基于分类和MERIS的近红外/红光波段估算内陆浑浊水体叶绿素a的浓度

In this paper, the classification criteria were established to classify the water of Taihu Lake into 4 classes based on above-water remote sensing reflectance (Rrs), i.e., types A to D. Among the four water types, type A spectra represented the case of waters that appeared algal blooms or aquatic plants, while type B referred to the water with high suspended matter concentration and low chlorophyll a concentration (Cchla). Both types A and B were not suitable for retrieving Cchla from image data. Hence, three-band, four-band and two-band ratio algorithms were constructed to retrieve Cchla from water types C and D. The obtained results showed that the relation trends between Cchla and Rrs were different between type C and type D waters. By using MERIS images, acquired on 11 November 2007 and 20 November 2008, the Cchla of Taihu Lake was mapped by band9/band7 models; it could be concluded that the Cchla mainly ranged from 0 mg m-3 to 20 mg m-3, accounting for 83.70% of the whole lake area in 2007 image, while the area was 86.63% in 2008 image. The estimation accuracies varied from different Cchla ranges. The MAPEs obtained by band9/band7 models were 106.23%, 56.79%, 38.04%, 33.80%, and 58.74% for the ranges 0 mg m-3< Cchla <=5 mg m-3, 5 mg m-3< Cchla <=10 mg m-3, 10 mg m-3< Cchla <=20 mg m-3, 20 mg m-3< Cchla <=30 mg m-3, and 30 mg m-3< Cchla, respectively. Correspondingly, the RMSEs were 5.02, 4.45, 5.59, 8.72 and 32.55 mg m-3, respectively.