EVALUATION OF WRF PHYSICS OPTIONS FOR HIGH-RESOLUTION WEATHER FORECASTING IN TROPICS USING SATELLITE PASSIVE MILLIMETER-WAVE OBSERVATIONS

This paper evaluates microphysics and cumulus parameterization schemes of the Weather Research and Forecasting (WRF) model for high-resolution weather forecasting in tropics. WRF forecasts at 5-km resolution between 8 and 9 hours after initial time for 5 representative storm systems over Thailand and nearby regions for 24 different combinations of microphysics and cumulus parameterization schemes are evaluated using brightness temperatures coincidentally observed by the passive millimeter-wave spectrometer Advanced Microwave Sounding Unit (AMSU) aboard the U. S. National Oceanic and Atmospheric Administration (NOAA)-16 satellite and corresponding retrieved precipitation parameters from the AMSU MIT Precipitation retrieval (AMP) products. Results show that forecasts are very sensitive to microphysics and cumulus parameterization schemes. The combination of the WRF Double-Moment 6-class microphysics scheme and the Betts-Miller-Janjic cumulus parameterization scheme performs best. By using the best physics combination, WRF forecasts generally agree with AMSU observations in terms of morphologies, locations, and intensities. Main forecast errors include storm location offsets and under-forecasting of graupel.