An improved algorithm for NSCAT measurements of hurricanes

Satellite scatterometer wind retrievals in tropical cyclones suffer from three major shortcomings. First, the geophysical relationship (model function) between the scatterometer measured normalized radar cross section and surface wind vector is not well defined at speeds greater than 20 m/s, and the resulting wind retrievals generally underestimate high wind speeds. Next, the relatively coarse spatial resolution scatterometer measurements produces wind field distortions, especially in high wind gradient regions. This results in incorrect wind direction solutions as well as producing smoothed fields with reduced peak wind speeds. Finally, contamination by heavy rain alters the ocean backscatter and thereby produces errors in the resulting wind retrievals. A novel scatterometer geophysical algorithm is presented that employs adaptive spatial resolution. This algorithm utilizes knowledge of the spatial characteristics of the hurricane surface winds to obtain an optimal wind retrieval. Simulated NASA Scatterometer data are presented that indicate significant improvements in spatial sampling and wind speed accuracy over conventional three "azimuth looks" wind retrievals.