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1. Precipitation frequency in Med-CORDEX and EURO-CORDEX ensembles from 0.44° to convection-permitting resolution: impact of model resolution and convection representation

Author

Ha, Minh T., Bastin, Sophie, Drobinski, Philippe, Fita, L., Polcher, J., Bock, O., Chiriaco, M., Belušić, D., Caillaud, C., Dobler, A., Fernandez, J., Goergen, K., Hodnebrog, Ø., Kartsios, S., Katragkou, E., Lavin-Gullon, A., Lorenz, T., Milovac, J., Panitz, H.-J., Sobolowski, S., Truhetz, H., Warrach-Sagi, K., and Wulfmeyer, V.

Published
2024
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3. Key results and implications from phase 1(c) of the Project for Intercomparison of Land-surface Parametrization Schemes

Author

Pitman, AJ, Henderson-Sellers, A, Desborough, CE, Yang, Z-L, Abramopoulos, F, Boone, A, Dickinson, RE, Gedney, N, Koster, R, Kowalczyk, E, Lettenmaier, D, Liang, X, Mahfouf, J-F, Noilhan, J, Polcher, J, Qu, W, Robock, A, Rosenzweig, C, Schlosser, CA, Shmakin, AB, Smith, J, Suarez, M, Verseghy, D, Wetzel, P, Wood, E, and Xue, Y

Subjects
Life on Land, Climate Action, Atmospheric Sciences, Oceanography, Physical Geography and Environmental Geoscience, Meteorology & Atmospheric Sciences
Abstract

Using atmospheric forcing data generated from a general circulation climate model, sixteen land surface schemes participating in the Project for the Intercomparison of Land-surface Parametrization Schemes (PILPS) were run off-line to equilibrium using forcing data from a GCM representative of a tropical forest and a mid-latitude grassland grid point. The values for each land surface parameter (roughness length, minimum stomatal resistance, soil depth etc.) were provided. Results were quality controlled and analyzed, focusing on the scatter simulated amongst the models. There were large differences in how the models' partitioned available energy between sensible and latent heat. Annually averaged, simulations for the tropical forest ranged by 79 W m-2 for the sensible heat flux and 80 W m-2 for the latent heat flux. For the grassland, simulations ranged by 34 W m-2 for the sensible heat flux and 27 W m-2 for the latent heat flux. Similarly large differences were found for simulated runoff and soil moisture and at the monthly time scale. The models' simulation of annually averaged effective radiative temperature varied with a range, between all the models, of 1.4 K for tropical forest and 2.2 K for the grassland. The simulation of latent and sensible heat fluxes by a standard 'bucket' models was anomalous although this could be corrected by an additional resistance term. These results imply that the current land surface models do not agree on the land surface climate when the atmospheric forcing and surface parameters are prescribed. The nature of the experimental design, it being offline and with artificial forcing, generally precludes judgements concerning the relative quality of any specific model. Although these results were produced de-coupled from a host model, they do cast doubt on the reliability of land surface schemes. It is therefore a priority to resolve the disparity in the simulations, understand the reasons behind the scatter and to determine whether this lack of agreement in decoupled tests is reproduced in coupled experiments.

Published
1999

4. A proposal for a general interface between land surface schemes and general circulation models

Author

Polcher, J, McAvaney, B, Viterbo, P, Gaertner, M-A, Hahmann, A, Mahfouf, J-F, Noilhan, J, Phillips, T, Pitman, A, Schlosser, CA, Schulz, J-P, Timbal, B, Verseghy, D, and Xue, Y

Subjects
PILPS, land surface schemes, general circulation models, coupling land surface schemes, Earth Sciences, Networking & Telecommunications
Abstract

The aim of this paper is to propose a general interface for coupling general circulation models (GCMs) to land surface schemes (LSS) in order to achieve a plug compatibility between these complex models. As surface parameterizations include more processes, they have moved from being subroutines of GCMs to independent schemes which can also be applied for other purposes. This evolution has raised the problem within climate modeling groups of coupling these schemes to GCMs in a simple and flexible way. As LSS reaches a larger independence, a general interface is needed to enable exchange within the community. This paper discusses the tasks LSS have to fulfill when coupled to a GCM after a review of the current state of the art and the likely future evolutions of both components. The numerical schemes used for the processes which couple the land surfaces to the atmosphere are reviewed to ensure that the interface can be applied to all LSS and GCMs after only minor changes.

Published
1998

5. Land Surface Energy and Moisture Fluxes: Comparing Three Models

Author

Schulz, J-P, Dümenil, L, Polcher, J, Schlosser, CA, and Xue, Y

Subjects
Atmospheric Sciences, Environmental Science and Management, Agriculture, Land and Farm Management, Meteorology & Atmospheric Sciences
Abstract

Three different land surface schemes that are designed for use in atmospheric general circulation models are compared. They were run in offline mode with identical atmospheric forcing values that were observed at Cabauw. This procedure allows one to analyze differences in the simulations that are not caused by different atmospheric conditions and to relate them to certain model characteristics. The intercomparison shows that the models produced similar results for surface temperature and total net radiation, which are also in good agreement with the observations. But they underestimate latent heat flux and overestimate sensible heat flux in summer. Differences in the components of energy and hydrological cycle as simulated by the schemes can be related to differences in model structures. The calculation of the surface temperature is of major importance, particularly on a diurnal timescale. Depending on the scheme chosen, the simulated surface temperature is closer to the observed radiative surface temperature or the observed soil temperature at a depth of a few centimeters. If a land surface scheme is going to be coupled to an atmospheric model, this needs to be considered. The simulation of the surface energy fluxes can be improved by careful calibration of the relevant parameters according to the conditions at the observational site. The stomatal resistance was found to be an essential parameter in determining the evolution of evapotranspiration for the Cabauw simulations.

