SOME MIDDLE ULTRAVIOLET RADIATIVE EFFECTS OF PARTICULATE POLLUTION IN THE STRATOSPHERE
The effect of increased stratospheric dust on the polarization and intensity of sunlight scattered by the terrestrial atmosphere in the spectral region near the ultraviolet transmission cutoff is examined. Particular interest is given to radiation reflected to space or transmitted to the surface in...
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| Language: | en_US |
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The University of Arizona.
1981
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| Online Access: | http://hdl.handle.net/10150/282067 |
| Summary: | The effect of increased stratospheric dust on the polarization and intensity of sunlight scattered by the terrestrial atmosphere in the spectral region near the ultraviolet transmission cutoff is examined. Particular interest is given to radiation reflected to space or transmitted to the surface in the direction perpendicular to the incident solar beam in a plane containing the sun and the local vertical. Theoretical results are presented from radiative transfer calculations using a simple single scattering model and a four layer model in which ground reflection and multiple scattering were treated. Results show that the polarization state of transmitted radiation of .2975 μ for an incident solar zenith angle of 70° is sensitive to dust loading above 50 mb. The depolarization caused by a moderate increase in stratospheric dust loading is found to be roughly comparable to that caused by ground reflection and tropospheric aerosol. The polarization of light reflected to space is found to be very sensitive to high altitude dust scattering while being much less sensitive to other sources of depolarization. Results show that increasing the amount of stratospheric dust can cause either an increase or a decrease in the daily dosage of ultraviolet radiation at the surface, depending on the altitude profile of the dust, the latitude and the season. Preliminary experimental results or polarization monitoring by a ground-based instrument are presented and discussed. Sky light polarization ratios in the direction normal to the solar beam at .2975 μ and .300 μ based on data collected in the spring and summer of 1980 from the roof of the Physics-Atmospheric Sciences building on the campus of The University of Arizona are presented and discussed. The stratospheric dust problem is considered in terms of stratospheric aerosol enhancement resulting from volcanic activity. |
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