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1.
利用我国第九次南极考察队获得的德雷克海峡地区水温资料,并结合国外锚碇浮标和测流资料,分析和研究了德雷克海峡绕极流和锋面的时间变化和空间变化.研究表明,德雷克海峡绕极流的流速共有3个强流区,就德雷克海峡上层海流的空间变化而言,以亚南极锋附近的海流最强,流向和流速也最稳定少变.德雷克海峡深层海流的空间分布特点与上层海流的空间分布特点不同,深层流速明显减弱,且稳定性差.德雷克海峡绕极流有着明显的时间变化,但是这种时间变化因地而异.极锋附近在冬春季节是稳定的深层北向流,它与南半球高纬度的冬、春季节的Ventilation过程有着密切的关系,德雷克海峡上层水温的空间分布具有明显的锋面分布特征.水温在德雷克海峡的高纬度区更加稳定少变,而极锋附近深层海水温度随时间的变化最大. 相似文献
2.
根据 2 0 0 2 ,2 0 0 0和 1999年中国南极考察和 1992年澳大利亚南极考察资料 ,分析了普里兹湾 73°E断面水团与地转流的结构及其多年变化 :(1)该断面上水团主要有南极表层水、绕极深层水、南极底层水和陆架水 ;(2 )南极表层水 1999,2 0 0 0年向北扩展最强 ,2 0 0 2年向北扩展最弱 ,绕极深层水 2 0 0 2年向南扩展也较强 ,1999和 1992年绕极深层水向南扩展较弱 ,南极底层水 ,位温在 - 0 .3～- 0 .4℃ ,盐度在 34.6 6左右 ,主要是本地形成 ,而 1992年高盐底层水可能来源于其他原因 ;(3)该海域深层水呈显著的升温 ,增暖率约为 0 .0 0 7～ 0 .0 0 8℃ /a;(4 )南极陆坡锋的强度和位置 ,与南极表层水的北向扩展和绕极深层水的变化一致 ;(5 ) 6 2°S～ 6 6°S是绕极流的南缘 ,东向流深度可达 2 0 0 0 m,最大流速中心在 6 4.5°S附近 ,2 0 0 0年北移至 6 3.5°S附近 ,最大流速为 3～ 5 cm/s;陆架上 6 8°S附近主要为流速 1cm /s左右的西向流。 相似文献
3.
宫古海峡通道海流的高分辨率数值模拟 总被引：1，自引：0，他引：1
运用美国麻省理工大学MITgcm模式、模式嵌套技术和高分辨率网格(水平方向为1°/48×1°/48,垂向为22层),模拟了宫古海峡通道中的海流流动状况。流场不同分辨率的模拟结果表明,海底地形对宫古海峡通道中的海流流动影响显著;宫古海峡通道中的海流流动结构具有如下特征:垂向流动可分为3层,每层均存在流速核心;400 m以浅的上层海流从太平洋流入到东海,平均流速约为10 cm/s,流速核心位于160 m附近;400~1 000 m的中层海流从东海流出到太平洋,平均流速约为2 cm/s,流速核心位于650 m附近;1 000 m以下的深层海流从太平洋流入到东海,平均流速约为1 cm/s,流速核心位于1 200 m附近。宫古海峡通道中的海流流动具有较强的季节变化特征,秋末冬初流动较强,夏季流动较弱。 相似文献
4.
南极普里兹湾及其邻近海域的水文结构特征和底层水的来源 总被引：8，自引：2，他引：8
利用中国第九次南大洋考察中南极普里兹湾及其邻近海域的CTD资料,分析研究了调查海域的水文结构特征及其该区南极底层水(AABW)的来源.研究结果表明,在研究海域,深水洋区近表层流由西向东流,而在普里兹湾内存在一个气旋型涡.水文结构中最明显的海洋学特征是:(1)绕极深层水(CDW)的涌升现象明显,涌升最强的位置是麦克罗伯逊地以北海域,最明显的深度是50～200m层,暖水涌升将冬季冷水分隔成南北两部分,并在其中形成孤立的暖水块;(2)陆缘水边界明显,这是绕极深层水与南极冷水之间形成的锋面,一般处在次表层水中,大致位于64°～66°S之间;(3)存在着双跃层结构.观测期间,普里兹湾以北探水海域存在着南极底层水,其来源可能有二:一为当地形成,二为源于威德尔海和罗斯海. 相似文献
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7.
