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1.
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   

2.
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   

3.
南极布兰斯菲尔德海峡及周边区域是南极大陆火山、地震等新构造活动最活跃的地区,与南设得兰海沟、南设得兰群岛一同构成南极大陆边缘现存唯一的"沟-弧-盆"构造体系。本文基于"雪龙"船第28、第30航次实测数据及两个航次的国际共享资料,利用均衡改正数据处理方法获得布兰斯菲尔德海峡的莫霍面深度及其分布规律,分析深部构造-断裂的区域分布及其重力异常特征等。布兰斯菲尔德海峡内的空间重力异常呈条带状分布,走向总体与地形相近,布格重力异常则由两侧向中间升高,大致在坡折处形成异常场值为100×10-5 m/s2的分界线,在中央次海盆和东部次海盆海山处形成两个异常高值圈闭,异常值最高为150×10-5 m/s2。莫霍面深度以弧后扩张中心为最低值,向南设得兰群岛和南极半岛两个方向递增,深度从12 km递增至陆坡位置的24 km。  相似文献   

4.
南极布兰斯菲尔德海峡及邻区地壳结构反演及构造解析   总被引：1，自引：0，他引：1  
马龙  邢健 《海洋与湖沼》2020,51(2):265-273
南极布兰斯菲尔德海峡及邻区是南极半岛海域火山、地震等新构造运动最活跃的地区,由于前人对资料处理解释的差异,导致盆地的构造格局仍部分存疑。本文以研究区的卫星重力数据为基础,以多道反射地震和部分岩性资料为约束,采用重震联合反演方法构建了三条横跨研究区的地壳结构剖面,并进一步研究布兰斯菲尔德海峡盆地的地壳结构。研究结果表明布兰斯菲尔德海峡盆地莫霍面深度为33—38km。菲尼克斯板块俯冲消减下沉至南设得兰岛弧之下,导致南设得兰海沟的俯冲带后撤,产生3—4km厚的岩浆混染地壳,密度为2.9g/cm~3。分析认为受板块运动和弧后扩张影响,沿布兰斯菲尔德海峡盆地扩张脊分布的海底火山裂隙式喷发,并进一步导致盆地的持续性扩张。  相似文献   

5.
The water mass structure and circulation of the continental shelf waters west of the Antarctic Peninsula are described from hydrographic observations made in March–May 1993. The observations cover an area that extends 900 km alongshore and 200 km offshore and represent the most extensive hydrographic data set currently available for this region. Waters above 100–150 m are composed of Antarctic Surface Water and its end member Winter Water. Below the permanent pycnocline is a modified version of Circumpolar Deep Water, which is a cooled and freshened version of Upper Circumpolar Deep Water. The distinctive signature of cold and salty water from the Bransfield Strait is found at some inshore locations, but there is little indication of significant exchange between Bransfield Strait and the west Antarctic Peninsula shelf. Dynamic topography at 200 m relative to 400 m indicates that the baroclinic circulation on the shelf is composed of a large, weak, cyclonic gyre, with sub-gyres at the northeastern and southwestern ends of the shelf. The total transport of the shelf gyre is 0.15 Sv, with geostrophic currents of order 0.01 m s-1. A simple model that balances across-shelf diffusion of heat and salt from offshore Upper Circumpolar Deep Water with vertical diffusion of heat and salt across the permanent pycnocline into Winter Water is used to explain the formation of the modified Circumpolar Deep Water that is found on the shelf. Model results show that the observed thermohaline distributions across the shelf can be maintained with a coefficient of vertical diffusion of 10-4 m2 s-1 and horizontal diffusion coefficients for heat and salt of 200 and 1200 m2 s-1, respectively. When the effects of double diffusion are included in the model, the required horizontal diffusion coefficients for heat and salt are 200 and 400 m2 s-1, respectively.  相似文献   

