The primary purpose of these experiments, as I understand it, is to improve the understanding of the differences in model predictions.
To compare the model against the real world, many other tests are used such as comparing clouds in the seasonal cycle, rainfall, temperature fields, etc, over seasonal cycles and over the past decades. Also, obviously, the kind of simulations that Alan Robock has been doing simulating effects of large volcanoes is critical. A climate intervention experiment would need to be very large to create a strong signal that would be detectable in climate fields against background variability. It is important to walk before you run. The kinds of simulations that you suggest, simulating possible experiments, would no doubt be valuable, but they do not need to be the basis at this time of a model intercomparison project. ___________________________________________________ Ken Caldeira Carnegie Institution Dept of Global Ecology 260 Panama Street, Stanford, CA 94305 USA [email protected] http://dge.stanford.edu/DGE/CIWDGE/labs/caldeiralab +1 650 704 7212; fax: +1 650 462 5968 On Mon, Dec 14, 2009 at 9:21 AM, Andrew Lockley <[email protected]>wrote: > Hi, > > Excuse my ignorance of modelling in general, but surely one of the main > points of the standardised model runs would be to give some data we can test > against in the real world? This would, IMO, be based on very small > injections, slowly scaling up. Maybe these models are just too coarse to > handle that kind of thing, but wouldn't it be a good idea to agree a > 'ladder' of experiments from the tiny to the global-scale? That way, we > could see if the system actually behaves like it does on the models. > > Excuse me if this is half-witted nonsense. > > A > > 2009/12/8 Alan Robock <[email protected]> > >> Dear Ken, >> >> Thanks for your thoughts. But as you know, they will already do a 1% >> per year CO2 increase, starting from a control run. That is pretty >> simple. Our G1 scenario just balances the radiative forcing from that >> by cranking down the solar irradiance. That is pretty simple, too. >> >> Alan >> >> Alan Robock, Professor II >> Director, Meteorology Undergraduate Program >> Associate Director, Center for Environmental Prediction >> Department of Environmental Sciences Phone: +1-732-932-9800 x6222 >> Rutgers University Fax: +1-732-932-8644 >> 14 College Farm Road E-mail: [email protected] >> New Brunswick, NJ 08901-8551 USA >> http://envsci.rutgers.edu/~robock<http://envsci.rutgers.edu/%7Erobock> >> >> >> On Tue, 8 Dec 2009, Ken Caldeira wrote: >> >> > Maybe we are talking about two different things then. >> > >> > Maybe there should be one set of semi-realistic simulations for the >> CMIP5 >> > modelers and another set of standard simple and idealized, but helpful, >> > reference simulations for people to do (as a courtesy to the community) >> if >> > they are planning to spend more time doing climate intervention >> simulations. >> > >> > Frankly, even for the CMIP5 modelers, I think we would learn more from >> very >> > simple and idealized simulations that we would learn from complex >> > "realistic" simulations, although both are valuable. >> > >> > >> > ___________________________________________________ >> > Ken Caldeira >> > >> > Carnegie Institution Dept of Global Ecology >> > 260 Panama Street, Stanford, CA 94305 USA >> > >> > [email protected] >> > http://dge.stanford.edu/DGE/CIWDGE/labs/caldeiralab >> > +1 650 704 7212; fax: +1 650 462 5968 >> > >> > >> > >> > >> > On Tue, Dec 8, 2009 at 1:20 PM, Alan Robock <[email protected] >> >wrote: >> > >> >> Dear Ken, >> >> >> >> Thanks for your comments. I agree that multiple experiments like you >> >> outline would be interesting, but the CMIP5 modelers made it clear that >> they >> >> are very busy with all the other agreed-on runs, and would only have >> time >> >> for a very small number of geoengineering runs. That is why we decided >> to >> >> make it very simple and have a small number of runs. >> >> >> >> The standard suite of parameters will be archived at PCMDI along with >> all >> >> the other CMIP5 runs, and this set has been standard for quite some >> time. >> >> You can look at the AR4 archive for more details. >> >> >> >> A preliminary version was already presented to the WGCM meeting in >> >> September, and if the modelers agree, PCMDI is onboard. >> >> >> >> >> >> Alan >> >> >> >> Alan Robock, Professor II >> >> Director, Meteorology Undergraduate Program >> >> Associate Director, Center for Environmental Prediction >> >> Department of Environmental Sciences Phone: +1-732-932-9800 >> x6222 >> >> Rutgers University Fax: >> +1-732-932-8644 >> >> 14 College Farm Road E-mail: >> [email protected] >> >> New Brunswick, NJ 08901-8551 USA >> http://envsci.rutgers.edu/~robock <http://envsci.rutgers.edu/%7Erobock>< >> http://envsci.rutgers.edu/%7Erobock> >> >> >> >> >> >> On Tue, 8 Dec 2009, Ken Caldeira wrote: >> >> >> >> Folks, >> >>> >> >>> This is a good first start, but ... >> >>> >> >>> I am a big believer in specifying some very simple idealized >> experiments >> >>> in >> >>> that I think these are often the easiest to analyze and the most >> >>> illuminating regarding system behavior. >> >>> >> >>> It is often good to change one thing at a time so that it is easy to >> >>> analyze >> >>> how the system responds to different perturbations. >> >>> >> >>> I think it is also good to