Mechanisms of aerosol-forced AMOC variability in a state of the art climate model
Article first published online: 25 APR 2013
©2013. American Geophysical Union. All Rights Reserved.
Journal of Geophysical Research: Oceans
Volume 118, Issue 4, pages 2087–2096, April 2013
How to Cite
2013), Mechanisms of aerosol-forced AMOC variability in a state of the art climate model, J. Geophys. Res. Oceans, 118, 2087–2096, doi:10.1002/jgrc.20178., , , , , , , , and (
- Issue published online: 17 MAY 2013
- Article first published online: 25 APR 2013
- Accepted manuscript online: 27 MAR 2013 05:33PM EST
- Manuscript Accepted: 25 MAR 2013
- Manuscript Revised: 21 MAR 2013
- Manuscript Received: 29 OCT 2012
- European Community's seventh framework programme. Grant Number: FP7/2007-2013
- Joint DECC and Defra Hadley Centre Climate Programme, DECC/Defra. Grant Number: GA01101
 Mechanisms of sustained multidecadal changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC) are investigated in a set of simulations with a new state-of-the-art Earth system model. Anthropogenic aerosols have previously been highlighted as a potential mitigator of AMOC weakening. In this study, we explain the oceanic mechanisms behind how anthropogenic aerosols force a strengthening of the AMOC by up to 20% in our state-of-the-art Earth system model. This strengthening is driven via atmospheric circulation changes which subsequently modulate the salinity budget of the North Atlantic subpolar gyre. Gradual salinification occurs via increased evaporation and decreased fluxes of ice through the Fram Straits. A component of the salinification is a positive feedback from the AMOC bringing more saline water northwards from the subtropical Atlantic. Salinification of the subpolar gyre results in increased deep convection and a strengthening of the AMOC. Following a reduction in aerosol concentrations, the AMOC rapidly weakens, approximately 3 times faster than in the case where anthropogenic aerosol concentrations had never been increased. Similarities and differences with available observational records and long term reanalysis products are also discussed.