Published
1998

6. Cabauw Experimental Results from the Project for Intercomparison of Land-Surface Parameterization Schemes

Author

Chen, TH, Henderson-Sellers, A, Milly, PCD, Pitman, AJ, Beljaars, ACM, Polcher, J, Abramopoulos, F, Boone, A, Chang, S, Chen, F, Dai, Y, Desborough, CE, Dickinson, RE, Dümenil, L, Ek, M, Garratt, JR, Gedney, N, Gusev, YM, Kim, J, Koster, R, Kowalczyk, EA, Laval, K, Lean, J, Lettenmaier, D, Liang, X, Mahfouf, J-F, Mengelkamp, H-T, Mitchell, K, Nasonova, ON, Noilhan, J, Robock, A, Rosenzweig, C, Schaake, J, Schlosser, CA, Schulz, J-P, Shao, Y, Shmakin, AB, Verseghy, DL, Wetzel, P, Wood, EF, Xue, Y, Yang, Z-L, and Zeng, Q

Subjects
Atmospheric Sciences, Oceanography, Geomatic Engineering, Meteorology & Atmospheric Sciences
Published
1997

7. Precipitation frequency in Med-CORDEX and EURO-CORDEX ensembles from 0.44° to convection-permitting resolution: impact of model resolution and convection representation

Author

Ha, Minh T., primary, Bastin, Sophie, additional, Drobinski, Philippe, additional, Fita, L., additional, Polcher, J., additional, Bock, O., additional, Chiriaco, M., additional, Belušić, D., additional, Caillaud, C., additional, Dobler, A., additional, Fernandez, J., additional, Goergen, K., additional, Hodnebrog, Ø., additional, Kartsios, S., additional, Katragkou, E., additional, Lavin-Gullon, A., additional, Lorenz, T., additional, Milovac, J., additional, Panitz, H.-J., additional, Sobolowski, S., additional, Truhetz, H., additional, Warrach-Sagi, K., additional, and Wulfmeyer, V., additional

Published
2022
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8. High-resolution hydrological simulation and projection over France with the ORCHIDEE land surface model

Author

Huang, P., Ducharne, A., Rinchiuso, L., Polcher, J., Baratgin, L., Peylin, P., Bastrikov, V., Héraut, L., and Sauquet, E.

Abstract

In land surface models (LSMs), the land surface components of ESMs, the spatial resolution is usually the one of the atmospheric component or the atmospheric forcing (in offline mode), thus too coarse to represent topographic details and achieve accurate hydrological simulations.Here, we present hydrological simulations over France, using the Organising Carbon and Hydrology in Dynamic Ecosystems (ORCHIDEE) LSM over France, forced with SAFRAN atmospheric reanalysis at 8-km resolution and hourly time step since 1959 (Vidal et al., 2010), and using a high-resolution river routing network relying on the MERIT-Hydro topography at 2-km resolution (Yamazaki et al., 2019). Each SAFRAN grid is decomposed into a graph of hydrological transfer units (HTUs) based on MERIT-Hydro (Polcher et al., 2022), so that lateral water movements are described at a higher spatial resolution than SAFRAN grids. In particular, it was possible to accurately position over 4000 stations from the national hydrometric network (filtered to drain an upstream area larger than 64 km²), at which the performance of the simulation is assessed over the 1976-2019 period, using classical hydrological indicators on river discharge and evapotranspiration, complemented by trend analysis.Finally, this ORCHIDEE setup will be used to simulate future French river discharges using the DRIAS-2020 climate forcing, consisting in a multi-model multi-scenario ensemble of climate projections selected from the Euro-Cordex ensemble, regionalized and bias-corrected with respect to the SAFRAN reanalysis. We will present an overview of the resulting river discharge projections, which contribute to the national Explore2 project (https://professionnels.ofb.fr/node/1244)., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023
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9. Precipitation frequency in Med-CORDEX and EURO-CORDEX ensembles from 0.44 degrees to convection-permitting resolution : impact of model resolution and convection representation

Author

Ha, Minh T., Bastin, Sophie, Drobinski, Philippe, Fita, L., Polcher, J., Bock, O., Chiriaco, M., Belušić, Danijel, Caillaud, C., Dobler, A., Fernandez, J., Goergen, K., Hodnebrog, O., Kartsios, S., Katragkou, E., Lavin-Gullon, A., Lorenz, T., Milovac, J., Panitz, H. -j., Sobolowski, S., Truhetz, H., Warrach-Sagi, K., Wulfmeyer, V., Ha, Minh T., Bastin, Sophie, Drobinski, Philippe, Fita, L., Polcher, J., Bock, O., Chiriaco, M., Belušić, Danijel, Caillaud, C., Dobler, A., Fernandez, J., Goergen, K., Hodnebrog, O., Kartsios, S., Katragkou, E., Lavin-Gullon, A., Lorenz, T., Milovac, J., Panitz, H. -j., Sobolowski, S., Truhetz, H., Warrach-Sagi, K., and Wulfmeyer, V.