6.
The spatial distribution of eddy diffusivity, basic characteristics of coherent mesoscale eddies and their relationship are analyzed from numerical model outputs in the Southern Ocean. Mesoscale fluctuation information is obtained by a temporal-spatial filtering method, and the eddy diffusivity is calculated using a linear regression analysis between isoneutral thickness flux and large-scale isoneutral thickness gradient. The eddy diffusivity is on the order of O (103 m2/s) with a significant spatial variation, and it is larger in the area with strong coherent mesoscale eddy activity. The mesoscale eddies are mainly located in the upper ocean layer, with the average intensity no larger than 0.2. The mean radius of the coherent mesoscale cyclonic (anticyclonic) eddy gradually decays from (121.2±10.4) km ((117.8±9.6) km) at 30°S to (43.9±5.3) km ((44.7±4.9) km) at 65°S. Their vertical penetration depths (lifespans) are deeper (longer) between the northern side of the Subpolar Antarctic Front and 48°S. The normalized eddy diffusivity and coherent mesoscale eddy activity show a significant positive correlation, indicating that coherent mesoscale eddy plays an important role in eddy diffusivity.  相似文献   

7.
The northward flowing Antarctic Intermediate Water (AAIW) is a major contributor to the large-scale meridional circulation of water masses in the Atlantic. Together with bottom and thermocline water, AAIW replaces North Atlantic Deep Water that penetrates into the South Atlantic from the North. On the northbound propagation of AAIW from its formation area in the south-western region of the Argentine Basin, the AAIW progresses through a complex spreading pattern at the base of the main thermocline. This paper presents trajectories of 75 subsurface floats, seeded at AAIW depth. The floats were acoustically tracked, covering a period from December 1992 to October 1996. Discussions of selected trajectories focus on mesoscale kinematic elements that contribute to the spreading of AAIW. In the equatorial region, intermittent westward and eastward currents were observed, suggesting a seasonal cycle of the AAIW flow direction. At tropical latitudes, just offshore the intermediate western boundary current, the southward advection of an anticyclonic eddy was observed between 5°S and 11°S. Farther offshore, the flow lacks an advective pattern and is governed by eddy diffusion. The westward subtropical gyre return current at about 28°S shows considerable stability, with the mean kinetic energy to eddy kinetic energy ratio being around one. Farther south, the eastward deeper South Atlantic Current is dominated by large-scale meanders with particle velocities in excess of 60 cm s-1. At the Brazil–Falkland Current Confluence Zone, a cyclonic eddy near 40°S 50°W seems to act as injector of freshly mixed AAIW into the subtropical gyre. In general, much of the mixing of the various blends of AAIW is due to the activity of mesoscale eddies, which frequently reoccupy similar positions.  相似文献   

8.
We use hydrological and current meter data collected in the Ross Sea, Antarctica between 1995 and 2006 to describe the spatial and temporal variability of water masses involved in the production of Antarctic Bottom Water (AABW). Data were collected in two regions of known outflows of dense shelf water in this region; the Drygalski Trough (DT) and the Glomar-Challenger Trough (GCT). Dense shelf water just inshore of the shelf break is dominated by High Salinity Shelf Water (HSSW) in the DT and Ice Shelf Water (ISW) in the GCT. The HSSW in the northern DT freshened by ∼0.06 in 11 y, while the ISW in the northern GCT freshened by ∼0.04 in 8 y and warmed by ∼0.04 °C in 11 y, dominated by a rapid warming during austral summer 2001/02. The Antarctic Slope Front separating the warm Circumpolar Deep Water (CDW) from the shelf waters is more stable near GCT than near DT, with CDW and mixing products being found on the outer DT shelf but not on the outer GCT shelf. The different source waters and mixing processes at the two sites lead to production of AABW with different thermohaline characteristics in the central and western Ross Sea. Multi-year time series of hydrography and currents at long-term moorings within 100 km of the shelf break in both troughs confirm the interannual signals in the dense shelf water and reveal the seasonal cycle of water mass properties. Near the DT the HSSW salinities experienced maxima in March/April and minima in September/October. The ISW in the GCT is warmest in March/April and coolest between August and October. Mooring data also demonstrate significant high-frequency variability associated with tides and other processes. Wavelet analysis of near-bottom moored sensors sampling the dense water cascade over the continental slope west of the GCT shows intermittent energetic pulses of cold, dense water with periods from ∼32 h to ∼5 days.  相似文献   

