cc: "Malcolm K. Hughes" , Crowley_Hegerl , jto@u.arizona.edu, rbradley@geo.umass.edu, Jan Esper , srutherford@gso.uri.edu, p.jones@uea.ac.uk, k.briffa@uea.ac.uk date: Mon, 10 Sep 2001 14:51:08 -0400 from: Ed Cook subject: Re: Esper/Cook paper to: "Michael E. Mann" Hi Mike et al., Okay, here is an overlay plot of MBH vs. RCS, with RCS scaled to the 1900-1977 period of MBH, and with 95% confidence limits. This has been done for the 40-yr low-pass RCS data to be consistent with the low-pass MBH series you sent me. The 95% confidence limits of the RCS are also scaled appropriately. Since correlations with both instrumental and MBH are O(0.95) after even 20-year smoothing because of the trend, the RCS limits are effectively based on the bootstrap 95% limits of the 14 chronologies. Assuming that the original RCS C.I.s are reasonably accurate (which I think they are), what is apparent (to me anyway) is that the confidence limits of MBH are uniformly narrower after AD 1600. Prior to that, they are comparable to RCS back to ca. AD 1200 where RCS C.I.s get bigger. Of course this is an odd comparison because the confidence limits are not derived the same way. However, I do think that they are somewhat informative nonetheless. What is also apparent is the much great amplitude of variability in the RCS estimates. This is consistent with the understanding that extratropical temperatures are more variable than tropical tempertures, which supports the idea that the MBH record does have more tropical temperature information in it. The other interesting thing about expressing the RCS data this way and overlaying it on MBH is the appearance that MBH is missing the LIA rather than the MWP, at least on multi-centennial timescales. This turns some of Broecker's criticism of the "hockey stick" on its head. I'm not sure where all this leads. Any comments and further suggestions are welcome as long as they come in by tomorrow. I am definately submitting the paper within a day or two. Cheers, Ed Attachment Converted: "c:\eudora\attach\Fig5.plt_eps1.eps" ================================== Dr. Edward R. Cook Doherty Senior Scholar Tree-Ring Laboratory Lamont-Doherty Earth Observatory Palisades, New York 10964 USA Email: drdendro@ldeo.columbia.edu Phone: 845-365-8618 Fax: 845-365-8152 ==================================