Wind Field Retrieval And Precision Analysis On Polarimetric Microwave Radiometer Sea Surface Measurements

Wind speed and directions not only play key roles in the ocean circulation and globalocean-air interactions, but also have important effect on sea surface temperature,hydrological cycle and global biochemical processes. Polarimetric microwave radiometeris a passive microwave remote sensor, which likes traditional microwave radiometer,could measure the orthogonal polarization components; besides, it could get the targetpolarization information and measure sea surface wind speed and direction. Polarimetricradiometer can be all-time, all-weather remote sensing of sea surface wind field in a largearea, broadening passive microwave remote sensing applications.Based on elaborating polarimetric microwave radiometer sea surface wind fieldmeasurement principle, the paper analyses sea surface microwave polarimetric radiationand introduces the forward model. Polarimetric microwave radiation of the sea surface notonly relates to sea surface temperature, water dielectric constant, frequency and otherfactors, but also associates with the atmosphere parameters.According to the forward model, we calculate the sea water brightness temperaturefor some frequencies. Based on the radiometer receives radiation brightness temperature,the retrieval algorithm is inversion for the radiative transfer model, or directly utilize thebrightness temperature data and synchronize field data to access the marine andatmosphere parameter with the statistic method. In the paper, we adopt two retrievalalgorithms---physical statistical algorithm and maximum likelihood estimation algorithmto inverse sea surface wind field. Then we analyze and compare these retrieval algorithms.Most of wind retrieval error is the Stokes parameters measurements error.Measurement errors mainly include the instrument system errors and calibration error.Firstly we analyze the measurement error have impact on the retrieval precision for thewind speed and direction. Then, we analyze the factors that affect the calibration error, andquantitatively give the calibration precision for the calibration error.