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湖泊透明度是湖泊水体性质的一个重要参数,是湖泊浮游生物和进入湖泊的有机和无机颗粒溶解程度的综合反映,对湖泊生态环境研究具有重要的科学及实践意义。遥感影像是获取面积广、时间长的湖泊透明度的重要手段,但由于实测数据缺乏,目前对青藏高原地区湖泊透明度的遥感反演研究相对不足。本文基于青藏高原地区24个湖泊实测透明度SD(Secchi Depth)值和相应的MODIS遥感影像,建立了该地区湖泊水体透明度SD值MODIS遥感反演模型。结果表明:基于MODIS绿色波段B4的单波段幂函数模型在该地区反演效果最好,精度较高(R2=0.91,N=24),并具有较好的稳定性。以当惹雍错为例,选用该模型反演得到湖泊透明度的时间变化序列,发现该湖存在明显的季节波动和较为明显的年际变化。初步分析得出,降水/融水季节的湖泊透明度与湖泊所在流域的降水率具有密切的关系。本文结果表明,利用遥感手段能够有效地开展青藏高原地区湖泊透明度的反演,可为进一步深入研究该地区湖泊透明度及其影响要素奠定基础。
Lake transparency is an important parameter of the lake water body and is a comprehensive reflection of the degree of dissolution of lake plankton and organic and inorganic particles entering the lake. It has important scientific and practical significance for the study of lake ecological environment. Remote sensing imagery is an important method to obtain the transparency of a large area and long time lakes. However, due to the lack of measured data, the retrieval of remote sensing of the transparency of lakes in the Tibetan Plateau is relatively inadequate. Based on the Secchi Depth (SD) values and corresponding MODIS remote sensing images of 24 lakes in the Qinghai-Tibet Plateau, a MODIS remote sensing inversion model for the SD value of the lake water transparency was established. The results show that the single-band power function model based on MODIS green band B4 has the best inversion accuracy and high accuracy (R2 = 0.91, N = 24) and has good stability. Taking the example of the repulsion of Yogyakarta, this series of models were used to retrieve the temporal variation of lake transparency. It is found that the lake has obvious seasonal fluctuations and obvious interannual variability. Preliminary analysis shows that the transparency of lakes during the precipitation / melting season is closely related to the precipitation in the basin where the lake is located. The results show that using remote sensing to effectively carry out the retrieval of the transparency of lakes in the Qinghai-Tibet Plateau lays the foundation for further study on the transparency of lakes in the region and its influencing factors.