date: Wed, 4 Jun 2003 11:16:10 -0400
from: Edward Cook <drdendro@ldeo.columbia.edu>
subject: Re: Review- confidential REALLY URGENT
to: Keith Briffa <k.briffa@uea.ac.uk>

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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
==================================
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