Agulhas leakage dynamics affects decadal variability in Atlantic overturning circulation

Area of Science:

• Oceanography
• Climate Science
• Geophysics

Background:

• Predicting decadal climate evolution hinges on understanding the meridional overturning circulation (MOC).
• Ocean measurement programs in the North Atlantic reveal significant intraseasonal to interannual MOC variability.
• Long-term MOC transport changes are poorly documented due to sparse historical data.

Purpose of the Study:

• To investigate the drivers of decadal MOC variability.
• To explore potential Southern Hemisphere influences on North Atlantic MOC dynamics.
• To provide a more comprehensive understanding of MOC variability for climate prediction.

Main Methods:

• Analysis of a comprehensive ocean model simulation.
• Tracking dynamic signals from the Agulhas leakage region.
• Comparing Northern and Southern Hemisphere contributions to MOC variability.

Main Results:

• Decadal MOC variability in the North Atlantic is influenced by factors beyond deep water formation in the Arctic.
• Dynamic signals from the Agulhas leakage region in the Southern Hemisphere contribute significantly to North Atlantic MOC.
• The Southern Hemisphere's contribution to MOC variability is of a similar magnitude to the Northern Hemisphere's.

Conclusions:

• Observed MOC changes require considering influences from both Northern and Southern Hemispheres.
• The Agulhas leakage region is a critical source of decadal MOC variability signals in the North Atlantic.
• Accurate climate prediction necessitates incorporating Southern Hemisphere ocean dynamics into MOC models.