| It is necessary to obtain spectral data in situ for the calibration and validation of Ocean Color, the development of bio-optical algorithms for local or world wide ocean application, the interpretation of the remote sensed data and the interdisciplinary process study. To meet the need of long-term and high-resolution spectral measurement for ocean optical buoy, a spectroradiometer system, composed of PC104 computer, miniature spectrometer, fiber optic, light collector and anti-fouling device, is developed to quickly measure the downwelling irradiance (Ed) and upwelling radiance (Lu) over the wavelength range from 400nm to 900nm at depths of 3m, 5m, 7m and 9m below ocean surface. The characteristics of spectrometer, such as dark signal and linearity, are analyzed. Then the method of eliminating the dark signal is proposed. By means of experiment, it is concluded that the linearity of spectrometer is good. After the calibration factors are calculated by measuring Hg lamp, the combination of spectral data is implemented. In order to improve the reliability and synchronicity of the spectral data, the automatic adjustment of integration time and times of acquiring data is accomplished by setting range of data obtained from CCD. In addition, the overlap of spectral data acquired from PC2000 spectrometer is analyzed. Then based on the Object-Oriented Programming (OOP), the CADCard class that provides all the base functionality of the PC2000-PC104 spectrometer is built to implement multi-channel data acquisition readily using C++. And the spectral data conforming to the actual one is got. And the controlling software is programmed to implement some functions such as acquiring, combining, packing and sending data. Finally, the scheme of calibrating the spectroradiometer is determined, including calibration in laboratory, in situ and under water. And their principles are described in detail.
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