cc: Eric Kreileman date: Mon, 9 Oct 2000 12:52:53 +0200 from: Rik Leemans subject: IMAGE climate model to: m.hulme@uea.ac.uk Mike, In the new IMAGE 2.2 release, we discovered very strange behavior of the climate module. At higher C02 concentrations the climate sensitivity tents to be much less than expected. This is probably a result of our new parameterization of the oceanic carbon uptake, which also directly influences the heat uptake. Unfortunately, no-one in the IMAGE team is familiar with the code, the changes that are made over the last years in order to implement the regional aerosol effect. With the IMAGE advisory board conclusions in mind, we would still like to continue with pursuing ECBilt but his is an long-term activity that does not help us finalizing IMAGE 2.2. We would therefore take you up on your suggestions during the advisory board and start to use a simpler 0-dimensional climate/ocean model. This model should calculate the oceanic carbon and heat uptake, In principle there are two candidates: MAGICC and COSMIC (Maybe CLIMBER but that seems to be to difficult). For us including a regional aerosol effect is important. The latter seems to have a better quantification of the regional aerosol effect, but its aerosol parametrisation is strongly dependent on Schlesingers GCM. Schlesinger does not have an ocean uptake, but that can easily be done with the Maier-Raimer simulations of carbon uptake. Because of the possibility to collaborate more closely with you (and the Tyndall Centre: I will participate in the opening ceremony) and the European funding possibilities, we strongly prefer to start using MAGICC and the SCENGEN approach. I would like to discuss this possibility. We still do not have the full overview over: - what this could mean for the coupling within IMAGE? - what state-of-the-art regional aerosols forcing can be made? - how about the ocean heat and carbon uptake? - Is MAGICC than becomming the de-facto front-end model for climate-scenario generators with Battelle and us using it? - copy-right and other legal issues. I will call you to tomorrow morning to discuss the possibilities with you. We would like to move forward quite rapidly on this subject because the finalization of IMAGE 2.2 depends on it and are eager to get your advise on this matter. regards, rik