REMOTE-SENSING ESTIMATES OF INHERENT OPTICAL-PROPERTIES IN A COASTAL ENVIRONMENT

High resolution aircraft remote sensing imagery and in situ optical da ta were coupled to characterize the spatial and temporal variability o f the inherent optical properties in the near-surf zone off Fort Walto n Beach, Florida in August 1994. Upwelling radiance measurements at Se aWiFS wavelengths were collected over a uniform, highly reflective whi te sand bottom at a ground resolution of 2.5 m using the CASI sensor ( Compact Airborne Spectral Imager). Following atmospheric correction, t he total remote sensing reflectance signal was partitioned into bottom and water volume reflectance components, using measurements of bottom albedo, water depth, and the diffuse attenuation coefficient at the t ime of the over-flight. The water components were entered in the Sea-W iFS biooptical model to derive spectral absorption and scattering coef ficients. After applying minor algorithm and coefficient adjustments, model results compared favorably with in situ measurements. The bioopt ical model was subsequently applied to the aircraft imagery to describ e the spatial distribution of absorption and scattering. Elevated abso rption and particle scattering were observed over the sand bar and sho reward (alpha 555=0.19 m(-1), b555=0.7 m(-1)). The temporal variabilit y of the inherent optical properties over a 1-week period was similar to the spatial variability along a 500-m offshore transect. Published by Elsevier Science Inc.