Spatial scale of chlorophyll-a concentration in Lake Taihu by using remote sensing images

Chlorophyll-a concentration is one of the most important indexes of Lake Eutrophication. Fine temporal and spatial resolution remote sensing images provide an effective way to monitor blue-green algae in Lake Taihu by studying the spatial distribution regularities of chla concentration. However, both low spatial resolution remote sensing images (e. g. MODIS) due to their heterogeneity and high or moderate spatial resolution remote sensing images (e. g. TM/ETM+) due to their low temporal resolution give rise to unsatisfactory estimate of chla concentration. Therefore, in this study, an effective method for estimating chla concentration using remote sensing images at different scales was developed. Chla concentration was inferred from Hyperion images at 30m resolution and MODIS images at 250m resolution. The spatial variability of Chla concentration was analyzed and Taihu Lake was divided into area with low variability and area with high variability. The quadratic polynomial (R-2=0.8709) and linear (R-2=0.7387) correlation was established. Finally, the obtained relationship between chla concentration estimate at different spatial scales were applied to correct the estimate from MODIS data.