Approximate bottom contribution to remote sensing reflectance in Taihu Lake, China
Approximate bottom contribution to remote sensing reflectance in Taihu Lake, China
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DOI：
10.1016/j.jglr.2010.12.002
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发表时间：
2011-03
影响因子：
2.2
通讯作者：
R. Ma;H. Duan;Qinhuo Liu;S. Loiselle
中科院分区：
文献类型：
--
作者：
R. Ma;H. Duan;Qinhuo Liu;S. Loiselle
遥感是分析湖泊生态系统时空变化趋势的基本工具。使用这些方法的一个主要挑战是确定水下植被或湖底反射的可能影响。在本研究中，我们研究了在中国东南部的一个大的浅湖太湖的大量站点测量的水的离开辐射。由于悬浮沉积物和浮游植物生物量的高浓度，大部分湖泊可以被认为是光学深的（即可以忽略底部反射率）。然而，在湖东侧的浅海湾中存在光学浅水。在这些地区，存在水下植被。为了探讨湖底和淹没植被对遥感反射率的贡献，我们比较了两种建模方法（Hydrolight和LEE）。结果表明，湖底光学特性和物理特性的差异对测量反射率的光谱特性有很大影响。使用可能发生底部效应的地点和不可能发生底部效应的地点的数据集测试了由此产生的对叶绿素-a浓度估计的影响。当从校准过程中去除受底部影响的区域时，基于反射率的浮游植物生物量估计的预测能力得到了显著改善。
Remote sensing is a fundamental tool for the analysis of spatial and temporal trends in lake ecosystems. A major challenge in using these approaches is determining the possible influence of reflectance from submerged vegetation or the lake bottom. In the present study, we examine the water leaving radiance measured in a large number of sites in Taihu Lake, a large shallow lake in southeast China. Due to the high concentrations of suspended sediment and phytoplankton biomass, a majority of the lake can be considered optically deep (i.e. bottom reflectance could be ignored). However, optically shallow waters were present in the shallow bays on the eastern side of the lake. In these areas, submerged vegetation was present. To explore the contribution of the lake bottom and submerged vegetation on remotely sensed reflectance, we compared two modeling approaches (Hydrolight and the LEE). The results show that differences in optical and physical characteristics of the lake bottom strongly influence the spectral characteristics of the measured reflectance. The resulting impact on the estimate of chlorophyll-a concentrations was tested using datasets with and without sites where bottom effects may occur. A significant improvement in the predictive capacity of the reflectance based estimated of phytoplankton biomass was made when areas with bottom influences were removed from the calibration procedure.