160:(ADP). This study was conducted to discover the impact WSBW has on the global climate. An 8-year time study of the potential temperature of the Weddell Gyre outflow was analyzed. Interannual variability was discovered in the winters of 1999 and 2002. The anomalies suggest ENSO influence with a 14-20 month lead time with influences from SAM at 14-20 month lead times as well. Warm ENSO events cause the increase of sea ice advection and more coastal polynyas which allows for more dense shelf water availability. These ENSO and SAM changes impact the WSBW 14–20 months later. Their research suggests that there needs to be large ENSO and SAM events in order for the anomalies in WSBW temperature can be noticed. These large fluctuations allow for warm and cold pulses in the WSBW. With a strong ENSO event, sea ice is greatly reduced during the summer which exposes more surface water to the wind allowing it sink. This makes the WSBW colder than normal allowing it to inject colder water into much of the world's oceans. If the ENSO even is weak enough, the surface winds off the Antarctic coast can shift direction which creates a reduction in shelf water. This will warm the WSBW as it does not have as much access to the cold, dense surface water.
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bottom water to entrained bottom water. Bottom water formation models based on hydrographic observations suggested that the bottom water formed at the edge of the continental shelf has an initial temperature of -1.4 to -1.2 °C. This range also represents the coldest bottom water observed at the base of the continental slope in the northwestern corner of the
Weddell Sea. The fraction of newly formed bottom water in the outflowing WSBW ranges from about 12 to 31%, so the flow of newly formed bottom water out of the Weddell Sea is about 2 to 5 Sv. On the other hand, the much larger production rates sometimes proposed are probably estimates of the total transport of bottom water out of the Weddell Sea that include a large fraction of Antarctic Bottom Water entering the Weddell Sea from the southeast.
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are carried by the western boundary current of the
Weddell Sea into the northwest corner of the Weddell Gyre. From there, these water masses flow eastward, either within the northern limb of the Weddell Gyre or reaching northward into the Scotia Sea, eventually cooling the lower 2 km of the world ocean as Antarctic Bottom Water.
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region of sinking, it eventually mixes with the warmer and more saline water above to form AABW. Along the Scotia Ridge-Cape
Norvegia section, potential temperature values at depths greater than 4,500 m (14,800 ft) range from -0.94 to -0.63 °C, while salinity values range from 34.639 to 34.652
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The low-salinity, better ventilated forms of WSDW and WSBW flowing along the outer rim of the
Weddell Gyre have the position and depth range that would lead to overflow of the topographic confines of the Weddell Basin, whereas the more saline forms may be forced to recirculate within the Weddell Gyre
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near the edge of the continental shelf to form a dense layer of bottom water, which in turn sinks along the continental slope and flows cyclonically around the western and northern perimeter of the
Weddell Sea basin. Because large quantities of the high salinity water are observed on the continental
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It is proposed that the more saline, lower-oxygen WSBW is derived from shelf water descending into the deep ocean in the southwest
Weddell Sea. The higher salinity of this WSBW is due to injection of high-salinity shelf water characteristic of the region. Fahrbach et al. propose that low-salinity
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The transport of
Weddell Sea Bottom Water out of the Weddell Sea represents the outflow of newly formed bottom water plus entrained bottom water that enters the Weddell Sea from the southeast. Carmack and Foster estimated the production rate of bottom water from the mixing ratio of newly formed
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It is important to distinguish between AABW and a subclass of this water mass, WSBW. WSBW is characterized by lower potential temperatures and larger near-bottom temperature gradients, suggesting recent formation in the southwestern and western
Weddell Sea. As this bottom water spreads from its
87:, and extending as far east as 20 to 30°E. The precursor to bottom water formation is derived from the broad continental shelf west of 40°W where brine released during sea-ice formation produces a large reservoir of cold (0 to - 1.8 °C), high salinity (S ≥ 34.62
103:, and a more saline, less oxygenated component observed farther into the gyre. The more saline WSBW is derived from the southwestern Weddell Sea, where high salinity shelf water is abundant. The less saline WSBW, like the more ventilated
30:
and closely follows the sea floor as it flows out into the rest of the world's oceans. It is created mainly due to the high surface winds blowing off the
Antarctic continent which helps cool and oxygenate it. It flows at a rate of 2 to
115:. The northern limit of the core of Weddell Sea Bottom Water lies against the southern edge of the Scotia Ridge, suggesting that the circulation and property distributions are strongly influenced by
55:. The potential temperature of WSBW is -0.7 °C. At this temperature, the potential temperature vs. salinity chart shows a sharp change in slope. The outflow of WSBW is influenced greatly by the
59:. The movement of WBSW is listed as 16 Sv which contributes to a total 97 Sv outflow of AABW. 2 to 5 Sv of this production is newly formed bottom water off the Antarctic coast.
