Self sustained thermohaline oscillations and their implications for biogeochemical cycles

An ocean general circulation model (OGCM) configured with a paleo ocean bathymetry such as late Permian shows that different modes of ocean circulation might exist in warm climate: a strong 'thermal mode' induced by cooling at high latitudes and a weak 'haline mode' induced by evaporation at subtropics. The 'haline mode', obtained with enhanced freshwater flux and reduced vertical diffusivity, is inherently unstable, flushed by thermally-driven polar convection every few thousand years. A 3-box model of the thermohaline circulation is developed to study the basic physical mechanism of thermohaline oscillations. By including convective adjustment and a parameterization of the localized nature of convection, the box model shows that haline mode is unstable over a certain freshwater forcing/vertical diffusivity range.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2001

Author dc:creator

• Zhang, Rong, 1971-

Advisor dc:contributor.advisor

• John Marshall.

• Earth, Atmospheric, and Planetary Sciences.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/8232

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/8232