[Retrieve phycocyanin concentrations based on semi-analytical model in the Dianchi Lake, China].

Phycocyanin (PC) in the blue-green algae is usually used to detective the quantity of the blue-green algae, because of its special absorption at band 620 nm. A semi-analytical model retrieving phycocyanin concentrations is been built, based on a nested semi-empirical band ratio algorithm, using the data sets collected in September 19 and September 20, 2009 from Dianchi Lake. The empirical relationship between the specific absorption coefficient at band 620 nm [a(PC)* (620)] and the absorption coefficient at band 620 nm [a(PC) (620)] reduces the impact of the variability of a(PC)* (620) in the model built by Simis. The new semi-analytical model is proved well done in retrieving phycocyanin concentrations and has a mean relative error (MRE) 21.63% by the dataset collected on December 1, 2009 from Dianchi Lake. The model error analysis prove that the main reason of the error is caused by the component and concentrations of pigments changing seasonally in the blue-green algae.