| Influence of Clouds on UV Irradiance at Ground Level and Backscattered Exittance |
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| 作者姓名： | Wang Pucai Jacqueline Lenoble |
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| 作者单位： | Laboratoire d’Optique Atmospherique, Universite des Sciences et Technologies de Lille, URA 713 CNRS, 59655 Villeneuve d’Ascq, France,Laboratoire d’Optique Atmospherique, Universite des Sciences et Technologies de Lille, URA 713 CNRS, 59655 Villeneuve d’Ascq, France |
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| 摘 要： | The influence of various cloud parameters and the interactions with the ground albedo and the solar zenith angle have been studied by means of model simulations. The radiative transfer model suitable for a cloudy atmosphere as well as for a clear atmosphere has been developed on the basis of the Discrete Ordinate Method. This study leads to a general understanding for cloudy atmospheres: in the presence of a uniform cloud, the cloud scattering is dominant to molecular and aerosol scattering, and it is also wavelength-independent; the ratio of transmitted irradiance in a cloudy atmosphere to that in the background clear atmosphere is independent of cloud height and solar zenith angle. That’s to say, the radiation downwelling out of a cloud is quite isotropic; it decreases approximately exponentially with the cloud optical depth at a rate related to the ground albedo; the reflected irradiance at the top of the atmosphere is dependent on cloud optical depth as well as on solar zenith angle, but not on ground albedo for clouds of not very thin optical depth.
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| 收稿时间： | 3 July 1995 |
Influence of clouds on UV irradiance at ground level and backscattered exittance |
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| Wang Pucai,Jacqueline Lenoble.Influence of clouds on UV irradiance at ground level and backscattered exittance[J].Advances in Atmospheric Sciences,1996,13(2):217-228. |
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| Authors: | Wang Pucai Jacqueline Lenoble |
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| Institution: | (1) Laboratoirc d’Optiquc Atmospherique, Universite des Sciences et Technologies de Lille, U RA 713 CNRS, 59655 Villeneuve d’Ascq, France |
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| Abstract: | The influence of various cloud parameters and the interactions with the ground albedo and the solar zenith angle have been
studied by means of model simulations. The radiative transfer model suitable for a cloudy atmosphere as well as for a clear
atmosphere has been developed on the basis of the Discrete Ordinate Method. This study leads to a general understanding for
cloudy atmospheres: in the presence of a uniform cloud, the cloud scattering is dominant to molecular and aerosol scattering,
and it is also wavelength-independent; the ratio of transmitted irradiance in a cloudy atmosphere to that in the background
clear atmosphere is independent of cloud height and solar zenith angle. That’s to say. the radiation downwelling out of a
cloud is quite isotropic; it decreases approximately exponentially with the cloud optical depth at a rate related to the ground
albedo; the reflected irradiance at the top of the atmosphere is dependent on cloud optical depth as well as on solar zenith
angle, but not on ground albedo for clouds of not very thin optical depth.
This work has been supported by the Commission of European Communities (Contract No. STEP0076). The authors are indebted to
K. Stamnes and his colleagues for providing a DOM radiation code. |
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| Keywords: | Cloud UV |
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