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1.
Hydrographic data from the World Ocean Circulation Experiment (WOCE) and South Atlantic Ventilation Experiment (SAVE) in the region of transition between the Scotia Sea and the Argentine Basin are examined to determine the composition of the deep water from the Southern Ocean that enters the Atlantic, and to describe the pathways of its constituents. The deep current that flows westward against the Falkland Escarpment is formed of several superposed velocity cores that convey waters of different origins: Lower Circumpolar Deep Water (LCDW), Southeast Pacific Deep Water (SPDW), and Weddell Sea Deep Water (WSDW).Different routes followed by the WSDW upstream of, and through, the Georgia Basin, lead to distinctions between the Lower-WSDW (σ4>46.09) and the Upper-WSDW (46.04<σ4 <46.09). The Lower-WSDW flows along the South Sandwich Trench, then cyclonically in the main trough of the Georgia Basin. Although a fraction escapes northward to the Argentine Basin, a comparison of the WOCE data with those from previous programmes shows that this component had disappeared from the southwestern Argentine Basin in 1993/1994. This corroborates previous results using SAVE and pre-SAVE data. A part of the Upper-WSDW, recognizable from different θ–S characteristics, flows through the Scotia Sea, then in the Georgia Basin along the southern front of the Antarctic Circumpolar Current. Northward leakage at this front is expected to feed the Argentine Basin through the northern Georgia Basin. The SPDW is originally found to the south of the Polar Front (PF) in Drake Passage. The northward veering of this front allows this water to cross the North Scotia Ridge at Shag Rocks Passage. It proceeds northward to the Argentine Basin around the Maurice Ewing Bank. The LCDW at the Falkland Escarpment is itself subdivided in two cores, of which only the denser one eventually underrides the North Atlantic Deep Water (NADW) in the Atlantic Ocean. This fraction is from the poleward side of the PF in Drake Passage. It also crosses the North Scotia Ridge at Shag Rocks Passage, then flows over the Falkland Plateau into the Atlantic. The lighter variety, from the northern side of the PF, is thought to cross the North Scotia Ridge at a passage around 55°W. It enters the Argentine Basin in the density range of the NADW.  相似文献   

2.
南极半岛周边海域水团及水交换的研究   总被引：1，自引：1，他引：0  
利用中国第34次南极考察于2018年1–2月在南极半岛周边海域获得的温盐、海流现场观测数据,分析了调查区域主要水团及水交换特征。结果表明,观测区域内主要存在南极表层水、绕极深层水、暖深层水、南极底层水、布兰斯菲尔德海峡底层水。威德尔海的暖深层水、威德尔海深层水通过南奥克尼海台东侧的奥克尼通道、布鲁斯通道和南奥克尼海台西侧的埃斯佩里兹通道进入斯科舍海,其中奥克尼通道的深层海流最强,流速最大可达0.25 m/s,密度较大的威德尔海深层水可以通过此通道进入斯科舍海;布鲁斯通道海流流速约为0.13 m/s,通过此通道的暖深层水位势温度较高;埃斯佩里兹通道海流流速约为0.10 m/s,通过此通道的暖深层水位势温度最低,威德尔海深层水密度最小。在南奥克尼海台东西两侧均观测到南向和北向的海流,但整体上来看,向北的海流和水交换更强。水体进入斯科舍海后,沿着南斯科舍海岭的北侧向西北方向流动,流速约为0.21 m/s。德雷克海峡中的南极绕极流仅有一部分向东进入斯科舍海南部海域,且受到向西流动的暖深层水、威德尔海深层水的影响,斯科舍海南部海域的绕极深层水明显比德雷克海峡中绕极深层水的高温高盐性质弱;受到南极绕极流的影响,南斯科舍海岭北侧的威德尔海深层水比南侧暖。南斯科舍海岭上的水体可能受到北侧绕极深层水、暖深层水,西侧陆架水,东侧冬季水的影响,因此海岭上水体结构较为复杂。  相似文献   

