Atmospheric Science

Serendipitous Surcease

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Science  06 Aug 2004:
Vol. 305, Issue 5685, pp. 755
DOI: 10.1126/science.305.5685.755a

The electrical blackout that affected the northeastern United States and southeastern Canada in August 2003 dramatically reduced the output of polluting species—sulfur dioxide (SO2), which produces fine particles, and nitrogen oxides (NOx), which produce ozone (O3)—from more than 100 power plants. This created a rare opportunity for evaluating directly the contribution of power plant emissions to the formation of regional haze and smog.

Marufu et al. report the results of a series of measurements made from airplanes that flew over central Pennsylvania (inside the affected region) and western Maryland (outside) about 24 hours after the beginning of the blackout. Concentrations of SO2 and O3 in Pennsylvania were much lower than those measured over western Maryland earlier that day and in comparison to the same location in Pennsylvania a year earlier. Light scattering due to small particles decreased, yielding an improvement in visibility of >40 km. These observations provide a test case for assessing how well numerical models can reproduce the contributions of specific pollution sources to regional air quality. — HJS

Geophys. Res. Lett. 31, 10.1029/2004GL019771 (2004).

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