Microwave Emissivity Over Ocean in All-Weather Conditions: Validation Using WINDSAT and Airborne GPS Dropsondes

Emissivity spectra computed by the FASTEM-3 model using global positioning system dropsonde wind as input are compared to emissivity retrieved from stringently coincident WINDSAT measurements, using a variational approach. This is done in both clear and rainy conditions to assess the validity of both the emissivity model and the retrieval technique in all conditions. Results of this comparison are presented for vertical and horizontal polarizations, in moderate to high wind conditions. In particular, a slope difference is found, and its potential sources are discussed in this paper.