cc: Dáithí Stone , "Myles Allen" , "Zwiers,Francis [Ontario]" , "Gabi Hegerl" , "David Pierce" , "Knutti Reto" , "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" date: Wed, 10 Sep 2008 10:29:19 -0700 (PDT) from: "Tim Barnett" subject: RE: priority list for MIP to: "Stott, Peter" 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.stott@metoffice.gov.uk > http://www.metoffice.gov.uk > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > -----Original Message----- > From: Dáithí 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 : >> >> >> >> -- >> 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: DáithĂ­ 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: stoned@atm.ox.ac.uk > WEBPAGE: http://www.atm.ox.ac.uk/user/stoned/ > -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- >