Photochemistry and transport of tropospheric ozone and its precursors in urban and remote environments

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dc.contributor.advisorDickerson, Russell Ren_US
dc.contributor.advisorSalawitch, Ross Jen_US
dc.contributor.authorAnderson, Daniel Craigen_US
dc.contributor.departmentAtmospheric and Oceanic Sciencesen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2016-06-22T06:11:11Z
dc.date.available2016-06-22T06:11:11Z
dc.date.issued2016en_US
dc.description.abstractTropospheric ozone (O3) adversely affects human health, reduces crop yields, and contributes to climate forcing. To limit these effects, the processes controlling O3 abundance as well as that of its precursor molecules must be fully characterized. Here, I examine three facets of O3 production, both in heavily polluted and remote environments. First, using in situ observations from the DISCOVER-AQ field campaign in the Baltimore/Washington region, I evaluate the emissions of the O3 precursors CO and NOx (NOx = NO + NO2) in the National Emissions Inventory (NEI). I find that CO/NOx emissions ratios derived from observations are 21% higher than those predicted by the NEI. Comparisons to output from the CMAQ model suggest that CO in the NEI is accurate within 15 ± 11%, while NOx emissions are overestimated by 51-70%, likely due to errors in mobile sources. These results imply that ambient ozone concentrations will respond more efficiently to NOx controls than current models suggest. I then investigate the source of high O3 and low H2O structures in the Tropical Western Pacific (TWP). A combination of in situ observations, satellite data, and models show that the high O3 results from photochemical production in biomass burning plumes from fires in tropical Southeast Asia and Central Africa; the low relative humidity results from large-scale descent in the tropics. Because these structures have frequently been attributed to mid-latitude pollution, biomass burning in the tropics likely contributes more to the radiative forcing of climate than previously believed. Finally, I evaluate the processes controlling formaldehyde (HCHO) in the TWP. Convective transport of near surface HCHO leads to a 33% increase in upper tropospheric HCHO mixing ratios; convection also likely increases upper tropospheric CH3OOH to ~230 pptv, enough to maintain background HCHO at ~75 pptv. The long-range transport of polluted air, with NO four times the convectively controlled background, intensifies the conversion of HO2 to OH, increasing OH by a factor of 1.4. Comparisons between the global chemistry model CAM-Chem and observations show that consistent underestimates of HCHO by CAM-Chem throughout the troposphere result from underestimates in both NO and acetaldehyde.en_US
dc.identifierhttps://doi.org/10.13016/M2N780
dc.identifier.urihttp://hdl.handle.net/1903/18364
dc.language.isoenen_US
dc.subject.pqcontrolledAtmospheric chemistryen_US
dc.subject.pqcontrolledAtmospheric sciencesen_US
dc.subject.pquncontrolledbiomass burningen_US
dc.subject.pquncontrolledcarbon monoxideen_US
dc.subject.pquncontrolledformaldehydeen_US
dc.subject.pquncontrolledozoneen_US
dc.titlePhotochemistry and transport of tropospheric ozone and its precursors in urban and remote environmentsen_US
dc.typeDissertationen_US

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