Removing upwind/downwind ambiguity of ocean wind direction by polarimetric microwave radiometer: Algorithmic basis
一种消除全极化微波辐射顺/逆风向遥感模糊性的新方案——算法研究

Polarimetric microwave radiometer can be used for remote sensing of ocean surface wind speed and direction. The globalminimum of the cost function corresponds to the bestestimate of the actualwind vector; butdue to the level of noise itmay not be the closest ambiguity to the true wind direction. The presence of these ambiguous solutionsmust be carefully considered in the retrieval of wind vector estimates. Expected errors in wind direction retrievals have been examined using Monte Carlo simulation analysis, as well as the maximum likelihood estimation (MLE) cost function in the presence of noise. An algorithm is proposed to obtainwind direction according to the first and second rank solutions of the first scan and the first rank solution of the second scan. The simulated results show that the algorithm can avoid ambiguous solution, and the cells near the position that along or perpendicular to spacecraft- heading vectorgive the largesterrorof retrievedwind direction. These cells can be used for cold andwarm calibration, and the residual cellswhich give smallerdirection errors can be used forwind direction remote sensing. A new scanning geometry for conical-scan is put forward.