Estimation of K(PAR) in inland waters across China in relation to the light absorption of optically active components.

The comprehensive analysis of the relationships between the attenuation of photosynthetic active radiation (K(PAR)) and light absorption is an imperative requirement to retrieve K(PAR) from remote sensing data for aquatic environments. The spatial distributions of the K(PAR) and light absorption of optically active components (a) were routinely estimated in China lakes and reservoirs. Spatial K(PAR) was relatively dependent on the inorganic particles (average relative contribution of 57.95%). The a could explain 70-87% of K(PAR) variations. A linear model is used to predict K(PAR), as a function of light absorption coefficient of phytoplankton (a), colored dissolved organic matter (a), and inorganic particles (a): K(PAR) = 0.41 + 0.57 × a + 0.96 × a + 0.57 × a (R = 0.87, n = 741, p < 0.001). In the lakes with low TSM concentration and non-eutrophic lakes with high TSM, a was the most powerful predicting factor on K(PAR). In eutrophic lakes with high TSM, a had the most significant impact on K(PAR). This study allowed K(PAR) to be predicted from a values in the inland waters.