Tropical response to increased CO₂ in a GCM with a simple mixed layer ocean: similarities to an observed Pacific warm event.

A version of the NCAR Community Climate Model (CCM), a global spectral atmospheric general circulation model, is coupled to a simple ocean mixed layer model with fixed depth. This mixed layer model is a simple slab of water that crudely accounts for seasonal heat storage but has no dynamics (eg advection, diffusion or upwelling). It is emphasized that the real climate system may respond differently to an increase in CO₂ due to the importance of tropical ocean dynamics that are not included in the present simple mixed-layer ocean model. The next step in the modeling hierarchy, an ocean GCM coupled to the NCAR CCM, will show the response in the tropics, documented here for SSTs determined only by surface energy balance and crude ocean heat storage, may be affected by the addition of ocean dynamics.-from Authors National Center for Atmos Res, Boulder, CO 80307, USA.