Sensitivity of the Antarctic Circumpolar Current transport to surface buoyancy conditions in the North Atlantic

2017 ◽  
Vol 118 ◽  
pp. 118-129 ◽  
Author(s):  
Shantong Sun ◽  
Jinliang Liu
Keyword(s):  
North Atlantic ◽  
Antarctic Circumpolar Current ◽  
Current Transport ◽  
The North ◽  
The North Atlantic ◽  
Circumpolar Current ◽  
Surface Buoyancy ◽  
The Antarctic

The Role of Oscillating Southern Hemisphere Westerly Winds: Global Ocean Circulation

2020 ◽  
Vol 33 (6) ◽  
pp. 2111-2130
Author(s):  
Woo Geun Cheon ◽  
Jong-Seong Kug
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
North Pacific ◽  
Global Ocean ◽  
The North ◽  
Westerly Winds ◽  
The North Atlantic ◽  
Global Ocean Circulation ◽  
The Antarctic ◽  
The North Pacific

AbstractIn the framework of a sea ice–ocean general circulation model coupled to an energy balance atmospheric model, an intensity oscillation of Southern Hemisphere (SH) westerly winds affects the global ocean circulation via not only the buoyancy-driven teleconnection (BDT) mode but also the Ekman-driven teleconnection (EDT) mode. The BDT mode is activated by the SH air–sea ice–ocean interactions such as polynyas and oceanic convection. The ensuing variation in the Antarctic meridional overturning circulation (MOC) that is indicative of the Antarctic Bottom Water (AABW) formation exerts a significant influence on the abyssal circulation of the globe, particularly the Pacific. This controls the bipolar seesaw balance between deep and bottom waters at the equator. The EDT mode controlled by northward Ekman transport under the oscillating SH westerly winds generates a signal that propagates northward along the upper ocean and passes through the equator. The variation in the western boundary current (WBC) is much stronger in the North Atlantic than in the North Pacific, which appears to be associated with the relatively strong and persistent Mindanao Current (i.e., the southward flowing WBC of the North Pacific tropical gyre). The North Atlantic Deep Water (NADW) formation is controlled by salt advected northward by the North Atlantic WBC.

Climate Response to External Sources of Freshwater: North Atlantic versus the Southern Ocean

2007 ◽  
Vol 20 (3) ◽  
pp. 436-448 ◽  
Author(s):  
Ronald J. Stouffer ◽  
Dan Seidov ◽  
Bernd J. Haupt
Keyword(s):  
Southern Ocean ◽  
Southern Hemisphere ◽  
North Atlantic ◽  
Surface Waters ◽  
Real World ◽  
The Other ◽  
Sea Surface ◽  
The North ◽  
The North Atlantic ◽  
The Antarctic

Abstract The response of an atmosphere–ocean general circulation model (AOGCM) to perturbations of freshwater fluxes across the sea surface in the North Atlantic and Southern Ocean is investigated. The purpose of this study is to investigate aspects of the so-called bipolar seesaw where one hemisphere warms and the other cools and vice versa due to changes in the ocean meridional overturning. The experimental design is idealized where 1 Sv (1 Sv ≡ 106 m3 s−1) of freshwater is added to the ocean surface for 100 model years and then removed. In one case, the freshwater perturbation is located in the Atlantic Ocean from 50° to 70°N. In the second case, it is located south of 60°S in the Southern Ocean. In the case where the North Atlantic surface waters are freshened, the Atlantic thermohaline circulation (THC) and associated northward oceanic heat transport weaken. In the Antarctic surface freshening case, the Atlantic THC is mainly unchanged with a slight weakening toward the end of the integration. This weakening is associated with the spreading of the fresh sea surface anomaly from the Southern Ocean into the rest of the World Ocean. There are two mechanisms that may be responsible for such weakening of the Atlantic THC. First is that the sea surface salinity (SSS) contrast between the North Atlantic and North Pacific is reduced. And, second, when freshwater from the Southern Ocean reaches the high latitudes of the North Atlantic Ocean, it hinders the sinking of the surface waters, leading to the weakening of the THC. The spreading of the fresh SSS anomaly from the Southern Ocean into the surface waters worldwide was not seen in earlier experiments. Given the geography and climatology of the Southern Hemisphere where the climatological surface winds push the surface waters northward away from the Antarctic continent, it seems likely that the spreading of the fresh surface water anomaly could occur in the real world. A remarkable symmetry between the two freshwater perturbation experiments in the surface air temperature (SAT) response can be seen. In both cases, the hemisphere with the freshwater perturbation cools, while the opposite hemisphere warms slightly. In the zonally averaged SAT figures, both the magnitude and the pattern of the anomalies look similar between the two cases. The oceanic response, on the other hand, is very different for the two freshwater cases, as noted above for the spreading of the SSS anomaly and the associated THC response. If the differences between the atmospheric and oceanic responses apply to the real world, then the interpretation of paleodata may need to be revisited. To arrive at a correct interpretation, it matters whether or not the evidence is mainly of atmospheric or oceanic origin. Also, given the sensitivity of the results to the exact details of the freshwater perturbation locations, especially in the Southern Hemisphere, a more realistic scenario must be constructed to explore these questions.

