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.