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ATTENUATION OF SOLAR UV RADIATION BY AEROSOLS DURING AIR POLLUTION EPISODES
Citation:
Kondragunta, S., P. M. Udelhofen, K L. Schere, S J. Roselle, AND B. Holben. ATTENUATION OF SOLAR UV RADIATION BY AEROSOLS DURING AIR POLLUTION EPISODES. Presented at AMS Conference, Long Beach, CA, January 9-14, 2000.
Impact/Purpose:
The goal of this research is to develop and test appropriate chemical and physical mechanisms for use in EPA's Models-3 chemical/transport models. These models will be addressing issues of tropospheric photochemistry, fine particles, toxic and semi-volatile substances, and acid deposition. As such, scientifically credible mechanisms for atmospheric gas- and aqueous-phase chemistry as well as heterogeneous chemistry, applicable to the particular pollutant regimes must be included in Models-3.
Description:
Increase in the amount of solar UV radiation reaching the surface due to decrease in stratospheric ozone continues to be a major concern (WMO, 1998). However, recent studies show that absorption and smattering by aerosols during air pollution episode decreases the amount of radiation reaching the surface (Dickerson el al.. 1997; Jacobson, 1998; Papayannis et al.. 1998; Repapis et al ..1998; Kondragunta et al.. 1999). To examine the role played by column ozone and aerosols in perturbing the solar radiation reaching the surface, we analyzed four years of spectrally resolved UV radiation measured by Brewer spectrophotometer at Gaithersburg, MD (39.1 N and 77.2 W). Transport from upwind regions and local pollution result in severe air pollution episodes at Gaithersburg when meteorological conditions are favorable. We present observations of aerosol optical depth and column ozone (from ground based sun photometers and satellites) and ground measurements of spectrally resolved UV flux. We will compare the observed and computed effects of aerosols on surface UV flux and discuss the implications.
This work was funded by the Environmental Ptorection Agency (EPA)/National Exposure Research Laboratory (NERL) and administered by the University Corporation for Atmospheric Research (UCAR).