cc: Scott Rutherford <srutherford@rwu.edu>
date: Tue, 20 Jan 2004 12:27:56 -0500
from: "Michael E. Mann" <mann@multiproxy.evsc.virginia.edu>
subject: Re: J. Climate paper - in confidence
to: "Malcolm Hughes" <mhughes@ltrr.arizona.edu>, Keith Briffa <k.briffa@uea.ac.uk>, "Malcolm Hughes" <mhughes@ltrr.arizona.edu>, Tim Osborn <t.osborn@uea.ac.uk>

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ok--thanks a bunch for the clarification Malcolm,

mike

At 10:27 AM 1/20/04 -0700, Malcolm Hughes wrote:
>Mike - you are right that we should probably leave the network
>uncahnged for this mss. In fact, however, as Keith indicated, the
>Vaganov data probably retained a fair amount of low frequency
>because of the use of the corridor method (i.e. were not "heavily
>standardized"). CHeers, Malcolm
>On 20 Jan 2004 at 7:58, Michael E. Mann wrote:
>
> > Thanks Keith,
> >
> > I agree w/ this--I think the Vaganov chronologies were pretty heavily
> > standardized, and the other issues you raise are important. In the
> > future, we would (and will) be a bit more circumspect about the use of
> > some of these data.
> >
> > In the present case, however, I think we are forced to use the exact
> > same network.
> >
> > Re, the omission of some results. I think we can probably keep them.
> > Simply by cleaning up the text, removing redundancy, etc. I've
> > shortened and tightened the manuscript considerably, and I think I've
> > improved the logical flow a bit in the process. So my feeling is that
> > we will not have to split this up, but I'll leave this to all of you
> > to decide after you see the revised draft from Scott and me...
> >
> > Thanks,
> >
> > mike
> >
> > At 09:45 AM 1/20/2004 +0000, Keith Briffa wrote:
> >     Malcolm seems to have done a good job sorting out these
> >     constituent sets , and I don't have anything to add other than
> >     agreeing that as a general principal , where possible, original
> >     chronologies should be used in preference to reconstructed
> >     temperature series ( the latter having been already optimized
> >     using simple or multiple regression to fit the target temperature
> >     series ). This applies not only to our western US reconstructions
> >     (which it should be stressed are based on very flexible curve
> >     fitting in the standardisation - and inevitably can show little
> >     variance on time scales longer than a decade or so) but also to
> >     the Tornetrask and Polar Urals reconstructions (each of which was
> >     based on ring width and density data , but standardised to try to
> >     preserve centennial variability - though the density series had by
> >     far the largest regression coefficients). There is though a
> >     question regarding the PCs of the Siberian network (presumably
> >     provided by Eugene?) . The correlation between density and ring
> >     width can get high in central and eastern parts of the network ,
> >     so even though these are different variables , it might not be
> >     strictly true to think of them as truly independent
> >     (statistically) of the density chronologies we use from the
> >     Schweingruber network ( there may also be a standardisation issue
> >     here , as the density chronologies were standardised with
> >     Hugershoff functions for our initial network work (as reported in
> >     the Holocene Special Issue) whereas your PC amplitudes may be
> >     based on "Corridor Standardisation" - which likely preserves less
> >     low frequency? ) . These remarks are simply for clarification and
> >     discussion , and I too will wait on your response draft , though I
> >     would throw in the pot the fact that omitting the time dependent
> >     stuff would simplify the message at his stage. cheers Keith
> >
> >     At 01:42 PM 1/19/04 -0700, Malcolm Hughes wrote:
> >     Mike - there are the following density data in that set:
> >     1) 20 Schweingruber/Frttss series from the ITRDB (those that
> >     met the criteria described in the Mann et al 2000 EI paper)
> >     2) Northern Fennoscandia reconstruction (from Keith)
> >     3) Northern Urals reconstruction (from Keith)
> >     4) 1 density series for China (Hughes data) and one from India
> >     (also Hughes data) - neither included in Keith's data set, I
> >     think. 5) To my great surprise I find that you used the Briffa
> >     gridded temperature reconstruction from W. N. America
> >     (mis-attributed to Fritts and Shao) - of course I should have
> >     picked up on this 6 years ago when reading the proofs of the
> >     Nature sup mat. It was my understanding that we had decided not to
> >     use these reconstructions, as the data on which they were based
> >     were in the ITRDB, and had been subject to that screening process.
> >     So depending on whether you used the long or the shorter versions
> >     of these, there will have been a considerable number of density
> >     series included , some of them twice. It means that there is
> >     considerably more overlap between the two data sets, in North
> >     America, than I have been telling people. I stand corrected.
> >     Cheers, Malcolm . .Malcolm Hughes Professor of Dendrochronology
> >     Laboratory of Tree-Ring Research University of Arizona Tucson, AZ
> >     85721 520-621-6470 fax 520-621-8229
> >
> >     --
> >     Professor Keith Briffa,
> >     Climatic Research Unit
> >     University of East Anglia
> >     Norwich, NR4 7TJ, U.K.
> >
> >     Phone: +44-1603-593909
> >     Fax: +44-1603-507784
> >
> >     http://www.cru.uea.ac.uk/cru/people/briffa/
> >
> > ____________________________________________________________
> > __
> > Professor Michael E. Mann
> >  Department of Environmental Sciences, Clark Hall
> > University of Virginia
> > Charlottesville, VA 22903
> > ______________________________________________________________________
> > _ e-mail: mann@virginia.edu Phone: (434) 924-7770FAX: (434) 982-2137
> > http://www.evsc.virginia.edu/faculty/people/mann.shtml
>
>Malcolm Hughes
>Professor of Dendrochronology
>Laboratory of Tree-Ring Research
>University of Arizona
>Tucson, AZ 85721
>520-621-6470
>fax 520-621-8229

_______________________________________________________________________
                      Professor Michael E. Mann
           Department of Environmental Sciences, Clark Hall
                       University of Virginia
                      Charlottesville, VA 22903
_______________________________________________________________________
e-mail: mann@virginia.edu   Phone: (434) 924-7770   FAX: (434) 982-2137
        http://www.evsc.virginia.edu/faculty/people/mann.shtml

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