Multimodel estimates of intercontinental source-receptor relationships for ozone pollution

Abstract

Understanding the surface 03 response over a "receptor" region to emission changes a foreign "source" region is key to evaluating the potential gains from an international approach to abate ozone (03) pollution. We apply an ensemble of 21 global hemispheric chemical transport models to estimate the spatial average surface 03 response over east Asia (EA), Europe (EU), North America (NA), and south Asia (SA) to decreases in anthropogenic emissions of the 03 precursors, NOx, NMVOC, and CO (individually and combined), from each of these regions. We find that the ensemble mean surface 03 concentrations in the base case (year 2001) simulation matches available observations throughout the year over EU but overestimates them by >10 ppb during summer and early fall over the eastern United States and Japan. The sum of the 03 responses to NOx, CO, and NMVOC decreases separately is approximately equal to that a simultaneous reduction of all precursors. We defme a continental-scale "import sensitivity" as the ratio of the 0 3 response to the 20% reductions in foreign versus. © 2009 by the American Geophysical Union.