Remote Estimation of Water Clarity in Optically Complex Estuarine Waters

AVHRR satellite imagery was evaluated as a potential data source for monitoring light attenuation (KPAR), as a measure of turbidity, in Pamlico Sound estuary, North Carolina. In situ water quality data and reflectance imagery collected on 10 different dates were used to calibrate a general optical equation relating satellite-derived reflectance (Rd), nominally R(630 nm) to KPAR. Additional spectral data (e.g., absorption, subsurface reflectance), related reflectance and KPAR to changes in phytoplankton pigments, organic matter, and suspended sediments. Optically, Pamlico Sound, North Carolina is dominated by scattering from suspended sediments, whereas the tributary rivers are dominated by absorption from both dissolved and particulate organic matter. A general relationship developed between Rd and KPAR (r2=0.72) in Pamlico Sound was found useful in a variety of environmental conditions; however a relationship between Rd and suspended sediment concentration was less robust, and affected by changing sediment characteristics. In the rivers, high and variable absorption in the visible wavelengths precluded development of a relationship between Rd and KPAR. The relationship developed between Rd and KPAR in Pamlico Sound is similar to those determined for Delaware Bay and Mobile Bay in previous studies, suggesting possible broader regional application of algorithms for coastal bays and estuaries having similar sediment characteristics, with direct application to SeaWiFS data. Published by Elsevier Science Inc.