Determination of reflectance of coral reefs through analysis of the diffuse attenuation coefficients for radiance through the water column

Abstract

Summary form only given. Landsat Thematic Mapper and SPOT satellite image data have been used in a qualitative manner to map the spatial characteristics of tropical reef systems. Recently, data available for shallow corals have been studied to determine a "Living Madrepora Index" that may form the basis for quantitative analysis of ecosystem viability. This may be of particular importance in studies of coral bleaching events that may be caused by climate variability or change, and/or pollutant stress. The challenge is to adjust the digital imagery for the optical attenuation through water to greater depths with corrections that will vary with the density of intervening sediment or plankton. In this paper the authors report on a study in Fiji in which they measured the vertical profiles of the diffuse attenuation coefficient for upwelling radiance in the SeaWiFS channels. They discuss the properties of these coefficients and derivation of an image independent procedure for retrieval of the bottom upwelling radiance without correction for depth.