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Published March 27, 2007 | Supplemental Material + Published
Journal Article Open

Biogenic secondary organic aerosol over the United States: Comparison of climatological simulations with observations


Understanding the effects of global climate change on regional air quality is central in future air quality planning. We report here on the use of the Goddard Institute for Space Studies (GISS) general circulation model (GCM) III to drive the GEOS-CHEM global atmospheric chemical transport model to simulate climatological present-day aerosol levels over the United States. Evaluation of model predictions using surface measurements from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network indicates that the GISS GCM III/GEOS-CHEM model is a suitable tool for simulating aerosols over the United States in the present climate. The model reproduces fairly well the concentrations of sulfate (mean bias of −0.36 μg m^(−3), normalized mean bias (NMB) of −25.9%), black carbon (−0.004 μg m^(−3), −1.9%), organic carbon that comprises primary and secondary components (−0.56 μg m^(−3), −34.2%), and PM_(2.5) (−0.87 μg m^(−3), −20.4%). Nitrate concentrations are overpredicted in the western United States (west of 95°W) with a NMB of +75.6% and underestimated in the eastern United States with a NMB of −54.4%. Special attention is paid to biogenic secondary organic aerosol (SOA). The highest predicted seasonal mean SOA concentrations of 1–2 μg m^(−3) and 0.5–1.5 μg m^(−3) are predicted over the northwestern and southeastern United States, respectively, in the months of June–July–August. Isoprene is predicted to contribute 49.5% of the biogenic SOA burden over the United States, with the rest explained by the oxidation of terpenes. Predicted biogenic SOA concentrations are in reasonable agreement with inferred SOA levels from IMPROVE measurements. On an annual basis, SOA is predicted to contribute 10–20% of PM_(2.5) mass in the southeastern United States, as high as 38% in the northwest and about 5–15% in other regions, indicating the important role of SOA in understanding air quality and visibility over the United States.

Additional Information

Copyright 2007 by the American Geophysical Union. Received 21 July 2006; revised 4 October 2006; accepted 2 November 2006; published 16 March 2007. This work was supported by the U.S. Environmental Protection Agency under Science to Achieve Results (STAR) grant R830959. Hong Liao was partially supported by the 100-Talent Project of Chinese Academy of Sciences.

Attached Files

Published - jgrd13400.pdf

Supplemental Material - jgrd13400-sup-0001-t01.txt

Supplemental Material - jgrd13400-sup-0002-t02.txt

Supplemental Material - jgrd13400-sup-0003-t03.txt

Supplemental Material - jgrd13400-sup-0004-t04.txt

Supplemental Material - jgrd13400-sup-0005-t05.txt

Supplemental Material - jgrd13400-sup-0006-t06.txt

Supplemental Material - jgrd13400-sup-0007-t07.txt


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August 19, 2023
October 18, 2023