Indications for a North Atlantic ocean circulation regime shift at the onset of the Little Ice Age

2015 ◽  
Vol 45 (11-12) ◽  
pp. 3623-3633 ◽  
Author(s):  
C.-F. Schleussner ◽  
D. V. Divine ◽  
J. F. Donges ◽  
A. Miettinen ◽  
R. V. Donner
Keyword(s):  
Atlantic Ocean ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Little Ice Age ◽  
Regime Shift ◽  
North Atlantic Ocean ◽  
Ice Age ◽  
Circulation Regime

scholarly journals Coupled Modes of North Atlantic Ocean‐Atmosphere Variability and the Onset of the Little Ice Age

2019 ◽  
Vol 46 (21) ◽  
pp. 12417-12426 ◽  
Author(s):  
Kevin J. Anchukaitis ◽  
Edward R. Cook ◽  
Benjamin I. Cook ◽  
Jessie Pearl ◽  
Rosanne D'Arrigo ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Little Ice Age ◽  
North Atlantic Ocean ◽  
Ice Age ◽  
Coupled Modes ◽  
Ocean Atmosphere

scholarly journals The Medieval Climate Anomaly and Little Ice Age in Chesapeake Bay and the North Atlantic Ocean

2010 ◽  
Vol 297 (2) ◽  
pp. 299-310 ◽  
Author(s):  
T.M. Cronin ◽  
K. Hayo ◽  
R.C. Thunell ◽  
G.S. Dwyer ◽  
C. Saenger ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Chesapeake Bay ◽  
North Atlantic ◽  
Little Ice Age ◽  
North Atlantic Ocean ◽  
Ice Age ◽  
Medieval Climate Anomaly ◽  
Climate Anomaly ◽  
The North ◽  
The North Atlantic

scholarly journals Response of North Atlantic Ocean Circulation to Atmospheric Weather Regimes

2014 ◽  
Vol 44 (1) ◽  
pp. 179-201 ◽  
Author(s):  
Nicolas Barrier ◽  
Christophe Cassou ◽  
Julie Deshayes ◽  
Anne-Marie Treguier
Keyword(s):  
Atlantic Ocean ◽  
Wind Stress ◽  
Ocean Circulation ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Meridional Overturning Circulation ◽  
Subpolar Gyre ◽  
Wind Stress Curl ◽  
Overturning Circulation ◽  
Weather Regimes

Abstract A new framework is proposed for investigating the atmospheric forcing of North Atlantic Ocean circulation. Instead of using classical modes of variability, such as the North Atlantic Oscillation (NAO) or the east Atlantic pattern, the weather regimes paradigm was used. Using this framework helped avoid problems associated with the assumptions of orthogonality and symmetry that are particular to modal analysis and known to be unsuitable for the NAO. Using ocean-only historical and sensitivity experiments, the impacts of the four winter weather regimes on horizontal and overturning circulations were investigated. The results suggest that the Atlantic Ridge (AR), negative NAO (NAO−), and positive NAO (NAO+) regimes induce a fast (monthly-to-interannual time scales) adjustment of the gyres via topographic Sverdrup dynamics and of the meridional overturning circulation via anomalous Ekman transport. The wind anomalies associated with the Scandinavian blocking regime (SBL) are ineffective in driving a fast wind-driven oceanic adjustment. The response of both gyre and overturning circulations to persistent regime conditions was also estimated. AR causes a strong, wind-driven reduction in the strengths of the subtropical and subpolar gyres, while NAO+ causes a strengthening of the subtropical gyre via wind stress curl anomalies and of the subpolar gyre via heat flux anomalies. NAO− induces a southward shift of the gyres through the southward displacement of the wind stress curl. The SBL is found to impact the subpolar gyre only via anomalous heat fluxes. The overturning circulation is shown to spin up following persistent SBL and NAO+ and to spin down following persistent AR and NAO− conditions. These responses are driven by changes in deep water formation in the Labrador Sea.

scholarly journals North Atlantic Ocean Circulation and Decadal Sea Level Change During the Altimetry Era

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Léon Chafik ◽  
Jan Even Øie Nilsen ◽  
Sönke Dangendorf ◽  
Gilles Reverdin ◽  
Thomas Frederikse
Keyword(s):  
Atlantic Ocean ◽  
Sea Level ◽  
Ocean Circulation ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Sea Level Change ◽  
Level Change

scholarly journals Bidecadal North Atlantic ocean circulation variability controlled by timing of volcanic eruptions

