cc: k.briffa@uea.ac.uk date: Thu, 7 Nov 2002 23:56:46 -0500 from: "drdendro@ldeo.columbia.edu" subject: RE: CCDD to: p.jones@uea.ac.uk Hi Phil, Thanks for the added info. If Mike said that my calibration procedure is "flawed", I will be extremely pissed off. His grad student just submitted a paper to The Holocene, with Mike and I as co-authors, that compares my point-by-point method with his RegEM method (Keith should have received the paper by now). There are "modest" improvements in some areas using RegEM, but overall the two methods produce statistically identical results on a regional basis. Indeed, it is mentioned in the paper that the P-B-P method could be improved by adding a dynamic search radius for each grid point, thus making it even closer to RegEM and maybe even better. Indeed, the P-B-P method produces classical calibration period information and estimates that are very useful in understanding the fitted models. In contrast, RegEM does not produce any such useful information and thus operates much more as a "black box". Re standardization and low-frequency stuff, the vast majority of the tree-ring chronologies have been standardized to preserve variance at least up to 100 years (and generally more). I also agree with you that PDSI ought not to have a great deal of multi-centennial variability because it is dominated by precipitation, which is dominated by high-frequency, nearly white, variance. I am surprised that Tom Karl does not seem to understand that. In all candor now, I think that Mike is becoming a serious enemy in the way that he bends the ears of people like Tom with words like "flawed" when describing my work and probably your and Keith's as well. This is in part a vindictive response to the Esper et al. paper. He also went crazy over my recent NZ paper describing evidence for a MWP there because he sees it as another attack on him. Maybe I am over-reacting to this, but I don't think so. Cheers, Ed Original Message: ----------------- From: Phil Jones p.jones@uea.ac.uk Date: Thu, 07 Nov 2002 16:17:30 +0000 To: drdendro@ldeo.columbia.edu Subject: RE: CCDD Ed, There isn't that much more I can expand on really. Conversation only last 5 minutes. Probably you need to add how standardization done and any impact on low-freq of you calibration with your AR-1 process (pre-whitening). Why Tom and others thought there should be a lot of low-freq is odd? I don't think there will be much in a PDSI series. By the way Mark also presented your in progress work with the enhanced grid and the work NCDC was doing to create the PDSI grid at 2 by 3 for you. May have got the wrong end of what they were doing here, but I got the impression that Mark at NCDC-West and NCDC itself were helping you through your CCDD project. The only person worth discussing this with is Mike Mann, who may be able to expand on what I said. He can at least say why your calibration process is flawed (in his mind). I was saying all your trees were very carefully and consistently standardized and you'd retained as much low-freq as possible. I hope you have ! I could find out from the paper I presume, but I don't have the time ! I now clasp my hands and bow in the buddhist way ! Cheers Phil At 05:53 07/11/02 -0500, you wrote: >Hi Phil, > >This is probably the first message you have received from Bhutan. I am here >now with Paul sorting out mainly political issues for doing a lot of >sampling here next year. > >Thanks for the heads-up on the low-frequency stuff. I return home on Nov 11 >and will deal with it as best I can. Any more inside info from you will >also be appreciated. > >Cheers, > >Ed > >Original Message: >----------------- >From: Phil Jones p.jones@uea.ac.uk >Date: Thu, 07 Nov 2002 10:36:51 +0000 >To: drdendro@ldeo.columbia.edu >Subject: CCDD > > > > Ed, > Just got back from the CCDD panel meeting. An issue arose outside the >main sessions, so > although important it is only scientific ! > Mark Eakin gave a presentation which showed how they have used your >PDSI recons to > show droughts back 500-1000 years for parts of the US. All on a web site, >which has come > about from Mark's group being part of NCDC. > All is well but Tom Karl said he was suspicious of the reconstructions >as we all know > trees lose low-frequency. I was trying to defend you but them Mike Mann >said your > pre-whitening recon method won't get low freq. My view is that you >probably need some > text up on the site to say what the truth is. It may be there, but it >needs to be more > prominent. All Mark said was that they carefully scaled your recons with >the instrumental > PDSI. Mark certainly needs to note when presenting something. > My other view is that PDSI may not have much low freq and it is also >one sided - trees > don't respond to heavy precip, beyond a certain limit. > > I can expand more if you want, but I have a mountain of email to go >through from being > away, but I'm sure you get the points. > > To some extent Keith, you and me have all oversold the tree/low-freq >thing and now > everyone believes it but don't appreciate it applies to all other >high-freq proxies to a > similar extent, but in different guises. > > Cheers > Phil > > > > > >Prof. Phil Jones >Climatic Research Unit Telephone +44 (0) 1603 592090 >School of Environmental Sciences Fax +44 (0) 1603 507784 >University of East Anglia >Norwich Email p.jones@uea.ac.uk >NR4 7TJ >UK >--------------------------------------------------------------------------- - > > >-------------------------------------------------------------------- >mail2web - Check your email from the web at >http://mail2web.com/ . Prof. Phil Jones Climatic Research Unit Telephone +44 (0) 1603 592090 School of Environmental Sciences Fax +44 (0) 1603 507784 University of East Anglia Norwich Email p.jones@uea.ac.uk NR4 7TJ UK ---------------------------------------------------------------------------- -------------------------------------------------------------------- mail2web - Check your email from the web at http://mail2web.com/ .