Publication Abstract

The Ocean's response to North Atalantic Oscillation Variability

By M. Visbeck, E.P. Chassignet, R.G. Curry, T.L. Delworth, R.R.Dickson and G. Krahmann

The North Atlantic Oscillation (NAO) is the dominant mode of atmospheric variability in the North Atlantic Sector. Basin scale changes in the atmospheric forcing significantly affect properties and circulation of the ocean. Part of the response is local and rapid (surface temperature, mixed-layer depth, upper ocean heat content, surface Ekman transport, sea ice cover). However, the geostrophically balanced large-scale horizontal and overturning circulation can take several years to adjust to changes in the forcing. The delayed response is non-local in the sense that waves and the mean circulation communicate perturbations at the airsea interface to other parts of the Atlantic basin. A delayed and non-local response can potentially give rise to oscillatory behavior if there is significant feedback from the ocean to the atmosphere. We conjecture that, on decadal and longer time scales, changes in the ocean's heat storage and transport should have an increasingly important impact on the climate. Finally, changes in the ocean circulation and distribution of heat and freshwater will also alter ventilation rates and pathways. Thus we expect a change in the net uptake of gases (e.g., _02, C0₂), altered nutrient balance, and changes in the dispersion of marine life. We review what is known about the oceanic response to changes in NAO-induced forcing from combined theoretical, numerical experimentation and observational perspectives.

Reference:

The Ocean's response to North Atalantic Oscillation Variability: 2003: M. Visbeck, E.P. Chassignet, R.G. Curry, T.L. Delworth, R.R.Dickson and G. Krahmann: The North Atantic Oscillation: Climmatic Significance and Environmental Impact Geophysical Monographa34: 113-145