3.
The northward outflow of cold, dense water from the Weddell Sea into the world ocean basins plays a key role in balancing the global heat budget. We estimate the geostrophic flow patterns in the northwestern Weddell Sea using box inverse methods applied to quasi-synoptic hydrographic data collected during the Brazilian DOVETAIL 2000 and 2001 austral summer cruises. The analysis is focused on the variations of the deep Weddell Sea outflow into the Scotia Sea within boxes that bound the main deep gaps over the South Scotia Ridge. To determine the geostrophic volume transports in each box, mass, salt, and heat are conserved within neutral density layers that are not in contact with the atmosphere. Implementing the inverse model and using property anomaly equations weighted by the flow estimate uncertainty our results are consistent with those reported in the literature. A bottom triangle extrapolation method is introduced, which improves the estimated property fluxes through hydrographic sections. In the austral summer of 2000 the transports of Weddell Sea Deep Water (WSDW) through the Philip Passage, Orkney Passage, and southwestern Bruce Passage are 0.01±0.01, 1.15±0.33, and 1.03±0.23 Sv (1 Sv=106 m3 s−1, >0 is northward), respectively. After extrapolation within bottom triangles these transports increase to 0.12±0.03, 3.48±1.81, and 1.20±2.16 Sv. Analysis of the hydrographic data reveal distinct oceanographic conditions over the Philip Passage region, with evidence of mesoscale meanders, warmer and saltier Warm Deep Water (WDW) and colder WSDW observed in 2001 than in 2000. Despite these differences the WSDW transport does not present a significant variation between 2000 and 2001. The WSDW transports through the Philip Passage in 2001 are 0.012±0.001 and 0.113±0.001 Sv after extrapolation within bottom triangles. The circulation derived from the inversion in the austral summer of 2001 suggests a sharp weakening of the barotropic cyclonic flow in the Powell Basin, which may be due to northerly and northeasterly winds associated with an atmospheric low-pressure center located west of the Antarctic Peninsula. We suggest that similar variations in atmospheric forcing may explain changes in the intensity of the cyclonic flow observed in the northwestern Weddell Sea and Powell Basin.  相似文献   

4.
It is shown on the basis of the data of the Russian Academy of Sciences expeditions in 2003–2010, the historical CTD database, the WOCE climatology, and the satellite altimetry that the area of the Scotia Sea and the Drake Passage is even a greater significant orographic barrier for the eastward Antarctic Circumpolar Current (ACC) than was previously thought. It is the current concept that this barrier is the most important for the ACC; it consists of three obstacles: the Hero Ridge with the Phoenix Rift, the Shackleton Ridge, and the North Scotia Ridge with the relatively shallow eastern part of the Scotia Sea. Despite the fact that all three obstacles are permeable for the layer of the Circumpolar Bottom Water (CBW; 28.16 < γ n < 28.26) being considered the lower part of the circumpolar water, the circulation in this layer throughout the Scotia Sea and the Drake Passage quite substantially differs from the transfer by the surface-intensified ACC jets. Herewith, the upper CBW boundary is the lower limit of the circumpolar coverage of the ACC jets. This result is confirmed by the near zero estimate of the total CBW transport according to the three series of the LADCP measurements on the sections across the Drake Passage. It is shown that the transformation (cooling and freshening) of the CBW layer, which occurs owing to the flow of the ACC over the Shackleton Ridge, is associated with the shape and location of the ridge in the Drake Passage. The high southern part of this ridge is a partially permeable screen for the eastward CBW transport behind which the colder and fresher waters of the Weddell Sea and the Bransfield Strait of the same density range as the CBW penetrate into the ACC zone. The partial permeability of the Shackleton Ridge for the CBW layer leads to the salinization of this layer on the eastern side of the ridge and to the CBW’s freshening on the western side of this ridge, which is observed across the entire Drake Passage.  相似文献   

5.
The Harvard Ocean Prediction System (HOPS) is configured to simulate the circulation of the Scotia Sea and environs. This is part of a study designed to test the hypothesis that Antarctic krill (Euphausia superba) populations at South Georgia in the eastern Scotia Sea are sustained by import of individuals from upstream regions, such as the western Antarctic Peninsula. Comparison of the simulated circulation fields obtained from HOPS with observations showed good agreement. The surface circulation, particularly through the Drake Passage and across the Scotia Sea, matches observations, with its northeastward flow characterized by three high-speed fronts. Also, the Weddell Sea and the Brazil Current, and their associated transports match observations. In addition, mesoscale variability, an important component of the flow in this region, is found in the simulated circulation and the model is overall well suited to model krill transport. Drifter simulations conducted with HOPS showed that krill spawned in areas coinciding with known krill spawning sites along the west Antarctic Peninsula continental shelf can be entrained into the Southern Antarctic Circumpolar Current Front (SACCF). They are transported across the Scotia Sea to South Georgia in 10 months or less. Drifters originating on the continental shelf of the Weddell Sea can reach South Georgia as well; however, transport from this region averages about 20 months. Additional simulations show that such transport is sensitive to changes in wind stress and the location of the SACCF. The results of this study show that krill populations along the Antarctic Peninsula and the Weddell Sea are possible source populations that can provide krill to the South Georgia population. However, successful transport of krill to South Georgia is shown to depend on a multitude of factors, such as the location of the spawning area and timing of spawning, and variations in the location of the SACCF. Therefore, this study provides insight into which environmental factors control the successful transport of krill across the Scotia Sea and with it a better understanding of krill distribution in the region.  相似文献   

