cc: Edward Cook <drdendro@ldeo.columbia.edu>, David Frank <david.frank@wsl.ch>, Jan Esper <esper@wsl.ch>, "Rosanne D'Arrgio" <druidrd@ldeo.columbia.edu>
date: Wed, 21 May 2008 07:40:20 -0400
from: Edward Cook <drdendro@ldeo.columbia.edu>
subject: Re: 
to: Keith Briffa <k.briffa@uea.ac.uk>

   Hi Keith,

   Some brief, initial thoughts and points:

   I am working on implementing a full bootstrap procedure for my principal components
   regression program PCREG. Hopefully, it will be sufficiently completed for some meaningful
   results to be shown at the workshop. Certain aspects of it are a bit complicated to
   implement, so I am hedging my bets a bit here. What I am working towards are much more
   realistic expressions of tree-ring reconstruction uncertainty than that normally presented
   based only on calibration period RSQ and MSE and on the usual suite of verification period
   statistics. Neither honestly tells us ANYTHING about the true uncertainty in the
   reconstructions prior to the calibration/verification periods. So the goal is to have
   uncertainties on the reconstructions back in time based on bootstrapped pseudo-samples
   taken from the actual data being used for reconstruction and weighted by pseudo-sample
   estimates of the betas over the calibration period. While this would only express the
   internal uncertainty of the estimates conditioned on the tree-ring series being used
   (NOTHING about the accuracy of the climate estimates back in time), it would still add to
   our evaluation of reconstruction uncertainty I believe. This procedure would also ignore
   the uncertainties in the tree-ring chronologies themselves, which would be extremely
   difficult, if not impossible, to fully account for in bootstrap model I am working on now.
   Some stats people I have talked to suggest that all (i.e. tree-ring chronology development
   AND climate reconstruction!) could be incorporated together in a hierarchical Bayes
   framework, but I think they are smoking the wrong stuff and talking largely out of
   ignorance of what we actually do in dendroclimatology and tree-ring chronology development.

   How does this sound for a brief, initial contribution?

   Cheers,

   Ed
   ==================================
   Dr. Edward R. Cook
   Doherty Senior Scholar and
   Director, Tree-Ring Laboratory
   Lamont-Doherty Earth Observatory
   Palisades, New York 10964  USA
   Email: [1]drdendro@ldeo.columbia.edu
   Phone: 845-365-8618
   Fax: 845-365-8152
   ==================================
   On May 15, 2008, at 9:47 AM, Keith Briffa wrote:

     A General Call for Input to a Meeting on Palaeoclimate Uncertainties
     PLEASE NOTE - this message has been sent to a representative selection of those working
     in different tree-ring laboratories - please forward to those of your colleagues who
     would be interested - THANK YOU

     Dear Colleagues,

     I have been tasked with drafting the White paper in the general topic of Reducing
     Uncertainties, in my case with a focus on tree-ring data. This is meant as the basis for
     discussion at a wider meeting dealing with various high-resolution proxy data, being
     held in Trieste funded by PAGES/CLIVAR.

      Hence I am asking for specific input from any of those among you who wish to contribute
     specific points or stress, even briefly or as concepts, areas of concern regarding
     present work or future requirements.

     The context is general dendroclimatology and the use of tree-ring-derived climate
     reconstructions specifically for establishing the precedence of instrumental
     observations in a recent multi-millennial context.

     The specific issues I have been asked to address include:

     1)      sources of climate interpretational uncertainty how can this be quantified and
     represented?

     2)      strategies for reducing these uncertainties?

     3)      database / data archiving needs and ideas?

     The white paper is only intended to be several pages long so specific ideas, concerns
     etc. along the lines indicated, would be very welcome. I would then try to condense them
     and draft the text.

     I must complete this task in the next 2 weeks so brief, initial thoughts and points that
     you consider must be included would be most welcome.

     At present Ed Cook ,Rosanne D'Arrigo and Dave Frank are included among the participants
     ( Congratulations to Jan Esper on the recent arrival of a brace of beautiful girls -
     provided they take after their mother that is) and I would particularly hope for input
     from them but I know it is vital to get wider input from others working in this area of
     dendroclimatology or who have real concerns with the issue of climate change detection
     and attribution and the use of tree-ring data for model validation or work aimed at
     quantifying transient climate sensitivity in the real world.

     Any thoughts, specific text or important PowerPoint slides would be most welcome.

     With very best wishes and thanks

     Keith Briffa
     15^th May 2008

     --
     Professor Keith Briffa,
     Climatic Research Unit
     University of East Anglia
     Norwich, NR4 7TJ, U.K.

     Phone: +44-1603-593909
     Fax: +44-1603-507784
     [2]http://www.cru.uea.ac.uk/cru/people/briffa/

