Quantifying the continental outflow and intercontinental transport of air pollutants is one of the greatest challenges of atmospheric chemistry today. It is expected that the industrialization of Asia will be one of the major drivers for changes in atmospheric composition in the coming decades. Recent studies have suggested that transpacific transport of Asian pollution has significant implications for ozone and aerosol air quality in the United States. In my Ph.D. work, tropospheric observations from space are linked with in situ observations and 3-D models to examine the mechanisms and impact of the intercontinental transport of these pollutants as well as the magnitude of their emission.

Satellite observations of carbon monoxide (CO) from the Measurement of Pollution in the Troposphere (MOPITT) instrument were combined with measurements from the TRACE-P aircraft mission over the northwest Pacific, and with a global 3-D chemical transport model (GEOS-CHEM), to examine Asian pollution outflow and its transpacific transport during spring 2001. Four major events of transpacific transport of Asian pollution were seen by MOPITT, in-situ platforms, and GEOS-CHEM, indicating that satellites can be used to successfully monitor long-range pollution transport. One of these events was sampled by TRACE-P over the NE Pacific and this analysis demonstrates the first field observation of PAN decomposition driving ozone production in polluted plumes transported to the remote troposphere.

Inverse modeling techniques were employed to compare the constraints on Asian sources of carbon monoxide from MOPITT satellite observations, and aircraft observations from the TRACE-P mission. MOPITT observations provide greater information towards geographically disaggregating source regions within Asia in comparison to the aircraft observations, reflecting the ability of the satellite to observe all outflow and source regions. The MOPITT and TRACE-P observations are independently consistent in the constraints that they provide on Asian CO sources, where biomass burning emissions are much less than previously thought and emissions from small industrial coal facilities in China have been underestimated.

Recent observations of Asian aerosol pollution at sites in western North America have raised concern about possible air quality implications. The value of MODIS satellite observations for quantifying transpacific aerosol pollution transport, forecasting Asian pollution events at sites in the United States, and testing a CTM (GEOS-CHEM) simulation of this process was explored. Most transpacific aerosol pollution events observed by MODIS in spring 2001 are associated with significant Asian sulfate enhancements simulated by the model at sites in the NW United States, occasionally exceeding 1 micro-g/m3.

More information available: www.fas.harvard.edu/~heald