Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 8 11 2008 10.5194/acp-8-2999-2008 http://www.atmos-chem-phys.net/8/2999/2008/ http://www.atmos-chem-phys.net/8/2999/2008/acp-8-2999-2008.html http://www.atmos-chem-phys.net/8/2999/2008/acp-8-2999-2008.pdf 2999 3014 2008-06-17 Analysis of aircraft and satellite measurements from the Intercontinental Chemical Transport Experiment (INTEX-B) to quantify long-range transport of East Asian sulfur to Canada A. van Donkelaar R. V. Martin W. R. Leaitch A. M. Macdonald T. W. Walker D. G. Streets Q. Zhang E. J. Dunlea J. L. Jimenez J. E. Dibb L. G. Huey R. Weber M. O. Andreae Dept. of Physics and Atmospheric Science, Dalhousie University, Canada Harvard-Smithsonian Center for Astrophysics, USA Science and Technology Branch, Environment Canada, Canada Dept. of Physics, University of Toronto, Canada Decision and Information Sciences Division, Argonne National Laboratory, USA Department of Chemistry and Biochemistry, and Cooperative Institute for Research in the Environmental Sciences (CIRES), University of Colorado, USA Climate Change Research Center/EOS, University of New Hampshire, USA School of Earth and Atmospheric Sciences, Georgia Institute of Technology, USA Biogeochemistry Department, Max Planck Institute for Chemistry, Germany We interpret a suite of satellite, aircraft, and ground-based measurements over the North Pacific Ocean and western North America during April–May 2006 as part of the Intercontinental Chemical Transport Experiment Phase B (INTEX-B) campaign to understand the implications of long-range transport of East Asian emissions to North America. The Canadian component of INTEX-B included 33 vertical profiles from a Cessna 207 aircraft equipped with an aerosol mass spectrometer. Long-range transport of organic aerosols was insignificant, contrary to expectations. Measured sulfate plumes in the free troposphere over British Columbia exceeded 2 μg/m³. We update the global anthropogenic emission inventory in a chemical transport model (GEOS-Chem) and use it to interpret the observations. Aerosol Optical Depth (AOD) retrieved from two satellite instruments (MISR and MODIS) for 2000–2006 are analyzed with GEOS-Chem to estimate an annual growth in Chinese sulfur emissions of 6.2% and 9.6%, respectively. Analysis of aircraft sulfate measurements from the NASA DC-8 over the central Pacific, the NSF C-130 over the east Pacific and the Cessna over British Columbia indicates most Asian sulfate over the ocean is in the lower free troposphere (800–600 hPa), with a decrease in pressure toward land due to orographic effects. 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