Measurements of spectral visible radiance of ocean water and overlying atmosphere

A nadir-viewing, visible spectrometer was flown over various ocean waters at altitudes from 500ft (0.15km) to 25,000 ft (7.6km). Data, presented in the form of spectral reflectivity, was obtained for a variety of water types and atmospheric conditions and correlated with chlorophyll and Secchi depth measurements obtained by boat. The spectral reflectivity measured was extrapolated, by use of standard atmosphere tables, to the top of the atmosphere. A range of spectral reflectivities that will be observed by satellite-borne ocean color sensors is presented. Results indicate the magnitude of the contrast to be expected from 400 to 700 nm and show that water color signatures can be obtained from satellite altitude.