第57回 ESCセミナー
Dynamics of the Atlantic meridional overturning circulation.
Part 1: buoyancy-forced response.
- 日時
- 2011年2月2日 (水) 13:30-15:00
- 場所
- 横浜研究所 シミュレータ研究棟1階 会議室
- 講演者
- 古恵 亮( IPRC, University of Hawaii )
- 使用言語
- 英語もしくは日本語
要旨
[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.
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