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
Citations
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Towards a risk assessment for shutdown of the Atlantic thermohaline circulation
TL;DR: In this paper, the authors present early results from a coupled GCM ensemble, demonstrating the feasibility of this approach, and discuss prospects for a more objective THC risk assessment in future.
Journal ArticleDOI
Sensitivity of the modeled present-day Greenland Ice Sheet to climatic forcing and spin-up methods and its influence on future sea level projections
Qing Yan,Qing Yan,Zhongshi Zhang,Zhongshi Zhang,Yongqi Gao,Yongqi Gao,Huijun Wang,Ola M. Johannessen,Ola M. Johannessen +8 more
Abstract: [1] The accuracy of the modeled present-day Greenland Ice Sheet (GrIS) is crucial for future projections of GrIS changes. In this study, we present a detailed evaluation of the modeled present-day GrIS sensitivity to different present-day climatology data sets and spin-up methods and further assess the influence of the modeled present-day GrIS on future sea level projections. Our study demonstrates that with present-day climatology data sets derived from the Regional Atmospheric Climate Model (RACMO2), the modeled ice volume, area, and elevation of the GrIS agree substantially better with observations compared to simulations with present-day climatology data sets from temperature parameterizations and ERA-interim reanalysis. With transient spin-up, the simulated rates of ice elevation changes for the 1993–2010 period are closer to observations than those with steady state spin-up. These results indicate that the RACMO2 forcing and transient spin-up may be preferable for use in the ice sheet model. Moreover, our results reveal that the present-day climatology data sets and spin-up methods affect future sea level projections. Using transient spin-up, the ice sheet model estimates a range of 26 mm in projected sea level rise by 2098 under the A1B emissions scenario, due to different present-day climatology data sets. Compared to the results with transient spin-up, the estimated sea level rise by 2098 is reduced by 5–21 mm with steady state spin-up. This discrepancy is attributed mainly to differences in ice thickness and ice velocity between the modeled present-day GrIS with transient and steady state spin-ups and the effect of paleoclimatic changes with transient spin-up.
Journal ArticleDOI
The sensitivity of the Atlantic meridional overturning circulation to enhanced freshwater discharge along the entire, eastern and western coast of Greenland
TL;DR: In this paper, the authors used a fully coupled climate model to examine the sensitivity of AMOC to a similar amount of freshwater forcing, but released separately along the eastern, the western and the entire Greenland coast.
Journal ArticleDOI
Destabilization of the thermohaline circulation by transient changes in the hydrological cycle
TL;DR: In this article, the authors consider the stability of the thermohaline circulation as described by a two-dimensional Boussinesq model with mixed boundary conditions and determine how the stability properties of the system depend on the intensity of the hydrological cycle.
Journal ArticleDOI
Variable influx of West Greenland Current water into the Labrador Current through the last 7200 years: a multiproxy record from Trinity Bay (NE Newfoundland)
Christina Sheldon,Marit-Solveig Seidenkrantz,P. Frandsen,H. V. Jacobsen,N. Van Nieuwenhove,Sandrine Solignac,Sandrine Solignac,Christof Pearce,Christof Pearce,M. G. Palitzsch,Antoon Kuijpers +10 more
TL;DR: In this article, a multiproxy study of marine sediment gravity core AI07-06G from Trinity Bay, Newfoundland, recorded changes in the strength of the Labrador Current (LC) during the Holocene.
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.
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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.
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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