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Global and Regional Decreases in Tropospheric Oxidants from Photochemical Effects of Aerosols
- Source :
- Journal of Geophysical Research. 108(D3)
- Publication Year :
- 2003
- Publisher :
- United States: NASA Center for Aerospace Information (CASI), 2003.
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Abstract
- We evaluate the sensitivity of tropospheric OH, O3, and O3 precursors to photochemical effects of aerosols not usually included in global models: (1) aerosol scattering and absorption of ultraviolet radiation and (2) reactive uptake of HO', NO2, and NO3. Our approach is to couple a global 3-D model of tropospheric chemistry (GEOS- CHEM) with aerosol fields from a global 3-D aerosol model (GOCART). Reactive uptake by aerosols is computed using reaction probabilities from a recent review (gamma(sub HO2) = 0.2, gamma(sub NO2) = 10(exp -4), gamma(sub NO3) = l0(exp -3). Aerosols decrease the O3 - O((sup 1)D) photolysis frequency by 5-20% at the surface throughout the Northern Hemisphere (largely due to mineral dust) and by a factor of 2 in biomass burning regions (largely due to black carbon). Aerosol uptake of HO2 accounts for 10-40% of total HOx radical ((triple bonds)OH + peroxy) loss in the boundary layer over polluted continental regions (largely due to sulfate and organic carbon) and for more than 70% over tropical biomass burning regions (largely due to organic carbon). Uptake of NO2 and NO3 accounts for 10-20% of total HNO3 production over biomass burning regions and less elsewhere. Annual mean OH concentrations decrease by 9% globally and by 5-35% in the boundary layer over the Northern Hemisphere. Simulated CO increases by 5- 15 ppbv in the remote Northern Hemisphere, improving agreement with observations. Simulated boundary layer O3 decreases by 15- 45 ppbv over India during the biomass burning season in March and by 5-9 ppbv over northern Europe in August, again improving comparison with observations. We find that particulate matter controls would increase surface O3 over Europe and other industrial regions.
- Subjects :
- Environment Pollution
Subjects
Details
- Language :
- English
- ISSN :
- 01480227
- Volume :
- 108
- Issue :
- D3
- Database :
- NASA Technical Reports
- Journal :
- Journal of Geophysical Research
- Notes :
- NAG1-2307
- Publication Type :
- Report
- Accession number :
- edsnas.20040111417
- Document Type :
- Report
- Full Text :
- https://doi.org/10.1029/2002JD002622