date: Wed Aug 3 09:08:34 2005
from: Phil Jones
subject: Re: pairing of model runs...
to: alex@gvc.gu.se
Alex,
OK, my misunderstanding. Treat each as a separate run then. Makes life easier.
Cheers
Phil
At 18:12 01/08/2005, you wrote:
Hi Phil,
I asked Jeff Knight for assistance regarding pairing of model runs. The model runs seem
to be not available in pairs as I understood his answer. See his answer below. So I'll
continue with applying the extremes rountine on each single run (start with one
"anthro+nat" and one "nat")?.
===========================================
...
There is no sense in which the runs are paired. The experimental design
is this:
We perform a 1-year spin-up run for each ensemble member starting 1st
December 1868. We use initial atmospheric conditions from a coupled run
of HadCM3 for circa 1870 conditions. Different initial conditions are
used for each member.
By the end of the spin-up calculations, the initial conditions are
forgotten, as the atmosphere on its own has memory for only a few
months. The atmospheric states at 1st December 1869 are a combination of
the response to the climate forcing factors (SST, GHG etc, and the same
for all ensemble members) and a random component (which varies between
ensemble members), such that each ensemble member starts with a
different plausible state.
We then perform the runs from 1st December 1869 to obtain the final
results that are published on the web site. The ensemble members
represent independent realisations of the 'weather noise' but with a
consistent forced component. As such there is no pairing between
ensembles as the 1/12/1869 conditions are unique for each and every run
performed.
I hope this helps. Please ask if you need any more information.
Jeff
PS. The remaining 3 all forcings and 2 natural runs will soon be added
to the site. We are just awaiting resolution of a technical difficulty
in getting more disk space added to the server.
=================================================
regards
Alex
--
***************************
Alexander Walther
Earth Sciences Centre
Göteborg University
Box 460
S-405 60 Göteborg, Sweden
---------------------------
Fon: (+46)-31-7734849
Fax: (+46)-31-7731986
[1]http://www.gvc.gu.se/rcg
***************************
Prof. Phil Jones
Climatic Research Unit Telephone +44 (0) 1603 592090
School of Environmental Sciences Fax +44 (0) 1603 507784
University of East Anglia
Norwich Email p.jones@uea.ac.uk
NR4 7TJ
UK
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