6.
Multibeam echosounder data and TOPAS seismic reflection profiles collected during the AntPac 1997, Scan 2004, and Scan 2008 cruises aboard the RV Hespérides reveal a host of surficial geomorphological features as yet poorly investigated in the Scan Basin, south-central Scotia Sea. This area represents one of the deep gateways between the Weddell Sea and the Scotia Sea, since it enables the northward flow of a branch of the Weddell Sea Deep Water (WSDW). Analysis of the data identifies numerous elongated depressions interpreted as furrows in the southernmost sector of the basin. These furrows show two main trends, i.e., either N?CNNW parallel to, or NE oblique to regional bathymetric contours. These trends plausibly reflect a tectonic influence on the bottom-flow distribution, conditioned by a set of recent, conjugate strike-slip faults that developed on the seafloor under dominant NNE?CSSW compression and orthogonal extension. The furrows exhibit distinct geomorphological patterns at either side of the basin, which can be related to west?Ceast asymmetry in the WSDW flow direction. Consistent with existing knowledge of regional WSDW dynamics, northward WSDW overflows would be channeled along the western part of the basin at higher bottom-current velocities, thereby generating more erosional-type furrows that are straighter, more elongated, and have more abrupt sidewalls than their eastern counterparts. In contrast, weaker southward WSDW would flow along the eastern part of the basin, resulting in more depositional-type furrows that are more curved, less elongated, and have gentler sidewalls.  相似文献   

7.
The southwestern part of the Scotia Sea, at the corner of the Shackleton Fracture Zone with the South Scotia Ridge has been investigated, combining marine magnetic profiles, multichannel seismic reflection data, and satellite-derived gravity anomaly data. From the integrated analysis of data, we identified the presence of the oldest part of the crust in this sector, which tentative age is older than anomaly C10 (28.7 Ma). The area is surrounded by structural features clearly imaged by seismic data, which correspond to gravity lows in the satellite-derived map, and presents a rhomboid-shaped geometry. Along its southern boundary, structural features related to convergence and possible incipient subduction beneath the continental South Scotia Ridge have been evidenced from the seismic profile. We interpret this area, now located at the edge of the south-western Scotia Sea, as a relict of ocean-like crust formed during an earlier, possibly diffuse and disorganized episode of spreading at the first onset of the Drake Passage opening. The successive episode of organized seafloor spreading responsible for the opening of the Drake Passage that definitively separated southern South America from the Antarctic Peninsula, instigated ridge-push forces that can account for the subduction-related structures found along the western part of the South Scotia Ridge. This seafloor accretion phase occurred from 27 to about 10 Ma, when spreading stopped in the western Scotia Sea Ridge, as resulted from the identification of the marine magnetic anomalies.  相似文献   

8.
The structural framework of the southern part of the Shackleton Fracture Zone has been investigated through the analysis of a 130-km-long multichannel seismic reflection profile acquired orthogonally to the fracture zone near 60° S. The Shackleton Fracture Zone is a 800-km-long, mostly rectilinear and pronounced bathymetric lineation joining the westernmost South Scotia Ridge to southern South America south of Cape Horn, separating the western Scotia Sea plate from the Antarctic plate. Conventional processing applied to the seismic data outlines the main structures of the Shackleton Fracture Zone, but only the use of enhanced techniques, such as accurate velocity analyses and pre-stack depth migration, provides a good definition of the acoustic basement and the architecture of the sedimentary sequences. In particular, a strong and mostly continuous reflector found at about 8.0 s two-way traveltime is very clear across the entire section and is interpreted as the Moho discontinuity. Data show a complex system of troughs developed along the eastern flank of the crustal ridge, containing tilted and rotated blocks, and the presence of a prominent listric normal fault developed within the oceanic crust. Positive flower structures developed within the oceanic basement indicate strike-slip tectonism and partial reactivation of pre-existing faults. Present-day tectonic activity is found mostly in correspondence to the relief, whereas fault-induced deformation is negligible across the entire trough system. This indicates that the E–W-directed stress regime present in the Drake Passage region is mainly dissipated along a narrow zone within the Shackleton Ridge axis. A reappraisal of all available magnetic anomaly identifications in the western Scotia Sea and in the former Phoenix plate, in conjunction with new magnetic profiles acquired to the east of the Shackleton Fracture Zone off the Tierra del Fuego continental margin, has allowed us to propose a simple reconstruction of Shackleton Fracture Zone development in the general context of the Drake Passage opening.  相似文献   