Published
2022
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10. Precipitation Frequency in Med-CORDEX and EURO-CORDEX Ensembles from 0.44° to Convection-Permitting Resolution: Impact of Model Resolution and Convection Representation

Author

Ha, Minh Truong, primary, Bastin, S., additional, Drobinski, P., additional, Fita, L., additional, Polcher, J., additional, Bock, O., additional, Chiriaco, M., additional, Belušić, D., additional, Caillaud, C., additional, Dobler, A., additional, Fernandez, J., additional, Goergen, K., additional, Hodnebrog, Ø., additional, Kartsios, S., additional, Katragkou, E., additional, Lavin-Gullon, A., additional, Lorenz, T., additional, Milovac, J., additional, Panitz, H.-J., additional, Sobolowski, S., additional, Truhetz, H., additional, Warrach-Sagi, K., additional, and Wulfmeyer, V., additional

Published
2022
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11. Reply

Author

Best, M. J., Beljaars, A., Polcher, J., and Viterbo, P.

Published
2006

14. The Rhône-Aggregation Land Surface Scheme Intercomparison Project : An Overview

Author

Boone, A., Habets, F., Noilhan, J., Clark, D., Dirmeyer, P., Fox, S., Gusev, Y., Haddeland, I., Koster, R., Lohmann, D., Mahanama, S., Mitchell, K., Nasonova, O., Niu, G.-Y., Pitman, A., Polcher, J., Shmakin, A. B., Tanaka, K., van den Hurk, B., Vérant, S., Verseghy, D., Viterbo, P., and Yang, Z.-L.

Published
2004

17. Climate change projections using the IPSL-CM5 Earth System Model: from CMIP3 to CMIP5

Author

Dufresne, J.-L., Foujols, M.-A., Denvil, S., Caubel, A., Marti, O., Aumont, O., Balkanski, Y., Bekki, S., Bellenger, H., Benshila, R., Bony, S., Bopp, L., Braconnot, P., Brockmann, P., Cadule, P., Cheruy, F., Codron, F., Cozic, A., Cugnet, D., de Noblet, N., Duvel, J.-P., Ethé, C., Fairhead, L., Fichefet, T., Flavoni, S., Friedlingstein, P., Grandpeix, J.-Y., Guez, L., Guilyardi, E., Hauglustaine, D., Hourdin, F., Idelkadi, A., Ghattas, J., Joussaume, S., Kageyama, M., Krinner, G., Labetoulle, S., Lahellec, A., Lefebvre, M.-P., Lefevre, F., Levy, C., Li, Z. X., Lloyd, J., Lott, F., Madec, G., Mancip, M., Marchand, M., Masson, S., Meurdesoif, Y., Mignot, J., Musat, I., Parouty, S., Polcher, J., Rio, C., Schulz, M., Swingedouw, D., Szopa, S., Talandier, C., Terray, P., Viovy, N., and Vuichard, N.

Published
2013
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18. Deforestation Impacts on Amazon-Andes Hydroclimatic Connectivity

Author

Sierra, Juan P., primary, Junquas, C., additional, Espinoza, J. C., additional, Segura, H., additional, Condom, T., additional, Andrade, M., additional, Molina-Carpio, J., additional, Ticona, L., additional, Mardoñez, V., additional, Blacutt, L., additional, Polcher, J., additional, Rabatel, A., additional, and Sicart, J.E., additional

Published
2021
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25. Challenges for drought assessment in the Mediterranean region under future climate scenarios

Author

Tramblay, Y., Koutroulis, A., Samaniego, Luis, Vicente-Serrano, S.M., Volaire, F., Boone, A., Le Page, M., Llasat, M.C., Albergel, C., Burak, S., Cailleret, M., Cindrić Kalin, K., Davi, H., Dupuy, J.-L., Greve, P., Grillakis, M., Hanich, L., Jarlan, L., Martin-StPaul, N., Martínez-Vilalta, J., Mouillot, F., Pulido-Velazquez, D., Quintana-Seguí, P., Renard, D., Turco, M., Türkeş, M., Trigo, R., Vidal, J.-P., Vilagrosa, A., Zribi, M., Polcher, J., Tramblay, Y., Koutroulis, A., Samaniego, Luis, Vicente-Serrano, S.M., Volaire, F., Boone, A., Le Page, M., Llasat, M.C., Albergel, C., Burak, S., Cailleret, M., Cindrić Kalin, K., Davi, H., Dupuy, J.-L., Greve, P., Grillakis, M., Hanich, L., Jarlan, L., Martin-StPaul, N., Martínez-Vilalta, J., Mouillot, F., Pulido-Velazquez, D., Quintana-Seguí, P., Renard, D., Turco, M., Türkeş, M., Trigo, R., Vidal, J.-P., Vilagrosa, A., Zribi, M., and Polcher, J.

