3-DIMENSIONAL MODELING OF INHERENT OPTICAL-PROPERTIES IN A COASTAL ENVIRONMENT - COUPLING OCEAN COLOR IMAGERY AND IN-SITU MEASUREMENTS

Three-dimensional distributions of inherent optical properties (absorp tion, a, scattering, b, and single-scattering albedo, omega(0)) were d efined for a coastal region in the north-eastern Gulf of Mexico by cou pling surface ocean colour aircraft imagery and models of vertical opt ical profiles. The study area encompassed the surf zone region and off shore sand bar of an open beach environment to a depth of 10 m. During the aircraft overflights, concurrent in situ depth profiles of a and b were collected along an offshore transect, modelled, and assigned to each image pixel based on water depth. The modelled a and b profiles were subsequently integrated over depth (weighted by the diffuse atten uation coefficient) to provide a 'remote sensing' estimate comparable to what the aircraft sensor would see. At each pixel in the image, the se initial optical depth profiles were then iteratively adjusted until the integrated values agreed to within +/-5% of the estimates derived from a bio-optical model using the aircraft-measured water-leaving ra diances. Thus, unique vertical distributions of the optical fields wer e defined at each pixel from the corresponding profile when convergenc e was achieved. The modelled optical profiles compared favourably both spatially and spectrally with measured values. The 3-D visualization of the optical fields provided insight into the biological and physica l processes affecting coloured dissolved organic matter (CDOM) and par ticle distributions in this coastal area.