P22  Impact of MODIS Surface Temperature Data on Warm Season Precipitation Simulations over the Southeastern United States

McCoy, Ripley and Jiming Jin, Utah State University

We conducted 50 km resolution simulations that focus on the southeastern United States (U. S.) using the Weather Research and Forecasting (WRF) model version 3.2 coupled with Community Land Model (CLM) version 3.5. This coupled model was forced with six hourly National Center for Environmental Prediction (NCEP) Reanalysis data for the year 2006. Our analysis shows that WRF-CLM significantly underestimates precipitation during the warm season in the southwestern U. S.  Further examination reveals that large cold biases in skin temperature in WRF over the southern U.S. and Mexico during this season lead to lower near-surface air temperature than observations.  This air is advected over the Gulf of Mexico and Southwest Atlantic Ocean, which leads to a more stable boundary layer over these regions.  Thus, the vertical transport of moisture evaporated from the surface of these water bodies is severely reduced, limiting the available moisture for transport into much of the southeastern U.S.  For this study, we replaced the simulated land and sea surface temperatures in WRF-CLM with Moderate Resolution Imaging Spectroradiometer (MODIS) data to assess the importance of accurate surface temperatures to southeastern U.S. precipitation simulations.