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1.
《Deep Sea Research Part I: Oceanographic Research Papers》1999,46(3):415-438
The mesoscale dynamics of the Scottish side of the Faroe–Shetland Channel have been investigated using synoptic in situ and remote sensing observations. A cold core cyclonic eddy, identified from an AVHRR image, had a diameter of about 50 km and surface current speeds of up to 50 cm s-1; it appeared to be attached to the 800 m isobath as it moved north-eastward along the edge of the channel at about 8 cm s-1. Speeds in the slope current were about 50 cm s-1 but increased to 70 cm s-1 where the current was compressed by the eddy. Offshore, over the 1000 m isobath in the cooler water, speeds in the current were slower (ca. 20 cm s-1). North-west of the Shetlands the offshore edge of the slope current was deflected across the channel for a distance of about 70 km from the shelf edge. The speed of drifters in the slope current increased to over 60 cm s-1 as they moved anti-cyclonically around this deflection. CTD profiles suggest that the movement of the surface waters was mirrored in the deep water of the channel. The deflection carried a very large quantity of North Atlantic Water into the central part of the channel; its cause and ultimate fate are not known, although it is likely to have had a significant impact on the dynamics of the channel. 相似文献
2.
Wu Dexing 《海洋学报(英文版)》1994,13(4):465-474
Ｐｒｅｌｉｍｉｎａｒｙｓｔｕｄｙｏｎｔｈｅｄｙｎａｍｉｃｍｅｃｈａｎｉｓｍｏｆｔｈｅｄｅｅｐｅｑｕａｔｏｒｉａｌｊｅｔｓ￥ＷｕＤｅｘｉｎｇ（ＲｅｃｅｉｖｅｄＤｅｃｅｍｂｅｒ１５，１９９３；ａｃｃｅｐｔｅｄＭａｒｃｈ７，１９９４）（Ｉｎｓｔｉｔｕｔｅｏ... 相似文献
3.
Three-D numerical simulation of wind-driven current and density current in the Beibu Gulf 总被引：4，自引：2，他引：4
The Beibu Gulf circulation plays an imPOrtant role in the long--term water rnass transportinside the gulf. It is also closely related to the Guangxi untal water mass transport and self-purification. Hence, it is of practical imPOrtance to study the circulation in the gUlf. The cir-culation in the gUlf is very comlicated, and is rnainly gOverned by wind, water density gradi-ent, the current outside the gulf and the bathpoetry. In spring, a cold water rnass generatesln the center of the gulf… 相似文献
4.
The characteristics of three-dimensional (3-D) tidal current in the Oujiang Estuary are investigated according to in situ observations. The Oujiang Estuary has features of irregular coastline, complex topography, many islands, moveable boundary, and submerged dyke, therefore, a 3-D numerical model on an unstructured triangular grid has been developed. The σ coordinate transformation, the moveable boundary and submerged dyke treatment techniques were employed in the model so it is suitable for the tidal simu... 相似文献
5.
Charles McCann 《新西兰海洋与淡水研究杂志》2013,47(4):619-640
6.
The Ninetyeast Ridge north of the equator in the eastern Indian Ocean is actively deforming as evidenced by seismicity and its eastward subduction below the Andaman Trench. Basement of the ridge is elevated nearly 2 km with respect to the Bengal Fan; seismic surveys demonstrate continuity of the ridge beneath sediment for 700 km north of 10° N where the ridge plunges below the Fan sediment. The ridge is characterised by a free-air gravity high of 50 mgal amplitude and 350 km wavelength, and along-strike continuity of 1500 km in a north-south direction, closely fringing (locally, even abutting) the Andaman arc-trench bipolar gravity field. Regression analysis between gravity and bathymetry indicates that the ridge gravity field cannot be explained solely by its elevation. The ridge gravity field becomes gradually subdued northwards where overlying Bengal Fan sediments have a smaller density contrast with the ridge material. Our gravity interpretation, partly constrained by seismic data, infers that the ridge overlies significant crustal mass anomalies consistent with the hot spot model for the ridge. The anomalous mass is less dense by about 0.27 g cm–3 than the surrounding oceanic upper mantle, and acts as a cushion for isostatic compensation of the ridge at the base of the crust. This cushion is up to 8 km thick and 400–600 km wide. Additional complexities are created by partial subduction of the ridge below the Andaman Trench that locally modifies the arc-trench gravity field. 相似文献
7.
Geomorphological features (derived from 16,000 lkm of echo‐sounding and bathymetric data) and deep‐seated tectonic structures of the continental margin off NW India are presented. The shelf break over the entire region occurs between 80 to 154 m water depth, and adjacent to Saurashtra and Bombay High the depth and orientation of the shelf edge show marked variations. The boundary of the slope is shallower in the northern portion (about 1450 m in the vicinity of the Indus) than in the southern region (2900 m off Bombay). The steep slope off the Gulf of Kachchh has relatively smooth physiography due to higher input of fluvial sediment and burial of structures. The gentler slope off Saurashtra and the Bombay High area has numerous complex features, the most prominent among them being benches at depths of 180–230 m (width 2–10 km) and 650–780 m and a series of bathymetric highs and lows. Slope breaks are also observed between 400 and 600 m off Bombay and between 560 and 960 m off Saurashtra. These features are surface manifestations of the anticlinal features extending along the shelf in this region. Unevenness (order of 100–300 m) due to slumping is also observed at the base of the slope. Based on the correlation between tectonic structures of this area and these subphysiographic features, extension of the Saurashtra Anticline onto the slope, a new strike slip fault (the southern boundary fault of Narmada graben) and an along‐shelf anticlinal structure off Saurashtra are delineated. 相似文献
8.
