ALBERT

Description: The Southern Ocean (SO) ecosystem plays a key role in the carbon cycle by sinking a major part (43%) of the ocean uptake of anthropogenic CO2, and being an important source of nutrients for primary producers. However, undersampling of SO biogeochemical properties limits our understanding of the mechanisms taking place in this remote area. The Southern Ocean Carbon and Climate Observions and Modeling project (SOCCOM) has been deploying a large number of autonomous biogeochemical floats to study the SO (as of December 2016, 74 floats out of 200 have been deployed). SOCCOM floats measurements can be used to extend remote sensing chlorophyll a (chla) and particulate organic carbon (POC) products under the clouds or during the polar night as well as adding the depth dimension to the satellite-based view of the SO. Chlorophyll a concentrations measured by fluorometers embedded on the floats and POC concentrations derived from backscattering coefficients were calibrated with samples collected during the floats' deployment cruise. Float chla and POC were compared with products derived from observations of MODIS and VIIRS sensors. We find the Ocean Color Index (OCI) global algorithm to agree well with the matchups (within 9%, on average, for the Visible Infrared Imaging Radioneter Suite (VIIRS) and 12%, on average, for the Moderate Resolution Imaging Spectroradiometer Aqua (MODIS)). SO specific algorithms estimating chla are offset by ∼45% south of the Sea Ice Extent Front (∼ 60°S). In addition, POC estimates based on floats agree well with NASA's POC algorithm.