Abstract

Droughts can have strong environmental and socio-economic impacts in the Mediterranean region, in particular for countries relying on rain-fed agricultural production, but also in areas in which irrigation plays an important role and in which natural vegetation has been modified or is subject to water stress. The purpose of this review is to provide an assessment of the complexity of the drought phenomenon in the Mediterranean region and present various perspectives on drought in the present and under future climate change scenarios. The projections of various model experiments on future climate change scenarios strongly agree on an increased frequency and severity of droughts in the Mediterranean basin. Nevertheless, given the complexity of the phenomenon, with different types of droughts and complex interrelated impacts, significant future uncertainties remain. For example, uncertainties are stronger for hydrological droughts than meteorological droughts due to human influences and water withdrawal. Significant drought impacts are expected in the future, in particular for developing countries in the southern and eastern parts of the Mediterranean basin. To improve the resilience and adaptive capacities of societies and environments faced with drought, we aim to provide an overview of the key issues in research on climate change impacts on droughts, with a specific focus on the Mediterranean region, in order to: i) redefine more meaningful drought metrics tailored to the Mediterranean context, ii) better take into account vegetation and its feedback on droughts, iii) improve the modelling and forecasting of drought events through remote sensing and land surface models, and iv) promote a more integrated vision of droughts taking into account both water availability and water use. This overview reflects the complexity of the problem and the need to combine scientific research with adaptation solutions to deal with drought in the future.

Published
2020

26. Challenges for drought assessment in the Mediterranean region under future climate scenarios

Author

Yves, T., Koutroulis, A., Samaniego, L., Vicente-Serrano, S.M., Volaire, F., Boone, A., Le Page, M., Llasat, M.C., Albergel, C., Burak, S., Cailleret, M., Kalin, K.C., Davi, H, Dupuy, J.-L., Greve, P., Grillakis, M., Jarlan, L., Martin-StPaul, N., Vilalta, J.M., Mouillot, F., Velazquez, D.P., Quintana-Seguí, P., Renard, D., Turco, M., Türkes, M., Trigo, R., Vidal, J.-P., Vilagrosa, A., Zribi, M., Polcher, J., Yves, T., Koutroulis, A., Samaniego, L., Vicente-Serrano, S.M., Volaire, F., Boone, A., Le Page, M., Llasat, M.C., Albergel, C., Burak, S., Cailleret, M., Kalin, K.C., Davi, H, Dupuy, J.-L., Greve, P., Grillakis, M., Jarlan, L., Martin-StPaul, N., Vilalta, J.M., Mouillot, F., Velazquez, D.P., Quintana-Seguí, P., Renard, D., Turco, M., Türkes, M., Trigo, R., Vidal, J.-P., Vilagrosa, A., Zribi, M., and Polcher, J.

Abstract

Droughts can have strong environmental and socio-economic impacts in the Mediterranean region, in particular for countries relying on rain-fed agricultural production, but also in areas in which irrigation plays an important role and in which natural vegetation has been modified or is subject to water stress. The purpose of this review is to provide an assessment of the complexity of the drought phenomenon in the Mediterranean region and present various perspectives on drought in the present and under future climate change scenarios. The projections of various model experiments on future climate change scenarios strongly agree on an increased frequency and severity of droughts in the Mediterranean basin. Nevertheless, given the complexity of the phenomenon, with different types of droughts and complex interrelated impacts, significant future uncertainties remain. For example, uncertainties are stronger for hydrological droughts than meteorological droughts due to human influences and water withdrawal. Significant drought impacts are expected in the future, in particular for developing countries in the southern and eastern parts of the Mediterranean basin. To improve the resilience and adaptive capacities of societies and environments faced with drought, we aim to provide an overview of the key issues in research on climate change impacts on droughts, with a specific focus on the Mediterranean region, in order to: i) redefine more meaningful drought metrics tailored to the Mediterranean context, ii) better take into account vegetation and its feedback on droughts, iii) improve the modelling and forecasting of drought events through remote sensing and land surface models, and iv) promote a more integrated vision of droughts taking into account both water availability and water use. This overview reflects the complexity of the problem and the need to combine scientific research with adaptation solutions to deal with drought in the future.

Published
2020

27. Deceleration of China’s human water use and its key drivers

Author

Zhou, F., Bo, Y., Ciais, P., Dumas, P., Tang, Q., Wang, X., Liu, J., Zheng, C., Polcher, J., Yin, Z., Guimberteau, M., Peng, S., Ottle, C., Zhao, X., Zhao, J., Tan, Q., Chen, L., Shen, H., Yang, H., Piao, S., Wang, H., Wada, Y., Zhou, F., Bo, Y., Ciais, P., Dumas, P., Tang, Q., Wang, X., Liu, J., Zheng, C., Polcher, J., Yin, Z., Guimberteau, M., Peng, S., Ottle, C., Zhao, X., Zhao, J., Tan, Q., Chen, L., Shen, H., Yang, H., Piao, S., Wang, H., and Wada, Y.

