Applications of Advanced Microwave Sounding Unit to improving the Analysis of Atmospheric Wind Field in Tropical Cyclones

As hurricanes or typhoons form over tropical oceans, satellite observations offer a unique way of monitoring their evolution. This study presents new technique for deriving three dimensional hurricane temperature and wind fields using the Advanced Microwave Sounding Unit-A (AMSU-A) on board NOAA-15 satellite. The AMSU-A has 12 sounding channels near 50 GHz oxygen absorption line and three window channels at 23.8, 31.4 and 89 GHz. This unique sensor is used to derive atmospheric temperature profiles over nearly-all weather conditions. Horizontal temperature gradient is related to hurricane tangential wind through the gradient balance equation. The temperature perturbation is also utilized to estimate the maximum pressure depression and therefore the hurricane intensity. The AMSU-A derived temperature and wind products, along with other non-sounding products such as cloud liquid and total precipitable water are now being assimilated into the Mesoscale Model Version 5 (MM5) to improve hurricane track forecast. The impacts of these products on assimilation will be presented on the conference.