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Aerosol climate feedback due to decadal increases in Southern Hemisphere wind speeds

Korhonen, H, Carslaw, KS, Forster, PM, Mikkonen, S, Gordon, ND and Kokkola, H (2010) Aerosol climate feedback due to decadal increases in Southern Hemisphere wind speeds. Geophysical Research Letters, 37. ISSN 0094-8276

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Abstract

Observations indicate that the westerly jet in the Southern Hemisphere troposphere is accelerating. Using a global aerosol model we estimate that the increase in wind speed of 0.45 + /- 0.2 m s(-1) decade(-1) at 50-65 degrees S since the early 1980s caused a higher sea spray flux, resulting in an increase of cloud condensation nucleus concentrations of more than 85% in some regions, and of 22% on average between 50 and 65 degrees S. These fractional increases are similar in magnitude to the decreases over many northern hemisphere land areas due to changes in air pollution over the same period. The change in cloud drop concentrations causes an increase in cloud reflectivity and a summertime radiative forcing between at 50 and 65 degrees S comparable in magnitude but acting against that from greenhouse gas forcing over the same time period, and thus represents a substantial negative climate feedback. However, recovery of Antarctic ozone depletion in the next two decades will likely cause a fall in wind speeds, a decrease in cloud drop concentration and a correspondingly weaker cloud feedback.

Item Type: Article
Copyright, Publisher and Additional Information: © 2010 American Geophyical Union. Reproduced in accordance with the publisher's self-archiving policy.
Keywords: model, microphysics, atmosphere
Institution: The University of Leeds
Academic Units: The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds)
Depositing User: Symplectic Publications
Date Deposited: 01 Sep 2011 14:39
Last Modified: 08 Jun 2014 09:19
Published Version: http://dx.doi.org/10.1029/2009GL041320
Status: Published
Publisher: American Geophysical Union
Identification Number: 10.1029/2009GL041320
URI: http://eprints.whiterose.ac.uk/id/eprint/43210

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