tag:blogger.com,1999:blog-9959776.post1931246236428370808..comments2024-02-15T04:42:41.606+00:00Comments on James' Empty Blog: Chylek on sensitivityJames Annanhttp://www.blogger.com/profile/04318741813895533700noreply@blogger.comBlogger12125tag:blogger.com,1999:blog-9959776.post-3077807537126404212008-07-04T03:17:00.000+01:002008-07-04T03:17:00.000+01:00Well, I wouldn't be too harsh on it yet for just h...Well, I wouldn't be too harsh on it yet for just having one citation, given that it was only published recently.<BR/><BR/>OTOH, I can't see it getting many more, but that is just my personal judgment based on scientific factors (ie, I haven't heard of anyone bothering to write a comment on it, although that doesn't mean such a thing does not exist). :-)James Annanhttps://www.blogger.com/profile/04318741813895533700noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-88277898027070890232008-07-03T19:25:00.000+01:002008-07-03T19:25:00.000+01:00Amusing: Chylek's 2008 paper has been cited exactl...Amusing: <BR/><BR/>Chylek's 2008 paper has been cited exactly one time to date<BR/>http://scholar.google.com/scholar?num=100&cites=17990027834477555820<BR/><BR/>What for? Cited by Schwartz (2008) where he corrects Schwartz (2007) to bring his estimate of climate sensitivity up about 70 percent, to 1.9 ± 1.0 K, as he acknowledges now within the low end of the IPCC range. <BR/><BR/>Why did he cite Chylek? I paraphrase: 'but anyhow Chylek also published a lower estimate, and besides, climate sensitivity is a stupid thing to estimate from a model'.<BR/><BR/>Nevertheless, it's about three degrees.Hank Robertshttps://www.blogger.com/profile/07521410755553979665noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-75483184501585789082008-03-11T12:21:00.000+00:002008-03-11T12:21:00.000+00:00Hi Micajah,I've seen that paper, and although it's...Hi Micajah,<BR/><BR/>I've seen that paper, and although it's not my area I get a strong sense that it's nonsense. Unknown authors don't overturn decades of science overnight, and the suggestion that a semi-infinite atmosphere is somehow radically different from one with a definite boundary (which seems to be the main claim), and moreover that no-one has been aware of this up to now, seems implausible to say the least.James Annanhttps://www.blogger.com/profile/04318741813895533700noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-83589591393820649712008-03-11T04:50:00.000+00:002008-03-11T04:50:00.000+00:00What do you think of the equations recently publis...What do you think of the equations recently published by Ferenc Miskolczi?<BR/><BR/>I confess to knowing so little that I won't even try to describe what his equations may mean, but it seems to have something to do with the effect on temperatures of increasing GHGs.<BR/><BR/>From what little I've read so far, it seems that a very basic part of the equations for measuring sensitivity to GHG may be wrong. Could that be?Micajahhttps://www.blogger.com/profile/16586317925722410844noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-33631683058968718122008-01-07T15:48:00.000+00:002008-01-07T15:48:00.000+00:00"The fundamental problem is that the expression dH..."The fundamental problem is that the expression dH/dt = k.T...."<BR/><BR/>A somewhat similar approximation was used by Rahmstorf (Science 315,368). Instead of dH/dt he uses dSLH/dt, where SLH is sea-level-height. SLH containes also the contribution of glacier melt, but in the 19th and 20th century dSLH/dt should be to a good approximation proportional to dH/dt at short timescales.vientohttps://www.blogger.com/profile/16194347485220215238noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-29962701381429802942007-12-30T14:25:00.000+00:002007-12-30T14:25:00.000+00:00Silly me, I should have remembered Nick's 'Bag of ...Silly me, I should have remembered Nick's 'Bag of Tricks'<BR/><BR/>http://www.climateprediction.net/board/viewtopic.php?p=49085#49085<BR/><BR/>Or Nick's presentation video<BR/>http://www.climateprediction.net/science/pubs/OpenDay2006/nick_f.wmv<BR/><BR/>http://www.climateprediction.net/science/pubs/OpenDay2006/NF_OpenDay2006.pdf<BR/><BR/>So yes there are flux adjustments and these were derived from the slab runs.crandleshttps://www.blogger.com/profile/15181530527401007161noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-45188642014565281502007-12-30T08:57:00.000+00:002007-12-30T08:57:00.000+00:00I would be surprised if the coupled models do not ...I would be surprised if the coupled models do not have flux corrections, as changing the atmosphere parameters will change the radiation balance so much that the equilibrium climate is awful (the Hadley Centre have