Optical Teledetection of Chlorophyll <i>a</i> in Estuarine and Coastal Waters

Abstract

A hand-held spectroradiometer was used for above-water determination of subsurface spectral irradiance reflectance in the Scheldt Estuary (Belgium/The Netherlands), the North Sea off the Belgian coast, and the Hudson/Raritan Estuary (New York/New Jersey). On the North Sea the measurement conditions were adverse, and elsewhere broken cloud caused considerable spectral variation. Despite this variation the retrieval of chlorophyll a (Chl- a ) from three reflectance spectra at all sampling stations was stable. The algorithm calibrated for the freshwater IJssel Lagoon (The Netherlands) proved to be applicable to these estuarine and coastal waters ( N = 30; standard error of estimate = 7 mg m - 3 for corrected Chl- a ranging from 1 to 93 mg m - 3 ).