Journal ArticleDOI
On the freshwater forcing and transport of the Atlantic thermohaline circulation
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In this article, it is argued that the freshwater loss to the atmosphere arises mainly in the subtropical South Atlantic and is balanced by northward freshwater transport in the wind-driven sub-tropical gyre, while the thermohaline circulation transports freshwater southward.Abstract:
The 'conveyor belt' circulation of the Atlantic Ocean transports large amounts of heat northward, acting as a heating system for the northern North Atlantic region. It is widely thought that this circulation is driven by atmospheric freshwater export from the Atlantic catchment region, and that it transports freshwater northward to balance the loss to the atmosphere. Using results from a simple conceptual model and a global circulation model, it is argued here that the freshwater loss to the atmosphere arises mainly in the subtropical South Atlantic and is balanced by northward freshwater transport in the wind-driven subtropical gyre, while the thermohaline circulation transports freshwater southward. It is further argued that the direction of freshwater transport is closely linked to the dynamical regime and stability of the 'conveyor belt': if its freshwater transport is indeed southward, then its flow is purely thermally driven and inhibited by the freshwater forcing. In this case the circulation is not far from Stommel's saddle-node bifurcation, and a circulation state without NADW formation would also be stable.read more
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Journal ArticleDOI
Simulation of climate phase lags in response to precession and obliquity forcing and the role of vegetation
Abstract: Long (130,000 years) transient simulations with a coupled model of intermediate complexity (CLIMBER-2) have been performed. The main objective of this study is to examine leads and lags in the response to the climate system to separate obliquity and precession-induced insolation changes. Focus is on the role of internal feedbacks in the coupled atmosphere/ocean/sea-ice/vegetation system. No interactive ice sheets were used. The results show that leads and lags occur in response to the African/Asian monsoon, temperatures at high latitudes and the Atlantic thermohaline circulation. For the monsoon, leads and lags of the monthly precipitation with respect to the precession parameter were found, which are strongly modified by vegetation. In contrast, no lag was observed for the annual precipitation. At high latitudes during late winter/early spring a vegetation-induced lag with respect to the precession parameter was found in surface air temperatures. Again, no annual lag was detected. The lag in the monthly surface air temperatures induces a lag in the annual overturning in the Atlantic Ocean by changing the strength of the deep convection. The lag is several thousand years. The obliquity-related forcing does not give rise to lags in the climate system. We conclude that lags in monthly climatic variables, which are due to vegetation feedbacks, can result in an annual lag when a climatic process (like deep water formation) acts as a filter for certain months.
Journal ArticleDOI
The dynamics of equatorially asymmetric thermohaline circulations
Jochem Marotzke,Barry A. Klinger +1 more
TL;DR: In this article, the three-dimensional dynamics of equatorially asymmetric thermohaline flow were investigated using an ocean general circulation model in a highly idealized configuration with no wind forcing and nearly fixed surface density.
Journal ArticleDOI
Forcing of the deep ocean circulation in simulations of the Last Glacial Maximum
TL;DR: In this article, the influence of different air-sea fluxes on simulated changes in the deep ocean circulation between the last glacial maximum and present day was examined and it was shown that changes in oceanic surface freshwater fluxes are the dominant forcing mechanism for the reduced Atlantic overturning.
Journal ArticleDOI
The relationship between U.S. East Coast Sea Level and the Atlantic Meridional Overturning Circulation: A review
Christopher M. Little,Aixue Hu,Chris W. Hughes,Chris W. Hughes,Gerard McCarthy,Christopher G. Piecuch,Rui M. Ponte,Matthew D. Thomas +7 more
TL;DR: Research is reviewed, finding consistent support in numerical models for an antiphase relationship between AMOC strength and dynamic sea level, however, simulations exhibit substantial along‐coast and intermodel differences in the amplitude of AMOC‐associated dynamic sealevel variability.
Journal ArticleDOI
Early warning signals of Atlantic Meridional Overturning Circulation collapse in a fully coupled climate model
TL;DR: It is shown that early warning signals of AMOC collapse are present in a fully coupled atmosphere-ocean general circulation model, subject to a freshwater hosing experiment, and the statistical significance of signals of increasing lag-1 autocorrelation and variance vary with latitude.
References
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Climatological atlas of the world ocean
TL;DR: A project to objectively analyze historical ocean temperature, salinity, oxygen, and percent oxygen saturation data for the world ocean has recently been completed at the National Oceanic and Atmospheric Administration's (NOAA) Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey.
Book
Climatological Atlas of the World Ocean
TL;DR: A project to objectively analyze historical ocean temperature, salinity, oxygen, and percent oxygen saturation data for the world ocean has recently been completed at the National Oceanic and Atmospheric Administration's (NOAA) Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey.
Journal ArticleDOI
Normal Monthly Wind Stress Over the World Ocean with Error Estimates
Sol Hellerman,Mel Rosenstein +1 more
TL;DR: In this paper, wind and air-minus-sea temperatures are calculated in a form suitable for determining stress by any bulk aerodynamics model in which the drag coefficient can be represented by six or less coefficients of a second-degree polynomial in wind speed and stability.
Journal ArticleDOI
Interocean Exchange of Thermocline Water
TL;DR: In this paper, it is proposed that this return flow is accomplished primarily within the ocean's warm water thermocline layer, where the main thermoclines of the ocean are linked as they participate in a thermohaline-driven global scale circulation cell associated with NADW formation.
Journal ArticleDOI
The Great Ocean Conveyor
TL;DR: The ocean's conveyor appears to be driven by the salt left behind as the result of water-vapor transport through the atmosphere from the Atlantic to the Pacific basin this paper.
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