基于振动拉曼散射的差分水Ring效应系数卷积计算模型

A convolution algorithm of differential coefficients of liquid water based on vibrational Raman scattering

利用被动差分吸收光谱算法反演水体上方尤其是海洋上方的大气痕量气体浓度时,水体的振动拉曼散射导致对太阳光谱中夫琅禾费线的填充.若不考虑这种类似大气Ring效应的水Ring效应,会直接影响反演精度.参考OMI传感器对大气Ring效应校正的卷积算法,针对痕量气体OClO的反演,利用经过大气消光计算后的太阳360—400nm入射光谱和对应波段的水体后向振动拉曼散射系数,通过卷积差分计算,得到了差分水Ring效应系数.与Vasilkov模型计算得到的结果比较,二者的相关系数R达到0.9665.

Inelastic vibrational Raman scattering by liquid water is one significant limitation to the accuracy of the retrieval of trace gas constituents in atmosphere over waters,particularly over clear ocean waters,while using satellite data with differential optical absorption spectroscopy technique（DOAS）.The effect which is similar to the Ring effect in atmosphere results in the filling-in of Fraunhofer lines,which is known as solar absorption lines.The inelastic component of the liquid water scattering causes a net increase of radiance in the line because more radiations shift to the wavelength of an absorption line than from this wavelength to other wavelengths.The solar spectrum transmitting atmosphere is convolved with vibrational Raman scattering coefficient of liquid water,divided by the original computed spectrum,with a cubic polynomial subtracted off,to create differential water Ring spectrum.This method is suggested in order to obtain an effective differential water Ring coeffient for the DOAS fitting process,which could be used to improve the accuracy of the retrieval of the trace gases concentration.The method does not rely on radiative transfer model of water,which would be time-consuming and depending on lot of parameters.Therefore,it is very fast and convenient.