date: Wed Aug  3 09:08:34 2005
from: Phil Jones <p.jones@uea.ac.uk>
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
     Gteborg University
     Box 460
     S-405 60 Gteborg, 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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