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Application of Satellite and Ground-based Data to Investigate the UV Radiative Effects of Australian AerosolsAn understanding of the effect of aerosols on biologically- and photochemically-active UV radiation reaching the Earth's surface is important for many ongoing climate, biophysical, and air pollution studies. In particular, estimates of the UV characteristics of the most common Australian aerosols will be valuable inputs to UV Index forecasts, air quality studies, and assessments of the impact of regional environmental changes. By analyzing climatological distributions of Australian aerosols we have identified sites where co-located ground-based UV-B and ozone measurements were available during episodes of relatively high aerosol activity. Since at least June 2003, surface UV global irradiance spectra (285-450 nm) have been measured routinely at Darwin and Alice Springs in Australia by the Australian Bureau of Meteorology (BoM). Using colocated sunphotometer measurements at Darwin and Alice Springs, we identified several episodes of relatively high aerosol activity. Aerosol air mass types were analyzed from sunphotometer-derived angstrom parameter, MODIS fire maps and MISR aerosol property retrievals. To assess aerosol effects we compared the measured UV irradiances for aerosol-loaded and clear-sky conditions with each other and with irradiances simulated using the libRadtran radiative transfer model for aerosol-free conditions. We found that for otherwise similar atmospheric conditions, smoke aerosols over Darwin reduced the surface UV irradiance by as much as 40-50% at 290-300 nm and 20-25% at 320-400 nm near active fires (aerosol optical depth, AOD, at 500 nm approximately equal to 0.6). Downwind of fires, the smoke aerosols over Darwin reduced the surface irradiance by 15-25% at 290-300 nm and approximately 10% at 320-350 nm (AOD at 500 nm approximately equal to 0.2). The effect of smoke increased with decrease of wavel strongest in the UV-B. The aerosol attenuation factors calculated for the selected cases suggest smoke over Darwin has an effect on surface 340-380 nm irradiances that is comparable to that produced by smoke over Sub-Saharan Africa. Dust activity was very low at Alice Springs during 2004, therefore we were not able to identify strong dust events to fully assess the UVeffect of dust. For the cases studied, smoke aerosols seem to produce a stronger reduction in surface UV irradiances than dust aerosols.
Document ID
20080045902
Acquisition Source
Jet Propulsion Laboratory
Document Type
Reprint (Version printed in journal)
Authors
Kalashnikova, Olga V.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Mills, Franklin P.
(Australian National Univ. Canberra, Australia)
Eldering, Annmarie
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Anderson, Don
(Bureau of Meteorology Melbourne, Australia)
Date Acquired
August 24, 2013
Publication Date
January 2, 2007
Publication Information
Publication: Remote Sensing of Environment: Multi-angle Imaging SpectroRadiometer (MISR) Special Issue
Publisher: Elsevier, Inc.
Volume: 107
Issue: 1-2
Subject Category
Meteorology And Climatology
Distribution Limits
Public
Copyright
Other
Keywords
UV surface irradiances
MISR
MODIS
Australian aerosols

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