Sources, distribution, and acidity of sulfate–ammonium aerosol in the Arctic in winter–spring

Authors

Jenny Fisher, Harvard University
Daniel J. Jacob, Harvard University
Qiaoqiao Wang, Harvard University
Roya Bahreini, University of Colorado Boulder
Claire C. Carouge, Harvard University
Michael J. Cubison, University of Colorado Boulder
Jack E. Dibb, University of New HampshireFollow
Thomas Diehl, NASA
Jose L. Jimenez, University of Colorado BoulderFollow
Eric M. Leibensperger, Harvard University
Zifeng Lu, Argonne National Laboratory
Macel B.J. Meinders, Wageningen Agricultural University
Havala O.T. Pye, California Institute of Technology
Patricia K. Quinn, NOAA
Sangeeta Sharma, Environment Canada
David G. Streets, Argonne National Laboratory
Aaron van Donkelaar, Dalhousie University
Robert Yantosca, Harvard University

Abstract

We use GEOS-Chem chemical transport model simulations of sulfate–ammonium aerosol data from the NASA ARCTAS and NOAA ARCPAC aircraft campaigns in the North American Arctic in April 2008, together with longer-term data from surface sites, to better understand aerosol sources in the Arctic in winter–spring and the implications for aerosol acidity. Arctic pollution is dominated by transport from mid-latitudes, and we test the relevant ammonia and sulfur dioxide emission inventories in the model by comparison with wet deposition flux data over the source continents. We find that a complicated mix of natural and anthropogenic sources with different vertical signatures is responsible for sulfate concentrations in the Arctic. East Asian pollution influence is weak in winter but becomes important in spring through transport in the free troposphere. European influence is important at all altitudes but never dominant. West Asia (non-Arctic Russia and Kazakhstan) is the largest contributor to Arctic sulfate in surface air in winter, reflecting a southward extension of the Arctic front over that region. Ammonium in Arctic spring mostly originates from anthropogenic sources in East Asia and Europe, with added contribution from boreal fires, resulting in a more neutralized aerosol in the free troposphere than at the surface. The ARCTAS and ARCPAC data indicate a median aerosol neutralization fraction [NH₄⁺]/(2[SO₄²⁻] + [NO₃⁻]) of 0.5 mol mol⁻¹ below 2 km and 0.7 mol mol⁻¹ above. We find that East Asian and European aerosol transported to the Arctic is mostly neutralized, whereas West Asian and North American aerosol is highly acidic. Growth of sulfur emissions in West Asia may be responsible for the observed increase in aerosol acidity at Barrow over the past decade. As global sulfur emissions decline over the next decades, increasing aerosol neutralization in the Arctic is expected, potentially accelerating Arctic warming through indirect radiative forcing and feedbacks.

Department

Earth Sciences, Earth Systems Research Center

Publication Date

12-2011

Journal Title

Atmospheric Environment

Publisher

Elsevier

Digital Object Identifier (DOI)

10.1016/j.atmosenv.2011.08.030

Document Type

Article

Recommended Citation

Jenny A. Fisher, Daniel J. Jacob, Qiaoqiao Wang, Roya Bahreini, Claire C. Carouge, Michael J. Cubison, Jack E. Dibb, Thomas Diehl, Jose L. Jimenez, Eric M. Leibensperger, Zifeng Lu, Marcel B.J. Meinders, Havala O.T. Pye, Patricia K. Quinn, Sangeeta Sharma, David G. Streets, Aaron van Donkelaar, Robert M. Yantosca, Sources, distribution, and acidity of sulfate–ammonium aerosol in the Arctic in winter–spring, Atmospheric Environment, Volume 45, Issue 39, December 2011, Pages 7301-7318, ISSN 1352-2310,

Rights

Copyright © 2011 Elsevier Ltd. Published by Elsevier Ltd. All rights reserved.