Remote sensing of diffuse attenuation coefficient using MODIS imagery of turbid coastal waters: A case study in Bohai Sea

摘要

The objectives of this study are to evaluate the applicability of three existing retrieval algorithms of diffuse attenuation coefficients of downwelling irradiance at 490nm, K_d(490), for turbid Case II waters, and to improve these existing models using a simple semi-analytical (SSA) model. In this study, based on comparison of the K_d(490) predicted by these models with field measurements taken in the Bohai Sea and Yellow Sea, it is shown that the SSA model provides a stronger performance than these three selected existing models. The atmospheric influences on the MODIS data are removed using an improved shortwave infrared band-based (ISWIR-based) model, which is capable of retrieving spectral remote sensing reflectance within 19% uncertainty. The K_d(490) data was quantified from the MODIS images after atmospheric correction using the SSA model and Wang's model. The study results indicate that the SSA model produces 31.51% uncertainty in deriving K_d(490) from MODIS data, which is 12.1% higher than Wang's model. This study demonstrates the potential of the SSA model in estimating K_d(490) even in highly turbid coastal waters.