Abstract

Increased human water use combined with climate change have aggravated water scarcity from the regional to global scales. However, the lack of spatially detailed datasets limits our understanding of the historical water use trend and its key drivers. Here, we present a survey-based reconstruction of China’s sectoral water use in 341 prefectures during 1965 to 2013. The data indicate that water use has doubled during the entire study period, yet with a widespread slowdown of the growth rates from 10.66 km3⋅y−2 before 1975 to 6.23 km3⋅y−2 in 1975 to 1992, and further down to 3.59 km3⋅y−2 afterward. These decelerations were attributed to reduced water use intensities of irrigation and industry, which partly offset the increase driven by pronounced socioeconomic development (i.e., economic growth, population growth, and structural transitions) by 55% in 1975 to 1992 and 83% after 1992. Adoptions for highly efficient irrigation and industrial water recycling technologies explained most of the observed reduction of water use intensities across China. These findings challenge conventional views about an acceleration in water use in China and highlight the opposing roles of different drivers for water use projections.

Published
2020

33. Improvement of the Irrigation Scheme in the ORCHIDEE Land Surface Model and Impacts of Irrigation on Regional Water Budgets Over China

Author

Yin, Z., primary, Wang, X. H., additional, Ottlé, C., additional, Zhou, F., additional, Guimberteau, M., additional, Polcher, J., additional, Peng, S. S., additional, Piao, S. L., additional, Li, L., additional, Bo, Y., additional, Chen, X. L., additional, Zhou, X. D., additional, Kim, H., additional, and Ciais, P., additional

Published
2020
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36. Hydrological assessment of atmospheric forcing uncertainty in the Euro-Mediterranean area using a land surface model

Author

Gelati, E., Decharme, B., Calvet, J.-C., Minvielle, M., Polcher, J., Fairbairn, D., Weedon, G. P., Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), 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), Joint Centre for Hydro-Meteorological Research, Met Office Hadley Centre (JCHMR), United Kingdom Met Office [Exeter], 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 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), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
010504 meteorology & atmospheric sciences, 0208 environmental biotechnology, Climate change, 02 engineering and technology, Forcing (mathematics), [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology, lcsh:Technology, 01 natural sciences, lcsh:TD1-1066, Precipitation, lcsh:Environmental technology. Sanitary engineering, Water cycle, Leaf area index, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, lcsh:Environmental sciences, 0105 earth and related environmental sciences, General Environmental Science, lcsh:GE1-350, lcsh:T, Discharge, Anomaly (natural sciences), lcsh:Geography. Anthropology. Recreation, 6. Clean water, 020801 environmental engineering, lcsh:G, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, General Earth and Planetary Sciences, Environmental science, Surface runoff
Abstract

Physically consistent descriptions of land surface hydrology are crucial for planning human activities that involve freshwater resources, especially in light of the expected climate change scenarios. We assess how atmospheric forcing data uncertainties affect land surface model (LSM) simulations by means of an extensive evaluation exercise using a number of state-of-the-art remote sensing and station-based datasets. For this purpose, we use the CO2-responsive ISBA-A-gs LSM coupled with the CNRM version of the Total Runoff Integrated Pathways (CTRIP) river routing model. We perform multi-forcing simulations over the Euro-Mediterranean area (25–75.5∘ N, 11.5∘ W–62.5∘ E, at 0.5∘ resolution) from 1979 to 2012. The model is forced using four atmospheric datasets. Three of them are based on the ERA-Interim reanalysis (ERA-I). The fourth dataset is independent from ERA-Interim: PGF, developed at Princeton University. The hydrological impacts of atmospheric forcing uncertainties are assessed by comparing simulated surface soil moisture (SSM), leaf area index (LAI) and river discharge against observation-based datasets: SSM from the European Space Agency's Water Cycle Multi-mission Observation Strategy and Climate Change Initiative projects (ESA-CCI), LAI of the Global Inventory Modeling and Mapping Studies (GIMMS), and Global Runoff Data Centre (GRDC) river discharge. The atmospheric forcing data are also compared to reference datasets. Precipitation is the most uncertain forcing variable across datasets, while the most consistent are air temperature and SW and LW radiation. At the monthly timescale, SSM and LAI simulations are relatively insensitive to forcing uncertainties. Some discrepancies with ESA-CCI appear to be forcing-independent and may be due to different assumptions underlying the LSM and the remote sensing retrieval algorithm. All simulations overestimate average summer and early-autumn LAI. Forcing uncertainty impacts on simulated river discharge are larger on mean values and standard deviations than on correlations with GRDC data. Anomaly correlation coefficients are not inferior to those computed from raw monthly discharge time series, indicating that the model reproduces inter-annual variability fairly well. However, simulated river discharge time series generally feature larger variability compared to measurements. They also tend to overestimate winter–spring high flows and underestimate summer–autumn low flows. Considering that several differences emerge between simulations and reference data, which may not be completely explained by forcing uncertainty, we suggest several research directions. These range from further investigating the discrepancies between LSMs and remote sensing retrievals to developing new model components to represent physical and anthropogenic processes.

