NASA Scatterometer high resolution winds for Hurricane Lili

Aircraft flights that measured the normalized radar backscattering coefficient in hurricanes for rain free areas show that the backscatter has properties that differ from those in larger scale extratropical cyclones. The backscatter values are lower for the higher winds and increase more slowly at upwind and downwind with increasing wind speed, and the values near crosswind increase in such a way that the upwind crosswind difference decreases with increasing wind speed. A Tropical Cyclone Geophysical Model Function, named the TCGMF, has been developed explicitly for tropical cyclones. It differs from NSCAT-1a and NSCAT-1b for winds above about 15 meters per second. This model function is used to obtain a high resolution wind field for Hurricane Lili whose eye has been located for Rev 900 on Julian day 292 in 1996 to be at 23.4 degrees north and 283.1 degrees east. The analysis involves the large gradients in wind speed and pressure and the effects on the measured backscatter resulting from the spiral bands of thick clouds and rain. Conventional data sources such as ship reports, data from a NOAA research aircraft that flew into the storm at the time of the pass and from other spacecraft are used to develop an independent wind field analysis called TC96 for the winds in the boundary layer for comparison to the winds obtained from NSCAT. For winds above 25 m/s, the values of the averages, of TCGMF-TC96 are 0.1 m/s for Rev. 900 and -1.3 m/s for Rev. 907. For NSCAT-1b, the corresponding values are -5.32 m/s and -5.95 m/s