Spectroradiometric Characteristics of Natural Light Under Water*

This paper presents spectroradiometric data on the natural radiant flux occurring underwater at three locations in the Gulf of California, in Pacific coastal water near San Diego, and in the plankton-rich water of San Vicente Reservoir (San Diego County). Spectral radiance and irradiance have been measured, and it is shown that under certain circumstances spectral data for these two radiometric quantities are directly proportional. The data have been used to calculate spectral values of the attenuation coefficient and of the reflection function. The various spectra correlate qualitatively with apparent chlorophyll concentration and water color.