Saturday, April 28, 2012

3597.txt

cc: D�ith� Stone <stonedatXYZxyz.ox.ac.uk>, "Myles Allen" <allenatXYZxyz.ox.ac.uk>, "Zwiers,Francis [Ontario]" <francis.zwiersatXYZxyzgc.ca>, "Gabi Hegerl" <gabi.hegerlatXYZxyzac.uk>, "David Pierce" <dpierceatXYZxyzd.edu>, "Knutti Reto" <reto.knuttiatXYZxyz.ethz.ch>, "Tim Barnett" <tbarnett-ulatXYZxyzd.edu>, "Hans von Storch" <hvonstorchatXYZxyz.de>, "ClaudiaTebaldi" <tebaldi@ucar.edu>, "Phil Jones" <p.jonesatXYZxyz.ac.uk>, "David Karoly" <dkarolyatXYZxyzmelb.edu.au>, "Toru Nozawa" <nozawa@nies.go.jp>, "Ben Santer" <santer1atXYZxyzl.gov>, "Richard Smith" <rlsatXYZxyzil.unc.edu>, "Nathan Gillett" <n.gillettatXYZxyz.ac.uk>, "Michael Wehner" <mfwehneratXYZxyz.gov>, "Doug Nychka" <nychkaatXYZxyzr.edu>, "Zhang,Xuebin [Ontario]" <xuebin.zhang@ec.gc.ca>, "Bamzai, Anjuli" <anjuli.bamzai@science.doe.gov>, "Chris Miller" <christopher.d.milleratXYZxyza.gov>, "Tom Knutson" <tom.knutson@noaa.gov>
date: Wed, 10 Sep 2008 10:29:19 -0700 (PDT)
from: "Tim Barnett" <tbarnett-ulatXYZxyzd.edu>
subject: RE: priority list for MIP
to: "Stott, Peter" <peter.stottatXYZxyzoffice.gov.uk>


