No abstract

No abstract

The climates simulated by 15 coupled atmosphere/ocean climate models participating in the ®rst phase of the Coupled Model Intercomparison Project (CMIP1) are intercompared and evaluated. Results for global means, zonal averages, and geographical distributions of basic climate variables are assembled and compared with observations. The current generation of climate models reproduce the major features of the observed distribution of the basic climate parameters, but there is, nevertheless, a considerable scatter among model results and between simulated and observed values. This is particularly true for oceanic variables. Flux adjusted models generally produce simulated climates which are in better accord with observations than do non-¯ux adjusted models; however, some non-¯ux adjusted model results are closer to observations than somē ux adjusted model results. Other model dierences, such as resolution, do not appear to provide a clear distinction among model results in this generation of models. Many of the systematic dierences (those differences common to most models), evident in previous intercomparison studies are exhibited also by the CMIP1 group of models although often with reduced magnitudes. As is characteristic of intercomparison results, dierent climate variables are simulated with different levels of success by dierent models and no one model is``best'' for all variables. There is some evidence that the``mean model'' result, obtained by averaging over the ensemble of models, provides an overall best comparison to observations for climatological mean ®elds. The model de®ciencies identi®ed here do not suggest immediate remedies and the overall success of the models in simulating the behaviour of the complex non-linear climate system apparently depends on the slow improvement in the balance of approximations that characterize a coupled climate model. Of course, the results of this and similar studies provide only an indication, at a particular time, of the current state and the moderate but steady evolution and improvement of coupled climate models.

No abstract

Two dynamical models are used to perform a series of seasonal predictions. One model, referred to as GCM2, was designed as a general circulation model for climate studies, while the second one, SEF, was designed for numerical weather prediction. The seasonal predictions cover the 26-year period 1969-1994