南极普里兹湾及其邻近海域水团研究 总被引：3，自引：3，他引：0
普里兹湾及其邻近海域是中国南大洋调查研究的传统优势海域与重点区域。围绕夏季表层水、冬季水、陆架水、绕极深层水、南极底层水、普里兹湾底层水、冰架水等研究海区主要水团的特征和分布,总结了前人在南极普里兹湾及其邻近海域基于调查资料开展的水团研究中所取得的成果。研究表明,前人在对陆架水的示性指标界定上,将陆架水是否区分为高盐陆架水和低盐陆架水存在较大争议,在高盐陆架水和普里兹湾底层水的定义上存在重叠;目前尚没有证据表明绕极深层水向南可以伸展到普里兹湾的陆架区域,也没有发现在普里兹湾附近海域生成南极底层水的直接证据。 相似文献
8.
南极半岛东北部海域表层沉积物稀土元素特征及物源指示意义 总被引：1，自引：0，他引：1
通过对南极半岛东北部海域36个表层沉积物样品的稀土元素分析发现:(1)研究区表层沉积物中稀土元素总量(REE)的分布范围为(45.47~183.60)×10-6,平均值为91.36×10-6;稀土元素含量的高低与铝硅酸盐黏土成正比,与生物硅含量成反比;(2)大致以象岛至南极半岛北部的茹安维尔岛为界,研究区西部的布兰斯菲尔德海峡及南设得兰群岛北部岛架-岛坡沉积物稀土含量较低,稀土元素页岩标准化模式与长城站周边土壤/湖泊沉积物、火山岩相一致,表现为重稀土相对富集,铕正异常明显,Sm/Nd分子比值大,推断该区沉积物主要来源于南设德兰群岛中-新生代火山岩分布区与现代火山活动区;(3)研究区东部鲍威尔海盆、南奥克尼群岛岛架和南斯科舍海脊区沉积物稀土元素的页岩标准化配分模式表现为平坦型,轻稀土明显抬升,铕正异常不显著,Sm/Nd分子比值小,稀土元素含量受沉积物中黏土组分含量、硅质生物组分等制约,推断沉积物陆源碎屑主要来源于威德尔海西部和南部,局部受南奥尼克群岛、南斯科舍海脊和南设德兰群岛物质的影响,沉积物的搬运主要受冰筏和海流制约。 相似文献
9.
本文利用在菲律宾海布放的一套锚系潜标获取的长时间海流和水温观测数据,分析了吕宋海峡以东的深海海洋环境特征,着重阐释了该海域海流的全水深垂向结构及其低频变化特征。研究表明,表层(100～160 m)平均流向为西偏北,流速约为12.5 cm/s;中层(810 m)的平均流为西向,流速为2.6 cm/s;深层(1 550 m和2 560 m)的平均流速在1 cm/s以内,近底(4 040 m)的流向为较稳定的西南向,流速为2.3 cm/s。上层海流的动能比中层和深层大1～2个量级,总动能、平均动能、涡动动能均在表层最大,中层次之、深层最小,各层次涡动能均大于平均动能。中上层海流的低频变化具有极高的相似性,全年为81～85 d的周期振荡;近底层海流则不同,变化周期约为51 d。 相似文献
10.
南极印度洋扇区分布了许多南极底层水的生成区,此海域海水盐度变化对全球的气候变化有着深远影响。本文采用EN4再分析数据、实测海豹资料和WOD18数据,结合大气再分析和海冰密集度数据,对南极印度洋扇区表面盐度长期变化及其对大尺度环流异常的响应进行探究。2008年以来,南极沿岸出现显著的海表面持续性高盐异常,其中印度洋扇区变化最为显著,表层高盐水主要集中在达恩利冰间湖附近与沙克尔顿冰架以北的海域。沿岸海域的高盐陆架水向北扩张且影响深度不断加深,高盐的绕极深层水上涌也更加明显。此高盐异常与南极涛动(Antarctic Oscillation,AAO)、印度洋偶极子(Indian Ocean Dipole,IOD)两种大尺度环流密切相关。AAO与IOD正位相下,西风显著增强,促进海冰大量生成,为海表面提供了大量的盐通量。同时,海表面出现更显著的风场旋度负异常与低压异常,促进高盐深层水上涌,对高盐异常有重要维持作用。此外,纬向风剪切与蒸发增强也是影响该高盐异常的重要局地过程。 相似文献
11.
