Hi Andrew--The key is to limit heat uptake by the Arctic Ocean, which takes up the energy in the sunny season and then releases it to the atmosphere in the winter, causing warming. Sea ice reflects solar when present during the summer season, but tends to retain heat in the Arctic during the dark season (i.e., slowing transfer of heat from ocean to atmosphere and then, at least for some fraction, out to space).
Mike On 9/11/12 6:06 AM, "Andrew Lockley" <[email protected]> wrote: > If the effect is unavoidably year round, what's the sign on the sea ice net > effect? Thus may be different to temp. > > A > > On Sep 11, 2012 10:03 AM, "Stephen Salter" <[email protected]> wrote: >> >> >> 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. >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "geoengineering" group. >>> To post to this group, send email to [email protected]. >>> To unsubscribe from this group, send email to >>> [email protected]. >>> For more options, visit this group at >>> http://groups.google.com/group/geoengineering?hl=en. >>> >>> >>> >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "geoengineering" group. >>> To post to this group, send email to [email protected]. >>> To unsubscribe from this group, send email to >>> [email protected]. >>> For more options, visit this group at >>> http://groups.google.com/group/geoengineering?hl=en. >>> >> >> >> -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