9.
南大洋涡旋在跨锋面物质热量输送方面具有重要作用,斯科舍海位于德雷克海峡东面,属于重要的经济渔区,因此针对斯科舍海的涡旋分布及其影响进行研究具有迫切意义.本文基于2005-2019年卫星遥感数据对斯科舍海涡旋进行了探测与追踪,并统计了涡旋半径、传播距离、生命周期等特征参数,分析涡旋的地理分布特点、涡旋跨锋面情况以及移动特...  相似文献   

10.
The boundary between the Atlantic and Indian sectors of the Southern Ocean is a key spot of the thermohaline circulation, where the following water masses mix up: Indian Central water (ICW), South Atlantic Central Water (SACW), Antarctic Intermediate Water (AAIW), Circumpolar Deep Water (CDW), North Atlantic Deep Water (NADW), Weddell Sea Deep Water (WSDW) and Antarctic Winter Water (WW). An optimum multiparameter analysis based on the distributions of potential temperature, salinity, NO (=O2+9.3×NO3) and silicate during the GoodHope 2004 (GH04) cruise allowed us to (i) define the realms of these water masses; (ii) obtain the water mass proportion weighted-average (archetypal) apparent oxygen utilization (AOU) and dissolved organic carbon (DOC) concentrations of each water mass; and (iii) estimate the contribution of DOC to the oxygen demand of the study area. WW represented only 5.2% of the water volume sampled during GH04, followed by WSDW with 10.8%, NADW with 12.7%, SACW with 15.3%, AAIW with 23.1% and CDW with 32.8%. The distributions of DOC and AOU were mainly explained by the mixing of archetypal concentrations of these variables, 75±5% and 65±3% respectively, which retained the variability due to the basin-scale mineralization from the formation area to the barycentre of each water mass along the GH04 line. DOC accounted for 26±2% and 12±5% of the oxygen demand of the meso- and bathypelagic ocean, respectively. Conversely, local mineralization processes, retained by the residuals of the archetypal concentrations of DOC and AOU, did not contribute to improve significantly the mixing model of DOC.  相似文献   

11.
南极绕极流(ACC)是南大洋中最显著的流动，流量超过130×106m3/s (Nowlin et al.，1986)。传统认为，由于以东向运动为主的ACC的存在极大地阻碍了南大洋中上层的南北向物质和能量的交换，绕极流区的经向输运是非常小的。但是近些年的研究发现，穿过ACC的通量并不是可以忽略不计的，它对维持南极和亚南极区的动力和热力平衡起着重要作用，在全球气候系统中也有着深刻的影响(Doos et al.，1994)。  相似文献   

12.
It has long been seen from satellite ocean color data that strong zonal gradients of phytoplankton biomass persistently occur in the southern Drake Passage during austral summer and fall, where the low productivity Antarctic Surface Water (ASW) within the Antarctic Circumpolar Current (ACC) region transforms to the high productivity water. An interdisciplinary cruise was conducted in February and March 2004 to investigate potential physical and biogeochemical processes, which are responsible for transporting nutrients and metals and for enhancing primary production. To explore physical processes at both the meso- and large-scales, surface drifters, a shipboard Acoustic Doppler Current Profiler and conductivity–temperature–depth sensors were used. Analyzing meso- and large-scale hydrography, circulation and eddy activities, it is shown that the topographic rise of the Shackleton Transverse Ridge plays the key role in steering an ACC branch southward west of the ridge, forming an eastward ACC jet through the gap between the ridge and Elephant Island and causing the offshelf transport of shelf waters approximately 1.2 Sv from the shelf near Elephant Island. High mesoscale eddy activities associated with this ACC southern branch and shelf waters transported off the shelf were found. The mixing between the iron-poor warmer ASW of the ACC and iron-rich waters on the shelf through horizontal transport and vertical upwelling processes provides a physical process which could be responsible for the enhanced primary productivity in this region and the southern Scotia Sea.  相似文献   

