Global thermohaline circulation. Part 1: Sensitivity to atmospheric moisture transport

Journal Article · Fri Jan 01 04:00:00 EST 1999 · Journal of Climate

DOI:https://doi.org/10.1175/1520-0442-12.1.71· OSTI ID:323734

Wang, X; Stone, P H; Marotzke, J ^[1]

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1. Massachusetts Inst. of Tech., Cambridge, MA (United States). Center for Global Change Science

A global ocean general circulation model of idealized geometry, combined with an atmospheric model based on observed transports of heat, momentum, and moisture, is used to explore the sensitivity of the global conveyor belt circulation to the surface freshwater fluxes, in particular the effects of meridional atmospheric moisture transports. The numerical results indicate that the equilibrium strength of the North Atlantic Deep Water (NADW) formation increases as the global freshwater transports increase. However, the global deep water formation--that is, the sum of the NADW and the Southern Ocean Deep Water formation rates--is relatively insensitive to changes of the freshwater flux. Perturbations to the meridional moisture transports of each hemisphere identify equatorially asymmetric effects of the freshwater fluxes. The results are consistent with box model results that the equilibrium NADW formation is primarily controlled by the magnitude of the Southern Hemisphere freshwater flux. However, the results show that the Northern Hemisphere freshwater flux has a strong impact on the transient behavior of the North Atlantic overturning. Increasing this flux leads to a collapse of the conveyor belt circulation, but the collapse is delayed if the Southern Hemisphere flux also increases. The perturbation experiments also illustrate that the rapidity of collapse is affected by random fluctuations in the wind stress field.

• Sponsoring Organization: USDOE, Washington, DC (United States); National Inst. for Global Environmental Change, Davis, CA (United States)
• DOE Contract Number: FC03-90ER61010
• OSTI ID: 323734
• Journal Information: Journal of Climate, Journal Name: Journal of Climate Journal Issue: 1 Vol. 12; ISSN JLCLEL; ISSN 0894-8755
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
EARTH ATMOSPHERE
ENVIRONMENTAL TRANSPORT
FRESH WATER
GLOBAL ASPECTS
MATHEMATICAL MODELS
OCEANIC CIRCULATION
WATER VAPOR