9.
The Bransfield Basin is a narrow and elongated active rift basin located between the Antarctic Peninsula and the South Shetland Islands. The Bransfield Basin is composed of three small basins, and two of them, the Central and Eastern Bransfield Basins, were surveyed during a recent cruise (GEBRA 93). The full swath bathymetry coverage as well as the single-channel seismic reflection and magnetic profiles that have been acquired, help us to better understand the morphostructure and recent evolution of the Bransfield Basin. Six large volcanic edifices aligned with the basin axis stick out of the sedimented seafloor of the Central Bransfield Basin. In contrast, the Eastern Bransfield Basin is characterised by four deep troughs displaying a rhombic-shape, and small, scattered volcanic cones located in the southwestern half basin. Seamount volcanism plays an important role in the formation of new crust in the Bransfield Basin. The larger seamounts of the Central Bransfield Basin are located at the intersection of the two main orthogonal sets of faults (longitudinal ENE-WSW and transversal NNW-SSE). Morphological analysis of the seamounts indicates a multi-staged volcano-tectonic construction. The distribution and shape of these edifices suggests that both volcanism and extension are concentrated at the same preferential areas through time. This might be related to the fracturation style of the continental crust. The Central and Eastern Bransfield Basins are very different in morphostructure, volcanism, and sedimentary cover. The Central Bransfield Basin shows evidence of NW-SE extensional faulting and focused active MORB-volcanism interpreted as result of incipient seafloor spreading. The Eastern Bransfield Basin is still in a rifting stage, mainly dominated by a NW-SE extension and some left-lateral strike-slip component probably related to the South Scotia Ridge.J. Acosta, J. Baraza, P. Bart, A.M. Calafat, J.L. Casamor, M. De Batist, G. Ercilla, G. Francés, E. Ramos, J.L. Sanz, and A. Tassone.  相似文献   

10.
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11.
Global observations of nonlinear mesoscale eddies   总被引：51，自引：0，他引：51  
Sixteen years of sea-surface height (SSH) fields constructed by merging the measurements from two simultaneously operating altimeters are analyzed to investigate mesoscale variability in the global ocean. The prevalence of coherent mesoscale features (referred to here as “eddies”) with radius scales of O(100 km) is readily apparent in these high-resolution SSH fields. An automated procedure for identifying and tracking mesoscale features based on their SSH signatures yields 35,891 eddies with lifetimes ?16 weeks. These long-lived eddies, comprising approximately 1.15 million individual eddy observations, have an average lifetime of 32 weeks and an average propagation distance of 550 km. Their mean amplitude and a speed-based radius scale as defined by the automated procedure are 8 cm and 90 km, respectively.The tracked eddies are found to originate nearly everywhere in the World Ocean, consistent with previous conclusions that virtually all of the World Ocean is baroclinically unstable. Overall, there is a slight preference for cyclonic eddies. However, there is a preference for the eddies with long lifetimes and large propagation distances to be anticyclonic. In the southern hemisphere, the distributions of the amplitudes and rotational speeds of eddies are more skewed toward large values for cyclonic eddies than for anticyclonic eddies. As a result, eddies with amplitudes >10 cm and rotational speeds >20 cm s−1 are preferentially cyclonic in the southern hemisphere. By contrast, there is a slight preference for anticyclonic eddies for nearly all amplitudes and rotational speeds in the northern hemisphere.On average, there is no evidence of anisotropy of these eddies. Their average shape is well represented as Gaussian within the central 2/3 of the eddy, but the implied radius of maximum rotational speed is 64% smaller than the observed radius of maximum speed. In part because of this mismatch between the radii of maximum axial speed in the observations and the Gaussian approximation, a case is made that a quadratic function that is a very close approximation of the mode profile of the eddy (i.e., the most frequently occurring value at each radius) is a better representation of the composite shape of the eddies. This would imply that the relative vorticity is nearly constant within the interiors of most eddies, i.e., the fluid motion consists approximately of solid-body rotation.Perhaps the most significant conclusion of this study is that essentially all of the observed mesoscale features outside of the tropical band 20°S-20°N are nonlinear by the metric U/c, where U is the maximum circum-average geostrophic speed within the eddy interior and c is the translation speed of the eddy. A value of U/c > 1 implies that there is trapped fluid within the eddy interior. Many of the extratropical eddies are highly nonlinear, with 48% having U/c > 5 and 21% having U/c > 10. Even in the tropics, approximately 90% of the observed mesoscale features are nonlinear by this measure.Two other nondimensional parameters also indicate strong degrees of nonlinearity in the tracked eddies. The distributions of all three measures of nonlinearity are more skewed toward large values for cyclonic eddies than for anticyclonic eddies in the southern hemisphere extratropics but the opposite is found in the northern hemisphere extratropics. There is thus a preference for highly nonlinear extratropical eddies to be cyclonic in the southern hemisphere but anticyclonic in the northern hemisphere.Further evidence in support of the interpretation of the observed features as nonlinear eddies is the fact that they propagate nearly due west with small opposing meridional deflections of cyclones and anticyclones (poleward and equatorward, respectively) and with propagation speeds that are nearly equal to the long baroclinic Rossby wave phase speed. These characteristics are consistent with theoretical expectations for large, nonlinear eddies. While there is no apparent dependence of propagation speed on eddy polarity, the eddy speeds relative to the local long Rossby wave phase speeds are found to be about 20% faster in the southern hemisphere than in the northern hemisphere. The distributions of the propagation directions of cyclones and anticyclones are essentially the same, except mirrored about a central azimuth angle of about 1.5° equatorward. This small, but we believe statistically significant, equatorward rotation of the central azimuth may be evidence of the effects of ambient currents (meridional advection or the effects of vertical shear on the potential vorticity gradient vector) on the propagation directions of the eddies.While the results presented here are persuasive evidence that most of the observed westward-propagating SSH variability consists of isolated nonlinear mesoscale eddies, it is shown that the eddy propagation speeds are about 25% slower than the westward propagation speeds of features in the SSH field that have scales larger than those of the tracked eddies. This scale dependence of the propagation speed may be evidence for the existence of dispersion and the presence of features that obey linear Rossby wave dynamics and have larger scales and faster propagation speeds than the nonlinear eddies. The amplitudes of these larger-scale signals are evidently smaller than those of the mesoscale eddy field since they are not easily isolated from the energetic nonlinear eddies.  相似文献   

