Recent increases in Asian emissions and consequences for transpacific ozone pollution in the United States: INTEX-B and Aura observations
Abstract
We examine ozone production in transpacific Asian pollution and its impact on surface ozone in the United States by using aircraft, satellite, and surface observations in April-May 2006 from the NASA/INTEX-B campaign. The observations are interpreted with a global three-dimensional chemical transport model (GEOS-Chem). We estimate anthropogenic NOx emissions from eastern Asia using tropospheric NO2 column observations from OMI for April-May 2006. We find a factor of two increase compared with 2000 estimates. Observations from Mount Bachelor Observatory (MBO) in the northwest United States indicate three major events of Asian transpacific pollution during INTEX-B. We study in detail one event that was also observed by the INTEX-B aircraft and by the TES and AIRS satellite instruments. The Asian plume was lifted ahead of a cold front and split into northern and southern branches over the northeast Pacific. Elevated ozone was observed in the subsiding southern branch and was consistent with production from PAN decomposition. This southern branch impacted the western United States including MBO. GEOS-Chem simulates well this transpacific event and the associated O3-CO correlations observed by TES. We find that continuous ozone formation over the Pacific from exported Asian NOx and PAN is comparable to direct transport of Asian ozone produced in the boundary layer. Model results indicate that the doubling of Asian anthropogenic NOx emissions from 2000 to 2006 increased surface ozone by 1.2-1.8 ppbv in the western United States. Rising Asian emissions, increases the possibility to detect Asian ozone plumes at mountain sites such as MBO.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AGUFM.A53H..04Z
- Keywords:
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- 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0368 Troposphere: constituent transport and chemistry;
- 3300 ATMOSPHERIC PROCESSES;
- 3360 Remote sensing