Transboundary Influences on Ozone Pollution in the United States: Present Conditions and Future Projections
The GEOS-Chem global chemical transport model (v7-02-01) with 1° x1° horizontal resolution over North America is used to investigate the influence of transboundary pollution from Canada and Mexico on surface ozone in the United States. We conduct a series of 4 simulations for present day conditions: (1) a standard simulation with 2001 anthropogenic emissions worldwide, (2) with zero U.S. anthropogenic emissions, (3) with zero anthropogenic emission in North America (Canada, U.S. and Mexico), and (4) with 2006 East Asian emissions and no emission in North America. For future projections, we repeat (1)-(3) with a 2020 worldwide emissions inventory, in addition to a run with U.S. Power plant emissions switched off. The standard simulation is evaluated with observations for U.S. regions most sensitive to transboundary pollution (northeast for Canada, southwest for Mexico). Monthly mean ozone enhancements from transboundary pollution are in the 5-10 ppb range for these regions in June-August, but can exceed 30 ppbv under conditions when ozone is above the U.S. air quality standard (84 ppbv). Unlike intercontinental pollution influence which mainly contributes to the ozone background and is depleted during regional smog episodes, transboundary pollution influence from Canada and Mexico is highly variable and can contribute significantly to these episodes.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 0345 Pollution: urban and regional (0305;
- 0368 Troposphere: constituent transport and chemistry