Pan-Atlantic decadal climate oscillation linked to ocean circulation

Atlantic climate displays an oscillatory mode at a period of 10–15 years described as pan-Atlantic decadal oscillation. Prevailing theories on the mode are based on thermodynamic air–sea interactions and the role of ocean circulation remains uncertain. Here we uncover ocean circulation variability associated with the pan-Atlantic decadal oscillation using observational datasets from 1900–2009. Specifically, a sea level-derived index of ocean circulation also exhibits 10–15 year periodicity and leads the surface climate oscillation. The underlying ocean circulation links the extratropical and tropical Atlantic, where the maximum variance in surface-ocean temperature feeds back on the North Atlantic Oscillation (the leading mode of atmospheric variability over the North Atlantic region). Our findings imply that, rather than a passive role postulated by the thermodynamic paradigm, ocean circulation across the Atlantic plays an active role for the pan-Atlantic decadal climate oscillation.

Hyacinth C. Nnamchi, Riccardo Farneti, Noel S. Keenlyside, Fred Kucharski, Mojib Latif, Annika Reintges, Thomas Martin