Climate Variability

The El Niño-Southern Oscillation (ENSO) of the tropical Pacific is the most conspicuous manifestation of the ocean's role in coupled climate variability. But ENSO represents only a fraction of the temporal variability of climate. Fluctuations in the strength of the westerlies in middle and high latitudes such as the North Atlantic Oscillation (NAO), for example, exhibit internannual-to- decadal fluctuations and influence climate from North America to Siberia and from Greenland to the equator. Moreover changes in sub-surface water properties of the Atlantic Ocean show a systematic relation to the NAO. - see Atlantic Climate Variability.

It is not yet know whether the dynamics of Atlantic climate variability are coupled or uncoupled on decadal time-scales, nor is the relative importance of the ocean and atmosphere understood. Does variability arise through internal instabilities in one component only, which are communicated to its passive partner? Or does variability arise through mutual interactions of the coupled systems?

CMI models are being used to explore the role of the oceans in climate variability.