deep convection, while the Seasonal did not. A simple model was derived, relating the anomaly scale forcing (the difference between the Control and Seasonal runs) and the seasonal scale forcing to the ocean response through the Stratification Index. This simple model revealed that the Mistral's effect on buoyancy loss depends more on its strength rather than its frequency or duration. The simple model also revealed that the seasonal cycle of the Stratification Index is equal to the net surface heat flux over the course of the year, with the stratification maximum and minimum occurring roughly at the fall and spring equinoxes. [ABSTRACT FROM AUTHOR]

Published
2021
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146. Sub-chapter 1.3.2. Strong winds

Author

Drobinski, Philippe, Alpert, Pinhas, Cavicchia, Leone, Flaounas, Emmanouil, Hochman, Assaf, and Kotroni, Vassilki

Abstract

Introduction The Mediterranean Sea is an almost enclosed basin surrounded by mountain chains with a complex coastal orography and numerous islands, many of which mountainous. The complexity of the physiographic characteristics deeply influences the atmospheric circulation at local scale, giving rise to strong regional wind regimes (see fig. 1) (HMSO, 1962). In the Alboran Sea (the westernmost Mediterranean), the levanter blows from the east and in winter it can be strong and long lasting (up ...

Published
2018

147. Sub-chapter 1.2.1. The water cycle in the Mediterranean

Author

Ducrocq, Véronique, Drobinski, Philippe, Gualdi, Silvio, and Raimbault, Patrick

Abstract

Introduction The Mediterranean region has quite a unique character that results both from physiographic conditions and historical and societal developments. Because of the latitude range it covers, the Mediterranean region is a transition area under the influence of both the temperate mid-latitude climate and the hotter-drier North-African climate. In addition, the region features a nearly enclosed sea surrounded by highly urbanized littorals and mountains in which numerous rivers have their ...

