Photometric and Colorimetric Properties of the Solar Aureole

[摘要] Based on accurate solutions of the transfer of solar radiation for realistic models of the turbid atmosphere, the photometric and colorimetric properties of the solar aureole were studied for various conditions of atmospheric turbidity. The radiation flux density in the vicinity of the sun becomes more predominant for turbid conditions especially at shorter visible wavelengths. In spite of this general feature, the percentage error of the Angstrom's turbidity parameter due to the aureole flux density involved in the sunphotometry becomes more serious for clear conditions than for turbid conditions. This is because even a small aureole flux density added to the direct solar radiation diminishes the aerosol optical thickness significantly for clear conditions. The colorimetric property of the solar aureole varies noticeably place by place for the atmosphere containing larger particles, although the most reddish (the lowest color temperature) point does not change its position of about 1.6° from the sun for different turbidity conditions. Comparing with non-absorbing aerosols, absorbing aerosols make the aureole region more bluish for clear conditions, and more reddish for turbid conditions.

[学科分类] 大气科学