NDCI法Ⅱ类水体叶绿素a浓度高光谱遥感数据估算

Estimation of chlorophyll-a concentration of case Ⅱ waters from hyperspectral remote sensing data in NDCI method

以太湖、巢湖为研究区,以Hyperion和HJ-1A卫星HSI高光谱数据以及实测水质浓度数据为实验数据,引入归一化叶绿素指数(NDCI),对Ⅱ类水体的高光谱叶绿素a浓度估算进行分析研究.首先对高光谱数据的光谱通道设置以及水体光谱特征进行分析,研究确定模型的最优波段.然后,将确定最优波段后的NDCI反射率因子作为变量与实测样本点数据进行回归分析,得到NDCI与叶绿素a浓度之间的回归关系,进行叶绿素a浓度的估算.与常用的比值法、一阶微分法和三波段法相比,NDCI的性能优于这3种方法,表明NDCI是一种计算简单、估算精度高、实用性强的Ⅱ类水体叶绿素a浓度估算方法.

A novel index, Normalized Difference Chlorophyll Index （ NDCI）, is introduced in this study to estimate the chlorophyll-a （Chl. a） concentration from Hyperspectral Hyperion data, HSI data, and measured Chl. a concentration data for Lake Taihu and Lake Chaohu in eastern China. The best bands were selected by analyzing spectral channels of the Hyperspectral data and the spectral characteristics of the water. The Chl. a concentration was estimated by considering the regression relationships between NDCI and the measured Chl. a concentrations through the analysis of the NDCI reflection factor and points data of measured samples. Comparing the results of the NDCI method to that of the normal ratio, first-order differential, and three bands methods, the NDCI method has performed better in simplicity, accuracy and applicability than the other three methods in the estimation of Chl. a concentration in case Ⅱ waters.