基于生物光学模型的水质参数反演分析方法是水质遥感监测算法的发展趋势.分析方法中需要以水体中悬浮物后向散射系数作为参数.水体中悬浮物后向散射系数目前主要有3种测量方法,但是这些方法要么因为仪器稀缺而无法普及,要么测量精度不高.提出了一种计算水体中的悬浮物后向散射系数的方法,该方法利用水面比较容易测量的反射率光谱和实验室内比较容易测量的水体各组分的吸收系数光谱,基于生物光学模型推导得出水体中的悬浮物后向散射系数.利用太湖梅梁湾试验区获取的数据检验了这种方法,并取得了较好的效果.这种方法的主要优势是:它基于生物光学模型,有严密的理论基础,具有较高的精度和通用性;另外,它使用的数据比较容易测量,方法容易实施,可为水质参数反演分析方法的建立奠定坚实的数据基础.

Analytical algorithm, which is based on bio-opticalmode,l represents the trends of algorithms in retrieving water quality parameters from remote sensing data. In analytical algorithm, inherentopticalproperties, including absorp-tion coefficients and back-scattering coefficients ofeach componentofwater, are mi portant inputparameters. The absorp-tion coefficients of each componentofwater can bemeasured easily in laboratory. On the other hand, themeasuring of back-scattering coefficients of suspendedmatter inwater is alwaysdifficult, especially for inlandwaters. There aremainly three kinds ofmethods inmeasuring back-scattering coefficients ofsuspendedmatter: (1) measuring in fieldwith specific instruments; (2) collectingwater samples in field, measuring the scattering phase functions of thewater samples in labo-ratory, and then calculating the back-scattering coefficients based on the scattering phase functions; (3) collectingwater samples in field, measuring the total absorption coefficients and beam attenuation coefficients of the water samples,and then calculating the back-scattering coefficientsby substracting the totalabsorption coefficients from beam attenuation coef- ficients, and thenmultiplying ratio ofback-scattering coefficients of suspendedmatter. However, all these threemethods have some drawbacks: (1) thesemethods aremainly designed foroceanwaters, andmaynotbe suitable for inlandwaters due to the greatdifferences in opticalpropertiesbetween them; (2) the scattering phase functionmeasuring instrument is hard to be designed and installed, and there are few such instruments in China; (3) the ratio ofback-scattering coeffi-cients of suspendedmatter, which is difficult tomeasure, has to be estmi ated in calculating back-scattering coefficients of suspendedmatter, and the estmi ationwill lead to some errors.In this paper, a newmethod of calculating back-scattering coefficients of suspendedmatter is put forward. Based on bio-opticalmode,l thismethod uses thewater surface reflectance spectra data and absorption coefficients ofwater compo-nents to retrieve back-scattering coefficients of suspended matter. Validated by data acquired from Meiliang Bay, Taihu Lake, thismethod shows advantages as follows: (1) based on bio-opticalmode,l ithas sound theoreticalbasis; (2) it is easy to be carried out because the data used in thismethod are easy to obtain. Provided the above advantages, data of back-scattering coefficients of suspendedmatter can be acquired for the application in the future.