Meteo 523, Spring 2001
Climate Modeling Project Two 
Validation of Climate General Circulation Models

Assertion: If global climate models (GCM) can be demonstrated to simulate the present climate accurately, we can have increased faith in their ability to simulate other climate regimes through sensitivity studies.

Corollary: If GCM do not accurately simulate the present climate, our faith in their validity when simulating other climate regimes is diminished.

The skill of Climate GCMs is assessed by comparison of simulations of the present climate with observations. This process of validation of the model in the present climate (hopefully) extends further than simple measures such as the global averaged surface temperature to include the model atmosphere's spatial structure (locations of key atmospheric features such as the Asian monsoon and the midlatitude storm track), and its range of temporal variability (diurnal, intra-annual, interannual and possibly interdecadal). For coupled models, similar studies of the ocean, cryosphere and biosphere would ideally be undertaken, although the period of record of observational data for validation (at least for the ocean and cryosphere) is problematic here. These validation studies are intended to impart confidence that the model is capable of simulating the key features of the present climate system.

(CMIP),the Coupled Model Intercomparison Project is the coupled climate modeling extension of the Atmospheric Model Intercomparison Project (AMIP) and was set up to evaluate the skills of coupled climate GCM. Phase I of CMIP began in 1995 and initially encompassed studies of 18 coupled GCM. CMIP is convened under the auspices of the Working Group on Coupled Models (WGCM) of the World Climate Research Programme (WCRP) under CLIVAR. The initial CMIP study period extended from 1 Jan 1979 - 31 December 1988.

Links to other model intercomparison projects, such as the Seasonal Prediction Model Intercomparison Project (SMIP), and the Paleoclimate Model Intercomparison Project (PMIP) can be found here.

Project Assessment

This project consists of (i) leading a classroom discussion and (ii) a paper summarizing key issues raised.
All class members must read and be familiar with all papers to be used in the discussions.

Class Member Discussion Focus References
KenPalaeoclimate
Hewitt, C. D., J. F. B. Mitchell, 1996: GCM Simulations of the Climate of 6kyr BP: Mean Changes and Interdecadal Variability. J. Climate, 9, 3505-3529.
Pielke, R. Sr., 1998: Climate prediction as an initial value problem. Bull. Amer. Meteor. Soc., 79, 2743-2746.
JasonAMIP water vapor validation
Gaffin, D. J., R. D. Rosen, D. A. Salstien and J. S. Boyle, 1997: Evaluation of tropospheric water vapor simulations from the Atmospheric Model Intercomparison Project. J. Climate, 10, 1648-1661.
XuguangAMIP 200 hPa dynamics
Boyle, J. S., 1998: Intercomparison of interannual variability of the global 200 hPa circulation for AMIP simulations. J. Climate, 11, pp.2505-2529.
JamesUCLA coupled GCM - effects of parameterizations
Ma, C.-C., C. J. Mechoso, A. Arakawa, and J. D. Farrara, 1994: Sensitivity of a coupled ocean-atmosphere model to physical parameterizations. J. Climate, 9, 1883-1896.
Model representation of El Niņo/forecasting skill
Krishnamurti, T. N., D. Bachiochi, T. LaRow, B. Jha, M. Tewari, D. R. Chakraborty, R. Correa-Torres, D. Oosterhof, 2000: Coupled atmosphere-ocean modeling of the El Niņo of 1997-98. J. Climate, 13, 2428-2460.
Landsea, C. W., and J. A. Knaff, 2000: How much skill was there in forecasting the very strong 1997-98 El Niņo? Bull. Amer. Meteor. Soc., 81, 2107-2119.

 

 

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Last Updated: 24 April 2001.