The impact of the SSM/I antenna gain function on land surface parameter retrieval

In order to investigate the effect of the antenna gain on land surface para meter retrievals with SSM/I, a Gauss-function is fitted to the 19 GHz anten na gain functions. Soil moisture and surface temperature distributions for the Red-Arkansas River basins are calculated from a soil-vegetation-atmosph ere model. A passive microwave emission model is applied to derive polarize d 19 GHz brightness temperatures. Those parameters are aggregated up to 19 GHz footprint size taking into account different spatial weighting accordin g to the Gauss-function. These reference averages represent the full radiom eter resolution, which is approximately three times the -3dB resolution. Th e comparisons between the reference values and simple linear averages for s everal spatial resolutions lead to differences varying from 2% to 17% volum etric soil moisture.