Rain, wind, and backscatter: modeling rain effects on Ku-band ocean wind scatterometers

Spaceborne Ku-band ocean wind scatterometers (SeaWinds, NSCAT) enable frequent global coverage of meso-scale ocean surface winds. These instruments measure the normalized backscatter cross-section (/spl sigma//sub 0/) of the ocean´s surface from multiple look directions and use this information to estimate ocean surface wind vectors. Although /spl sigma//sub 0/ is strongly related to surface winds, at Ku-band it is also impacted to varying degrees by rain. Arguably, the most important error source for Ku-band wind scatterometers is rain contamination. In order to calibrate out the effects of rain as much as possible, we must understand the impact of rain on the backscatter measurements which are used to retrieve wind vectors.