The influence of foreign vs. North American emissions on surface ozone in the US

Reidmiller, D. R.; Keating, T.; Jonson, J.E.; Hess, P.; Marmer, E.; Zuber, A.; Wild, O.; Fiore, A.M.; Jaffe, D.A.; Lupu, A.; Dentener, F.J.; Gong, S.; Szopa, S.; Vivanco, M.G.; Cuvelier, C.; Duncan, B. N.; Schultz, M. G.; Shindell, D. T.; Park, R.; Folberth, G.; Gauss, M.; Bergmann, D.

Journal Article

The influence of foreign vs. North American emissions on surface ozone in the US

Reidmiller, D. R. ; Fiore, A. M. ; Jaffe, D. A. ; Bergmann, D. ; Cuvelier, C. ; Dentener, F. J. ; Duncan, B. N. ; Folberth, G. ; Gauss, M. ; Gong, S. ; Hess, P. ; Jonson, J. E. ; Keating, T. ; Lupu, A. ; Marmer, E. ; Park, R. ; Schultz, M. G.FZJ* ; Shindell, D. T. ; Szopa, S. ; Vivanco, M. G. ; Wild, O. ; Zuber, A.

2009
EGU Katlenburg-Lindau

Atmospheric chemistry and physics 9, 5027 - 5042 (2009)

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Please use a persistent id in citations: http://hdl.handle.net/2128/10170

Abstract: As part of the Hemispheric Transport of Air Pollution (HTAP; < a href='http://www.htap.org' target='_blank'> http:// www.htap.org </a >) project, we analyze results from 15 global and 1 hemispheric chemical transport models and compare these to Clean Air Status and Trends Network (CASTNet) observations in the United States (US) for 2001. Using the policy-relevant maximum daily 8-h average ozone (MDA8 O-3) statistic, the multi-model ensemble represents the observations well (mean r(2)=0.57, ensemble bias = +4.1 ppbv for all US regions and all seasons) despite a wide range in the individual model results. Correlations are strongest in the northeastern US during spring and fall (r(2)=0.68); and weakest in the midwestern US in summer (r(2)=0.46). However, large positive mean biases exist during summer for all eastern US regions, ranging from 10-20 ppbv, and a smaller negative bias is present in the western US during spring (similar to 3 ppbv). In nearly all other regions and seasons, the biases of the model ensemble simulations are < 5 ppbv. Sensitivity simulations in which anthropogenic O-3-precursor emissions (NOx + NMVOC + CO + aerosols) were decreased by 20% in four source regions: East Asia (EA), South Asia (SA), Europe (EU) and North America (NA) show that the greatest response of MDA8 O-3 to the summed foreign emissions reductions occurs during spring in the West (0.9 ppbv reduction due to 20% emissions reductions from EA + SA + EU). East Asia is the largest contributor to MDA8 O-3 at all ranges of the O-3 distribution for most regions (typically similar to 0.45 ppbv) followed closely by Europe. The exception is in the northeastern US where emissions reductions in EU had a slightly greater influence than EA emissions, particularly in the middle of the MDA8 O-3 distribution (response of similar to 0.35 ppbv between 35-55 ppbv). EA and EU influences are both far greater (about 4x) than that from SA in all regions and seasons. In all regions and seasons O-3-precursor emissions reductions of 20% in the NA source region decrease MDA8 O-3 the most - by a factor of 2 to nearly 10 relative to foreign emissions reductions. The O-3 response to anthropogenic NA emissions is greatest in the eastern US during summer at the high end of the O-3 distribution (5-6 ppbv for 20% reductions). While the impact of foreign emissions on surface O-3 in the US is not negligible - and is of increasing concern given the recent growth in Asian emissions - domestic emissions reductions remain a far more effective means of decreasing MDA8 O-3 values, particularly those above 75 ppb (the current US standard).

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Meteorology & Atmospheric Sciences

Note: This work has been funded in large part by NSF grant ATM-0724327. The authors wish to thank Jenise Swall and Steve Howard (EPA) for providing daily MDA8 O3 CASTNet data from 1988 through 2004 and Tracey Holloway (University of Wisconsin) for many fruitful discussions and comments. CA and DB were supported primarily by the US DOE Atmospheric Science Program (Office of Science, BER) at LLNL under Contract DE-AC52-07NA27344; BND from NASA MAP; AL from the Canadian Foundation for Climate and Atmospheric Sciences, the Ontario Ministry of the Environment, the Canadian Foundation for Innovation and the Ontario Innovation Trust; MGV from the Spanish Ministry of the Environment; and RJP was partly supported by the Korea Meteorological Administration Research and Development Program under Grant CATER 2007-3205.

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