In my view, this is just why geoengineering efforts to cool the Arctic should consider as approaches: (a) spring-summer only injection of the appropriate sulfur compound (whatever will lead to sulfates) into the LOWER stratosphere or free troposphere, (b) cloud brightening in region or over currents carrying heat into the region, (c) approaches to brighten the surface albedo (e.g., microbubbles) in or near the region, and, perhaps, (d) approaches to reduce cirrus that are reducing IR loss.
Parallel to these efforts, we should also be working to limit emissions of substances that amplify Arctic warming above and beyond the amplification that happens due to natural processes, so black carbon from sources in and near the region, etc. Mike On 9/11/12 5:03 AM, "Stephen Salter" <s.sal...@ed.ac.uk> 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: geoengineering@googlegroups.com [geoengineering@googlegroups.com] on >> behalf of Andrew Lockley [andrew.lock...@gmail.com] >> 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 geoengineering@googlegroups.com. >> To unsubscribe from this group, send email to >> geoengineering+unsubscr...@googlegroups.com. >> 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 geoengineering@googlegroups.com. >> To unsubscribe from this group, send email to >> geoengineering+unsubscr...@googlegroups.com. >> 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 geoengineering@googlegroups.com. To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
