ESC seminar No. 57

Dynamics of the Atlantic meridional overturning circulation.
Part1: buoyancy-forced response.

Date
Wednesday, February 2, 2011, 13:30-15:00
Place
Conference room , 1F Earth Simulator Research Building, YES
Speaker
Ryo Furue ( IPRC, University of Hawaii )
Language
English or Japanese

Abstract

[This is the same presentation as given by Jay McCreary last fall at the Hongo campus of the Univ. of Tokyo.] The dynamics of the thermally-driven, deep, meridional overturning circulation is studied using a variable-density, two-layer model and a full OGCM in a rectangular basin.
Kelvin-wave adjustments deepen the thermocline along the eastern boundary to the north, its structure depending on a parameter, H_e, the eastern-boundary thermocline depth in the tropics. In (nearly) inviscid versions of the models, the eastern-boundary stratification is carried across the basin by Rossby waves, and subsequently solutions adjust to a steady state without an MOC. With mixing, the Rossby waves are damped before they cross the basin. As a result, there is an across-basin pressure gradient, which drives a geostrophic transport into the northern ocean to form the surface branch of the MOC. These processes determine the MOC strength, M, as a function of H_e. In steady state, the transports of the MOC upwelling and downwelling branches must balance, and this additional constraint determines both M and H_e.

Contact

Wataru Ohfuchi
Earth Simulator Center
TEL: 045-778-5765
e-mail: ohfuchi