frost ppr 2006GL027749

frost ppr 2006GL027749 - Click Here GEOPHYSICAL RESEARCH...

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Satellite-observed U.S. power plant NO x emission reductions and their impact on air quality S.-W. Kim, 1,2 A. Heckel, 3 S. A. McKeen, 1,2 G. J. Frost, 1,2 E.-Y. Hsie, 1,2 M. K. Trainer, 1 A. Richter, 3 J. P. Burrows, 3 S. E. Peckham, 2,4 and G. A. Grell 2,4 Received 1 August 2006; revised 21 September 2006; accepted 24 October 2006; published 29 November 2006. [ 1 ] Nitrogen oxide (NO x ) emissions resulting from fossil fuel combustion lead to unhealthy levels of near-surface ozone (O 3 ). One of the largest U.S. sources, electric power generation, represented about 25% of the U.S. anthropogenic NO x emissions in 1999. Here we show that space-based instruments observed declining regional NO x levels between 1999 and 2005 in response to the recent implementation of pollution controls by utility companies in the eastern U.S. Satellite-retrieved summertime nitrogen dioxide (NO 2 ) columns and bottom-up emission estimates show larger decreases in the Ohio River Valley, where power plants dominate NO x emissions, than in the northeast U.S. urban corridor. Model simulations predict lower O 3 across much of the eastern U.S. in response to these emission reductions. Citation: Kim, S.-W., A. Heckel, S. A. McKeen, G. J. Frost, E.-Y. Hsie, M. K. Trainer, A. Richter, J. P. Burrows, S. E. Peckham, and G. A. Grell (2006), Satellite- observed U.S. power plant NO x emission reductions and their impact on air quality, Geophys. Res. Lett. , 33 , L22812, doi:10.1029/2006GL027749. 1. Introduction [ 2 ] In the lower troposphere, high ozone (O 3 ) mixing ratios are a key component of photochemical smog that frequently occurs during summertime under high pressure systems, near or downwind of industrial and urban areas. Elevated levels of O 3 are hazardous to human health and vegetation and are a primary focus of pollution control strategies. Nitric oxide (NO) and nitrogen dioxide (NO 2 ), which together are known as NO x , play a crucial role in producing O 3 via photochemistry that is further controlled by the amount of volatile organic compounds (VOC), carbon monoxide, sunlight, and temperature [e.g., Crutzen , 1979; Haagen-Smit , 1952; McKeen et al. , 1991; Ryerson et al. , 2001]. [ 3 ] In the eastern United States (U.S.), summertime O 3 often exceeds the U.S. Environment Protection Agency (EPA) 8-hour standard [ Environmental Protection Agency ( EPA ), 2005a, 2005b]. O 3 exceedances in the northeast U.S. have been associated with NO x emissions from point sources, especially coal-burning power plants, in the Ohio River Valley (EPA, Ozone transport assessment group, final report, vol. I: Executive summary, 1997, available at http:// As a result, numerous programs to control point source NO x emissions in the eastern U.S. have been implemented [ EPA , 2005a]. In particular, the recent control program, the 1998 NO x State Implementation Plans Call, focused on the summertime reduction of power industry NO x emissions to limit ozone formation [ EPA
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frost ppr 2006GL027749 - Click Here GEOPHYSICAL RESEARCH...

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