date: Mon, 28 Sep 1998 09:28:17 +0100 from: "Noguer, Maria" subject: FW: A quick, late comment on Agenda item one to: "scenarios," > ---------- > From: Tom Wigley > Sent: Friday, September 25, 1998 10:47 pm > To: Peter Whetton > Cc: Noguer, Maria > Subject: Re: A quick, late comment on Agenda item one > > At 10:48 AM 9/22/98 +1000, you wrote: > >Dear All, > > > >This is a brief follow-up to Mike Hulme's contribution of a few days > >ago, where he suggested that modelling groups may well be happy to use > >all four marker scenarios. I agree that this would be best, particularly > >if it was done using GCMs with a range of sensitivities. In this > >context, the group may be interested to know that CSIRO would be willing > >to undertake AOGCM simulations for all four scenarios (once converted to > >concentrations in an agreed manner) and that this could be undertaken > >within a reasonable timetable. (However, there is still interest here > >in the selection of a single scenario for use in ensemble runs.) I also > >should note that clearing up inconsistencies between scenarios and > >observed emissions over the period 1990-2000 is seen here as of vital > >importance. > > > >Peter Whetton > > > > > >Peter Whetton > >CSIRO Atmospheric Research > >Private Bag No 1, Aspendale, Vic, 3195, Australia > >Ph +61 3 9239 4535 > >Fax +61 3 9239 4444 > >Email peter.whetton@dar.csiro.au > > > > Peter, > > A fine offer, but I don't think you can do these runs. To do the > SO4, you need to have a full S cycle. Otherwise you have to > use 4-D SO4 loadings, or an albedo proxy. For our collaborative > work, using the ACACIA/NCAR scenarios (which are superior > to what is on the IPCC table, because we thought of all the > problems beforehand), we will be handing over the SO4 data > for you to use. To get these data requires running our model, > which has full S chemistry, out to 2100. For the IPCC scenarios, > someone will have to do a similar full-chem run before you could > run your model -- and, if they did such a run, IPCC would already > have what you were offering! > > There was an indication in an email from Prather that Penner might > produce the SO4 loadings. I pointed out to him that she cannot do > this because, to my knowledge, she does not have access to an > appropriate coupled model. She might think it can be done with an > equilibrium model, but this would be wrong. Think of 2050 as an > example. To get the SO4 loadings with an MLO/AGCM requires > getting the correct (or at least consistent) climate for 2050. To do > this, in turn, requires using some artificial CO2 or CO2-equiv that > would give an MLO/AGCM equilibrium climate response that simulated > the response in 2050 of an OAGCM. In fact, to really do this 'right' > one would also have to 'fake up' the SO2 emissions! We have thought > this issue through at great length here, and decided that there simply > was no adequate MLO/AGCM-based 'short cut' to getting the SO4 > loadings -- which is why we go the full-chem route. > > I presume you are going to China. If so, enjoy. I will be at the CMIP > workshop on Oct 14,15 and will be at CSIRO on the 16th. > > Cheers, Tom. >