{"id":24832,"date":"2014-11-04T09:00:53","date_gmt":"2014-11-04T15:00:53","guid":{"rendered":"http:\/\/rankexploits.com\/musings\/?p=24832"},"modified":"2014-11-04T09:00:53","modified_gmt":"2014-11-04T15:00:53","slug":"volcanoes-ridley-et-al-bleg","status":"publish","type":"post","link":"https:\/\/rankexploits.com\/musings\/2014\/volcanoes-ridley-et-al-bleg\/","title":{"rendered":"Volcanoes: Ridley et al. (Bleg)"},"content":{"rendered":"

I’m reading “Total volcanic stratospheric aerosol optical depths and implications for global climate change<\/em>
\nD. A Ridley1, S. Solomon2, J. E. Barnes3, V.D. Burlakov4, T. Deshler5, S.I. Dolgii4, A.B. Herber6, T. Nagai7, R. R. Neely III8, A.V. Nevzorov4, C. Ritter9, T. Sakai7, B. D. Santer10, M. Sato11, A. Schmidt12, O.Uchino7, J. P. Vernier13,14″ <\/p>\n

It’s an interesting paper. I have a big question and I’m hoping to that some readers might be able to point to resources. Briefly:<\/p>\n

Is there a brief resource that lists the volcanic forcings<\/I> used by groups who contributed projections to the AR5. <\/p>\n

Specifically, I want to know which groups ‘froze’ volcanic forcings after 2000 and which did not. For groups that did not freeze volcanic forcings in 2000, I’d be interested in knowing when the year they did freeze them, and at what level those forcings were frozen. <\/p>\n

\"RidleySaysFroze\"<\/a>The reason I wish to know: Ridley seems to suggest “many” froze forcings. I don’t know what fraction ‘many climate model studies to date’ constitutes nor which models. Are the “many climate model[s]” the AOGCM’s used to create projections in the AR5? Or are they EMICs? Etc. Of the AOGCM runs, is ‘many’ 20% ‘froze’ or was it more like 80%? <\/p>\n

My impression (which could be incorrect) is that Model E did not<\/em> freeze volcanic aerosols in 2000<\/em>. (NASA’s Model E page<\/a> says, <\/p>\n

“The simulations (using TCADI) denoted by p3001 are continuations from 1991 of the p3 simulations including further updates to the volcanic and solar forcings through to 2012<\/strong><\/em>. The volcanic forcings are from a more recent version of the Sato et al. data than used in the historicalExt runs described below.”<\/p><\/blockquote>\n

But perhaps I’m jumping to the conclusion that these were the runs used for “projections” in the AR5 and perhaps they did ‘freeze’ volcanic aerosols in 2000 and then use that to create projections. (Note: if they ‘froze’ in 2012, one might expect the ‘mean’ for their trends from 2012-2014 should be lower<\/I> than the earths, because the volcanic aerosol cleared somewhat. Any discrepancy would be undetectable as it would be swamped by ‘weather noise’.)<\/p>\n

I would like to know the year other<\/i> modeling groups who contributed to the AR5 (or AR4) ‘froze’ volcanic aerosols. <\/p>\n

BTW: I’m pretty sure it’s true<\/i> that of those that included volcanic aerosols in the AR4, ‘many’ did freeze in 2000, though once again, I believe Model E did not. I think they froze later– around 2003 or so. That said: many models in the AR4 did not include volcanic aerosols at all<\/i>; that makes it very difficult to speculate how the variation in aerosols in 2000 mattered– as one ought<\/i> to two off-setting factors: (a) that those models were not<\/i> including the tail end of the ‘recovery’ to Pinatubo — which might be small but still not zero– and (b)also did not include the ‘cooling’ effect of newer, but much smaller, eruptions. Nevertheless, it would be interesting to have a listing. <\/p>\n

