Optical remote sensing of marine constituents in coastal waters: a feasibility study

Optical remote sensing of ocean color is a well-established technique for i nferring ocean properties. However, most retrieval algorithms are based on the assumption that the radiance received by satellite instruments is affec ted only by the phytoplankton pigment concentration and correlated substanc es. This assumption works well for open ocean water but becomes questionabl e for coastal waters. To reduce uncertainties associated with this assumpti on, we developed a new algorithm for the retrieval of marine constituents i n a coastal environment. We assumed that ocean color can be adequately desc ribed by a three-component model made up of chlorophyll a, suspended matter , and yellow substance. The simultaneous retrieval of these three marine co nstituents and of the atmospheric aerosol content was accomplished through an inverse-modeling scheme in which the difference between simulated radian ces exiting the atmosphere and radiances measured with a satellite sensor w as minimized. Simulated radiances were generated with a comprehensive radia tive transfer model that is applicable to the coupled atmosphere-ocean syst em. The method of simulated annealing was used to minimize the difference b etween measured and simulated radiances. To evaluate the retrieval algorith m, we used simulated (instead of measured) satellite-received radiances tha t were generated for specified concentrations of aerosols and marine consti tuents, and we tested the ability of the algorithm to retrieve assumed conc entrations. Our results require experimental validation but show that the r etrieval of marine constituents in coastal waters is possible. (C) 1998 Opt ical Society of America.