A study of the effect of swell in scatterometer wind measurements using ERS SAR wave mode data

Coincident and nearly co-located SAR wave mode data and scatterometer data are used to study the effect of swells in the ERS scatterometer measurements. It is shown that the speckle power in the SAR wave mode spectrum is a good measure of the mean radar backscatter from the ocean surface. The wind dependence of the speckle power is compared with the scatterometer winds with and without the effects of swell. It is shown that the speckle power increases in the presence of swell. The swells travelling in the azimuth direction have a greater impact on the speckle power than range travelling swells. It is argued that the wind speed dependence of the SAR speckle power enables the SAR to be used as a high resolution wind mapper.