[Remote Sensing Inversion of Diffuse Attenuation Coefficient in Lake Taihu Based on the GOCI Images]

Diffuse attenuation coefficient (K(d)) is an important parameter in water body optics. The spectral characteristics of K(d) in Lake Taihu and its impact factors were analyzed using the in situ measured data from 2006-2009. Then, empirical models and semi-analysis models were built based on the GOCI data to estimate K(d), in order to find a suitable retrieval model for GOCI and analyze the spatial and temporal variations of diffuse attenuation coefficient in Lake Taihu. The result indicates that: (1) The main impact factor of diffuse attenuation coefficient at 490 nm is the non-algal particles absorption coefficient, and the combination model with GOCI bands 4, 5 and 7, namely the near infrared band, the red band and the green band, has the highest precision for the inversion of K(d) (490); (2) the range of K(d) of Lake Taihu distributes between 0 to 15 m(-1), and that can be divided into three levels generally, i. e., the range of the low value between 0-4 m(-1), the range of the medium value between 4-8 m(-1), and the range of the high value between 8-15 m(-1). While, occasionally, some values are higher than 15 m(-1); (3) the K(d) of Lake Taihu distributes with notable spatial and temporal difference. At the view of spatial distribution, the K(d) values get higher from the east to the west of Lake Taihu; from the perspective of time, the K(d) is relatively high in the morning and then shows a tendency of gradually reduce with the time.