Open AccessGlobal and regional decreases in tropospheric oxidants from photochemical effects of aerosols
Author(s) -
Martin Randall V.,
Jacob Daniel J.,
Yantosca Robert M.,
Chin Mian,
Ginoux Paul
Publication year - 2003
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2002jd002622
Subject(s) - aerosol , troposphere , atmospheric sciences , northern hemisphere , environmental science , chemical transport model , sulfate aerosol , planetary boundary layer , total organic carbon , boundary layer , atmosphere (unit) , sulfate , mineral dust , southern hemisphere , ozone , biomass burning , atmospheric chemistry , climatology , photochemistry , environmental chemistry , chemistry , meteorology , geology , physics , organic chemistry , thermodynamics
We evaluate the sensitivity of tropospheric OH, O 3 , and O 3 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 2 , NO 2 , and NO 3 . 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 (γ HO2 = 0.2, γ NO2 = 10 −4 , γ NO3 = 10 −3 ). Aerosols decrease the O 3 → O( 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 HO 2 accounts for 10–40% of total HO x radical (≡ 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 NO 2 and NO 3 accounts for 10–20% of total HNO 3 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 O 3 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 O 3 over Europe and other industrial regions.