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Didier Swingedouw ◽  
Pablo Ortega ◽  
Juliette Mignot ◽  
Eric Guilyardi ◽  
Valérie Masson-Delmotte ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Ocean Circulation ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Volcanic Eruptions

scholarly journals The Atmosphere’s Response to the Ice Sheets of the Last Glacial Maximum

1990 ◽  
Vol 14 ◽  
pp. 32-38 ◽  
Author(s):  
Kerry H. Cook
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Ice Age ◽  
Laurentide Ice Sheet ◽  
Stationary Waves ◽  
The North ◽  
The Last Glacial

This paper discusses some modeling results that indicate how the atmospheric response to the topography of the continental ice of the Last Glacial Maximum (LGM) may be related to the cold North Atlantic Ocean of that time. Broccoli and Manabe (1987) used a three-dimensional general circulation model (GCM) of the atmosphere coupled with a fixed-depth, static ocean mixed-layer model with ice-age boundary conditions to investigate the individual influences of the CLIMAP ice sheets, snow-free land albedos, and reduced atmospheric CO2 concentrations. They found that the ice sheets are the most influential of the ice-age boundary conditions in modifying the northern hemisphere climate, and that the presence of continental ice sheets alone leads to cooling over the North Atlantic Ocean. One approach for extending these GCM results is to consider the stationary waves generated by the ice sheets. Cook and Held (1988) showed that a linearized, steady-state, primitive equation model can give a reasonable simulation of the GCM’s stationary waves forced by the Laurentide ice sheet. The linear model analysis suggests that the mechanical effect of the changed slope of the surface, and not changes in the diabatic heating (e.g. the high surface albedos) or time-dependent transports that necessarily accompany the ice sheet in the GCM, is largely responsible for the ice sheet’s influence. To obtain the ice-age stationary-wave simulation, the linear model must be linearized about the zonal mean fields from the GCM’s ice-age climate. This is the case because the proximity of the cold polar air to the region of adiabatic heating on the downslope of the Laurentide ice sheet is an important factor in determining the stationary waves. During the ice age, cold air can be transported southward to balance this downslope heating by small perturbations in the meridional wind, consistent with linear theory. Since the meridional temperature gradient is more closely related to the surface albedo (ice extent) than to the ice volume, this suggests a mechanism by which changes in the stationary waves and, therefore, their cooling influence at low levels over the North Atlantic Ocean, can occur on time scales faster than those associated with large changes in continental ice volume.

Changes in the Bathymetry and Volume of Glacial Lake Agassiz Between 11,000 and 9300 14C yr B.P.

2000 ◽  
Vol 54 (2) ◽  
pp. 174-181 ◽  
Author(s):  
David W. Leverington ◽  
Jason D. Mann ◽  
James T. Teller
Keyword(s):  
Atlantic Ocean ◽  
Great Lakes ◽  
Ocean Circulation ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Glacial Lake ◽  
Lake Agassiz ◽  
The North ◽  
Glacial Lake Agassiz ◽  
The North Atlantic

The volume and surface area of glacial Lake Agassiz varied considerably during its 4000-year history. Computer models for seven stages of Lake Agassiz were used to quantify these variations over the lake's early history, between about 11,000 and 9300 14C yr B.P. (ca. 13,000 to 10,300 cal yr B.P.). Just after formation of the Herman strandlines (ca. 11,000 14C yr B.P.), the volume of Lake Agassiz appears to have decreased by >85% as a consequence of the abrupt rerouting of overflow to its eastern outlet from its southward routing into the Mississippi River basin. This drainage released about 9500 km3 of water into the North Atlantic Ocean via the Great Lakes and Gulf of St. Lawrence. Following closure of this eastern routing of overflow, the lake reached its maximum size at about 9400 14C yr B.P. with an area of >260,000 km2 and a volume of >22,700 km3. A second major reduction in volume occurred shortly after that, when its volume decreased >10% following the opening of the Kaiashk outlet to the east into the Great Lakes, and 2500–7000 km3 of water was released into the North Atlantic Ocean. These discharges may have affected ocean circulation and North Atlantic Deep Water production.

Higher Laurentide and Greenland ice sheets strengthen the North Atlantic ocean circulation

2015 ◽  
Vol 45 (1-2) ◽  
pp. 139-150 ◽  
Author(s):  
Xun Gong ◽  
Xiangdong Zhang ◽  
Gerrit Lohmann ◽  
Wei Wei ◽  
Xu Zhang ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Ocean Circulation ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Ice Sheets ◽  
The North ◽  
The North Atlantic
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