Remarks on the deep-sea genus Pseudolamprops (Cumacea: Lampropidae)

Zootaxa ◽  
2012 ◽  
Vol 3542 (1) ◽  
pp. 69 ◽  
Author(s):  
DANIEL ROCCATAGLIATA ◽  
UTE MÜHLENHARDT-SIEGEL
Keyword(s):  
Adult Female ◽  
North Atlantic ◽  
Deep Sea ◽  
New Records ◽  
New Combination ◽  
The North ◽  
New Material ◽  
The North Atlantic ◽  
The Antarctic ◽  
First Time

Based on two specimens collected in the Antarctic deep-sea (4928 m) the adult female and male of the genusPseudolamprops Gamô, 1989 are described for the first time. A new combination is proposed, Pseudolamprops profundus(Reyss, 1978) comb. nov., and several new records from the North Atlantic and Antarctica are provided. The diagnosis of Pseudolamprops is revised on the account of the new material available.

scholarly journals Southern Ocean overturning across streamlines in an eddying simulation of the Antarctic Circumpolar Current

Ocean Science ◽  
2007 ◽  
Vol 3 (4) ◽  
pp. 491-507 ◽  
Author(s):  
A. M. Treguier ◽  
M. H. England ◽  
S. R. Rintoul ◽  
G. Madec ◽  
J. Le Sommer ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Antarctic Circumpolar Current ◽  
Meridional Circulation ◽  
Dimensional Structure ◽  
Residual Circulation ◽  
Mean Flow ◽  
Buoyancy Forcing ◽  
Circumpolar Current ◽  
Surface Buoyancy ◽  
The Antarctic

Abstract. An eddying global model is used to study the characteristics of the Antarctic Circumpolar Current (ACC) in a streamline-following framework. Previous model-based estimates of the meridional circulation were calculated using zonal averages: this method leads to a counter-intuitive poleward circulation of the less dense waters, and underestimates the eddy effects. We show that on the contrary, the upper ocean circulation across streamlines agrees with the theoretical view: an equatorward mean flow partially cancelled by a poleward eddy mass flux. Two model simulations, in which the buoyancy forcing above the ACC changes from positive to negative, suggest that the relationship between the residual meridional circulation and the surface buoyancy flux is not as straightforward as assumed by the simplest theoretical models: the sign of the residual circulation cannot be inferred from the surface buoyancy forcing only. Among the other processes that likely play a part in setting the meridional circulation, our model results emphasize the complex three-dimensional structure of the ACC (probably not well accounted for in streamline-averaged, two-dimensional models) and the distinct role of temperature and salinity in the definition of the density field. Heat and salt transports by the time-mean flow are important even across time-mean streamlines. Heat and salt are balanced in the ACC, the model drift being small, but the nonlinearity of the equation of state cannot be ignored in the density balance.

scholarly journals Response of the antarctic circumpolar current transport to global warming in a coupled model

2002 ◽  
Vol 29 (24) ◽  
pp. 26-1-26-4 ◽  
Author(s):  
Daohua Bi ◽  
William F. Budd ◽  
Anthony C. Hirst ◽  
Xingren Wu
Keyword(s):  
Global Warming ◽  
Antarctic Circumpolar Current ◽  
Coupled Model ◽  
Current Transport ◽  
Circumpolar Current ◽  
The Antarctic

scholarly journals An Analytical Model of the Response of the Meridional Overturning Circulation to Changes in Wind and Buoyancy Forcing

2012 ◽  
Vol 42 (8) ◽  
pp. 1270-1287 ◽  
Author(s):  
Callum J. Shakespeare ◽  
Andrew McC. Hogg
Keyword(s):  
Surface Layer ◽  
Layer Thickness ◽  
Analytical Model ◽  
Wind Stress ◽  
North Atlantic ◽  
Meridional Overturning Circulation ◽  
The North ◽  
The North Atlantic ◽  
Surface Buoyancy ◽  
Surface Layer Thickness

Abstract An analytical model of the full-depth ocean stratification and meridional overturning circulation for an idealized Atlantic basin with a circumpolar channel is presented. The model explicitly describes the ocean response to both Southern Ocean winds and the global pattern and strength of prescribed surface buoyancy fluxes. The construction of three layers, defined by the two isopycnals of overturning extrema, allows the description of circulation and stratification in both the upper and abyssal ocean. The system is fully solved in the adiabatic limit to yield scales for the surface layer thickness, buoyancies of each layer, and overturning magnitudes. The analytical model also allows scaling of the Antarctic Circumpolar Current (ACC) transport. The veracity of the three-layer framework and derived scales is confirmed by applying the analytical model to an idealized geometry, eddy-permitting ocean general circulation model. Consistent with previous results, the abyssal overturning is found to scale inversely with wind stress, whereas the North Atlantic overturning and surface-layer thickness scale linearly with wind stress. In terms of the prescribed surface buoyancy fluxes, increased negative fluxes (buoyancy removal) in the North Atlantic increase the North Atlantic overturning and surface-layer thickness, whereas increased positive fluxes in the middle and low latitudes lead to a decrease in both parameters. Increased negative surface buoyancy fluxes to the south of Drake Passage increase the abyssal overturning and reduce the abyssal buoyancy. The ACC transport scales to first order with the sum of the Ekman transport and the abyssal overturning and thus increases with both wind stress and southern surface buoyancy flux magnitude.

Sign in / Sign up

Export Citation Format

Share Document