TEST AND ANALYSIS ON OPTICAL CHARACTERISTICS OF AN UNDERWATER MULTI-CHANNEL SPECTRAL RADIOMETER

To meet the need of high-accuracy underwater optical measurements in ocean color remote sensing, an underwater multi-channel spectral radiometer, which can measure downward irradiance and upward irradiance at twelve wavelengths and upward radiance at seven wavelengths simultaneously, have been designed and constructed. In this paper, some of the key specifications of this radiometer such as cosine characteristics of the irradiance collector, immersion factors of each channel and the spectral radiometric accuracy are tested in laboratory, shading errors are modeled by Monte Carlo simulation, the field experimental data and some optical properties derived from these data are described and analyzed. The results indicate that, the errors of the center wavelength and bandwidth of each channel are smaller than 1.6nm, which are compatible to those of remote sensors such as SeaWiFS; the stability of each channel is larger than 5%; the shading errors can bee controlled within 5%; the cosine characteristics is very good. It is very suitable for application to the in situ optical measurements in ocean color remote sensing.