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Fahrbach, E.; Rohardt, G.; Scheele, N.; Schroder, M.; Strass, V.; Wisotzki, A. (1995). "Formation and discharge of deep and bottom water in the northwestern
Weddell Sea".
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plays an important role in the movement of the world's oceans. An important part of the Weddell Sea is Weddell Sea Bottom Water (WSBW). WSBW is a major contributor to
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26:(AABW) that is at a temperature of -0.7 °C or colder. It consists of a higher salinity branch and a lower salinity branch. It originates in the
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Weddell Sea Bottom Water exhibits two forms: a low-salinity, better oxygenated component confined to the outer rim of the
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107:(WSDW), is derived from lower-salinity shelf water at a point farther north along the Antarctic Peninsula.
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186:, Deep-Sea Research, 1975, Vol. 22, pp. 711 to 724. Pergamon Press. Printed in Great Britain.
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McKee et al., conducted a study of the variability of bottom water temperature relative to
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McKee, Darren C., Yuan, Xiaojun, Gordon, Arnold L., Huber, Bruce A., and Dong, Zhaoqian,
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51:(AABW). While WSBW is considered part of AABW, the distinction comes in its
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Climate impact on interannual variability of Weddell Sea Bottom Water
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shelf even during summer, bottom water may form throughout the year.
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91:) shelf water. This water mass then mixes with a modified form of
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Subset of Antarctic Bottom Water mass that is at -0.7 °C or colder
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Gordon, Arnold L.; Visbeck, Martin; Huber, Bruce (May 2001).
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272:, Journal of Geophysical Research, Vol. 116, C05020,
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35:and contributes to the overall flow of the AABW.
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203:"Export of Weddell Sea Deep and Bottom Water"
184:On the Flow of Water out of the Weddell Sea
182:Carmack, Eddy C. and Foster, Theodore D.,
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136:bottom water is formed near the
207:Journal of Geophysical Research
71:is characterized by a cyclonic
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1:
306:Geology of the Southern Ocean
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150:El Niño-Southern Oscillation
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75:bounded on the south by the
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7:
10:
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244:Journal of Marine Research
296:Environment of Antarctica
256:10.1357/0022240953213089
20:Weddell Sea Bottom Water
105:Weddell Sea Deep Water
83:, on the north by the
49:Antarctic Bottom Water
24:Antarctic Bottom Water
22:(WSBW) is a subset of
154:Southern Annular Mode
79:, on the west by the
53:potential temperature
278:10.1029/2010JC006484
228:10.1029/2000JC000281
219:2001JGR...106.9005G
81:Antarctic Peninsula
77:Antarctic continent
213:(C5): 9005–9017.
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158:Antarctic Dipole
138:Larsen Ice Shelf
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144:Climate impacts
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93:Warm Deep Water
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250:(4): 515–538.
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301:Water masses
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101:Weddell Gyre
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85:Scotia Ridge
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57:Scotia Ridge
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39:Introduction
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156:(SAM), and
69:Weddell Sea
45:Weddell Sea
28:Weddell Sea
290:Categories
164:References
117:bathymetry
123:Transport
63:Formation
152:(ENSO),
215:Bibcode
31:5
280:, 2011
73:gyre
67:The
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33:Sv
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