《Deep Sea Research Part I: Oceanographic Research Papers》2002,49(4):681-705
An unprecedented high-quality, quasi-synoptic hydrographic data set collected during the ALBATROSS cruise along the rim of the Scotia Sea is examined to describe the pathways of the deep water masses flowing through the region, and to quantify changes in their properties as they cross the sea. Owing to sparse sampling of the northern and southern boundaries of the basin, the modification and pathways of deep water masses in the Scotia Sea had remained poorly documented despite their global significance.Weddell Sea Deep Water (WSDW) of two distinct types is observed spilling over the South Scotia Ridge to the west and east of the western edge of the Orkney Passage. The colder and fresher type in the west, recently ventilated in the northern Antarctic Peninsula, flows westward to Drake Passage along the southern margin of the Scotia Sea while mixing intensely with eastward-flowing Circumpolar Deep Water (CDW) of the antarctic circumpolar current (ACC). Although a small fraction of the other WSDW type also spreads westward to Drake Passage, the greater part escapes the Scotia Sea eastward through the Georgia Passage and flows into the Malvinas Chasm via a deep gap northeast of South Georgia. A more saline WSDW variety from the South Sandwich Trench may leak into the eastern Scotia Sea through Georgia Passage, but mainly flows around the Northeast Georgia Rise to the northern Georgia Basin.In Drake Passage, the inflowing CDW displays a previously unreported bimodal property distribution, with CDW at the Subantarctic Front receiving a contribution of deep water from the subtropical Pacific. This bimodality is eroded away in the Scotia Sea by vigorous mixing with WSDW and CDW from the Weddell Gyre. The extent of ventilation follows a zonation that can be related to the CDW pathways and the frontal anatomy of the ACC. Between the Southern Boundary of the ACC and the Southern ACC Front, CDW cools by 0.15°C and freshens by 0.015 along isopycnals. The body of CDW in the region of the Polar Front splits after overflowing the North Scotia Ridge, with a fraction following the front south of the Falkland Plateau and another spilling over the plateau near 49.5°W. Its cooling (by 0.07°C) and freshening (by 0.008) in crossing the Scotia Sea is counteracted locally by NADW entraining southward near the Maurice Ewing Bank. CDW also overflows the North Scotia Ridge by following the Subantarctic Front through a passage just east of Burdwood Bank, and spills over the Falkland Plateau near 53°W with decreased potential temperature (by 0.03°C) and salinity (by 0.004). As a result of ventilation by Weddell Sea waters, the signature of the Southeast Pacific Deep Water (SPDW) fraction of CDW is largely erased in the Scotia Sea. A modified form of SPDW is detected escaping the sea via two distinct routes only: following the Southern ACC Front through Georgia Passage; and skirting the eastern end of the Falkland Plateau after flowing through Shag Rocks Passage. 相似文献
12.
《Deep Sea Research Part II: Topical Studies in Oceanography》1999,46(1-2):475-499
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
13.
R. Yu. Tarakanov 《Oceanology》2012,52(2):157-170
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
14.
《Deep Sea Research Part I: Oceanographic Research Papers》2007,54(10):1815-1840
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
15.
Oceanology - Measurements of currents and Antarctic Bottom Water properties overflowing the sill from the Weddell to the Scotia Sea are described. The bottom water overflows the sill of one of the... 相似文献
16.
《Deep Sea Research Part I: Oceanographic Research Papers》2006,53(6):987-1010
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
17.
