Optical properties of the upper ocean in the Arabian Sea in August 1994

Upwelling was observed close to the Omani shelf during August 1994, and high values of chlorophyll concentration were observed in the upper mixed layer on the offshore region of the raised isopycnals. A rapid increase of phytoplankton biomass was observed over the whole area of the survey 7 days later. Values of the diffuse attenuation coefficient and beam transmittance were closely related to the phytoplankton concentrations, but spatial variations were observed. Spectral variations in reflectance were also observed. These observations are considered in relation to the distribution of the major phytoplankton taxonomic groups and light absorbing pigments.