Multi-Spectral Polarized Properties of Ocean Aerosol
YANG Bin1, 2, YAN Chang-xiang1*
1. Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China 2. University of Chinese Academy of Sciences, Beijing 100049, China
Abstract：In order to improve the retrieval accuracy of ocean aerosol , quantitative study was carried out in terms of the multi-spectral polarized properties of the aerosol in visible and near-infrared wavebands. Firstly, an aerosol model and a sea surface model were built. And the vector radiative transfer procedure of light in aerosol and atmosphere-ocean interface was simulated accurately based on the successive order of scattering method. Then from the perspective of the spectrum, the reflectance and polarized reflectance at the top of atmosphere in typical wavebands were quantitatively analyzed. Based on this, the spectrum distribution model of ocean aerosol polarized radiation was presented. And the model was validated with satellite data. Lastly, the influences of aerosol optical depth, viewing angle, chlorophyll a concentration and wind speed on multi-spectral polarized radiation of ocean aerosol were studied. The study shows that the changes of aerosol multi-spectral polarized radiation with wavelength can be best described with power function model when ignoring the absorbtion of atmosphere and solar flare effect in visible and near-infrared wavebands. This phenomenon can be caused by Rayleigh scattering and Mie scattering.The influences of chlorophyll a concentration and wind speed on multi-spectral polarized radiation of ocean aerosol emerge as very different in different wavebands. Specifically, the influences of chlorophyll a concentration on reflectance and polarized reflectance both can be neglected in near-infrared waveband. But in visible waveband, the influence on the reflectance must not be neglected any longer. Due to the increasement of the wind speed, the reflectance and the polarized reflectance increased significantly. But there are differences in the increases in different wavebands. The multi-spectral polarized radiative information of ocean aerosol can embody its own charactersitics effectively. And furthermore, the change of polarized reflectance with each factor has more obvious differences in different wavebands compared with reflectance. As a result, the multi-spectral polarized information of ocean aerosol can be used to retrieve the parameters of the aerosol over the ocean. The achievement of multi-spectral information has great significance for improving the retrieval accuracy of the ocean aerosol.
Key words：Ocean aerosol;Multi-spectral;Vector radiative transfer equation;Polarization
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