recognize that different people are doing >> >>> simulations in different kinds of models that include different kinds >> of >> >>> processes, and these different kinds of models have utility for >> different >> >>> kinds of applications. >> >>> >> >>> So, I think it would describe a suite of experiments: >> >>> >> >>> 1. Step function change in atmospheric CO2 concentration. >> >>> 2. Step function change in solar constant (perhaps decrease). >> >>> 3. Combined step function change in atmospheric CO2 concentration + >> solar >> >>> constant (= 1+2) >> >>> 4. Step function change in specified aerosols distribution and >> >>> concentrations >> >>> 5. Combined step function change in atmospheric CO2 concentration and >> >>> aerosol distribution and concentration (=1 + 4) >> >>> 6. Unit pulse of stratospheric aerosol emissions >> >>> 7. Step function change in stratospheric aerosol emissions (ie, >> continuous >> >>> emissions) >> >>> 8. Combined step function change in atmospheric CO2 concentration and >> >>> aerosol emissions (=1+7) >> >>> >> >>> Following these I would have the experiments described in the document >> >>> that >> >>> Alan sent around. Groups could do as many of these as that are >> relatively >> >>> easy to do. >> >>> >> >>> In analyzing the differences between the more complex runs, these >> simpler >> >>> runs will prove extremely useful. For example, it will show whether >> the >> >>> differences in the model response is due to model response to a >> specified >> >>> aerosol distribution or whether the difference is because the model >> >>> produces >> >>> a different distribution from the same emissions. >> >>> >> >>> This will also allow groups who are unable to do the full suite of >> runs to >> >>> at least do these simplified experiments to allow a common basis for >> >>> comparison of a broader range of models. >> >>> >> >>> Also, a major piece missing from the document is the specification of >> what >> >>> model output is required. >> >>> >> >>> Before going too far with this, I would consult with people from PCMDI >> who >> >>> were involved in analyzing AR4 results, and I would also consult with >> Jim >> >>> Orr who led the ocean carbon-cycle model intercomparison program >> (OCMIP). >> >>> One problem with C4MIP (the coupled carbon climate MIP) is that not >> enough >> >>> data was collected from each group to allow for adequate analysis of >> >>> results. >> >>> >> >>> I believe that it is often the simplest simulations that teach you the >> >>> most. >> >>> >> >>> >> >>> Best, >> >>> >> >>> Ken >> >>> >> >>> >> >>> >> >>> >> >>> >> >>> ___________________________________________________ >> >>> Ken Caldeira >> >>> >> >>> Carnegie Institution Dept of Global Ecology >> >>> 260 Panama Street, Stanford, CA 94305 USA >> >>> >> >>> [email protected] >> >>> http://dge.stanford.edu/DGE/CIWDGE/labs/caldeiralab >> >>> +1 650 704 7212; fax: +1 650 462 5968 >> >>> >> >>> >> >>> >> >>> >> >>> On Tue, Dec 8, 2009 at 1:46 AM, Alan Robock < >> [email protected] >> >>>> wrote: >> >>> >> >>> Dear All, >> >>>> >> >>>> After extensive discussion of our original proposal by email and at a >> >>>> geoengineering workshop in Hamburg a week ago, I attach our final >> >>>> proposal for standardized geoengineering experiments. As Atm. >> Research >> >>>> Letters will have a special geoengineering issue, we have written it >> for >> >>>> possible submission. >> >>>> >> >>>> In any case, I hope this will allow climate modeling groups and >> others >> >>>> to look at it and comment, and we welcome all such comments. >> >>>> >> >>>> Alan >> >>>> >> >>>> Alan Robock, Professor II >> >>>> Director, Meteorology Undergraduate Program >> >>>> Associate Director, Center for Environmental Prediction >> >>>> Department of Environmental Sciences Phone: +1-732-932-9800 >> x6222 >> >>>> Rutgers University Fax: >> +1-732-932-8644 >> >>>> 14 College Farm Road E-mail: >> [email protected] >> >>>> New Brunswick, NJ 08901-8551 USA >> http://envsci.rutgers.edu/~robock <http://envsci.rutgers.edu/%7Erobock>< >> http://envsci.rutgers.edu/%7Erobock> >> >>>> <http://envsci.rutgers.edu/%7Erobock> >> >>>> >> >>>> >> >>>> -- >> >>>> >> >>>> You received this message because you are subscribed to the Google >> Groups >> >>>> "Climate Intervention" group. >> >>>> To post to this group, send email to >> >>>> [email protected]. >> >>>> To unsubscribe from this group, send email to >> >>>> [email protected]<climateintervention%[email protected]> >> <climateintervention%[email protected]<climateintervention%[email protected]> >> > >> >>>> <climateintervention%[email protected]<climateintervention%[email protected]> >> <climateintervention%[email protected]<climateintervention%[email protected]> >> > >> >>>>> >> >>>> >> >>>> . >> >>>> For more options, visit this group at >> >>>> http://groups.google.com/group/climateintervention?hl=en. >> >>>> >> >>>> >> >>>> >> >>>> >> >>> >> > >> >> -- >> >> You received this message because you are subscribed to the Google Groups >> "geoengineering" group. >> To post to this group, send email to [email protected]. >> To unsubscribe from this group, send email to >> [email protected]<geoengineering%[email protected]> >> . >> For more options, visit this group at >> http://groups.google.com/group/geoengineering?hl=en. >> >> >> > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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