Optical water column properties of a coral reef environment: towards correction of remotely sensed imagery

Abstract

Multispectral vertical water column profiles collected in the field with a dropsonde radiometer provide the necessary information to examine the wavelength-specific extinction of light with increased water depth in a tropical coral reef environment with variable water depths and bottom types. A thorough and descriptive investigation of the anomalous behaviour of light in shallow coral reef and related environments is presented with the objective of evaluating the utility of accurate and reliable remote mapping and monitoring of changes in submerged coral reefs. Cluster analysis results indicate that on a wavelength-specific basis, the majority (no less than 70%) of both the downwelling irradiance and upwelling radiance profiles are similar enough to be grouped into one cluster, but that the anomalous profiles are more than simply outliers. Analysis of variance reveals that a significant amount of variability in both downwelling irradiance and upwelling radiance attenuation coefficients can be attributed to water depth when bottom type remains constant.