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Authors: Jennifer Mecking, Noel Keenlyside, Richard Greatbatch, Nour-Eddine Omrani
The Atlantic Multi-Decadal Oscillation (AMO) is a large scale, low frequency variability of the North Atlantic sea surface temperatures. The multi-decadal oscillatory nature of this variability has been questioned due to the short amount of sea surface temperature data available. Composite analysis between the AMO index and the observed sea level pressure show connections between the AMO and the North Atlantic Oscillation (NAO). A strong connection between the AMO index and a NAO-like index can be shown, with a negative correlation at zero lag, negative correlations with the AMO leading out to about 25 years, and positive correlations when the NAO leads from about 10 to 30 years. Furthermore, using a simple model relating the meridional overturning circulation computed from a NAO forced ocean circulation model to the NAO index shows a damped relation between the NAO index and the overturning circulation with a damping timescale of ~8 years. A hybrid coupled model (complex ocean/simple atmosphere) is being developed to study the details of the physics of the AMO, and in particular it's oscillatory nature. |
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