Estimates of the relative roles of diapycnal, isopycnal and double-diffusive mixing in Antarctic Bottom Water in the North Atlantic

1984 ◽  
Vol 89 (C6) ◽  
pp. 10479 ◽  
Author(s):  
Trevor J. McDougall ◽  
J. A. Whitehead
Keyword(s):  
North Atlantic ◽  
Bottom Water ◽  
Antarctic Bottom Water ◽  
The North ◽  
The North Atlantic ◽  
Diffusive Mixing ◽  
Double Diffusive

scholarly journals Flow of Antarctic Bottom Water from the Vema Channel 

2020 ◽  
Author(s):  
Eugene G Morozov ◽  
Dmitry I. Frey ◽  
Roman Y. Tarakanov
Keyword(s):  
Continental Slope ◽  
Water Flow ◽  
North Atlantic ◽  
Bottom Water ◽  
The Other ◽  
Antarctic Bottom Water ◽  
The North ◽  
The North Atlantic ◽  
Current Flows ◽  
Western Wall

Abstract We analyze measurements of bottom currents and thermohaline properties of water north of the Vema Channel with the goal to find pathway continuations of Antarctic Bottom Water flow from the Vema Channel into the Brazil Basin. The analysis is based on CTD/LADCP casts north of the Vema Channel. The flow in the deep Vema Channel consists of two branches. The deepest current flows along the bottom in the center of the channel and the other branch flows above the western wall of the channel. We found two smaller channels of the northern continuation of the deeper bottom flow. These flows become weak and almost disappear at a latitude of 25°30’S. The upper current flows at a depth of 4100-4200 m along the continental slope. We traced this current up to 24°S over a distance exceeding 250 km. This branch transports bottom water that eventually fills the deep basins of the North Atlantic.

scholarly journals Flow of Antarctic Bottom water from the Vema Channel

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Eugene G. Morozov ◽  
Dmitry I. Frey ◽  
Roman Y. Tarakanov
Keyword(s):  
Continental Slope ◽  
Water Flow ◽  
North Atlantic ◽  
Bottom Water ◽  
The Other ◽  
Antarctic Bottom Water ◽  
The North ◽  
The North Atlantic ◽  
Current Flows ◽  
Western Wall

Abstract We analyze measurements of bottom currents and thermohaline properties of water north of the Vema Channel with the goal to find pathway continuations of Antarctic Bottom Water flow from the Vema Channel into the Brazil Basin. The analysis is based on CTD/LADCP casts north of the Vema Channel. The flow in the deep Vema Channel consists of two branches. The deepest current flows along the bottom in the center of the channel and the other branch flows above the western wall of the channel. We found two smaller channels of the northern continuation of the deeper bottom flow. These flows become weak and almost disappear at a latitude of 25° 30′ S. The upper current flows at a depth of 4100–4200 m along the continental slope. We traced this current up to 24° S over a distance exceeding 250 km. This branch transports bottom water that eventually fills the deep basins of the North Atlantic.

Variability of Antarctic bottom water flow into the North Atlantic

2005 ◽  
Vol 52 (3-4) ◽  
pp. 495-512 ◽  
Author(s):  
Richard Limeburner ◽  
J.A. Whitehead ◽  
Claudia Cenedese
Keyword(s):  
Water Flow ◽  
North Atlantic ◽  
Bottom Water ◽  
Antarctic Bottom Water ◽  
The North ◽  
The North Atlantic

Stability of Antarctic Bottom Water Formation to Freshwater Fluxes and Implications for Global Climate

2008 ◽  
Vol 21 (13) ◽  
pp. 3310-3326 ◽  
Author(s):  
Jessica Trevena ◽  
Willem P. Sijp ◽  
Matthew H. England
Keyword(s):  
Steady State ◽  
North Atlantic ◽  
Deep Water ◽  
Bottom Water ◽  
Ekman Transport ◽  
Antarctic Bottom Water ◽  
The North ◽  
Control Climate ◽  
Freshwater Fluxes ◽  
The North Atlantic

Abstract The stability of Antarctic Bottom Water (AABW) to freshwater (FW) perturbations is investigated in a coupled climate model of intermediate complexity. It is found that AABW is stable to surface freshwater fluxes greater in volume and rate to those that permanently “shut down” North Atlantic Deep Water (NADW). Although AABW weakens during FW forcing, it fully recovers within 50 yr of termination of FW input. This is due in part to a concurrent deep warming during AABW suppression that acts to eventually destabilize the water column. In addition, the prevailing upwelling of Circumpolar Deep Water and northward Ekman transport across the Antarctic Circumpolar Current, regulated by the subpolar westerly winds, limits the accumulation of FW at high latitudes and provides a mechanism for resalinizing the surface after the FW forcing has ceased. Enhanced sea ice production in the cooler AABW suppressed state also aids in the resalinization of the surface after FW forcing is stopped. Convection then restarts with AABW properties only slightly colder and fresher compared to the unperturbed control climate state. Further experiments with larger FW perturbations and very slow application rates (0.2 Sv/1000 yr) (1 Sv ≡ 106 m3 s−1) confirm the lack of multiple steady states of AABW in the model. This contrasts with the North Atlantic, wherein classical hysteresis behavior is obtained with similar forcing. The climate response to reduced AABW production is also investigated. During peak FW forcing, Antarctic surface sea and air temperatures decrease by a maximum of 2.5° and 2.2°C, respectively. This is of a similar magnitude to the corresponding response in the North Atlantic. Although in the final steady state, the AABW experiment returns to the original control climate, whereas the North Atlantic case transitions to a different steady state characterized by substantial regional cooling (up to 6.0°C surface air temperature).

