SeaWiFS satellite ocean color data from the Southern Ocean

SeaWiFS estimates of surface chlorophyll concentrations are reported for th e region of the U.S. JGOFS study in the Southern Ocean (similar to 170 degr ees W, 60 degrees S). Elevated chlorophyll was observed at the Southern Oce an fronts, near the edge of the seasonal ice sheet, and above the Pacific-A ntarctic Ridge. The elevated chlorophyll levels associated with the Pacific -Antarctic Ridge are surprising since even the crest of the ridge is at dep ths > 2000 m. This elevated phytoplankton biomass is likely the result of m esoscale physical-biological interactions where the Antarctic Circumpolar C urrent (ACC) encounters the ridge. Four cruises surveyed this region betwee n October 1997 and March 1998, as part of the U.S. JGOFS. Satellite-derived chlorophyll concentrations were compared with in situ extracted chlorophyl l measurements from these cruises. There was good agreement (r(2) of 0.72, from a linear regression of shipboard vs, satellite chlorophyll), although SeaWiFS underestimated chlorophyll concentrations relative to the ship data .