Friday, May 18, 2012

4420.txt

cc: Scott Rutherford <srutherfordatXYZxyz.edu>
date: Tue, 20 Jan 2004 12:27:56 -0500
from: "Michael E. Mann" <mannatXYZxyztiproxy.evsc.virginia.edu>
subject: Re: J. Climate paper - in confidence
to: "Malcolm Hughes" <mhughesatXYZxyzr.arizona.edu>, Keith Briffa <k.briffaatXYZxyz.ac.uk>, "Malcolm Hughes" <mhughesatXYZxyzr.arizona.edu>, Tim Osborn <t.osbornatXYZxyz.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: mannatXYZxyzginia.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: mannatXYZxyzginia.edu Phone: (434) 924-7770 FAX: (434) 982-2137
http://www.evsc.virginia.edu/faculty/people/mann.shtml

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