Improved models for Chla estimation by considering the effect of phytoplankton specific absorption

In remote chlorophyll-a (Chla) retrieval in Case-II waters, the uncertainties from Chla specific absorption coefficient a*_ph has a significant effect on the retrieving accuracy. In this paper, we presented newly improved three-band model and four-band model by a case study in Shitoukoumen Reservoir. The proposed three-band model can be expressed as [Rrs^-1 (λ₁)-Rrs^-1 (λ₂)]×Rrs(λ₃)×a^*_ph^-1 (λ₁), while the improved four-band model is [Rrs^-1 (λ₁)-Rrs^-1 (λ₂)]×[Rrs^-1(λ₄)×Rrs^-1(λ₃)]^-1×a^*ph^-1(λ₁). Results showed that the latter one was slightly superior to the former one. Comparison with original models without correction of a*_ph, the improved models achieved higher precision and stability. The findings underlined the rationale behind the proposed models and demonstrated a potentially use for assessing Chla in Case-II waters.