Estimates of particulate organic carbon over the euphotic depth from in situ measurements. Application to satellite data over the global ocean

Knowledge of the oceanic particulate organic carbon (POC) pool and of its spatio-temporal variability is important for understanding the oceanic carbon cycle. Until now, POC estimates from space have been restricted to the surface layer. An empirical algorithm is developed to derive the POC content integrated over the euphotic layer (POCZeuPOCZeu) from the near-surface POC concentration (POCsurfPOCsurf). The relationship follows a power-law distribution, POCZeu=A×POCsurfB, with A and B   depending on the type of waters (stratified or well-mixed) and on the near-surface chlorophyll concentration. A global climatology of POCsurfPOCsurf and POCZeuPOCZeu is generated from the SeaWiFS archive between 1998 and 2006. The global patterns of POCsurfPOCsurf and POCZeuPOCZeu follow the major gyre systems and other large-scale circulation features. High surface and integrated POC content, around 150mgm−3 and 6000mgm−2, are encountered at high latitude, whereas low content, <50mgm−3 and 2000mgm−2, are observed in subtropical gyres. The mean global values of POCsurfPOCsurf and POCZeuPOCZeu over the global ocean are 53mgm−3 and 3742mgm−2. The standing stocks of POC are 3.92×10143.92×1014 and 1.19×1015g over the first penetration and euphotic depth, respectively.