Diffusion Coupling of Bottom to Deep Water in the Atlantic
Dr. Anders Levermann
Potsdam Institute for Climate Impact Research
Date: Tuesday, May 10, 2005
Time: 3:00 p.m.
Location: Clark 507, Quissett Campus
Abstract
We give a theoretical discussion of the coupling between Atlantic
Antarctic Bottom Water (AABW) and North Atlantic Deep Water (NADW). We
propose that AABW is driven mainly by NADW through diffusive exchange
of buoyancy forcing. Based on minimal assumptions on the geometry of
the circulation we derive robust expressions for the overturning
strength and the vertical extension of the AABW cell as a function of
the strength of NADW in equilibrium. The result is a characteristic
curve, which shows an increase of AABW strength with NADW and
saturation for strong NADW volume fluxes. In contrast, the vertical
extension of the AABW cell decreases and then saturates with increasing
NADW strength. The theoretical results are supported by comparison with
simulations using the coupled climate model CLIMBER-3alpha.
*Co-sponsored by PO and OCCI