Published
2018

37. Cabauw Experimental Results from the Project for Intercomparison of Land-Surface Parameterization Schemes

Author

Chen, Tian Hong, Henderson-Sellers, A, Milly, P. C. D, Pitman, A. J, Beljaars, A. C. M, Polcher, J, Abramopoulos, F, Boone, A, Chang, S, Chen, F, Dai, Y, Desborough, C. E, Dickinson, R. E, Duemenil, L, Ek, M, Garratt, J. R, Gedney, N, Gusev, Y. M, Kim, J, and Koster, R

Subjects
Meteorology And Climatology
Abstract

In the Project for Intercomparison of Land-Surface Parameterization Schemes phase 2a experiment, meteorological data for the year 1987 from Cabauw, the Netherlands, were used as inputs to 23 land-surface flux schemes designed for use in climate and weather models. Schemes were evaluated by comparing their outputs with long-term measurements of surface sensible heat fluxes into the atmosphere and the ground, and of upward longwave radiation and total net radiative fluxes, and also comparing them with latent heat fluxes derived from a surface energy balance. Tuning of schemes by use of the observed flux data was not permitted. On an annual basis, the predicted surface radiative temperature exhibits a range of 2 K across schemes, consistent with the range of about 10 W/m in predicted surface net radiation. Most modeled values of monthly net radiation differ from the observations by less than the estimated maximum monthly observational error (+/- 10 W/sq m). However, modeled radiative surface temperature appears to have a systematic positive bias in most schemes; this might be explained by an error in assumed emissivity and by models' neglect of canopy thermal heterogeneity. Annual means of sensible and latent heat fluxes, into which net radiation is partitioned, have ranges across schemes of 30 W/sq m and 25 W/sq m, respectively. Annual totals of evapotranspiration and runoff, into which the precipitation is partitioned, both have ranges of 315 mm. These ranges in annual heat and water fluxes were approximately halved upon exclusion of the three schemes that have no stomatal resistance under non-water-stressed conditions. Many schemes tend to underestimate latent heat flux and overestimate sensible heat flux in summer, with a reverse tendency in winter. For six schemes, root-mean-square deviations of predictions from monthly observations are less than the estimated upper bounds on observation errors (5 W/m for sensible beat flux and 10 W/m for latent heat flux). Actual runoff at the site is believed to be dominated by vertical drainage to ground water, but several schemes produced significant amounts of runoff as overland flow or interflow. There is a range across schemes of 184 mm (40% of total pore volume) in the simulated annual mean root-zone soil moisture. Unfortunately, no measurements of soil moisture were available for model evaluation. A theoretical analysis suggested that differences in boundary conditions used in various schemes are not sufficient to explain the large variance in soil moisture. However, many of the extreme values of soil moisture could be explained in terms of the particulars of experimental setup or excessive evapotranspiration.

Published
1997

38. Streamflows over a West African Basin from the ALMIP2 Model Ensemble

Author

Getirana, Augusto, Boone, Aaron, Peugeot, Christophe, Ait-Mesbah, S., Polcher, J., Anderson, M., Balsamo, G., Boussetta, S., Dutra, E., Pappenberger, F., Hain, C., Favot, F., Guichard, F., Kaptue, A., Cappelaere, B., Demarty, Jérôme, Seguis, L., Chaffard, V., Cohard, J. M., Gascon, T., Galle, S., Hector, B., Lebel, T., Pellarin, T., Richard, A., Quantin, G., Vischel, T., Chan, E., Verseghy, D., Ducharne, Agnès, Magand, C., Grippa, Manuela, Hiernaux, Pierre, Kergoat, Laurent, Pierre, C., Nasonova, Y. Gusev O., Harris, P., He, X., Yorozu, K., Kotsuki, S., Tanaka, K., Kim, H., Oki, T., Kumar, S., Lo, M.-H., Mahanama, S., Maignan, F., Ottlé, C., Mamadou, O., Shmakin, A., Sokratov, V., Turkov, D., 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), Hydrosciences Montpellier (HSM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut de Recherche pour le Développement (IRD), Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols (METIS), École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), 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), Modélisation des Surfaces et Interfaces Continentales (MOSAIC), 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), 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 national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), 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)-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), and Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Recherche pour le Développement (IRD)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
Hydrology, Atmospheric Science, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Hydrological modelling, 0208 environmental biotechnology, Mesoscale meteorology, Drainage basin, 02 engineering and technology, Groundwater recharge, Infiltration (HVAC), Monsoon, 01 natural sciences, 6. Clean water, 020801 environmental engineering, Climatology, Streamflow, Environmental science, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, Surface runoff, 0105 earth and related environmental sciences
Abstract

Comparing streamflow simulations against observations has become a straightforward way to evaluate a land surface model’s (LSM) ability in simulating water budget within a catchment. Using a mesoscale river routing scheme (RRS), this study evaluates simulated streamflows over the upper Ouémé River basin resulting from 14 LSMs within the framework of phase 2 of the African Monsoon Multidisciplinary Analysis (AMMA) Land Surface Model Intercomparison Project (ALMIP2). The ALMIP2 RRS (ARTS) has been used to route LSM outputs. ARTS is based on the nonlinear Muskingum–Cunge method and a simple deep water infiltration formulation representing water-table recharge as previously observed in that region. Simulations are performed for the 2005–08 period during which ground observations are largely available. Experiments are designed using different ground-based rainfall datasets derived from two interpolation methods: the Thiessen technique and a combined kriging–Lagrangian methodology. LSM-based total runoff (TR) averages vary from 0.07 to 1.97 mm day−1, while optimal TR was estimated as ~0.65 mm day−1. This highly affected the RRS parameterization and streamflow simulations. Optimal Nash–Sutcliffe coefficients for LSM-averaged streamflows varied from 0.66 to 0.92, depending on the gauge station. However, individual LSM performances show a wider range. A more detailed rainfall distribution provided by the kriging–Lagrangian methodology resulted in overall better streamflow simulations. The early runoff generation related to reduced infiltration rates during early rainfall events features as one of the main reasons for poor LSM performances.

