[Estimation and remote sensing inversion of diffuse attenuation coefficient Kd(490) in Lake Taihu in spring based on semi-analytical model].

Diffuse attenuation coefficient is not only an important optical parameter, but also an important factor of water ecological system. Two datasets measured in April 2009 and May 2010 were firstly used to calculate absorption coefficient [a (490)] and backscattering coefficient [b(b) (490)] at 490 nm, and then, the relationship between b(b) (490) and simulated remote sensing reflectance at different bands of HJ-1 was studied. The semi-analytical model of Kd (490) in Lake Taihu in spring was constructed based on this basis, and it was used to estimate Kd (490) of Lake Taihu via an image of HJ-1 finally. The results show that: 1) The values of a(490) and b(b)(490) can be calculated accurately based on optical closure principle, and the mean absolute percent error (MAPE) of a(490) between calculated and measured is 17.1%. In addition, the backscattering coefficient at 490 nm [b(b) (490)] exponentially relate with the simulated remote sensing reflectance at the fourth band of HJ-1; 2) The semi-analytical model constructed in this study has good accuracy and stability. The MAPE is 21.6% and RMSE is 1.68 m(-1) by comparing inversion result and quasi-synchronous measured data; 3) Kd (490) of Lake Taihu in spring differs a lot in space distribution. The values are relatively smaller in north and east part of Lake Taihu, but larger in west and south part.