date: Wed, 4 Jun 2003 11:16:10 -0400 from: Edward Cook subject: Re: Review- confidential REALLY URGENT to: Keith Briffa Hi Keith, Here is my review. I must admit to not being quite as negative about it as Stahle, but I do feel that it is marginal at best and could be justifiably rejected. Read my review. Of course, you will want to cut out the review and send it to the authors as a separate document. _______________________________________________________________________________ Review of "Using a New 672-Year Tree-Ring Drought Reconstruction from West-Central Montana to Evaluate Severe Drought Teleconnections in the Western U.S. and Possible Climatic Forcing by the Pacific Decadal Oscillation" by D.A. Hunzicker and P. Camill This paper is reasonably well written, but has some problems in it that bother me. The first issue relates to the tree-ring chronology that was developed at Lindberg Lake. Anytime less than half of the core samples (61 or 152) are used in developing a chronology, this is cause for concern. The fact that there are "unresolvable sections of missing rings" (p. 10) can mean a lot of things. However, ponderosa pine is known to cross-date well, which includes "locating" locally-absent rings during the cross-dating phase, so it is surprising that the authors have chosen not to work through these problems. Presumably, the trees with missing rings are also those most sensitive to drought, so isn't there a chance that the chronology being analyzed in this paper is less sensitive to drought than it ought to be? I also wonder how much their chronology is truly contributing to the overall stated goal of this paper, i.e. evaluating "Severe Drought Teleconnections in the Western U.S. and Possible Climatic Forcing by the Pacific Decadal Oscillation". The authors extensively use the PDSI reconstructions of Cook et al. (1999) in their analyses. Aside from the increased length of their new tree-ring chronology, what does it contribute that was not possible simply by using the Cook et al. reconstructions to test for teleconnections and forcing. None of the indices of forcing (ENSO, PDO, sunspots) extend back before the beginning of the Cook et al. reconstructions, so there is little to be gained in using one longer series from west-central Montana in this analysis. One could point to Fig. 3, which compares the MT reconstruction vs the SWDI series. But even this comparison is limited in its overall contribution to the paper. I also don't like the use of the FFT for estimating power spectra, even if the confidence limits are determined by bootstrapping. The power spectra calculated by the FFT are still inconsistent estimates. A more contemporary and consistent method of spectral estimation, like the Multi-Taper Method, should be used. For the reasons stated above, I do not consider this paper to be ready for publication as is. I will leave it to the Editor to decide how to proceed with it past this point. _______________________________________________________________________________ -- ================================== Dr. Edward R. Cook Doherty Senior Scholar and Director, 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 ==================================