cc: Christoph Kull <christoph.kull@pages.unibe.ch>, Keith Briffa <k.briffa@uea.ac.uk>
date: Fri, 23 Jun 2006 11:23:15 -0600
from: Caspar Ammann <ammann@ucar.edu>
subject: Re: climate reconstruction challenge
to: Tim Osborn <t.osborn@uea.ac.uk>
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Hi Tim,
just back from the various trips and meetings, most recently
Breckenridge and the CCSM workshop until yesterday. This coincided with
the release of the NRC report...
Thanks Tim for getting in touch with Simon and Eduardo. And I would
think it would be excellent if you would be on the reconstruction side
of things here. We really need to make sure that all the reconstruction
groups (the ones that show up in the spaghetti-graph) also provide
reconstructions for the Challenge. By the way, Mike Mann is fine with
the participation of the german group in this as he has spoken now
favorably on the project.
I think the separation you point at is absolutely crucial. So, as I
indicated in Wengen, I would suggest that we could organize a small
group of modelers to define the concepts of the experiments, and then
make these happen completely disconnected from standard data-centers. A
Pseudo-Proxy group should then develop concepts of how to generate
pseudo-proxy series and tell the modelers where they need what data. But
what they do is not communicated to the modelers. Based
The underlying concept as well as the technical procedure of how we
approach the pseudo-proxies should be made public, so that everybody
knows what we are dealing with. We could do this under the PAGES-CLIVAR
intersection umbrella to better ensure that the groups are held separate
and to give this a more official touch. Below a quick draft, we should
iterate on this and then contact people for the various groups.
So long and have a good trip to Norway,
Caspar
Here a very quick and simple structural draft we can work from: (all
comments welcome, no hesitations to shoot hard!)
Primary Goals:
- cross-verification of various emulations of same reconstruction
technique using same input data
- comparison of skill at various time scales of different techniques if
fed with identical pseudo-proxy data
- sensitivities of hemispheric estimates to noise, network density
- identify skill of resolving regional climate anomalies
- isolate forced from unforced signal
- identify questionable, non-consistent proxies
- modelers try to identify climate parameters and noise structure over
calibration period from pseudo-proxies
Number of experiments:
- available published runs
- available unpublished, or available reordered runs
- CORE EXPERIMENTS OF CHALLENGE: 1-3 brand new experiments
^one experiment should look technically realistic: trend in
calibration, and relatively reasonable past (very different phasing)
^one experiment should have no trend in calibration at all, but
quite accentuated variations before
^...one could have relatively realistic structure but contains a
large landuse component (we could actually do some science here...)
Pseudo-Proxies and "instrumental-data":
- provide CRU-equivallent instrumental data (incl. some noise) that is
degrading in time
- provide annually resolved network of pseudo proxies ((we could even
provide a small set of ~5 very low resolution records with some
additional uncertainty in time))
- 2 networks: one "high" resolution (100 records), one "low" resolution
(20), though only one network available for any single model experiment
to avoid "knowledge-tuning", or through time separation: first 500-years
only low-red, then second 500-years with both.
- pseudo-proxies vary in representation in climate (temperature, precip,
combination), time (annual, seasonal) and space (grid-point, small region)
Organization of three separate and isolated groups, and first steps:
- Modeler group to decide on concept of target climates, forcing series.
Provide only network information to Proxy-Group (People? Ammann, Zorita,
Tett, Schmidt, Graham, Cobb, Goosse...).
- Pseudo-proxy group to decide on selection of networks, and
representation of individual proxies to mimic somewhat real world
situation, but develop significant noise (blue-white-red) concepts,
non-stationarity, and potential "human disturbance" (People? Brohan,
Schweingruber, Wolff, Thompson, Overpeck/Cole, Huybers, Anderson, ...).
- Reconstruction group getting ready for input file structures: netCDF
for "instrumental", ascii-raw series for pseudo-proxy series. Decide
common metrics and reconstruction targets given theoretical pseudo-proxy
network information. (People: everybody else)
Direct science from this: (important!)
- Forced versus internal variations in climate simulations (Modelers)
- Review and catalog of pseudo-proxy generation: Noise and stationarity
in climate proxy records, problems with potential human/land use
influence (Proxy Group)
- Detection methods and systematic uncertainty estimates (Reconstruction
Group)
Tim Osborn wrote:
> Hi Caspar and Christoph,
>
> I just wanted to let you know that:
>
> (1) I have emailed Simon Tett (for HadCM3) and Eduardo Zorita (for
> ECHO-G Erik-I, not sure about Erik-II) to ask if they would be
> prepared for surface temperature fields to be made available from
> their model runs and placed on a pseudo-proxy website for use in
> pseudo-proxy studies. I'll let you know their response.
>
> (2) In Wengen I suggested that Philip Brohan, a colleague of Simon
> Tett, might be interested in creating pseduo-proxies from the output
> of Caspar's secret model simulation, because of Philip's interest in
> statistical error models (e.g. in the error model he just published of
> the instrumental temperature record, HadCRUT3). I have emailed Philip
> to ask him if he would be interested. Again, I'll let you know his
> response.
>
> With regard to the "climate reconstruction challenge", Keith and I
> were wondering how it is going to be run. Obviously some kind of
> organising group would be useful to ensure it is designed to be as
> scientifically useful an experiment as possible. Yet there needs to
> be a clear distinction between provided experimental design advice
> (and things like convening EGU sessions) and having too much knowledge
> of the setup that would prevent such people from taking part in the
> challenge. Keith and I would be interested in the former, but would
> also like to keep our distance and take part in the challenge. I'm
> not sure that it was clear in Wengen exactly who is to organise this all.
>
> Cheers
>
> Tim
>
> Dr Timothy J Osborn, Academic Fellow
> Climatic Research Unit
> School of Environmental Sciences, University of East Anglia
> Norwich NR4 7TJ, UK
>
> e-mail: t.osborn@uea.ac.uk
> phone: +44 1603 592089
> fax: +44 1603 507784
> web: http://www.cru.uea.ac.uk/~timo/
> sunclock: http://www.cru.uea.ac.uk/~timo/sunclock.htm
>
> **Norwich -- City for Science:
> **Hosting the BA Festival 2-9 September 2006
>
>
--
Caspar M. Ammann
National Center for Atmospheric Research
Climate and Global Dynamics Division - Paleoclimatology
1850 Table Mesa Drive
Boulder, CO 80307-3000
email: ammann@ucar.edu tel: 303-497-1705 fax: 303-497-1348
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