P15  Refined Dynamical Downscaling from Previous Work at 36-km Resolution

Bullock, Russell, Jerry Herwehe, Megan Mallard, and Tanya Otte, US Environmental Protection Agency

Previous dynamical downscaling techniques developed using WRF at 108- and 36-km resolution are applied for further downscaling to 12-km resolution over the eastern United States and southeastern Canada.  The previous work investigated both analysis nudging and spectral nudging to constrain the WRF simulation.  This work investigates the adjustments to the nudging parameters required for an optimum application at 12-km resolution.  Lake surface temperatures for the previous work were determined from 2.5-degree latitude/longitude resolved sea surface temperature data and that technique is also applied here with the results suggesting that a more realistic approach to estimating or simulating lake surface temperatures is needed for 12-km resolution.  Simulated surface-level temperature, water vapor mixing ratio, and wind speed are compared to hourly observations collected by the Meteorological Assimilation Data Ingest System (MADIS) to demonstrate the improved accuracy of the 12-km downscaling results.  Simulated precipitation is compared to Multisensor Precipitation Estimator (MPE) data showing a general excess of precipitation, especially in the southeast during summer.