12.
Eleven subtropical coccolithophore species were identified in three samples taken in the austral autumn from the Weddell Sea, Antarctic, between 69°S and 70°S, just south of the Antarctic Slope Front. This is the first report of coccolithophores present at such southern latitudes. We provide three hypotheses for their occurrence in the Weddell Sea: (1) Coccolithophore species have wider temperature tolerances than previously believed. (2) Coccolithophores found in the Weddell Sea were part of a remnant community from the Agulhas Current. (3) Coccolithophores were transported by a N–S eddy crossing the Brazil–Malvinas confluence region and then subsequently transported to the east by warm water eddies of the Antarctic Circumpolar Current to the study location. Further temperature tolerance experiments with coccolithophores are recommended.  相似文献   

13.
A one-dimensional, temperature-dependent model is implemented to simulate the descent–ascent cycle of Antarctic krill (Euphausia superba) embryos and larvae. Inputs to the model are monthly mean climatologies of ambient temperature and density fields obtained from the World Ocean Atlas Database for Southern Ocean waters. Simulations are done with a 1° resolution at a circumpolar scale, south of 60°S, and the results are interpolated to a 5′ grid to match the resolution of the bottom bathymetry data. Simulations of the descent–ascent cycle using environmental conditions corresponding to the Antarctic krill spawning season (December–March) resulted in unconstrained success in completion of the cycle in water deeper than 1000 m. Continental shelf regions favorable to successful hatching of Antarctic krill embryos are limited to areas along the west Antarctic Peninsula, large areas in the Bellingshausen and Amundsen Seas, offshore of Wilkes Land, and to the east and west of Prydz Bay. These are regions where the Southern Antarctic Circumpolar Current Front is along the shelf slope, the Antarctic Slope Front is absent, and Circumpolar Deep Water is present. The effect of seasonal variability in temperature on the descent–ascent cycle tends to enhance the probability of success in regions offshore of Wilkes Land, Queen Maud Land, and the eastern shelf of the Antarctic Peninsula later in the spawning season. The simulations show that success of the descent–ascent cycle is sensitive to initial embryo diameter and larval ascent rate. Initial embryo diameter may provide an additional constraint on success of the descent–ascent cycle, especially in continental shelf waters, where small embryos tend to encounter the bottom before hatching. The circumpolar distributions of simulated embryo hatching depth and larval success show that all regions of the Antarctic are not equal in the ability to support successful completion of the Antarctic krill descent–ascent cycle, which has implications for the overall circum-Antarctic krill distribution and for the development of nutrient and material budgets, especially for Antarctic continental shelf areas.  相似文献   

