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SEAS Colloquium in Climate Science (SCiCS)

Thursday, October 4, 2012 - 2:45pm - 3:45pm
Columbia University, Morningside Campus, Room 214 S.W. Mudd
Alan Plumb
Department of Earth, Atmospheric and Planetary Sciences at M.I.T.

"The Brewer-Dobson circulation and its relationship with the age of stratospheric air"

The Brewer-Dobson circulation, the overturning of the stratosphere, was first deduced from tracer (water and ozone) observations but has since come to be recognized as describing the residual, or diabatic, circulation driven by mostly large-scale eddy momentum transport. Models consistently predict an acceleration of this circulation under global warming scenarios, yet analysis of "age" from observations has failed to detect the downward trend that one might expect to accompany an accelerating circulation. The most likely resolution of this apparent discrepancy seems to be that the observational record is yet not long enough to separate a trend from the background of strong interannual variability. Nevertheless, it is also important to clarify the relationship between "age," which is affected by both the mean circulation and eddy mixing, and the mean circulation. It turns out that there are some very simple results that allow us to use age to make straightforward deductions about the circulation.

Host: Tiffany Shaw