Premium
Mechanisms of aerosol‐forced AMOC variability in a state of the art climate model
Author(s) -
Menary Matthew B.,
Roberts Christopher D.,
Palmer Matthew D.,
Halloran Paul R.,
Jackson Laura,
Wood Richard A.,
Müller Wolfgang A.,
Matei Daniela,
Lee SangKi
Publication year - 2013
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/jgrc.20178
Subject(s) - ocean gyre , climatology , aerosol , climate model , environmental science , subtropics , general circulation model , oceanography , atmospheric sciences , climate change , geology , meteorology , geography , fishery , biology
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.