Two microwave land emissivity parameterizations suitable for AMSU observations

In this work, two microwave emissivity parameterizations are proposed to estimate the land emissivity at Advanced Microwave Sounding Units (AMSU) frequencies and scanning conditions in order to help processing AMSU measurements over land surfaces. Both parameterizations are derived from previously calculated land emissivities directly from satellite observations and take into account different surface types from bare soil to areas with high vegetation density. The first parameterization uses best-fit functions derived from February 2000 observations whereas the second parameterization is based on the first one with the addition of a mean nadir emissivity map at 23.8 GHz to allow a more precise surface description. The emissivity parameterizations have been evaluated by comparing emissivity and Tb simulations to target emissivity and Tb observations.