13.
Morozov  E. G.  Flint  M. V.  Spiridonov  V. A.  Tarakanov  R. Yu. 《Oceanology》2019,59(6):989-991
Oceanology - The research program of the dynamics and ecosystem of the Drake Passage and Scotia Sea is scientifically substantiated. Measurements will be carried out by the interdepartmental...  相似文献   

14.
Data on bottom-water potential temperature, turbidity and current indications show that in the Southern Ocean west of the Kerguelen Plateau, Antarctic Bottom Water (AABW) of Weddell Sea origin spreads northwards from the Atlantic—Indian Basin in two directions: (1) AABW enters the Agulhas Basin through relatively deep areas in the Mid-Indian Ridge at 20–25°E and possibly at 35°E, and flows northwards into the Mozambique Basin as far as its northern limits; (2) a more easterly spreading path extends from the Atlantic—Indian Basin through the Crozet into the Madagascar, Mascarene, Somali and Arabian Basins. The passage in the western branch of the Indian Ridge for the AABW spreading from the Crozet into the Madagascar Basin appears to be at 29-26°S and 60–64°E.East of the Kerguelen Plateau in the South Indian Basin, the bottom water formed mainly along the Adélie Coast and Ross Sea travels west towards the Kerguelen Plateau and then parallel to it. This water finally flows eastwards hugging the Southeast Indian Ridge. Significant deviations from this general circulation pattern occur due to local topographic effects. Some AABW in the South Indian Basin exits through a passage at 120–125°E in the region of the Australian—Antarctic discordance in the Southeast Indian Ridge and enters the South Australian Basin and subsequently the Wharton Basin. This passage is clearly indicated by the northward extension of a cold, bottom-water tongue as shown by the temperature distribution in the region; the bottom-water effects in the passage are reflected in the high turbidity and current lineations on the sea floor.In the Southern Ocean basins, bottom-water turbidity is generally high, reflecting in part the strong bottom-water activity. The effects of AABW circulation on the sea floor—in the form of well-developed small- or large-scale current ripples and erosional/depositional features, manganese-nodule formations, and unconformities and reworking of sediments observed in cores — are also marked in these basins. Even though the AABW in the Wharton Basin is cold, its spreading effects on the sea floor are minimal in this basin in contrast to the basins west of the Mid-Indian Ridge at comparable latitudes.  相似文献   

15.
The quantitative properties and circulation of the lower layer of circumpolar water in the Scotia Sea with density 28.16 < γ n < 28.26 (potential temperature 0.9° > θ > 0.2°C) are investigated using the original procedure for determination of boundaries between water masses. The primary objective of this work is data analyses of four Russian sections, which were occupied in the vicinity of the Shackleton Fracture Zone in 2003, 2005, and 2007. It is shown that the ridges in the Hero and Shackleton fracture zones essentially constrain overflow of the lower layer of circumpolar water, and thereby, they produce the conditions to the east of the Shackleton Ridge for transformation (freshening and warming) of this layer reaching the northern side of the Antarctic Circumpolar Current. These ridges also promote formation of several quasi-permanent and semi-enclosed abyssal and deep-water eddies adjacent to these ridges. The estimation of overflow of the lower part of the investigated layer with density 28.23 < γ n < 28.26 (0.9° > θ > 0.2°C) through the Shackleton Ridge based on LADCP measurements in 2007 is 0.5 Sv (0.1 Sv) to the east (west). The upper part of the overflow is estimated as 8.0 (7.9) Sv. Thus, the total transport of the lower layer of circumpolar water through the ridge is practically zero. It is confirmed by LADCP measurements carried out on the section across the Drake Passage in 2003.  相似文献   

16.
Based on the satellite altimetry dataset of sea level anomalies, the climatic hydrological database World Ocean Atlas-2009, ocean reanalysis ECMWF ORA-S3, and wind velocity components from NCEP/NCAR reanalysis, the interannual variability of Antarctic Circumpolar Current (ACC) transport in the ocean upper layer is investigated for the period 1959–2008, and estimations of correlative connections between ACC transport and wind velocity components are performed. It has been revealed that the maximum (by absolute value) linear trends of ACC transport over the last 50 years are observed in the date-line region, in the Western and Eastern Atlantic and the western part of the Indian Ocean. The greatest increase in wind velocity for this period for the zonal component is observed in Drake Passage, at Greenwich meridian, in the Indian Ocean near 90° E, and in the date-line region; for the meridional component, it is in the Western and Eastern Pacific, in Drake Passage, and to the south of Africa. It has been shown that the basic energy-carrying frequencies of interannual variability of ACC transport and wind velocity components, as well as their correlative connections, correspond to the periods of basic large-scale modes of atmospheric circulation: multidecadal and interdecadal oscillations, Antarctic Circumpolar Wave, Southern Annual Mode, and Southern Oscillation. A significant influence of the wind field on the interannual variability of ACC transport is observed in the Western Pacific (140° E–160° W) and Eastern Pacific; Drake Passage and Western Atlantic (90°–30° W); in the Eastern Atlantic and Western Indian Ocean (10°–70° E). It has been shown in the Pacific Ocean that the ACC transport responds to changes of the meridional wind more promptly than to changes of the zonal wind.  相似文献   

