Satellite estimation of marine particulate organic carbon in waters dominated by different phytoplankton taxa

Abstract

The relationship between in situ remote sensing reflectance (Rrs) and particulate organic carbon (POC) was assessed for the continental shelf waters of the southwestern Ross Sea, Antarctica. This sector of the Southern Ocean supports two distinct phytoplankton communities, one dominated by diatoms and the other dominated by the haptophyte Phaeocystis antarctica. In both communities, Rrs exhibited a statistically significant (p < 0.05) positive linear correlation with POC concentration, although the slope of the regression was over twofold higher in waters dominated by P. antarctica. These distinct relationships between POC and Rrs are likely due to differences in the cell size and composition, as well as detrital degradation products, of the dominant taxa within each of these phytoplankton communities. Taxon‐specific POC‐Rrs relationships were translated into a bio‐optical algorithm for estimation of surface POC concentration from remotely sensed estimates of Rrs. Applying this algorithm to satellite‐derived Rrs from the Ross Sea, where distributions of P. antarctica and diatoms are reasonably well known, yields distributions of POC and POC:chlorophyll ratios that are in good agreement with field measurements. Performance of the algorithm can be improved by in situ characterization of the detrital contribution to total particle backscatter.