Sunday, January 15, 2012

1946.txt

date: Tue, 3 Jul 2007 23:15:26 +0200
from: Jan Esper <esperatXYZxyz.ch>
subject: Re: Mitrie
to: Martin Juckes <m.n.juckesatXYZxyzac.uk>, anders.mobergatXYZxyzgeo.su.se, Eduardo.ZoritaatXYZxyzs.de, hegerlatXYZxyze.edu, k.briffaatXYZxyz.ac.uk, m.allen1atXYZxyzsics.ox.ac.uk, weberatXYZxyzi.nl, t.osbornatXYZxyz.ac.uk

Martin

This is quite a task, as I do not really remember which version of a dataset was used in
which paper.

For ECS2002, I detrended all data via two RCS runs applied to the "linear" and "non-linear"
sub-groups as identified in that paper. All data except for Boreal and Upper Wrigth (both
from Lisa Graumlich) and Mongolia (from Gordon Jacoby) were measured at WSL.

I wouldn't necessarily claim that the regional chronologies from the ECS approach are
highly useful records, i.e. for a regional analysis I would use data that are detrended
region-by-region.

(that used by ECS2002 is based on the same tree-ring data as that used by MSH2005, but with
a different standardisation method.)

Not fully sure what MSH2005 did, but this is very likely correct, i.e. they likely used a
"regional" version from Briffa and/or Grudd.

(The Fennoscandia data used by JBB1998, MBH1999 also come from the Tornetraesk area, but
from a different group of trees.)

Hm..., I don't believe that these studies used different trees. Up to the recent update by
Hakan Grudd, that is currently in review with Climate Dynamics, there was effectively only
one dataset from Tornetrask. Keith or Tim might know this better.

(The Polar Urals series used by ECS2005 is also a reanalysis of the data used to create the
Northern Urals series used by JBB1998, MBH1999.)

I wouldn't necessarily call this a reanalysis. Perhaps better say 'differently detrended'.
Anyway, I doubt that there is a long dataset from the Northern Ural as there is little wood
preserved in that area. This is likely the same data, i.e. both are Polar Ural.

(The Taymir data used by HCA2007 is a smoothed version of that used in ECS2002, MSH2005.)

This I really don't know but it would be better to use a regionally detrended version of
the data...

(The Greenland stack data used by MBH1999 is a composite of data analysed by
\citet{fisher_etal1996}, but the precise nature of the composite is not described by
\citet{fisher_etal1996}.")
Agreed. Just read the paper again, and it is indeed difficult to say which data was
combined.
(I've kept the phrase about "serious flaws" in the conclusion, despite Tim's suggestion,
supported by Nanne, of a weaker wording, because I think it is important to draw attention
to the serious flaws which are there.)

I also think that a less aggressive wording would be more effective.
-- Jan

At 16:41 Uhr +0100 3.7.2007, Martin Juckes wrote:

Hello,
another version of our paper is attached.
I've added the following paragraph to the discussion of Table 1, and I'd be
grateful if Jan and Keith could check that it is accurate:
"Evaluation of past work is further compicated by confusion between closely
related proxy series. In Tab.~1 there are two series referred to as
Tornetraesk: that used by ECS2002 is based on the same tree-ring data as that
used by MSH2005, but with a different standardisation method. The
Fennoscandia data used by JBB1998, MBH1999 also come from the Tornetraesk
area, but from a different group of trees. The Polar Urals series used by
ECS2005 is also a reanalysis of the data used to create the Northern Urals
series used by JBB1998, MBH1999. The Taymir data used by HCA2007 is a
smoothed version of that used in ECS2002, MSH2005.
The Greenland stack data used by MBH1999 is a composite of data analysed by
\citet{fisher_etal1996}, but the precise nature of the composite is not
described by \citet{fisher_etal1996}."
I've also moved a few things around and tried to follow most of the
suggestions from Anders and Nanne. I've kept the phrase about "serious flaws"
in the conclusion, despite Tim's suggestion, supported by Nanne, of a weaker
wording, because I think it is important to draw attention to the serious
flaws which are there. One reviewer has implied that we should not discuss
flawed work at length because in oding so we give it credibility it does not

deserve. I believe that since this stuff is published and influential in some
quarters we should discuss it and draw attention to the fact that it is
seriously flawed.
cheers,
Martin
Attachment converted: Hennes:cp-2006-0049-rv 3.pdf (PDF /�IC�) (001588D6)

--

Jan Esper
Head Dendro Sciences Unit
Swiss Federal Research Institute WSL
Zuercherstrasse 111, 8903 Birmensdorf, Switzerland
Voice: +41-44-739 2510 or +41-44-739 2579
Fax: +41-44-739 2515
http://www.wsl.ch/staff/jan.esper

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