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 (cp) 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 cp data collected in the Atlantic, Pacific, Indian and Southern oceans during JGOFS and other programs were used to make cp:POC regressions to convert cp data to POC values. During the two programs, satellite data were available when synchronous POC samples and cp profiles were obtained over several seasons. cp 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 (LWN(555)) and diffuse attenuation coefficient at 490 nm (K-490). Using a combined K490:cp regression from the two areas, global maps of the estimated mean cp 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. (c) 2006 Elsevier Ltd. All rights reserved.