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Communication Dans Un Congrès Année : 2009

Evaluation of the performance of the WRF model to reproduce the cloud cover and clouds features over the Mediterranean area using the CALIPSO lidar observations

Résumé

It is widely accepted that clouds play a major role on weather and climate forecast. However, the representation of clouds in models is largely uncertain due (i) to the number of processes and interactions involved in the formation and persistence of a cloud and (ii) the difficulty in obtaining accurate observations of clouds at all altitudes and locations. The evaluation of mesoscale models using recently developed parameterizations in different areas is therefore an essential step towards the improvement of clouds representation in models. The Aqua-Train offers an unprecedented set of observations for the microphysical properties of clouds that is very useful for validation of clouds features in models, especially over the sea where ground based instrumentation can not furnish observations. To avoid any inversion of the observed lidar signal that could induce errors responsible for discrepancies between observations and model, we use a model-to-satellite approach (Chepfer et al., 2008) to diagnose the lidar signal directly from model outputs. We then compare the observed space borne lidar profiles with the simulated ones. In this paper, we choose to evaluate the Thompson et al. (2004, 2008) microphysics scheme within the WRF model over the Mediterranean area. The occurrence of severe weather phenomenons, as well as the probable role of Mediterranean sea on climate change make the understanding and the representation of processes in this area a challenge for the future. A statistical study is carried out over several full months of observations. The first stage of the analysis focuses on the cloud occurrence discrepancy between observations and model for the three classes of clouds (low-level, middle and high clouds). In particular the analysis aims to evaluate how much the absence of aerosols in the simulations may be a cause of discrepancies in this area. Chepfer H., S. Bony, D. Winker, M. Chiriaco, J-L. Dufresne, G. Sèze, 2008: Use of CALIPSO lidar observations to evaluate the cloudiness simulated by a climate model. Geophys. Res. Let., 35, L15704, doi:10.1029/2008GL034207. Thompson G., R. M. Rasmussen, K. Manning, 2004: Explicit forecasts of winter precipitations using an improved bulk microphysics scheme. Part I: description and sensitivity analysis. Mon. Wea. Rev., 132, 519-542. Thompson G., P. Field, R. M. Rasmussen, W. D. Hall, 2008: Explicit forecasts of winter precipitations using an improved bulk microphysics scheme. Part II: Implementation of a new snow parameterization. Mon. Wea. Rev., 136, 5095-5115.

Domaines

Météorologie
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Dates et versions

hal-00668863 , version 1 (10-02-2012)

Identifiants

  • HAL Id : hal-00668863 , version 1

Citer

Sophie Bastin, H. Chepfer, Marjolaine Chiriaco, G. Cesana. Evaluation of the performance of the WRF model to reproduce the cloud cover and clouds features over the Mediterranean area using the CALIPSO lidar observations. American Geophysical Union, Fall Meeting 2009, Dec 2009, San Francisco, United States. ⟨hal-00668863⟩
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