cc: Thomas Stocker date: Tue, 20 Dec 2005 08:49:32 +0100 from: Fortunat Joos subject: Re: [Wg1-ar4-ch06] Follow-up from Christchurch to: Jonathan Overpeck Hi Peck, We are running the BernCC and we could do simulations with different solar (and volcanic and GHGs) forcing over the past millennium. The BernCC as used in the AR4 includes the 2.5d Stocker Wright climate model and a marine carbon cycle (Marchal et al.) and LPJ for the terrestrial carbon cycle. The Bern CC is used in chapter 2 for the calculation of the carbon cycle impulse response function to determine GWPs. It is used in chapter 10 to do the set of SRES simulations and stabilization pathways scenarios (SP450 to SP1000). It is forseen that we will run the mitigation scenarios for WGIII with BernCC as well (The plan was to have those in WGI report already, but the scenarios are not in press within the WGI time line). The plan is to to run BernCC with different climate sensitivities following the probability density function for clim. sens given in chapter 10. This would yield a band of climate response both for the old and new solar forcing. I think using BernCC would provide a nice, consistent link of chap 6 with chap2, chap10 and WGIII modelling efforts. Finally, it is always good to have more than one model for consistency check. With best regards, Fortunat Jonathan Overpeck wrote: > Hi Stefan and team - great. David Rind is getting the solar forcing > series de jour (latest Lean). I expect Keith back on line soon, and then > he can help us figure out what type of simulation(s) we'd like, and what > other forcings we ought to use. My take is that it would be good to use > the same forcing used in the runs currently in Fig 6.10 (or at least the > "best" of those runs - subjective, I'm sure, and all with the old larger > amplitude Lean solar), but with the new reduced amplitude forcing. > > Fig 6.10 currently has the Bauer et al, 2003 run w/ CLIMBER - is it > CLIMBER2? Could/should we just re-run with the new solar in place of the > old solar (I don't have the paper here - was the solar used scaled to > Lean?). > > I'll cc this to the entire team, as there might be other ideas on how to > do this - I think we would want two simulations over the last 400 years. > One w/ the old Lean solar, one with the new. If we could use one of the > existing plotted runs as the "old Lean" run, then we only need one new > run. The idea is to show what difference TAR solar (old Lean) vs. AR4 > solar (new Lean) means. > > So, lets see what Keith and others say, and then line things up to get > the run done. If we can do it w/ CLIMBER, great. If we need to involve > another EMIC (assuming we're not going to get a AOGCM run done in less > than a month), then we need to line that up. Whatever model we use, it > should be one already in use by the AR4, so we don't have to worry about > the results being published - just the model. Make sense? > > Thanks again for the quick reply. Best, Peck > >> Dear Jonathan, >> >> concerning item 8: we can deliver a millennium simulation with any >> given forcing provided to us within days. (Actually takes just about 1 >> hour to run on the computer with CLIMBER-2.) >> >> Cheers, >> Stefan > > > -- Climate and Environmental Physics, Physics Institute, University of Bern Sidlerstr. 5, CH-3012 Bern Phone: ++41(0)31 631 44 61 Fax: ++41(0)31 631 87 42 Internet: http://www.climate.unibe.ch/~joos/ _______________________________________________ Wg1-ar4-ch06 mailing list Wg1-ar4-ch06@joss.ucar.edu http://www.joss.ucar.edu/mailman/listinfo/wg1-ar4-ch06