Manfred Mensch Reinhold Bayer John L. Bullister Peter Schlosser Ray F. Weiss 《Progress in Oceanography》1996,38(4):377-388
Transient tracer data (tritium, CFC11 and CFC12) from the southern, central and northwestern Weddell Sea collected during Polarstern cruises ANT III-3, ANT V-2/3/4 and during Andenes cruise NARE 85 are presented and discussed in the context of hydrographic observations. A kinematic, time-dependent, multi-box model is used to estimate mean residence times and formation rates of several water masses observed in the Weddell Sea.Ice Shelf Water is marked by higher tritium and lower CFC concentrations compared to surface waters. The tracer signature of Ice Shelf Water can only be explained by assuming that its source water mass, Western Shelf Water, has characteristics different from those of surface waters. Using the transient nature of tritium and the CFCs, the mean residence time of Western Shelf Water on the shelf is estimated to be approximately 5 years. Ice Shelf Water is renewed on a time scale of about 14 years from Western Shelf Water by interaction of this water mass with glacial ice underneath the Filchner-Ronne Ice shelf. The Ice Shelf Water signature can be traced across the sill of the Filchner Depression and down the continental slope of the southern Weddell Sea. On the continental slope, new Weddell Sea Bottom Water is formed by entrainment of Weddell Deep Water and Weddell Sea Deep Water into the Ice Shelf Water plume. In the northwestern Weddell Sea, new Weddell Sea Bottom Water is observed in two narrow, deep boundary currents flowing along the base of the continental slope. Classically defined Weddell Sea Bottom Water (θ ≤ −0.7°C) and Weddell Sea Deep Water (−0.7°C ≤ θ ≤ 0°C) are ventilated from the deeper of these boundary currents by lateral spreading and mixing. Model-based estimates yield a total formation rate of 3.5Sv for new Weddell Sea Bottom Water (θ = −1.0°C) and a formation rate of at least 11Sv for Antarctic Bottom Water (θ = −0.5°C). 相似文献
18.
G. G. Panteleev M. N. Koshlyakov E. G. Morozov R. Yu. Tarakanov A. Yu. Goldin A. Yu. Shcherbina M. Ikeda 《Oceanology》2006,46(6):772-783
Computation of ocean currents in the Drake Passage is carried out with variational assimilation of the data of the hydrographical section across the Drake Passage carried out on December 11–15, 2003, and other data. A stream-eddy structure of the easterly Antarctic Circumpolar Current and a westerly current on the Antarctic Slope are obtained. Water transports by the different current field components and the integral transport across the Drake Passage are estimated. The necessity of direct current measurements in the Drake Passage for a correct estimate of the transport is confirmed. 相似文献
19.
The Vema Channel acts as a major conduit for the equatorward spreading of Antarctic Bottom Water between the Argentine and Brazil Basins. For almost two years the thermal stratification above its saddle depth (4660 m) – called Vema Sill – was recorded by moored thermistors and current meters. The lowest 490 m of the water column was instrumented to monitor the well-developed benthic boundary layer of Antarctic Bottom Water. The latter can be subdivided into Weddell Sea Deep Water on the sea bed and lower Circumpolar Deep Water above it. The data show fluctuations on various scales including periods, each about 1–2 weeks long, when the abyssal stratification virtually disappeared. Assuming a stable ratio between density and temperature, time series of bulk Richardson numbers are estimated from temperature and current shear data. The results suggest a potential for intermittent episodes of locally generated vertical mixing. 相似文献
20.
中国南大洋水团、环流和海冰研究进展(1995-2002) 总被引：2，自引：0，他引：2
总结了1995年以来中国在南大洋物理海洋学研究和南极海冰研究中所取得的成果。普里兹湾海区是中国南大洋研究的重点区域，研究表明，在该海区存在显著的深层水涌升和陆架水北扩现象，某些年份深层水与陆架水混合后产生了较重的水体，但是尚未发现生成南极底层水的直接证据。在普里兹湾所处的印度洋区段，亚热带锋、亚南极锋和极锋表现出显著的时空变化，特别是不同年份的锋面位置存在较大的摆动。该海区的南极绕极流既是风生的，也受到密度场的影响。在凯尔盖朗海台的地形引导作用下，南极绕极流表现出显著的非纬向性特征。南极海冰除了显著的季节变化以外，也表现出长期变化的趋势。此变化与海洋、大气中的其它变化有一定的相关性，表现为两极海冰涛动、南方海洋涛动等多种变化模态，对我国气候也有一定的影响。 相似文献