Radiometric system for measuring spectrum below ocean surface

To meet the need of long-term and high-resolution spectral measurement for the validation and calibration of ocean color remote sensing and interdisciplinary study, a radiometric system is developed to quickly measure the in situ downwelling; irradiance (Ed) and upwelling radiance (Lu) over the wavelength range from 400nm to 900nm at depths of 3, 5, 7 and 9m below ocean surface. Light entering Ed or Lu collector, is transmitted by fiber optic cables to respective spectrometer. The radiometric system can acquire up to eight spectrometer channels from the marine environment with 2.5nm spectral resolution, using eight Ocean Optics PC2000-PC104 fiber optic spectrometers. The configuration of the radiometric system is introduced as well as that of light sensor. Moreover, several characteristics of this radiometric system such as wavelength calibration, linearity test, combination of spectral data and the working process under water are also described. This radiometric system is compact and can implement both data acquisition and communication under program control.