SIMULATIONS OF PHYSICAL RETRIEVAL OF TROPICAL CYCLONE THERMAL STRUCTURE USING 55-GHZ BAND PASSIVE MICROWAVE OBSERVATIONS FROM POLAR-ORBITING SATELLITES

A method for estimating the horizontal structure of the upper-troposph eric warm anomaly of tropical cyclones from 55-GHz microwave observati ons is presented. Because the peak warming occurs over an area smaller than that viewed by current and planned satellite antenna systems, it is necessary to model explicitly the interaction of the warm anomaly structure and antenna gain pattern. The anomaly is approximated by an analytic function whose parameters are estimated using a maximum-likel ihood algorithm with constraints analogous to that used for thermodyna mic sounding retrieval or optimal interpolation. Simulation studies de monstrate the overall soundness of the technique and its possible perf ormance and limitations when applied to two different polar-orbiting m icrowave sensors, MSU (Microwave Sounding Unit) and SSM/T (Special Sen sor Microwave/Temperature).