Published
2017

41. HyMeX: mid-term program review and perspectives Report of the 9th HyMeX workshop in Mykonos, Greece

Author

Drobinski P., Ducrocq V., Kotroni V., Lagouvardos K., Ahrens B., Anquetin S., Bouin M.N., Braud I., Coppola E., Coquillat S., Davolio S., Delanoé J., Di Girolamo P., Flamant C., Flaounas E., Fourrié N., Garcia-Moya J., Giordani H., Homar V., Jorda G., Kalthoff N., Khodayar S., Llasat C., Lebeaupin-Brossier C., Michel Y., Morin E., Nuissier O., Petrucci O., Polcher J., Quintana-Segui P., Richard E., Sannino G., Somot S., Testor P., Tramblay Y., Ruin I., and Von Schuckmann K.

Subjects
climate change
Abstract

The Hydrological Cycle in the Mediterranean Experiment (HyMeX; Drobinski et al., 2014) is a 10-year (2010-2020) GEWEX Hydroclimatology Panel (GHP) Regional Hydroclimate Project (RHP). Its objectives are to: (i) improve the understanding of the water cycle, with emphasis on extreme events, by monitoring and modeling the Mediterranean coupled system (atmosphere-land-ocean), its variability (from the event scale to the seasonal and interannual scales) and characteristics over one decade in the context of global change; and (ii) evaluate societal and economical vulnerability, and adaptation capacity to extreme meteorological and climate events.

Published
2015

44. The effect of background wind on mesoscale circulations above variable soil moisture in the Sahel

Author

Dixon, N.S., Parker, D.J., Taylor, C.M., Garcia-Carreras, L., Harris, P.P., Marsham, J.H., Polcher, J., Woolley, A., School of Earth and Environment [Leeds] (SEE), University of Leeds, Centre for Ecology and Hydrology, Wallingford, United Kingdom, National Centre for Atmospheric Science [Leeds] (NCAS), Natural Environment Research Council (NERC), 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), Facility for Airborne Atmospheric Measurements, Cranfield, United Kingdom, 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), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
Atmospheric Science, Aircraft data, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], LES, West Africa, NCMCs, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, AMMA, Convective triggering, JULES
Abstract

International audience; Observational data are presented from several low-level flights carried out during the afternoon over areas of the Sahel that had been previously wetted by rain. The measurements are used to quantify the response of boundary-layer circulations to surface heterogeneity over a range of ambient conditions. Satellite observations of surface temperature anomalies show that soil moisture is significantly correlated with the surface heterogeneity in a majority of flights. By analysing the flight data in frequency space, consistently high levels of coherence are found between surface and flight-level measurements at length-scales around 25 km, indicating the presence of mesoscale circulations induced by the surface variability. The circulations are detectable in all of the nine flights where the mean sensible heat flux is high enough and they persist in a range of background wind speeds up to 5 m s-1. Further analysis confirms that the spatial phase-difference between surface and flight-level variables increases with the strength of the mean wind along the flight track. The boundary-layer thermal anomalies and circulations are advected downstream by the mean wind, and lead to convergent uplift on the order of 0.25 m s-1 at the 25 km scale. These results compare well with those from a cloud-resolving model and are broadly consistent with an analytical, linear model of a heated boundary layer. By demonstrating the significance of soil moisture in driving the circulations, the study shows that soil moisture is a likely cause of the negative precipitation feedback seen in recent remote sensing studies over the region. © 2012 Royal Meteorological Society.

Published
2013

45. Response of land surface fluxes and precipitation to different soil bottom hydrological conditions in a general circulation model

Author

Campoy, A., Ducharne, Agnès, Cheruy, F., Hourdin, F., Polcher, J., Dupont, J.C., 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), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), 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), 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, 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), and 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)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology
Abstract

International audience; Very different approaches exist in land surface models (LSMs) to describe the water fluxes at the soil bottom, from free drainage to zero flux, and even upward fluxes if the soil is coupled to a water table. To explore the influence of these conditions on the water cycle in a unified framework, we introduce new boundary conditions in the ORCHIDEE LSM, which is coupled to the atmospheric general circulation model LMDZ. We use a zoomed and nudged configuration centered over France to reproduce the observed regional weather. Soil moisture and evapotranspiration increase ranging from free drainage to impermeable bottom, then by prescribing saturation closer and closer to the surface. The corresponding response patterns can be related to both climate regimes and soil texture. When confronted to observations from the SIRTA observatory 25 km south of Paris, which exhibits a shallow water table, the best simulations are the ones with prescribed saturation. The local precipitation, however, is only increased if the new bottom boundary conditions are applied globally. The magnitude of this increase depends on the evaporation and on the relative weight of local versus remote sources of moisture for precipitation between Western and Eastern Europe. This suggests that the summer warm/dry bias of many climate models in this region might be alleviated by including a sufficiently realistic ground water description. Key Points Sensitivity to reduced drainage and saturation within the soil column Confrontation to local scale observations exhibiting a shallow water table European scale analysis of the resulting precipitation increase ©2013. American Geophysical Union. All Rights Reserved.