Published
2018

148. The Mediterranean region under climate change

Author

A. Osman, Mona, Aboul-Naga, Adel, Adallal, Rachid, Aderghal, Mohamed, Afif, Charbel, Alary, Véronique, Alifriqui, Mohamed, Alkama, Rezak, Alleaume, Samuel, Alpert, Pinhas, Ancona, Carla, Annabi, Mohamed, Annesi-Maesano, Isabella, Anquetin, Sandrine, Ardilouze, Constantin, Auclair, Laurent, Aumeeruddy-Thomas, Yildiz, Azuara, Julien, B. Nicolas, José, Badri, Wadi, Bailly, Alicia, Baldy, Virginie, Bard, Edouard, Barouki, Robert, Barre, Philippe, Bassetti, Maria-Angela, Batté, Lauriane, Baudoin, Ezekiel, Beekmann, Matthias, Belhimer, Ammar, Benaïssa, Fatima, Benedetti, Fabio, Benjelloun, Badr, Benkaddour, Abdel, Ben Rais Lasram, Frida, Bergametti, Gilles, Berger, Jean-François, Bernoux, Martial, Beveren, Elisabeth Van, Bissonnais, Yves Le, Blanchet, Juliette, Blanfuné, Aurélie, Boissard, Christophe, Bonnet, Pascal, Boone, Aaron, Borbon, Agnès, Borga, Marco, Boudevillain, Brice, Bouet, Christel, Boulet, Gilles, Bounouara, Zohra, Bou Dagher, Magda, Brahim, Nadhem, Bras, Jean-Philippe, Braud, Isabelle, Briche, Elodie, Brousseau, Pierre, Cardinael, Rémi, Carozza, Jean-Michel, Carozza, Laurent, Cavicchia, Leone, Chapron, Emmanuel, Charef, Mohamed, Charki, Abderafi, Chenu, Claire, Chevallier, Tiphaine, Chiraz, Belhadj Kheder, Chotte, Jean-Luc, Colette, Augustin, Coll, Marta, Combourieu-Nebout, Nathalie, Coppola, Erika, Costes, Evelyne, Cournac, Laurent, Courp, Thierry, Cozannet, Gonéri Le, Cramer, Wolfgang, Creutin, Jean-Dominique, Dahech, Salem, Dakhlaoui, Hamouda, Daoud, Ibrahim, Darmaraki, Sofia, Darras, Sabine, Dayan, Uri, Débevec, Cécile, Delon, Claire, Delrieu, Guy, Déqué, Michel, Derridj, Arezki, Desboeufs, Karine, Dezileau, Laurent, Diakakis, Michalis, Di Sarra, Alcide, Dollé, Vincent, Doraï, Kamel, Dounias, Edmond, Douvinet, Johnny, Driouech, Fatima, Drobinski, Philippe, Ducrocq, Véronique, Dulac, François, Duponnois, Robin, Dupret, Baudouin, Durand, Pierre, Dusanter, Sébastien, D’Anna, Barbara, Elyazami, Driss, El Mehdi Saidi, Mohamed, Fady, Bruno, Fakir, Younes, Farah, Wehbeh, Fehri, Noômène, Fernandez, Catherine, Fischer, Claude, Flaounas, Emmanouil, Forastiere, Francesco, Formenti, Paola, Forslund, Agneta, Fourrié, Nadia, François Boudouresque, Charles, Galiana, Antoine, Gallali, Tahar, Garcia, Marta, Gaume, Eric, Gauquelin, Thierry, Geniez, Philippe, Genin, Didier, Genty, Dominique, Ghilardi, Matthieu, Gourley, Jonathan, Gros, Valérie, Gualdi, Silvio, Guégan, Jean-François, Guilhaumon, François, Guiot, Joël, Hachicha, Mohamed, Haddouch, Hassan, Hafidi, Mohamed, Haité, Hakima El, Halouani, Ghassen, Hamdi, Salwa, Hamdi-Aissa, Baelhadj, Hamonou, Eric, Hanich, Lahoucine, Harzallah, Ali, Hattab, Tarek, Hebert, Bertil, Himbert, Marc, Hmimsa, Younes, Hochman, Assaf, Hugot, Laetitia, Jalali, Bassem, Jambert, Corinne, Jarlan, Lionel, Javelle, Pierre, Joffre, Richard, Jorda, Gabriel, Jouve, Guillaume, Kallel, Nejib, Kallida, Rajae, Kathra, Nabil Ben, Khabba, Saïd, Khadari, Bouchaib, Khatteli, Houcine, Kotroni, Vassilki, Kuzucuoglu, Catherine, Labiadh, Mohamed, Lacroix, Denis, Lang, Michel, Lasram, Frida Ben Rais, Lasseur, Jacques, Lathière, Juliette, Laurent, Benoît, Leduc, Christian, Legave, Jean-Michel, Leriche, Maud, Lespez, Laurent, Le Loc’H, François, Li, Laurent, Lili-Chabaane, Zohra, Limousin, Jean-Marc, Lionello, Piero, Liousse, Catherine, Llasat, Maria Carmen, 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Raclot, Damien, Raimbault, Patrick, Rajot, Jean-Louis, Ramadan Ali, Rafat, Rambal, Serge, Regnard, Jean-Luc, Remini, Boualem, Renard, Jean-Baptiste, Rhaz, Khalid EL, Rhoujjati, Ali, Ricaud, Philippe, Richard, Franck, Ruelland, Denis, Ruin, Isabelle, Sabir, Mohamed, Saint-Martin, Clotilde, Salah, Ehab, Salameh, Thérèse, Sánchez, Enrique, Sanguin, Hervé, Saraux, Claire, Sartelet, Karine, Satta, Alessio, Sauvage, Stéphane, Schatz, Bertrand, Schmitt, Bertrand, Sciare, Jean, Scolobig, Anna, Sellegri, Karine, Shin, Yunne-Jai, Sicard, Michaël, Sicre, Marie-Alexandrine, Silva, Anne Da, Simenel, Romain, Simmoneau, Anaëlle, Slimani, Said, Snoussi, Maria, Solmon, Fabien, Somot, Samuel, Sonzogni, Corinne, Soussana, Jean-François, Stafoggia, Massimo, Sylvestre, Florence, Szczypta, Camille, Tachikawa, Kazuyo, Taschen, Elisa, Thibaut, Thierry, Thibon, Maxime, Thiébault, Stéphanie, Torquebiau, Emmanuel, Tramblay, Yves, Valentin, Christian, Vallet-Coulomb, Christine, Vanniere, Boris, Vennetier, Michel, Verlaque, Marc, Vicente-Serrano, Sergio, Vidal, Jean-Philippe, Vidal, Laurence, Vinet, Freddy, Viry, Elisabeth, Vogt-Schilb, Hélène, Volaire, Florence, Voltz, Marc, Waked, Antoine, Wattrelot, Eric, Yazami, Driss El, Zaher, Hayat, Zappa, Massimiliano, Zbinden, Régina, Zitouna-Chebbi, Rim, Zribi, Mehrez, Moatti, Jean-Paul, and Thiébault, Stéphane

