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

Abstract

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 ( POC Zeu ) from the near-surface POC concentration ( POC surf ). The relationship follows a power-law distribution, POC Zeu = A × POC surf B , 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 POC surf and POC Zeu is generated from the SeaWiFS archive between 1998 and 2006. The global patterns of POC surf and POC Zeu follow the major gyre systems and other large-scale circulation features. High surface and integrated POC content, around 150 mg m − 3 and 6000 mg m − 2 , are encountered at high latitude, whereas low content, < 50 mg m − 3 and 2000 mg m − 2 , are observed in subtropical gyres. The mean global values of POC surf and POC Zeu over the global ocean are 53 mg m − 3 and 3742 mg m − 2 . The standing stocks of POC are 3.92 × 10 14 and 1.19 × 10 15 g over the first penetration and euphotic depth, respectively.