Global maps of microwave land surface emissivities: Potential for land surface characterization

Microwave land surface emissivities are derived from special sensor microwave imager (SSM/I) observations. Cloud-free SSM/I observations are first isolated with the help of collocated visible/infrared satellite observations (International Satellite Cloud Climatology Project (ISCCP) data). Then, the cloud-free atmospheric contribution is calculated from an estimate of the local atmospheric temperature-humidity profile (National Centers for Environmental Prediction (NCEP) analyses). Finally, with the surface skin temperature derived from IR observations (ISCCP estimate), the surface emissivity is calculated for all the SSM/I channels. The method is applied to the SSM/I data for the globe for October 1991. Correspondences between geographical patterns of the emissivities and surface characteristics are briefly analyzed to investigate the potential of microwave emissivities to monitor vegetation phenology and surface properties at regional and continental scales.