Ocean Wind Speed Retrieval Method with a Relative Wind Direction Using Microwave Radiometer Data

An ocean wind speed retrieval method with microwave radiometer data is proposed considering relative wind directions on observed brightness temperature. The conventional method is based on regressive analysis between in-situ ocean wind and brightness temperature observed with microwave radiometer without consideration of relative wind direction. Although geophysical parameters are also taken into account for the conventional method based on regression analysis based on least square method such as steepest descent method, conjugate gradient method, etc., global optimum solution cannot be expected. The proposed method is based on the geophysical models and uses a modified simulated annealing. In the experiment, Advanced Microwave Scanning Radiometer (AMSR-E) data and the corresponding NCEP Global Data Assimilation System (GDAS) data are used. It is found the discrepancy between the wind speed derived from AMSR-E and GDAS depending on Relative Wind Direction (RWD). Also, it is found that the estimation accuracy is improved by up to 61.2% which depends on location and seasons in concern. In the worst case, ocean speed estimation accuracy was degraded by 0.94% though.