The research has indicated that in shallow turbid lake, the absorption and scattering by total particulate matters (TSM) in water column determine the euphotic depth and furthermore determine the spatial distribution of aquatic macrophytes. Besides, TSM is an important carrier of heavy metal and nutritive salt in the water, determining the migration and transform of these substances. Therefore, TSM’s temporal-spatial variation is of great significance for the research on lake water photology especially large shallow lake photology, geo-biological-chemical cycle and lake ecosystem evolution. The inherited advantage of remote sensing technology has made it a effective and powerful tool in acquiring the data of TSM temporal-spatial variation. With the joint support by the National Science Fund for Distinguished Young Scholars and other programs, Zhang Yunlin’s research panel from Nanjing Institute of Geography & Limnology, CAS, has made a significant progress in developing a remote sensing estimation algorithm of TSM in Taihu Lake, as well as in research on the long-term dynamic evolution law and its origin. Relevant research finding has been carried on the newly published Remote Sensing of Environment (Remote Sensing of Environment, 2015, 164:43-56).
The research, firstly, on the basis of the multiple and wide-ranging biological optical surveys on Taihu Lake conducted in 2003-2012, analyzed the relation between TSM and such optical parameters as diffuse attenuation coefficient and transparency, especially the inherent relationship between TSM and optical properties of water and thus verified the role of TSM in Taihu Lake light ecosystem. The research developed an atmospheric correction method for Taihu MODIS data based on the adjacent dark macrophyte target. With this method, atmospheric correction has been made against 11 years’ of MODIS image data in Taihu Lake from 2003 to 2013 (images of 1109 scenes), thus acquiring the long-term sequence remote sensing reflectance data. Based on the synchronized image data and TSM data measured on the ground, a MODIS-based Taihu Lake TSM remote sensing estimation model is established and verified. Furthermore, based on this model and in reference to the TSM temporal-spatial pattern acquired with Taihu Lake MODIS atmospheric correction data in 2003-2013, the research has found that Taihu Lake TSM has an obvious spatial-temporal heterogeneity, with TSM in winter significantly higher than that in summer and autumn and TSM in center of Taihu Lake higher than off-shore and bay area. Such a TSM temporal-spatial pattern in Taihu Lake mainly depends on topography of the lake, input of streams, wind speed and distribution of macrophytes; the research has also found that TSM evidently correlates with disturbance index and wind speed. The topography of lake, as the prerequisite, determines the disturbance index and wind-wave disturbance intensity, thus furthermore influences the TSM spatial-temporal pattern of Taihu Lake, and exogenous stream input and submerged plants superimposed on the lake topography jointly control the temporal-spatial variation of TSM distribution.
For the original text, link to http://www.sciencedirect.com/science/article/pii/S0034425715000887
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