17.
During the EPOS leg 2 cruise (European Polarstern Study, November 1988–January 1989), the production rate of biogenic silica in the euphotic zone was measured by the 30Si method at stations in the Scotia and Weddell Seas.The highest integrated production rates were observed in the Scotia Sea (range: 11.2–20.6 mmol Si m−2 day−1), the marginal ice zone of the Weddell Sea exhibiting somewhat lower values (range: 6.0–20.0 mmol Si m−2day−1).Our results demonstrate that as far as biogenic silica production is concerned the marginal ice zone of the Weddell Sea is considerably less productive than that of the Ross Sea. Our results also indicate that the water of the Antarctic Circumpolar Current (ACC) could be more productive in late spring and early summer than at the beginning of spring. Possible reasons for the differences among the three subsystems (Ross Sea, Weddell Sea and ACC) are discussed.  相似文献   

18.
Currents in the Drake Passage are studied using the data of a hydrographic section along the Shackleton Transverse Ridge observed in November 2007. The distribution of the velocity component normal to the section was computed by two methods: (a) directly on the basis of the lowered acoustic Doppler current profiler (LADCP) data; (b) by the calculation of geostrophic currents based on the CTD data with estimating the depth averaged velocity on the basis of the LADCP data. The main results of the research are the relatively low estimated value of the Antarctic Circumpolar Current (ACC) transport, which accounts for 65–70% of the ACC transports in December 2003 and November 2005, and the confirmation of the existence of several abyssal currents confined to the deep passages of the bottom topography.  相似文献   

19.
An experiment using a global ocean–ice model with an interannual forcing data set was conducted to understand the variability in the Southern Ocean. A winter-persisting polynya in the Weddell Sea (the Weddell Polynya, WP) was simulated. The process of WP breaking out after no-WP years was explored using the successive WPs found in the late 1950s. The results suggested that the anomalously warm deep water, saline surface layer, and a cyclonic wind stress over the Maud polynya region in early winter are essential for the surface layer to be dense enough to trigger deep convections which maintain a winter-persisting polynya; also, the reanalyzed surface air temperature (SAT) over the observed polynya region is too high for an ocean–ice model’s bulk formula to yield sufficient upward heat fluxes to induce WP formation. Therefore the Weddell Polynya, a series of WPs observed from satellite in the mid-1970s, is reproduced by replacing the SAT with a climatological one. Subsequent to the successive WP events, density anomalies excited in the Weddell Sea propagate northward in the Atlantic deep basins. The Antarctic Circumpolar Current (ACC) is enhanced through the increased meridional density gradient. The enhanced ACC and its meandering over the abyssal ridges excite buoyancy anomalies near the bottom at the southwestern end of the South Pacific basin. The buoyancy signals propagate northward and eventually arrive in the northern North Pacific.  相似文献   

20.
Hydrographic station and current meter data are used to estimate circulation and transport in the eastern basin of the Bransfield Strait. The short distance between adjacent hydrographic stations (20 km) allows evaluation of structures at scales seldom addressed in previous studies. The main feature of the derived circulation is the Bransfield Front and its associated baroclinic jet (the Bransfield Current). This frontal current crosses the northern half of the basin in a generally SW–NE direction, has maximum geostrophic speeds of 22 cm s−l (at the jet entrance), and has geostrophic transport relative to 500 dbar estimated to be 1 Sv. Dynamically significant mesoscale features associated with the Bransfield Current are seen to be relevant down to 500 dbar. Specific aspects inferred from our analysis are the apparent high degree of stationarity of the described circulation, the shallow intrusions of Circumpolar Deep Water through the northern boundary of the domain (from the Drake Passage), and the northward sinking of Weddell Sea water over most of the domain.  相似文献   

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