Model analysis of sulfate and SO2 over the Asian-Pacific region during Spring 2001: Sources, distributions, and intercontinental transport

During Spring 2001, two field campaign programs, the Transport and Chemical Evolution over the Pacific (TRACE-P) and the Aerosol Characterization Experiment-Asia (ACE-Asia), were conducted over the north-western Pacific, with a common goal of understanding the impact of the growing pollution sources from the Asian continent to the regional and global atmosphere. We have used the Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model to simulate sulfate aerosol and its precursor SO2 that predominantly originate from anthropogenic sources. Model results are compared with aircraft measurements during TRACE-P and ACE-Asia. Model results show that anthropogenic emissions from Asia dominates SO2 and sulfate loading over the western Pacific at mid- and lower latitudes (< 45N), however, transport from Europe could account for as much as 60-80% of SO2 and 30-40% of sulfate at latitudes of 45N and higher over large area of Asian continent and Pacific. Asian pollution plumes often reached the west coast of the U.S., contributing to about 30% of sulfate loading during Spring 2001.