Sea truth validation of SeaWiFS ocean colour sensor in the coastal waters of the Eastern Arabian Sea

In this paper we report bio-optical measurements made during an ocean colou r validation cruise SK 149C in November 1999 of the research vessel Sagar K anya in the coastal waters of the Eastern Arabian Sea. The chlorophyll conc entration in these waters was in the range 0.2 to 4 mg/m(3) Although the ma tch-ups between in situ and satellite data from SeaWifs were sparse, it ind icates that direct application of the standard SeaWifs algorithm - the OC2- V4 algorithm - in the coastal waters of the Arabian Sea will underestimate chlorophyll by up to 30%, Comparison of our in situ normalized water-leavin g radiance [Lwn] and chlorophyll measurements at sea with that derived from the SeaWifs colour sensor shows that SeaWifs overestimates both Lwn and ch lorophyll, Various authors have earlier reported under and over estimation of SeaWifs water-leaving radiances, speculated as arising from variable err ors when correcting atmospheric effects in coastal regions. These errors ar e produced most probably by absorbing aerosols and also from increases in w ater-leaving radiance caused by enhanced particle backscatter effects from sea water constituents other than chlorophyll. Further studies are required to resolve the problem of validating satellite sensors in coastal waters.