Hi All
Six out of the eight models in the Driscoll et al paper show near
surface-warming in Arctic winters following volcanic eruptions. This is
in line with figure 2a the Jones Hayward Boucher Robock 2010 paper in
Atmospheric Chemistry and Physics. The obvious mechanisms are blanketing
of outgoing radiation and side-scatter of high solar rays that might
have missed the polar regions. Given the concerns about the loss of
Arctic ice and increased methane release we will have to be very careful
not to let any geo-engineering sulphur that we inject at low latitudes
reach the Arctic in winter.
Stephen
On 10/09/2012 16:52, Simon Driscoll wrote:
Dear all,
the published version (no longer PiP) is now available here:
http://www.agu.org/pubs/crossref/2012/2012JD017607.shtml
Warm regards,
Simon
________________________________________________
Simon Driscoll
Atmospheric, Oceanic and Planetary Physics
Department of Physics
University of Oxford
Office: 01865 272930
Mobile: 07935314940
http://www2.physics.ox.ac.uk/contacts/people/driscoll
http://www.geoengineering.ox.ac.uk/people/who-are-we/simon-driscoll/
------------------------------------------------------------------------
*From:* [email protected]
[[email protected]] on behalf of Andrew Lockley
[[email protected]]
*Sent:* 14 August 2012 02:06
*To:* geoengineering
*Subject:* [geo] Coupled Model Intercomparison Project 5 (CMIP5)
simulations of climate following volcanic eruptions
http://www.agu.org/pubs/crossref/pip/2012JD017607.shtml
The ability of the climate models submitted to the Coupled Model
Intercomparison Project 5 (CMIP5) database to simulate the Northern
Hemisphere winter climate following a large tropical volcanic eruption
is assessed. When sulfate aerosols are produced by volcanic injections
into the tropical stratosphere and spread by the stratospheric
circulation, it not only causes globally averaged tropospheric cooling
but also a localized heating in the lower stratosphere, which can
cause major dynamical feedbacks. Observations show a lower
stratospheric and surface response during the following one or two
Northern Hemisphere (NH) winters, that resembles the positive phase of
the North Atlantic Oscillation (NAO). Simulations from 13 CMIP5 models
that represent tropical eruptions in the 19th and 20th century are
examined, focusing on the large-scale regional impacts associated with
the large-scale circulation during the NH winter season. The models
generally fail to capture the NH dynamical response following
eruptions. They do not sufficiently simulate the observed
post-volcanic strengthened NH polar vortex, positive NAO, or NH
Eurasian warming pattern, and they tend to overestimate the cooling in
the tropical troposphere. The findings are confirmed by a superposed
epoch analysis of the NAO index for each model. The study confirms
previous similar evaluations and raises concern for the ability of
current climate models to simulate the response of a major mode of
global circulation variability to external forcings. This is also of
concern for the accuracy of geoengineering modeling studies that
assess the atmospheric response to stratosphere-injected
particles.Received 13 February 2012; accepted 24 July 2012.
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