鄱阳湖水体悬浮颗粒物散射光谱分解方法研究

Partitioning of the Suspended Particulate Spectral Scattering Coefficient in Poyang Lake

内陆水体复杂性为水体悬浮颗粒物散射光谱分解带来难题,也制约着水色遥感理论算法的发展。以2009年鄱阳湖秋季观测数据为基础,提出一种二元简化主轴(ranged major axis,RMA)方法的水体悬浮颗粒物散射光谱分解模型,对鄱阳湖水体中悬浮无机颗粒物与有机颗粒物的散射光谱进行了提取研究。结果表明采用RMA方法建立的悬浮颗粒物散射光谱分解模型在鄱阳湖具有很好的分离效果,在高浑浊水体区域总悬浮颗粒物散射系数预测误差在15%以内,与现有方法相比具有明显优势。分解结果显示鄱阳湖悬浮颗粒物散射主要来自以伊利石/蒙脱石为主要成分的无机颗粒物,RMA方法能够反映占主导地位悬浮颗粒物的散射特性,可以为高浑浊水体散射模型与水色遥感反演算法的研究提供重要依据。

A model for partitioning the particulate scattering coefficient into the contributions of suspended mineral particle and organic particle was proposed based on the measured data.The independent variables,i.e.the concentrations of mineral particles and organic particles in this study,were used to determine the mass-specific scattering cross section with the concurrent total suspended particulate scattering coefficients collected during the field trip in Poyang Lake 2009.Results show that the scattering spectra of inorganic particles and organic particles can be successful derived by the proposed model,and the reconstructed total particulate scattering coefficients are in better agreement with the measured values by the ordinary least square linear regression.For the whole South Poyang Lake,mean absolute percentage errors between the measured scattering coefficients and reconstructed value were less than 25% over the main remote sensing effective wavebands such as 440,532,555 and 676 nm.A remarkable lower predicted error,which can be controlled within 15%,were found at all stations with higher concentration of total suspended matters,while the spectral partitioning is less efficient at stations with total suspended particle concentration less than 15 mg·L-1.Particulate scattering spectrum retrieved by RMA shows that illite and montmorillonite are the major constituents of inorganic matters which dominate the light scattering properties of Poyang Lake.It is possible that scattering spectrum partitioned by the model could infer the major effective components in waters,and could be used to predict particulate scattering properties for highly turbid waters.