Global POC concentrations from in-situ and satellite data

During the last three decades significant contributions have been made to understanding regional and global distribution of chlorophyll in the ocean by developing algorithms from ocean-color products. Analogously, in this work empirical algorithms are developed to derive concentrations of particulate organic carbon (POC) from ocean-color products. We combined vertical profiles of particulate beam attenuation coefficient at 660 nm ( c p) collected on numerous cruises during World Ocean Circulation Experiment (WOCE), Joint Global Ocean Flux Study (JGOFS), South Atlantic Ventilation Experiment (SAVE), and other programs since the 1980s to create a global database. Discrete samples of POC and synchronously measured c p data collected in the Atlantic, Pacific, Indian and Southern oceans during JGOFS and other programs were used to make c p:POC regressions to convert c p data to POC values. During the two programs, satellite data were available when synchronous POC samples and c p profiles were obtained over several seasons. c p averaged over one attenuation depth in the South Pacific and northeast Gulf of Mexico was correlated with four synchronous ocean-color products. A good correlation was obtained with both normalized water-leaving radiance at 555 nm ( L WN(555)) and diffuse attenuation coefficient at 490 nm ( K 490). Using a combined K 490: c p regression from the two areas, global maps of the estimated mean c p were created and converted to mean POC concentration down to one attenuation depth for summer and winter seasons. Seasonal c p, POC and chlorophyll distributions were used to map %CHL and c p:CHL ratios within one attenuation depth as a possible index of phytoplankton physiology.