date: Fri, 25 Feb 2005 09:42:41 -0000
from: "Myles Allen" <m.allen1atXYZxyzsics.ox.ac.uk>
subject: RE: Millenial Temperature Reconstruction Intercomparison and
to: "Keith Briffa" <k.briffaatXYZxyz.ac.uk>, "Martin Juckes" <M.N.JuckesatXYZxyzac.uk>, <hegerlatXYZxyze.edu>
I floated the idea of bringing Anders Moberg and Jan Esper in on the
proposal (offering them both travel money), because one of the things I
would want to do would be to get a better grasp of their error analysis,
and it's always a lot easier to do this by talking friendlily to people
than by reverse-engineering their papers. I tried and failed to
understand Mann's error analysis using both approaches about 5 years
ago, so I don't think it is worth trying again, particularly given his
current level of sensitivity. I don't think anyone was particularly
against the idea, but we haven't done anything about it. Would people
like me to?
Can we make a deliverable of this project a piece of public-domain IDL
code (or matlab, if people prefer and someone else volunteers to write
it) that takes temperature and proxy inputs and generates
reconstructions using at least two methods (Moberg and Crowley et al,
for example, plus ideally MBH, Juckes et al, Osborne & Briffa etc etc),
providing a framework for comparison. This kind of exercise was hugely
valuable in teasing out the origins of differences between different
approaches to optimal fingerprinting prior to the TAR. If people
provide me with inputs and exact specification of algorithms, I would be
happy to produce this (if it's in IDL) as my contribution.
Climate Dynamics Group
Atmospheric, Oceanic and Planetary Physics
Department of Physics, University of Oxford
From: Keith Briffa [mailto:firstname.lastname@example.org]
Sent: 25 February 2005 07:59
To: Martin Juckes; hegerlatXYZxyze.edu
Cc: Martin Juckes; Myles Allen; t.osbornatXYZxyz.ac.uk
Subject: Re: Millenial Temperature Reconstruction Intercomparison and
just for interest , Tim and I (and Philip Brohan at the Hadley Centre)
also been playing with "classic regression" and variants to avoid bias .
have also looked at the Esper stuff in detail and am convinced that that
the application of the Regional Curve standardisation he employs
significant bias in his reconstruction , and coupled to the way he uses
cosign lat. weighting , another early bias . These act together to make
early part of his scaled series ( I do not call it a reconstruction ,
because some series included do not have a clear temperature signal )
cold. So while the differences between reconstructions , and the
of each can be varied by using similar scaling in each, there are real
differences in represented signal (and spatial and processing questions)
related to them also.
There will be a significant job to do here just describing the
character and biases in these data . The outline looks good .
At 16:40 24/02/2005, Martin Juckes wrote:
>I think that will fit in well, especially the systematic checking --
>which is precisely what they want to pay for, I think.
>I'll try to send out a slightly extended outline tomorrow.
>On Wed, 23 Feb 2005 hegerlatXYZxyze.edu wrote:
> > Hi all,
> > WIthout having looked at the proposal (my home day today, so can
> > 't look), I have already looked
> > into scaling various reconstructions with a nonbiased technique
> > find that it makes some difference particularly to records that
> > correlate magnificently with the target of reconstruction. So my
> > to sell this as part of the plan, and write it up. But there also
> > real difference, Mann and
> > jones for example even if tls scaled has less variance than Esper et
> > because in that reconstruction, the early 20th century is probably
> > strongest excursion, while in Esper et al earlier variability is
> > So there still is real differences in record.
> > so what I hope to add to the proposal is stuff I have already well
> > started, but
> > needs to be checked more systematically, and
> > written up). Tom and I also have a new reconstruciton taht is
> > for publication (apart from one last iteration with Cos) with tls
> > quite similar to Moberg et al
> > Gabi
> > On Wed, 23 Feb 2005, Martin Juckes wrote:
> > >
> > > Hello,
> > >
> > > I've finally got around to sketching a rough plan of objectives
> > > deliverables. Given the small amount of money and the specific
> > > there is not much room for innovative thinking, but hopefully the
> > > work done within the poroject will be helpful to work which people
> > > are already doing.
> > >
> > > Essentially, I'm proposing to assemble/get hold of a
> > > proxy database and run a representative set of reconstruction
> > > on the same data.
> > >
> > > The proposal has to be submitted before Thursday, March 10, so we
> > > two weeks to come up with it.
> > >
> > > A rough outline is attached.
> > >
> > > Martin
> > >
> > >
> > --------------------------------------------------------------------
> > Gabriele Hegerl
> > Dept. of Earth and Ocean Sciences, Nicholas School of the
> > Duke University, Durham NC 27708
> > phone 919-684-6167, fax 919-684-5833
> > email: hegerlatXYZxyze.edu http://www.eos.duke.edu/Faculty/hegerl.html
Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.