Empirical ocean-color algorithms to retrieve chlorophyll-a, total suspended matter, and colored dissolved organic matter absorption coefficient in the Yellow and East China Seas

A bio-optical dataset collected during the 1998-2007 period in the Yellow and East China Seas (YECS) was used to provide alternative empirical ocean-color algorithms in the retrieval of chlorophyll-a (Chl-a), total suspended matter (TSM), and colored dissolved organic matter (CDOM) absorption coefficients at 440 nm (ag(440)). Assuming that remote-sensing reflectance (Rrs) could be retrieved accurately, empirical algorithms for T-Chl (regionally tuned Tassan's Chl-a algorithm) in case-1 waters (T(Chl)2i in case-2 waters), T-TSM (regionally tuned Tassan's TSM algorithm), and T-ag440 or C-ag440 (regionally tuned Tassan's or Carder's ag(440) algorithm) were able to retrieve Chl-a, TSM, and ag(440) with uncertainties as high as 35, 46, and 35%, respectively. Applying the standard SeaWiFS Rrs, T-Chl was not viable in the eastern part of the YECS, which was associated with an inaccurate SeaWiFS Rrs retrieval because of improper atmospheric correction. T-Chl behaved better than other algorithms in the turbid case-2 waters, although overestimation was still observed. To retrieve more reliable Chl-a estimates with standard SeaWiFS Rrs in turbid water (a proxy for case-2 waters), we modified T-Chl for data with SeaWiFS normalized water-leaving radiance at 555 nm (nLw(555)) > 2 mW cm(-2) mu m(-1) sr(-1) (T(Chl)2s). Finally, with standard SeaWiFS Rrs, we recommend switching algorithms from T(Chl)2s (for case-2 waters) to MOCChl (SeaWiFS-modified NASA OC4v4 standard algorithm for case-1 waters) for retrieving Chl-a, which resulted in uncertainties as high as 49%. To retrieve TSM and ag(440) using SeaWiFS Rrs, we recommend empirical algorithms for T-TSM (pre-SeaWiFS-modified form) and MTag440 or MCag440 (SeaWiFS Rrs-modified forms of T-ag440 or C-ag440). These could retrieve with uncertainties as high as 82 and 52%, respectively.