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Land-atmosphere feedbacks in a high-resolution RCM: sensitivity to the land-surface forcing

Within the framework of CORDEX-FPS on convective phenomena over Europe and the Mediterranean (FPS-CEM), a multi-model ensemble of regional climate models (RCMs) on convection permitting (CP) resolution is being produced for the first time. In these high resolution RCMs the accuracy of static input information, such as land use and soil texture, are becoming more relevant, and may impact not only surface fluxes, but also the representation of boundary layer evolution and precipitation. In this study we investigate the sensitivity of the Weather Research and Forecasting (WRF) model to land-surface static data by applying the extended case-study experimental design of FPS-CEM (Coppola et al. 2018). Apart from the default WRF static information based on MODIS land use and FAO soil texture, we adapted higher resolution and up-to-date data for WRF based on CORINE land use and HWSD/BÜK top soil texture info, which have been used by all WRF groups involved in FPS-CEM. Combining these 4 data sets for a summer and a winter case, with 2 WRF physical parameterization settings, we generated two 8-member ensembles. We focus here on the model representation of land-atmosphere (LA) feedback processes over the CP Alpine domain, and its sensitivity to (1) land-surface static forcing, (2) season, and (3) WRF configuration. We investigate correlation between the strength of the LA coupling and the model sensitivity to the land-surface static data, and we explore the impact of land-surface changes on the potential for convection and precipitation occurrence. To quantify the strength of LA coupling we use coupling metrics appropriate for monthly time scales (e.g. mixing diagram).
Acknowledgement: This work is partially funded by the Spanish Government R+D programme through grant INSIGNIA (CGL2016-79210-R) co-funded by the ERDF/FEDER.
Keywords: Land-atmosphere; Feedbacks; WRF; RCM; Land use; Soil texture
References: Coppola E, Sobolowski S, Pichelli E, et al. (2018). A first-of-its-kind multi-model convection permitting ensemble for investigating convective phenomena over Europe and the Mediterranean. Climate Dynamics. DOI 10.1007/s00382-018-4521-8