A New Algorithm for Determining the Wind Direction Using Satellite Radiopolarimetric Measurements
The paper presents an original MicRAWinD algorithm (Microwave Radiometric Algorithm for Wind Direction retrieval) with the help of which it is planned to restore the direction of the near-surface wind in the Space Experiment (SE)“Convergence”. The possibility of determining the direction of the wind from radiometric measurements in the two bands of the radiometer is related to the anisotropy of the surface radiation, which is best appear in the third Stokes parameter. Combining the results of measurements obtained at diff erent frequencies makes it possible to improve the accuracy of restoring the direction of the wind. A new algorithm for increasing the reliability of measurements is proposed, which takes into account the real errors in the measurement of brightness temperatures. The algorithm was tested on the basis of real data obtained by the radiometric system WindSat. The result of the wind direction retrieval according to the developed algorithm was compared with the data obtained from Remote Sensing Systems (RSS). For comparison, a region of the surface with diff erent geophysical parameters was chosen. These parameters are: sea surface temperature, vapor content, wind speed and direction, and the cloud liquid water. The MicRAWinD algorithm solves the direct problem of calculating the radio brightness temperatures on linear ±45° polarizations with the subsequent calculation of the third Stokes parameter for frequencies 37, 18.7 and 10.7 GHz. The initial meteorological parameters for solving a direct problem were the products presented by RSS. The sensitivity of radiometric instruments was taken into account in the modeling process. The solution of the inverse problem and the results of the comparison showed that the developed algorithm retrieves the wind direction with good qualitative agreement, both with the use of radiometric observations at one frequency and with joint multifrequency measurements.