基于MODIS的西藏典型湖泊叶绿素a浓度反演

叶绿素a浓度是反映湖泊富营养化状态的一个重要参数。以MODIS L1B数据为基础,结合叶绿素a浓度实测数据,基于经验分析法实现了西藏典型湖泊叶绿素a浓度反演研究,并探索了西藏典型湖泊2019年春、夏、秋季叶绿素a浓度的时空变化特征。首先,利用叶绿素a浓度实测数据和MODIS L1B影像不同波段的反射率值进行组合试验,选择最佳波段组合建立模型;其次,分别选用2015年、2017年叶绿素a浓度实测值和反演值对模型进行对比验证;最后,利用叶绿素a浓度反演模型对西藏典型湖泊2019年春、夏、秋季叶绿素a浓度的时空变化特征进行分析。结果表明：在空间尺度上,西藏典型湖泊叶绿素a浓度整体上呈现出周围高、中部低的分布特征,且湖岸水体叶绿素a浓度变化较大;在季节尺度上,不同湖泊叶绿素a浓度的季节变化存在较大差异,格仁错和色林错的季节变化幅度较大,纳木错、塔若错和羊卓雍错的季节变化幅度较小。

Inversion of Chlorophyll-a Concentration in Typical Lakes of Tibet Based on MODIS

Chlorophyll-a concentration is an important parameter reflecting eutrophication state of lake.Based on MODIS L1B data and measured data of chlorophyll-a concentration,this paper realized remote sensing inversion of chlorophyll-a concentration in eight typical lakes in Tibet,and explored the spatio-temporal variation characteristics of chlorophyll-a concentration in spring,summer and autumn of 2019.Firstly,the combined experiment was carried out using the measured data of chlorophyll-a concentration and the reflectance values of different bands of the corresponding MODIS L1B image,and the best band combination was selected to establish the inversion model.Secondly,the measured and inverse values of chlorophyll-a concentration in 2015 and 2017 were selected to compare and verify the models.Finally,based on the inversion model of chlorophyll-a concentration,the spatio-temporal variation characteristics of chlorophyll-a concentration in spring,summer and autumn of 2019 in eight typical lakes in Tibet were analyzed.The results showed that at the spatial scale,the concentration of chlorophyll-a in lakeshore water showed a trend of "high in the periphery,low in the middle".At the seasonal scale,the seasonal variation of chlorophyll-a concentration in different lakes showed great difference,with the greater variation in Gerentso and Selintso,and the smaller variation in Namtso,Taruoco and Yamdroyongtso.