UNDERWATER SPECTROSCOPY: METHODS AND APPLICATIONS IN A CORAL REEF ENVIRONMENT

摘要

Rising concern over the declining health of coral reef communities has prompted significantinterest in applications of remote sensing toward the monitoring and assessment of theseecosystems. In that regard, hyperspectral imaging systems such as NASA's Airborne VisibleInfraRed Imaging Spectrometer (AVIRIS) provide promising results for the utility of such sensorsto examine benthic habitats in this complex marine environment. The spectral resolution ofhyperspectral instruments is not only an advantage for discriminating between different habitattypes, but also for resolving the confounding effects contributed by the overlying water columnand its constituents. In accordance with the associated analysis methods, a demand has arisen toestablish field methods in underwater spectroscopy as support for processing hyperspectralimagery. Discussed here are the methods and results obtained using a GER 1500 field portablespectroradiometer in a custom underwater housing to obtain reflectance measurements in bothcontrol experiments and under field conditions. As a focus for these experiments, different lightingconditions were employed to establish the reliability of field spectra obtained under variablesituations. Experiments were first performed in a controlled pool environment at the UC DavisBodega Marine Laboratory, followed by a series of field measurements in Kaneohe Bay, Oahu,Hawaii. Conclusions address the utility of the resulting reflectance measurements for processingAVIRIS imagery acquired over Kaneohe Bay.