The characterization of a Coupled Charged Device (CCD) spectrometer developed at the Laboratory of Atmospheric Physics, Thessaloniki is presented. The absolute sensitivity of the instrument for direct sun and sky radiance measurements was determined with an uncertainty of ~3% in UVB and ~2% in UVA, Vis and NIR wavelength ranges. The total uncertainties associated with the direct sun and sky radiance measurements are in the order of ~8 %, increasing to 17% for low signals (e.g. at solar zenith angles (SZA) larger than 70°) and ~6% in the UVA, Vis and NIR.
Direct solar spectral irradiance measurements from an independently calibrated spectroradiometer, (Bentham DTM 300) were compared with the corresponding CCD measurements. Their agreement in the wavelength range 310-500 nm is within 0.5±1.1% (for SZA between 20° and 70°).
Aerosol optical depth derived by the two instruments using direct sun measurements agree to within 0.02±0.02 in the range 315 to 500nm. Significant correlation coefficients with maximum of 0.99 in the range 340-360 nm and minimum of 0.94 at 500 nm were found between the
Kouremeti, N., Bais, A., Kazandzis, S., Blumthaler, M. and Schmitt, R., 2007, September. A CCD spectrometer for direct solar irradiance and sky radiance measurements. In Proceedings of the UV Conference “One Century of UV Radiation Research,” edited by: Gröbner, J (pp. 18-20).
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Categories: Solar & Photovoltaics