P2.15 Evaluation of cloud microphysical processes and their implications for intensification in numerical model simulations of Hurricane Dennis (2005)

Wednesday, 12 July 2006
Grand Terrace (Monona Terrace Community and Convention Center)
Eric Schneider, Univ. of Illinois, Urbana, IL; and G. M. McFarquhar, B. F. Jewett, M. Gilmore, R. E. Hood, and G. M. Heymsfield

The Weather Research and Forecasting model (WRF) is used with a movable, 1 km innermost grid to simulate Hurricane Dennis (2005) observed during the Tropical Cloud Systems and Processes (TCSP) field campaign as it transitioned from a tropical storm to a category 1 hurricane and subsequently as a category 2 storm. The simulations utilize the Ferrier microphysics scheme and are initialized at three separate times during storm development corresponding to TCSP flight operations on July 5, 6 and 9. The simulations cover the time from 4 July 1200 UTC to 10 July 0000Z, during which Dennis evolved from a tropical depression to a category 4 hurricane. Advanced Microwave Precipitation Radiometer (AMPR) and radar data collected during TCSP on three separate days over Hurricane Dennis offer a unique set of remotely retrieved cloud and precipitation properties. Frequency diagrams of simulated brightness temperature, contoured frequency by altitude diagrams (CFADs) of equivalent reflectivity and Doppler velocity are compared against similar quantities derived from modeled fields in order to determine if WRF captures changes in cloud properties observed during three different stages of intensification of Hurricane Dennis. In particular, it is examined whether WRF simulations of Dennis overproduce graupel compared to observations, a trend noted in some simulations of previous hurricanes.
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