I know someone is going to be telling me I can hunt these down at PCMDI: I prefer not<\/i> to slog away at PCMDI. What I want is for someone to tell me if someone else<\/i> has already<\/em> gone through and at least has information on a ‘yes\/no’ froze in 2000 level and\/or ‘which year froze’. Or if someone else<\/I> wants to slog through PCMDI and find out the year any particular group ‘froze’ volcanic aerosols, that would be lovely. This is not a task that requires high technical skills: just time. So if you are curious, and have time, you could look. \ud83d\ude42 )<\/p>\n

The effort is interesting because it is important because the degree to which one ‘ought’ to believe the discrepancy between either AR4 or<\/I> AR5 models and observations can be ‘explained’ by projections being based on ‘frozen in 2000’ aerosols depends on the fraction of modeling groups that froze volcanic aerosol forcings in their input files when creating runs to actually contributed to the AR4 or AR5. I have no idea what this fraction is.<\/p>\n

If “many” froze them means roughly 20% did, then the discrepancy between model mean and runs is difficult to explain by the difference in ‘real’ and ‘modeled’ volcanic aerosols. In contrast, if 80% froze them, we can test that too. We can also dig through and see whether there is any systematic difference between 2000th century trends between models that did<\/I> ‘freeze’ volcanic aerosols and those that did not. (Assuming some did and some did not, of course.)<\/p>\n

I have a few other comments that I could make on this paper. The main one that first comes to me is this:<\/p>\n

When finding likely effect of forcings on trends in the 2000’s it strikes me as a bit ambitious to simply do everything relative to the volcanic forcing in<\/I> 2000. The reason is that the atmosphere does have a response time. So, if one wants to find out the effect incorporating forcings in the lower stratosphere into the recent trends, one ought<\/I> to know what those were in past years before deciding the effect of any increase in Stratospheric Aerosol Optical Depth (SAOD) during the 2000’s. It appears no AERONET data exists prior to 1995; I’ll take the researchers word that the data are tenuous prior to 2000. But this is a factor we should consider– and possibly one ought to widen the range of possible effect on temperature in that paper. (Perhaps doubling it.)<\/p>\n

That said: it’s an interesting exercise, and worth being aware of. It could potentially explain the discrepancy between the model mean and the observed trend. (Which will mean that the discrepancy between a projected model mean trend of “about 0.2 C\/decade” existed<\/i> and still does<\/i> as opposed to ‘did not exist’.)<\/p>\n","protected":false},"excerpt":{"rendered":"

I’m reading “Total volcanic stratospheric aerosol optical depths and implications for global climate change D. A Ridley1, S. Solomon2, J. E. Barnes3, V.D. Burlakov4, T. Deshler5, S.I. Dolgii4, A.B. Herber6, T. Nagai7, R. R. Neely III8, A.V. Nevzorov4, C. Ritter9, T. Sakai7, B. D. Santer10, M. Sato11, A. Schmidt12, O.Uchino7, J. P. Vernier13,14″ It’s an … Continue reading Volcanoes: Ridley et al. (Bleg)<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17,5],"tags":[],"class_list":["post-24832","post","type-post","status-publish","format-standard","hentry","category-gcms","category-global-climate-change"],"_links":{"self":[{"href":"https:\/\/rankexploits.com\/musings\/wp-json\/wp\/v2\/posts\/24832","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rankexploits.com\/musings\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rankexploits.com\/musings\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rankexploits.com\/musings\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/rankexploits.com\/musings\/wp-json\/wp\/v2\/comments?post=24832"}],"version-history":[{"count":0,"href":"https:\/\/rankexploits.com\/musings\/wp-json\/wp\/v2\/posts\/24832\/revisions"}],"wp:attachment":[{"href":"https:\/\/rankexploits.com\/musings\/wp-json\/wp\/v2\/media?parent=24832"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rankexploits.com\/musings\/wp-json\/wp\/v2\/categories?post=24832"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rankexploits.com\/musings\/wp-json\/wp\/v2\/tags?post=24832"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}