Intercontinental transport of anthropogenic and biomass burning pollution

I apply a global 3-dimensional model of tropospheric ozone-NO _x-hydrocarbon chemistry to investigate intercontinental transport of anthropogenic and biomass burning pollution, and its impact on global atmospheric chemistry and regional air quality.; Model simulation of tropospheric ozone shows a summer maximum over the Middle East which is supported by observations. The maximum results from anticyclonic circulation in the middle-upper troposphere over the region funneling northern midlatitude pollution transported in the westerly midlatitude jet and lightning outflow from the Indian monsoon and pollution from China transported in an easterly tropical jet. This ozone maximum is a major diagnostic feature for intercontinental transport.; An important diagnostic site for transatlantic transport of North American pollution is Bermuda, where surface ozone shows a spring maximum. Boundary layer transport of North American pollution behind cold fronts is responsible for springtime high-ozone events at Bermuda. Model reproduces positive ozone correlations with 7Be and 210Pb; the ozone- 7Be correlation reflects subsidence behind cold fronts, resulting in mixing of middle-tropospheric air with boundary layer outflow (an obfuscating factor in past interpretations of subsiding back-trajectories as evidence for a stratospheric origin for ozone).; Export efficiency of NO_y from continental boundary layer has important implication for intercontinental transport. Lagrangian analyses of the NO_y-CO correlations observed from aircraft downwind of North America indicated significantly lower NO _y export efficiency and NO_x fraction in exported NO_y than 3-dimensional model Eulerian budget analyses. Model reproduces observed NO_y-CO correlations. Previous Lagrangian analyses of NO_y export efficiency were biased low due to underestimate of CO background. Correcting for this bias results in similar NO_y export efficiencies in the model and observations from Lagrangian analysis that are consistent with Eulerian analysis. Different NO_x fractions in exported NO_y from Lagrangian and Eulerian analyses reflect fast oxidation of NO_x. Eventual ozone production due to exported NO_y is comparable to direct ozone export.; I examined transatlantic transport of ozone pollution and its effects on surface ozone in Europe and North America. Surface ozone and CO observations at Sable Island and Mace Head were used for model evaluation. North American emissions contribute 5 ppbv to Mace Head ozone (10–20 ppb during transatlantic events). This North American influence is strongly correlated with the North Atlantic Oscillation index, implying that this index could be used to forecast transatlantic transport. European emissions contribute <2 ppb to Sable Island ozone (5–10 ppb during transatlantic events). North American emissions enhance surface ozone in Europe by 2–4 ppb (5–10 ppb during transatlantic events).; I evaluated atmospheric budgets of biomass burning tracers HCN and CH ₃CN. Observations imply a much shorter lifetime for HCN than previously thought. I proposed ocean uptake as the missing HCN sink, and found that model can reproduce observations with biomass burning and ocean uptake as the main source and sink. Aircraft observations of HCN and CH₃CN confirm dominant ocean sink and biomass burning source for both. HCN enhancements in Chinese urban plumes are attributed to residential coal burning. Exclusive biomass burning source for CH₃CN implies that it is a sensitive biomass burning tracer.