Published
2013

46. Soil moisture retrieval from multi-instrument observations: Information content analysis and retrieval methodology

Author

Kolassa, J., Aires, F., Polcher, J., Prigent, Christophe, Jimenez, Chloé, Pereira, Jean-Michel, Estellus S.A.S., 93 Boulevard de Sébastopol, F-75014, Paris, France, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-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), Instituto Superior de Agronomia, Universidade Tecnica de Lisboa, Lisbon, Portugal, Estellus, École normale supérieure - Paris (ENS-PSL), 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), Instituto Superior de Agronomia [Lisboa] (ISA), and Universidade de Lisboa = University of Lisbon (ULISBOA)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [PHYS]Physics [physics], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; An algorithm has been developed that employs neural network technology to retrieve soil moisture from multi-wavelength satellite observations (active/passive microwave, infrared, and visible). This represents the first step in the development of a methodology aiming to combine beneficial aspects of existing retrieval schemes. Several quality metrics have been developed to assess the performance of a retrieval product on different spatial and temporal scales. Additionally, an innovative approach to estimate the retrieval uncertainty has been proposed. An information content analysis of different satellite observations showed that active microwave observations are best suited to capture the soil moisture temporal variability, while the amplitude of the surface temperature diurnal cycle is best suited to capture the spatial variability. In a synergy analysis, it has been found that through the combination of all observations the retrieval uncertainty could be reduced by 13%. Furthermore, it was found that synergy benefits are significantly larger using a data fusion approach compared to an a posteriori combination of retrieval products, supporting the combination of different retrieval methodology aspects in a single algorithm. In a comparison with model data, it was found that the proposed methodology also shows potential to be used for the evaluation of modeled soil moisture. A comparison with in situ observations showed that the algorithm is well able to capture soil moisture spatial variabilities. It was concluded that the temporal performance can be improved through incorporation of other existing retrieval approaches. Key Points Multi-instrument soil moisture retrieval algorithm has been developedData fusion was found to perform better than a posteriori combinationAlgorithm has been evaluated and used to create soil moisture data base ©2012. American Geophysical Union. All Rights Reserved.

Published
2013

47. Harmonic propagation of variability in surface energy balance within a coupled soil-vegetation-atmosphere system

Author

Gentine, P., Polcher, J., Entekhabi, D., Department of Applied Physics and Applied Mathematics [New York], Columbia University [New York], 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), MIT Parsons Laboratory, Massachusetts Institute of Technology (MIT), 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), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Physics::Geophysics
Abstract

International audience; The response of a soil-vegetation-atmosphere continuum model to incoming radiation forcing is investigated in order to gain insights into the coupling of soil and atmospheric boundary layer (ABL) states and fluxes. The response is characterized through amplitude and phase propagation of the harmonics in order to differentiate between the response of the system to forcing at different frequencies (daily to hourly to near instantaneous). Stochastic noise is added to the surface energy balance. The amplitude of the noise is maximum at midday when the incoming radiative forcing is also at its peak. The temperatures and turbulent heat fluxes are shown to act as low-pass filters of the incoming radiation or energy budget noise variability at the surface. Conversely, soil heat flux is shown to act as a high-pass filter because of the strong contrast in the soil and air heat capacities and thermal conductivities. As a consequence, heat diffusion formulations that numerically dampen such forcing are potentially incapable of representing rapid fluctuations in soil heat flux (=30 min) and therefore introduce errors in the land-surface energy partitioning. The soil-vegetation-ABL continuum model and an electrical analogy for it are used to explain the frequency-dependent differences in the relative effectiveness of turbulent heat fluxes versus ground heat flux in dissipating noise in radiative forcing. Copyright 2011 by the American Geophysical Union.

Published
2011

50. An Overview of the SCOUT-O3-AMMA stratospheric aircraft, balloons and sondes campaign in West Africa August 2006: rationale, roadmap and highlights

Author

Cairo, F., Pommereau, P., Berthelier, J.J., Blom, C., Christensen, T., D'Amato, F., Di Donfrancesco, G., Deshler, T., Diedhiou, A., Durry, G., Engelsen, O., Goutail, F., Law, K.S., Harris, N., Khaykin, S., Kylling, A., Konopka, P., Lebel, T., Liu, X., MacKenzie, R., Nielsen, J., Sitnikov, N., Qulanowski, A., Schlager, H., Parker, D., Pelon, J., Polcher, J., Pyle, J., Ravegnani, F., Reviere, E., Robinson, E.D., Roeckmann, T., Schiller, C., Simoes, F., Garnier, A., Stefanutti, L., Stroh, F., Some, L., Siegmund, P., Vernier, J.P., Volk, M., Voigt, C., von Hobe, M., Viciani, S., Fierli, F., Yushkov, V., Ern, M., Streibel, M., Arabas, S., and Borrmann, S.

Subjects
ddc:550
Published
2009

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