PHYSICAL INITIALIZATION USING SSM I RAIN RATES/

Following our recent study on physical initialization for tropical pre diction using rain rates based on outgoing long-wave radiation, the pr esent study demonstrates a major improvement from the use of microwave radiance based rain rates. A rain rate algorithm is used on the data from a special sensor microwave instrument (SSM/I). The initialization , as before, uses a reverse surface similarity theory, a reverse cumul us parameterization algorithm and a bisection method to minimize the d ifference between satellite-based and the model-based outgoing long-wa ve radiation. These are invoked within a preforecast Newtonian relaxat ion phase of the initialization. These tests are carried out with a hi gh-resolution global spectral model. The impact of the initialization on forecast is tested for a complex triple typhoon scenario over the W estern Pacific Ocean during September 1987. A major impact from the in clusion of the SSM/I is demonstrated. Also addressed are the spin-up i ssues related to the typhoon structure and the improved water budget f rom the physical initialization.