From: Kevin Trenberth To: Michael Mann Subject: Re: ENSO blamed over warming - paper in JGR Date: Wed, 29 Jul 2009 10:23:09 -0600 Cc: Grant Foster , p.jones@uea.ac.uk, "J. Salinger" , j.renwick@niwa.co.nz, b.mullan@niwa.co.nz, Gavin Schmidt , James Annan Hi all Wow this is a nice analysis by Grant et al. What we should do is turn this into a learning experience for everyone: there is often misuse of filtering. Obviously the editor and reviewers need to to also be taken to task here. I agree with Mike Mann that a couple of other key points deserve to be made wrt this paper. Making sure that the important relationships and role of ENSO on interannual variability of global temperatures should also be pointed out with some select references (as in recent emails and the refs therein). In terms of the paper, I recommend consolidating the figures to keep them fewer in number if this is a comment: combine Figs 3 with 4 , and 6 with 7. Make sure the plots of spectra have period prominently displayed as well as frequency and maybe even highlight with stipple some bands like >10 years. Glad to sign on: I would need an acknowledgment that NCAR is sponsored by NSF. Regards Kevin Michael Mann wrote: thanks Grant, the paper is starting to shape up well now. Jim and I (well, mostly Jim, w/ some input from me) are iterating on a blurb about past studies on ENSO/temperature relationships and should have something for you soon on that, As James has pointed out, its important to stick to the key points and not get sidetracked with nonsense. I would avoid any commentary on their ignorant ramblings about the Hadley Cell, etc. We want to cut straight to the deep flaws in their analysis which are, in order of importance in my view, 1. indefensible use of a differencing filter, which has the effect of selectively damping low-frequency variability and renders any conclusions about factors underlying long-term trends completely spurious. 2. ignoring the fact that the influence of ENSO on global temperature has been known for decades, and much better quantified in past studies than in the current deeply flawed analysis. 3. the selective use of a flawed temperature data and curious splicing in of inappropriate recent data (UAH TMT) to further suppress trends. A bit of overkill given that they already eliminated the trends anyway. Guess they wanted to play it extra cautious just in case some bit of warming trend tried to sneak in. The other stuff is just a distraction. mike On Jul 29, 2009, at 10:51 AM, Grant Foster wrote: Gentlemen, Attached is a zip file with LaTeX and pdf for a first draft. I've included everybody's name (in alphabetical order after mine), but of course it should only include in submission those who give explicit consent. There are a few other issues. One is that MFC have recently removed the pdf version of their paper from the "New Zealand Climate Coalition" website. They've replaced it with this: [1]http://nzclimatescience.net/index.php?option=com_content&task=view&id=502&Itemid=1 which refers to a graph showing only part of figure 7, and suggests that there's not trend in GTTA so "nothing to worry about." Yet the plotted GTTA is from UAH TMT (*not* TLT) so of course it shows no trend, and the MT channel is contaminated by stratospheric cooling. In figure 7 of the paper itself they compare the 50-year record of SOI and GTTA, but their graph of GTTA is made of RATPAC-A data until 1980 grafted onto UAH TMT data afterward -- hence the lack of an obvious trend. I think this too should be mentioned, especially as the entire RATPAC-A record shows a very pronounced trend. One last thing: there's a lot of stuff in the paper about Hadley cells and heat transport and so forth. I suspect this is really a bunch of gobbledygook -- but I don't know. But I'll bet you guys do. Comments? Sincerely, Grant ______________________________________________________________________________________ Windows Live(TM) HotmailŪ: Celebrate the moment with your favorite sports pics. [2]Check it out. -- Michael E. Mann Professor Director, Earth System Science Center (ESSC) Department of Meteorology Phone: (814) 863-4075 503 Walker Building FAX: (814) 865-3663 The Pennsylvania State University email: [3]mann@psu.edu University Park, PA 16802-5013 website: [4]http://www.meteo.psu.edu/~mann/Mann/index.html "Dire Predictions" book site: [5]http://www.essc.psu.edu/essc_web/news/DirePredictions/index.html -- **************** Kevin E. Trenberth e-mail: [6]trenbert@ucar.edu Climate Analysis Section, [7]www.cgd.ucar.edu/cas/trenbert.html NCAR P. O. Box 3000, (303) 497 1318 Boulder, CO 80307 (303) 497 1333 (fax) Street address: 1850 Table Mesa Drive, Boulder, CO 80305 References 1. http://nzclimatescience.net/index.php?option=com_content&task=view&id=502&Itemid=1 2. http://www.windowslive.com/Online/Hotmail/Campaign/QuickAdd?ocid=TXT_TAGLM_WL_QA_HM_sports_photos_072009&cat=sports 3. mailto:mann@psu.edu 4. http://www.meteo.psu.edu/%7Emann/Mann/index.html 5. http://www.essc.psu.edu/essc_web/news/DirePredictions/index.html 6. mailto:trenbert@ucar.edu 7. http://www.cgd.ucar.edu/cas/trenbert.html