26 How well is the physics of intense rainfall events in the Sahel captured by a regional climate?

Monday, 7 January 2013
Exhibit Hall 3 (Austin Convention Center)
Julien Crétat, University of Texas, Austin, TX; and K. H. Cook and E. K. Vizy

This study evaluates the ability of the non-hydrostatic regional model WRF to capture the physics of intense rainfall events in the Sahel. Twenty-years continuous simulations are performed over two large domains (a one-way parent domain [52.7S-60.4N / 61.4W-101.4E] and a one-way inner domain [39.9S-39.5N / 25.5W-59.5E]) to limit constraints imposed by lateral conditions and provide ample space for the development of fine-scale circulation. The two domains are set up with 90-km and 30-km horizontal resolutions and 32 vertical levels, and lateral and surface boundary conditions are provided by 6-hourly NCEP2 reanalyses. First, a clustering approach is applied to identify the main daily rainfall patterns during intense rainfall. Second, composite analyses are used to determinate the physical mechanisms associated with these main rainfall patterns, focusing particularly on the role of African easterly waves known to be associated with the occurrence of intense rainfall events. The same analysis is also applied to TRMM and GPCP satellite-derive rainfall and the ERA-INTERIM reanalyses to evaluate the accuracy of the regional simulations.
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