A Sst-Dependent Geophysical Model Function For Hy-2a Microwave Scatterometer

Satellite scatterometer provides an effective approach to obtaining the ocean surface winds on a global scale. However, none of the geophysical model functions(GMF) currently used in wind retrieval takes the effect of sea surface temperature(SST) into account. Many experiments demonstrate that SST indeed have an impact on the behavior of the microwave backscatter of the ocean surface. This paper utilized the co-located backscatter coefficients from HY-2A scatterometer, re-analysis wind speed and direction data of ECMWF(European Center for Medium-Range Weather Forecast), and SST(sea surface temperature) data acquired by WindSat to examine the dependence of radar backscatter coefficient on SST and then derive a SST-dependent geophysical model function(SST-GMF). The validation experiment results indicate that the SST-GMF leads to a smaller wind speed bias at the low(0-10 degrees C) and the high(20-30 degrees C) SST ranges compared to the NSCAT-2 model, resulting in a higher wind speed retrieval precision.