cc: Scott Rutherford <srutherford@rwu.edu>, mann@virginia.edu
date: Mon, 19 Jan 2004 14:37:39 -0700
from: "Malcolm Hughes" <mhughes@ltrr.arizona.edu>
subject: Re: J. Climate paper - in confidence
to: "Malcolm Hughes" <mhughes@ltrr.arizona.edu>, Tim Osborn <t.osborn@uea.ac.uk>, Briffa Keith <k.briffa@uea.ac.uk>, "Michael E. Mann" <mann@virginia.edu>

Hi Mike - I'd forgotten the connection with the BJ93 paper. I'm 
working at home today (university closed for MLK day), so it 
will be tomorrow before I can check a couple of things. Both the 
Fritts and Shao gridded reconstructions from ring width (and the 
density based one attributed to them) were gridded 
recosntructions based on many chronologies. When reading the 
supmat today, I assumed that these were what was used. From 
what you say I assume that Ray and Phil must have made some 
regional means out of these rather than using the gridpoints 
directly? 
Anyway, we shouldn't include the two Western North America  
series in question     (Dendro ring widths   air temp          39N  
111W   1602     Fritts & Shao 1992) or (Western North America      
Dendro density       air temp     39N  111W   1600          ") in 
anything we do now or in the future if we are also including the 
original chronologies on which they were based in our screening 
(as we did).
Apart from this (i.e. the trd.dat series is entirely  based on Keith's 
reconstruction using density data) the only Briffa/Schweingruber 
data explicitly used were 20 from the ITRDB (with the 'x' suffix, 
plus the Fennoscandia and Polar(northern) Urals, i.e. 22 series. 
CHeers, Malcolm
.
.. 
On 19 Jan 2004 at 15:59, Michael E. Mann wrote:

> Malcolm,
> 
> series (5) is 'trd.dat', a Bradley & Jones (93) series.BJ93 was of
> course the nucleus of the MBH98 network, which was constructed by
> adding other indicators to that initial dataset. Of course, that does
> imply some redundancy, since many of the BJ93 series were composites
> of other data, etc. I might have gotten the reference from BJ93 for
> trd.dat wrong (Fritts and Shao is for correct for trw.dat, but perhaps
> not trd.dat, right?). I don't have BJ93 w/ me? What reference does it
> give for trd.dat? Scott should fix this in the revised MBH98 data
> list:
> 
> ftp://holocene.evsc.virginia.edu/pub/sdr/temp/nature/MANNETAL98/PROXY/
> mbh98dat asummary.txt
> 
> In any case, this hardly constitutes "considerably more overlap". This
> represents 1 series/indicator out of 415 series/112 indicators used. 
> 
> So, in total, there are 24 density series used out of a total of 415
> proxy indicators, in the MBH98 network. Its fair to say this comprises
> a "very small fraction" of the network, but of course we must be
> careful to point out that the two networks are therefore not entirely
> independent. I will modify the wording in the paper accordingly.
> 
> One final question, was each of the 24 density series in question
> actually used in the Briffa et al MXD network (Tim/Keith?).
> 
> Thanks all for the feedback,
> 
> mike
> 
> At 01:42 PM 1/19/2004 -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 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

