PCMDI > WCRP CMIP3 Model Output > Diagnostic Subprojects

PI:	Andrew Jarvis
Institution:	Lancaster University, UK
Additional Investigators:	Sile Li
Abstract:
Various studies have compared the behaviour of AOGCM’s to their simpler Energy Balance Models (EBMs) equivalents (e.g. Wigley and Raper 1993; Sokolov et al 2001). Such studies are useful in that they lead to the characterisation of the aggregated systems behaviour of AOGCMs, hence aiding interpretation of these complex models. This proposal seeks to also do an intercomparison of AOGCM responses using transfer function based systems identification and estimation techniques commonly employed in engineering. In particular, we are interested in evaluating the standard input-output response of AOGCMs forced with 1% annually incremented atmospheric CO2 concentrations. Early investigations using the 4xCO2 HadCM3 forcing experiment response confirm Lowe’s (2003) finding that the dynamics are predominately second order, and we have demonstrated the feedback disaggregation of this response into its EBM unit components. We would like to extend this analysis to a wider range of contemporary AOGCMs and use it as a basis for evaluating differences and similarities of these models within this framework.
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