Subjects
Méditerranée, Allenvi, changement climatique, climatic change, RNK, Environmental Studies, COP22, Mediterranean, NAT011000
Abstract

This book has been published by Allenvi (French National Alliance for Environmental Research) to coincide with the 22nd Conference of Parties to the United Nations Framework Convention on Climate Change (COP22) in Marrakesh. It is the outcome of work by academic researchers on both sides of the Mediterranean and provides a remarkable scientific review of the mechanisms of climate change and its impacts on the environment, the economy, health and Mediterranean societies. It will also be valuable in developing responses that draw on “scientific evidence” to address the issues of adaptation, resource conservation, solutions and risk prevention. Reflecting the full complexity of the Mediterranean environment, the book is a major scientific contribution to the climate issue, where various scientific considerations converge to break down the boundaries between disciplines.

Published
2018

149. The VALUE perfect predictor experiment of statistical downscaling methods: process-based evaluation

Author

Soares, Pedro, Maraun, Douglas, Brands, Swen, Jury, Martin, Gutiérrez, Jose, San Martin, Daniel, Hertig, Elke, Huth, Radan, Belušić, Andreina, Cardoso, Rita, Kotlarski, Sven, Drobinski, Philippe, and Obermann Hellhund, Anika

Subjects
VALUE, downscaling, atmospheric circulation
Abstract

Statistical downscaling methods (SDMs) are techniques used to downscale and/or bias correct climate model results to regional or local scales. The European network VALUE developed a framework to evaluate and intercompare SDMs. One of VALUE’s experiments is the perfect predictor experiment that uses reanalysis predictors to isolate downscaling skill. Most evaluation papers for SDMs employ simple statistical diagnostics and do not follow a process-based rationale. Thus, in this paper, a process-based evaluation has been conducted for the more than 40 participating model output statistics (MOS, mostly bias correction) and perfect prognosis (PP) methods, for temperature and precipitation at 86 weather stations across Europe. The SDMs are analysed following the so-called “regime-oriented” technique, focussing on relevant features of the atmospheric circulation at large to local scales. These features comprise the North Atlantic Oscillation, blocking and selected Lamb weather types and at local scales the bora wind and the western Iberian coastal-low level jet. The representation of the local weather response to the selected features depends strongly on the method class. As expected, MOS is unable to generate process sensitivity when it is not simulated by the predictors (ERA-Interim). Moreover, MOS often suffers from an inflation effect when a predictor is used for more than one station. The PP performance is very diverse and depends strongly on the implementation. Although conditioned on predictors that typically describe the large-scale circulation, PP often fails in capturing the process sensitivity correctly. Stochastic generalized linear models supported by well- chosen predictors show improved skill to represent the sensitivities.

Published
2018

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