Spatial scale effect and spatial scaling of chlorophyll-a concentration in Lake Taihu, China

Retrieval of chlorophyll-a concentration using multi-source remote sensing images is one of the trends of inland water quality monitoring by remote sensing. In this paper, Lake Taihu in the east of China was selected as the study site. Based on the analysis of the spatial heterogeneity using measured data and semi-variance function, a method for up scaling 30m spatial resolution chla concentration to 240m was developed by using HJ-1 CCD image. Therefore, the algorithm was applied to correct chla estimation with MODIS data. The results indicated that there was an appreciable scale effect on chla concentration at the resolution of 250m, and the degree of spatial heterogeneity enhanced with increasing scale. In addition, the method for up scaling can improve the precision of the results estimated from low spatial resolution image. After correction, the accuracy increased by 10% and the result was much closer to actual values.