14.
黄浩  陈学恩  林璘 《海洋与湖沼》2019,50(6):1191-1200
本文基于现场观测资料并结合FVCOM三维海洋模式的模拟结果,研究了2010年青岛冷水团生消过程和演变机制。结果表明,山东半岛东南海域的中层冷水是青岛冷水团的雏形,于4月中旬演变为青岛冷水团,位于青岛东南外海40m以下的盐度锋面中;刻画了青岛冷水团的消亡过程:5月青岛冷水团的北部底层水并入南黄海底层冷水中,构成南黄海的西部冷中心;而南部水团面积大幅减小,温盐特征大幅上升;6月上旬,青岛冷水团完全被南黄海底层冷水吞并,青岛冷水团完全消亡;揭示了青岛-石岛近海反气旋涡、黄海冷水团锋面密度环流对青岛冷水团的作用,前者是青岛冷水团存在的动力机制,后者加剧了底层海域的水平热量交换,促使了青岛冷水团的消亡。  相似文献   

15.
An unusual region of high meso-scale turbulence has been identified in the Indian Ocean sector of the Southern Ocean. It has been shown that this is the result of eddy shedding from the Antarctic Polar Front. These eddies may dramatically affect the local distribution of marine organisms. To investigate this, the euphausiid community structure and species composition in the region of a cold eddy within the Antarctic Polar Frontal Zone (APFZ) was investigated during April 2005. Water masses within the core of the eddy were typically Antarctic, showing they had come from south of the Antarctic Polar Front. Results of numerical analyses indicate that the euphausiid community within the survey area consisted of three distinct groups: those in APFZ waters, those at the edge of the eddy and those in the core of the eddy. These results indicate that eddies generated by the interaction of the Antarctic Circumpolar Current with the South-West Indian Ridge play an important role in transporting Antarctic euphausiid species equatorward, thus contributing to the spatial heterogeneity of the zooplankton community within the region.  相似文献   

16.
Fronts and strong currents of the upper southeast Indian Ocean   总被引：3，自引：1，他引：2  
1 IntroductionBaroclinic component is the dominant part ofAntarcticCircum polarCurrent (ACC) (FandryandPillsbury,1979),and a baroclinictransportation asso-ciatedwithfrontsmakesupthem ajoritypartoftheto-talbaroclinictransportation oftheACC (Nowlin andCliff…  相似文献   

17.
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   

18.
冬季青岛-石岛近海中尺度涡旋数值模拟   总被引：1，自引：0，他引：1  
利用二维全流水动力方程组,在考虑了海面风应力,潮余流和一开边界入流等条件下,首次模拟出了石了石岛附近的中尺度反旋式涡旋海水运动,并对南黄海西部冬季环流的特征作了初步探讨。数值模拟结果和实测吻合良好,数值模拟表明：冬季南黄海西部环流形式主要决定因子是海面风应力、潮余流及从开边界的流入该海域的黄海暖流及黄海沿岸流。黄海暖流在偏北风作用下沿西北方向可直达山东半岛近岸,后分为两支：一支向南汇入黄海沿岸流流  相似文献   

19.
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   

20.
We use a 9-km pan-Arctic ice–ocean model to better understand the circulation and exchanges in the Bering Sea, particularly near the shelf break. This region has, historically, been undersampled for physical, chemical, and biological properties. Very little is known about how water from the deep basin reaches the large, shallow Bering Sea shelf. To address this, we examine here the relationship between the Bering Slope Current and exchange across the shelf break and resulting mass and property fluxes onto the shelf. This understanding is critical to gain insight into the effects that the Bering Sea has on the Arctic Ocean, especially in regard to recent indications of a warming climate in this region. The Bering Sea shelf break region is characterized by the northwestward-flowing Bering Slope Current. Previously, it was thought that once this current neared the Siberian coast, a portion of it made a sharp turn northward and encircled the Gulf of Anadyr in an anticyclonic fashion. Our model results indicate a significantly different circulation scheme whereby water from the deep basin is periodically moved northward onto the shelf by mesoscale processes along the shelf break. Canyons along the shelf break appear to be more prone to eddy activity and, therefore, are associated with higher rates of on-shelf transport. The horizontal resolution configured in this model now allows for the representation of eddies with diameters greater than 36 km; however, we are unable to resolve the smaller eddies.  相似文献   

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