RETRIEVAL OF 91 AND 150 GHZ EARTH SURFACE EMISSIVITIES

Surface emissivities at 91 and 150 GHz are retrieved using a microwave radiative transfer model and the atmospheric profiles and brightness temperatures (TBs) for the cloud-free cases from a global data set of collocated SSM/T-2 and radiosonde measurements. The retrieved emissivity values for various Earth surface types are consistent with those from other studies. The retrieval scheme displays limited sensitivity to uncertainty in the input data and the retrieved values are found to have good reproducibility for a given region. The possible use of special sensor microwave/imager (SSM/I) TB measurements for estimation of 91- and 150-GHz emissivities is explored using a subset of the retrieved emissivity cases which was augmented with SSM/I data. It is demonstrated that SSM/I TBs are potentially useful for making accurate estimates of surface emissivities at 91 and 150 GHz. This should lead to improved SSM/T-2 lower tropospheric water vapor profile retrievals.