scholarly journals Flow of Antarctic Bottom Water from the Vema Channel

2020 ◽  
Author(s):  
Eugene G Morozov ◽  
Dmitry I. Frey ◽  
Roman Y. Tarakanov
Keyword(s):  
North Atlantic ◽  
Bottom Water ◽  
Bottom Layer ◽  
The Other ◽  
Antarctic Bottom Water ◽  
The North ◽  
The North Atlantic ◽  
Current Flows ◽  
Abyssal Currents ◽  
Western Wall

Abstract We analyze measurements of bottom currents and thermohaline properties of water north of the Vema Channel with the goal to find pathway continuations of Antarctic Bottom Water flow from the Vema Channel into the Brazil Basin. The analysis is based on CTD/LADCP casts north of the Vema Channel. The flow in the deep Vema Channel consists of two branches. The deepest current flows along the bottom in the center of the channel and the other branch flows above the western wall of the channel. We found two smaller channels of the northern continuation of the deeper bottom flow. These flows become weak and almost disappear at a latitude of 25°30’S. The upper current flows at a depth of 4100-4200 m along the continental slope. We traced this current up to 24°S over a distance exceeding 250 km. This branch transports bottom water that eventually fills the deep basins of the North Atlantic. Key words: Vema Channel; abyssal currents; Antarctic Bottom Water; CTD/LADCP profiles; bottom layer

scholarly journals Flow of Antarctic Bottom Water from the Vema Channel

2020 ◽  
Author(s):  
Eugene G Morozov ◽  
Dmitry I. Frey ◽  
Roman Y. Tarakanov
Keyword(s):  
North Atlantic ◽  
Bottom Water ◽  
Antarctic Bottom Water ◽  
Coriolis Forces ◽  
The North ◽  
Deep Current ◽  
The North Atlantic ◽  
Current Flows ◽  
The Antarctic ◽  
Western Wall

Abstract We analyze measurements of bottom currents and thermohaline properties of water north of the Vema Channel with the goal to find pathway continuations of the Antarctic Bottom Water flow from the Vema Channel into the Brazil Basin. The analysis is based on the CTD/LADCP casts north of the Vema Channel. The flow in the deep-water Vema Channel consists of two branches. The deep current flows along the bottom of the channel and the other branch flows above the western wall of the channel. We found two smaller channels of the continuation of the bottom flow. These flows become weak and cease at a latitude of 26°S. The upper current that flows at a depth of 4100-4200 m along the continental slope is balanced by the gravity and Coriolis forces. We traced this current up to 24°S over a distance exceeding 250 km. This branch transports bottom water that eventually fills the deep basins of the North Atlantic.

scholarly journals Changes in Global Ocean Bottom Properties and Volume Transports in CMIP5 Models under Climate Change Scenarios*

2015 ◽  
Vol 28 (8) ◽  
pp. 2917-2944 ◽  
Author(s):  
Céline Heuzé ◽  
Karen J. Heywood ◽  
David P. Stevens ◽  
Jeff K. Ridley
Keyword(s):  
Climate Change ◽  
North Atlantic ◽  
Bottom Water ◽  
Global Ocean ◽  
Cmip5 Models ◽  
Climate Change Scenarios ◽  
Antarctic Bottom Water ◽  
The North ◽  
The Mean ◽  
The North Atlantic

Abstract Changes in bottom temperature, salinity, and density in the global ocean by 2100 for CMIP5 climate models are investigated for the climate change scenarios RCP4.5 and RCP8.5. The mean of 24 models shows a decrease in density in all deep basins, except the North Atlantic, which becomes denser. The individual model responses to climate change forcing are more complex: regarding temperature, the 24 models predict a warming of the bottom layer of the global ocean; in salinity, there is less agreement regarding the sign of the change, especially in the Southern Ocean. The magnitude and equatorward extent of these changes also vary strongly among models. The changes in properties can be linked with changes in the mean transport of key water masses. The Atlantic meridional overturning circulation weakens in most models and is directly linked to changes in bottom density in the North Atlantic. These changes are the result of the intrusion of modified Antarctic Bottom Water, made possible by the decrease in North Atlantic Deep Water formation. In the Indian, Pacific, and South Atlantic Oceans, changes in bottom density are congruent with the weakening in Antarctic Bottom Water transport through these basins. The authors argue that the greater the 1986–2005 meridional transports, the more changes have propagated equatorward by 2100. However, strong decreases in density over 100 yr of climate change cause a weakening of the transports. The speed at which these property changes reach the deep basins is critical for a correct assessment of the heat storage capacity of the oceans as well as for predictions of future sea level rise.

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