certainly taken this approach in their coupled runs). OTOH what I was talking about was some vaguely-remembered stuff probably relating to coupled models both with and without flux corrections, so perhaps does not apply anyway in comparing slab to coupled. As you say, a slab model certainly has flux corrections.James Annanhttps://www.blogger.com/profile/04318741813895533700noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-26409971822415602782007-12-29T14:28:00.000+00:002007-12-29T14:28:00.000+00:00AFAIK Slab model used flux corrections. Coupled mo...AFAIK Slab model used flux corrections. Coupled models ran for long periods in spin up to get close to equilibrium then a control was used to remove remaining drift. I wonder if this means the coupled models don't have flux corrections?<BR/><BR/>Have asked at<BR/>http://www.climateprediction.net/board/viewtopic.php?t=7808<BR/><BR/>Any answers to any of the questions there would be gratefully received. (Well by me anyway, don't know about the CPDN team ;) )crandleshttps://www.blogger.com/profile/15181530527401007161noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-84756559508366999972007-12-29T01:43:00.000+00:002007-12-29T01:43:00.000+00:00Well, one thing to note about that sort of calcula...Well, one thing to note about that sort of calculation is that the seasonal climate does not reach equilibrium (note that July/Aug and Jan/Feb are peak and trough in temperature, even though the radiation forcing peaks are late Dec and June). Several people have looked at using the seasonal cycle to estimate sensitivity, and got rather weak results since the basic mechanisms are rather different - the season cycle is strongly influenced by circulation changes.<BR/><BR/>I also have another comment with ref to Chris' post: I think it is already known that flux corrections in 3D models alter the relationship between seasonal cycle and sensitivity (as they effectively allow the ocean heat uptake to be a new free parameter). I assume the coupled CPDN runs use flux corrections, so it will be interesting to see how Rosalind extends our knowledge about this.James Annanhttps://www.blogger.com/profile/04318741813895533700noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-2477346912842995312007-12-28T14:12:00.000+00:002007-12-28T14:12:00.000+00:00hi, thanks a lot for this post.One more question, ...hi, <BR/><BR/>thanks a lot for this post.<BR/>One more question, then, if you have time, about climate sensitivity:<BR/><BR/>reading a book about climate change (here in france), i found this (by P.Morel and M.Chahine), which is probably well-known (?) but new to me:<BR/><BR/>they use differences in seasonal variations in the energy budget of each hemisphere to derive a rough "atmophere-only" Climate Sensitivity.<BR/><BR/>With data from ERBE, it yields (for nothern hemisph.):<BR/>DF (summer - winter) = 21 Wm-2 <BR/>DT (summer - winter) = 11.7° K<BR/>CS=0.56 K/W.m-2<BR/><BR/>and for the southern hemisph.:<BR/>DF (summer - winter) = 9 Wm-2 <BR/>DT (summer - winter) = 5.1 K<BR/>CS=0.57 K/W.m-2<BR/><BR/>they argue that this should hold, as long as GW remains weak compared to seasonal temperature variations; and that this atmo-only CS is compatible with model-derived (and more complete) CS, of more of less 1K/W.m-2.<BR/><BR/>Do you think this is a useful constraint on CS, specially regarding estimations like the one by Chylek et al.( CS=0.3-0.4) ?ICEhttps://www.blogger.com/profile/13099679682895985843noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-86578333496814372512007-12-28T12:46:00.000+00:002007-12-28T12:46:00.000+00:00Hi Chris,Thanks for that - I don't seem to be on t...Hi Chris,<BR/><BR/>Thanks for that - I don't seem to be on their Christmas Card list for some reason :-)James Annanhttps://www.blogger.com/profile/04318741813895533700noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-38071776975723969812007-12-28T12:31:00.000+00:002007-12-28T12:31:00.000+00:00Off topic of that paper but perhaps just about on ...Off topic of that paper but perhaps just about on the topic of estimating climate sensitivity.<BR/><BR/>Wondered if you were aware of CPDN work in progress.<BR/><BR/>http://www.climateprediction.net/board/viewtopic.php?p=71930#71930<BR/><BR/>eg "Earlier this year ROSALIND WEST completed her fourth year MPhys project in which she used CPDN data to investigate using the seasonal cycle in temperature to constrain climate sensitivity. She found quite different results for the slab and the coupled experiments and is in the process of writing this up for publication in the peer-reviewed literature."crandleshttps://www.blogger.com/profile/15181530527401007161noreply@blogger.com