Bio-optical relationships in south-west Atlantic sector of Antarctic ocean

Optical and Phytoplankton pigment data collected from around 80 stations in the south-west Atlantic sector of Antarctic ocean between the Drake Passage and Antarctic Peninsula during three Antarctic Expeditions of Japan Fisheries Agency in Austral summer were analyzed for bio-optical characterization. Three optical water types were identified based on the spatial variability of phytoplankton pigment in the euphotic zone and corresponding profile of physical parameters along with total beam attenuation coefficient, c(t)(m(-1)) and diffuse attenuation coefficient, Kd (m(-1)) The derived pigment specific particulate beam attenuation coefficient (c*) and diffuse attenuation coefficients (K-d*) were effectively used to identify optical stations under dominant influence of non-chlorophyll substances. The pigment specific coefficients were compared with the coefficients reported from typical case I waters (mostly temperate) and polar waters as well. Significant variations from temperate model and agreement with polar region model are discussed. Chlorophyll remote sensing model was examined with two sets of reflectance, R(lambda) and subsurface upwelling radiance, L(U) (lambda) ratios (441/565 and 520/565). The typical case I water remote sensing algorithm and the algorithm derived from present analysis were implemented on the CZCS image, and satellite derived chlorophyll values were compared with in situ estimates available in the same area from the Polish BIOMASS - FIBEX expedition. The results point to the need of more critical study on the bio-optical aspects before implementation of local algorithms for this region on ocean color image.