hi peter....just the kind of experiences we had w/ ocean D&A. think this
figures into just how they construct the experiments. Gabi....hope you
can convey these real life experiences to the exp planners. best, tim
> I have a paper on d+a of Atlantic salinity changes in the works where we
> had to remove ocean drifts for which we needed to have parallel segments
> of the control which means several centuries of control if you want a 4
> member forced ensemble and you want to try to separate them out enough
> that they might sample different phases of the AMO.
>
> Peter
>
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Dr. Peter Stott
> Head Climate Monitoring and Attribution
> Met Office Hadley Centre, Fitzroy Road, Exeter. EX1 3PB, UK
> Tel +44(0)1392 886646 Fax +44(0)1392885681
> Email: peter.stottatXYZxyzoffice.gov.uk
> http://www.metoffice.gov.uk
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> -----Original Message-----
> From: D�ith� Stone [mailto:stoned@atm.ox.ac.uk]
> Sent: 09 September 2008 11:29
> To: Myles Allen
> Cc: Zwiers,Francis [Ontario]; Gabi Hegerl; David Pierce; Knutti Reto;
> Stott, Peter; Tim Barnett; Hans von Storch; ClaudiaTebaldi; Phil Jones;
> David Karoly; Toru Nozawa; Ben Santer; Richard Smith; Nathan Gillett;
> Michael Wehner; Doug Nychka; Zhang,Xuebin [Ontario]; Bamzai, Anjuli; Chris
> Miller; Tom Knutson
> Subject: RE: priority list for MIP
>
> I think about 1/3 of the models submitted to CMIP3 had a visible linear
> drift over the length of their pre-industrial control simulation. So for
> CMIP5 I think we still need a control sufficiently long to check this.
> DA
>
> On Mon, 8 Sep 2008, Myles Allen wrote:
>
>> Dear Francis,
>>
>> I've always argued for large ensembles rather than long controls, but
>> a practical problem we have found in the very large ensembles that we
>> generate in climateprediction.net is the difficulty of telling how far
>> apart in time two initial conditions have to be to "count" as
>> independent. We've seen epochs of many decades duration in which the
>> behavior of long control runs, even if they are nominally drift-free,
>> changes quite substantially from epoch to epoch. I'd be inclined to
>> vote for a minimum 200-year control (and ideally a lot longer) just to
>> provide a representative set of initial conditions for any subsequent
>> ensemble.
>>
>> Myles
>> -----Original Message-----
>> From: Zwiers,Francis [Ontario] [mailto:francis.zwiers@ec.gc.ca]
>> Sent: 07 September 2008 15:04
>> To: Gabi Hegerl; David Pierce
>> Cc: Myles Allen; Knutti Reto; Stott, Peter; Tim Barnett; Hans von
>> Storch; ClaudiaTebaldi; Phil Jones; David Karoly; Toru Nozawa; Ben
>> Santer; Daithi Stone; Richard Smith; Nathan Gillett; Michael Wehner;
>> Doug Nychka; Zhang,Xuebin [Ontario]; Bamzai, Anjuli; Chris Miller; Tom
>> Knutson
>> Subject: RE: priority list for MIP
>>
>> Hi all, sorry to chime in late ... if I had to chose between a long
>> control run or multi-run ensembles with a given model, I think I would
>> chose the latter in almost all cases (assuming that modelling groups
>> have gotten drift more or less under control) and then use
>> inter-simulation differences to estimate internal variability.
>>
>> Cheers, Francis
>>
>>
>> Francis Zwiers
>> Director, Climate Research Division, Environment Canada
>> 4905 Dufferin St., Toronto, Ont. M3H 5T4
>> Phone: 416 739 4767, Fax 416 739 5700
>>
>> -----Original Message-----
>> From: Gabi Hegerl [mailto:Gabi.Hegerl@ed.ac.uk]
>> Sent: September 1, 2008 9:55 AM
>> To: Gabi Hegerl; David Pierce
>> Cc: Myles Allen; Knutti Reto; Stott, Peter; Zwiers,Francis [Ontario];
>> Tim Barnett; Hans von Storch; ClaudiaTebaldi; Phil Jones; David
>> Karoly; Toru Nozawa; Ben Santer; Daithi Stone; Richard Smith; Nathan
>> Gillett; Michael Wehner; Doug Nychka; Zhang,Xuebin [Ontario]; Bamzai,
>> Anjuli; Chris Miller; Tom Knutson
>> Subject: priority list for MIP
>>
>> Hi IDAG people, I forwarded the comments to Karl.
>>
>> One thing that Jerry and Karl would find helpful is a priority list
>> from us about runs important for detection and attribution.
>> if I write this (in a hurry so dont take terribly serious) I would get
>> the following priorities:
>> 0. control simulation longer than 150 yrs
>> 1. 1 All forcing 20th century simulation (1860-2015, ideally
>> even earlier start)
>> 2. two more 20th century simulations particularly if control
>> shorter than 500 yrs
>> 3. 1 Natural only forcing 20th century simulation
>> 4. 1 Ghg only simulation
>> 5. 2 more natural only simulations
>> 6. 2 more ghg only simulations
>> from here on its a bit of a tossup
>> 7. 1-3 land use change simulation
>> 8. 1-1 volcano simulation
>>
>> what do you think - how would you splice? I tend to favor the
>> simualtion that is closest to whats actually happening if having an
>> opion of say ALLminus a forcing or a forcing alone.
>>
>> ALso, as soon as Karl has the suggested list of variables to be saved
>> I will circulate for feedback!
>>
>> Gabi
>>
>> Quoting Gabi Hegerl <gabi.hegerl@ed.ac.uk>:
>>
>>
>>
>> --
>> Gabriele Hegerl
>> School of GeoSciences
>> University of Edinburgh
>> http://www.geos.ed.ac.uk/people/person.html?indv=1613
>>
>> --
>> The University of Edinburgh is a charitable body, registered in
>> Scotland, with registration number SC005336.
>>
>>
>>
>
> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> AOPP, Department of Physics, University of Oxford, U.K.
> Tyndall Centre for Climate Change Research, U.K.
> MAIL: Dáithí Stone, AOPP, Department of Physics, University of Oxford,
> Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
> TELEPHONE: 44-1865-272342 FACSIMILE: 44-1865-272923
> E-MAIL: stonedatXYZxyz.ox.ac.uk
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