利用准分析算法由遥感反射比反演黄海水体吸收系数

Deriving Absorption Coefficients from Remote Sensing Reflectance Using the Quasi-Analytical Algorithm(QAA) in the Yellow Sea

利用2006年4月份在黄海现场测量的海洋光学数据集测试准分析算法(QAA)在黄海的适用性。QAA从实测的遥感反射比数据反演水体总吸收系数、黄色物质和碎屑、浮游植物的吸收系数,反演的平均误差分别为14.4%,26.1%,44.2%。结果表明QAA可以很好的反演黄海海域包括沿岸水体的总吸收系数与黄色物质和碎屑的吸收系数,但反演浮游植物的吸收系数有较大的误差。根据实测数据分析发现,在黄海海域浮游植物的吸收对总吸收(去掉纯水体吸收)在蓝绿波段的平均相对贡献为20%,远低于黄色物质和碎屑的贡献。因此文中对QAA进行了修正,用浮游植物的光谱模型代替QAA算法中黄色物质和碎屑的吸收光谱模型。修正后的QAA反演的黄色物质和碎屑、浮游植物的平均误差分别为:23.4%和28.1%,可以有效改善原来算法反演浮游植物吸收系数的能力。

The ocean optics in situ data collected from the Yellow Sea in April 2006 were used to test the performance of the quasi-analytical algorithm(QAA).QAA was applied to derive the total absorption coefficient,absorption coefficients of yellow substance and detritus,and the absorption coefficient of phytoplankton.The relative errors were 14.4%,26.1% and 44.2%,respectively.The results indicate that the QAA worked quite satisfactorily for deriving the total absorption and the absorption of yellow substance and detritus,but not so well for the absorption coefficient of phytoplankton.It was found from the measured in situ data that the relative contribution to the total absorption(the absorption of water excluded) of phytoplankton was about 20% in the blue band in the Yellow Sea,which was much less than the contributions of yellow substance and detritus.Therefore the QAA algorithm was modified by using the spectral model of phytoplankton instead of those of CDOM and detritus,and then the relative errors of the derived absorption coefficients of yellow substance and detritus and phytoplankton were 23.4% and 28.1%,respectively,which really improved the accuracy of the QAA in deriving the absorption coefficient of phytoplankton.