Summary: Transpacific transport of Asian anthropogenic aerosols and its impact
on surface air quality in the United States
Colette L. Heald,1,2
Daniel J. Jacob,1
Rokjin J. Park,1
Becky Alexander,1,3
T. Duncan Fairlie,1
Robert M. Yantosca,1
and D. Allen Chu4
Received 2 November 2005; revised 24 February 2006; accepted 5 April 2006; published 22 July 2006.
[1] We use satellite (MODIS) observations of aerosol optical depths (AODs) over the
North Pacific, together with surface aerosol measurements at a network of remote
U.S. sites (IMPROVE), to improve understanding of the transpacific transport of Asian
aerosol pollution and assess the ability of a global 3-D chemical transport model
(GEOS-Chem CTM) to quantify Asian aerosol enhancements in U.S. surface air. The
MODIS observations show the strongest transpacific transport occurring in spring at
40­55°N. This transport in the model takes place mainly in the lower free troposphere
(900­700 hPa) because of scavenging during transport either in the boundary layer or
during lifting to the upper troposphere. The preferential altitude of aerosol transpacific
transport results in direct impact on the elevated terrain of the NW United States. Sulfate

Source: Alexander, Becky - Department of Atmospheric Sciences, University of Washington at Seattle

Collections: Environmental Sciences and Ecology; Geosciences