Tang Yuxiang 《海洋学报(英文版)》1989,8(2):179-190
-A two-dimensional.nonlinear numerical model is used to study the residual current generated by tides in the East China Sea (ECS)and the South Huanghai Sea (SHS). At first, the principal semidiurnal lunar tide (M2)and the tidal current are derived in these areas. The results obtained with the model are strongly supported by the observational results available. Then, the tide-induced residual flow is determined by using the currents generated by the tidal input. The main features of the residual current in ECS and SHS are presented by analyzing the calculated results. Some of the problems are discussed such as the cause of generating residual current and the contribution of the residual current to the observed current. 相似文献
9.
The Bohai Strait is the only passage-way of the semienclosed Bohai Sea into the outer ocean. The various dynamical processes have great effects on both sides of the strait, especially on the Bohai Sea. Tidal current dominates in the strait, and among the tida! components the M, component tide is prevailing.The seawater in the strait is homogeneous vertically almost the whole year because of strong tidal mixing. The M, component tide was simulated numerically using two dimensional barotropical model, and the Eulerian tide-induced residual currents were also deduced. The results showed that the tidal currents were dominated by the coastal line and topography. There exist many eddies in the tide-induced residual current fields, particularly near the northern coast.On the basis of the simulation of the tidal currents, the movements of the water particles in the strait were tracked by means of Lagrangian techniques. Consequently the Lagrangian residual currents were obtained. Somewhat similar to the Eulerian 相似文献
10.
《Marine Policy》2016
The 1982 United Nations Convention on the Law of the Sea declares the seabed beyond national jurisdiction and its mineral resources as the “common heritage of mankind” (CHM). This article examines the operationalisation of the CHM principle in the international seabed mining regime, with focus placed on the sharing of benefits derived from mining. The article begins by providing an overview of the CHM principle, before examining four modalities provided for in the Convention, both institutional and substantial, and their role in giving effect to the CHM principle: (1) financial benefits; (2) the “Enterprise”; (3) the parallel system of reserved areas; and, (4) marine scientific research. Finally, overarching issues are discussed and some suggestions on ways forward are presented. The article considers that the deep seabed mining regime is not yet ready to effectively share the benefits derived from the common heritage of mankind. In particular, the future of the Enterprise is uncertain and changes to the so-called parallel system that affect the CHM have received minimal discussion. Moreover, a lack of publicly available research data related to seabed mining is hindering current benefits for humankind. However, work is underway at the International Seabed Authority to establish rules and policies with respect to the sharing of financial benefits. While the CHM principle remains largely untested, approaches that are transparent, inclusive, accountable, and equitable are more likely to be successful. 相似文献
11.
The continuous research and improvement of ocean modelling helps to provide a more sustainable development of coastal and offshore regions. This paper focuses on ocean modelling at the NW Mediterranean using the POLCOMS–WAM model with new developments. The Stokes’ drift effect on currents has been included and the distribution of surface stress between waves and currents has also been considered. The system is evaluated in the NW Mediterranean and an evaluation of different forcing terms is performed. The temperature and salinity distributions control the main patterns of the Mediterranean circulation. Currents are typically small and therefore the modification of waves due to the effect of currents is minimal. However, the wave induced currents, mainly caused by a modified wind drag due to waves, produce changes that become an important source of mass transport. POLCOMS was able to reproduce the main Mediterranean features, its coupling with WAM can be a very useful tool for ocean and wave modelling in the Mediterranean and other shelf seas. 相似文献
12.
Ocean current forecasting is still in explorative stage of study. In the study, we face some problems that have not been met before. The solving of these problems has become fundamental premise for realizing the ocean current forecasting. In the present paper are discussed in depth the physical essence for such basic problems as the predictability of ocean current, the predictable currents, the dynamical basis for studying respectively the tidal current and circulation, the necessity of boundary model, the models on regions with different scales and their link. The foundations and plans to solve the problems are demonstrated. Finally a set of operational numerical forecasting system for ocean current is proposed. 相似文献
13.
The tidal current is generally predominant in China's offshore areas. The vertical structure of the observedtidal current is quite complicated with the presence of seasonal thermocline. The observed tidal current may be divided into two parts, an averaged barotropic tide current and a variation tide current. A method for studying the vertical structure of tidal current is developed from the constitution and distribution of energy, and the vertical structure of the observed tide current in the North Huanghai Sea is studied on the basis of the method. The result shows that the reason why the energy of the tidal current is concentrated on the neighbourhood of the thermocline mainly lies in the internal tides i under certain conditions, the fact that the direction of the internal tide current above the thermocline is opposite to the one below the thermocline will be able to cause the rotary directions of the observed tidal current above and below the thermocline to be in opposite. The interaction between th 相似文献
14.
The wave climate at the Maui site off the west coast of the North Island and off the east coast of Great Barrier Island to the east of the North Island are examined. This is done by means of average wave spectra derived from a 2‐year database, acquired from Waverider buoy measurements made over 1980 and 1981. The average spectra provide information about the individual sea states which characterise the wave climate, and show that on average the sea state on the east coast is less energetic than it is on the west coast. Further, it is seen that this difference results largely from a dominant and persistent long‐period south‐westerly swell of 12.4 s period which is present at the Maui location but absent from the Great Barrier Island seas. 相似文献
15.
The breaking of wind-generated waves is an important phenomenon in the ocean, having close relation to many aspects of the ocean, such as air-sea interaction, ocean wave dynamics, oceanic remote sensing and ocean engineering. The first problem encountered in both its theoretical study and practical measurement is how to detect the breaking of waves. 相似文献
16.
An array of four sediment trap moorings recorded the particulate flux across the Antarctic Circumpolar Current (ACC) at 170 °W, between November 1996 and January 1998, as part of the US JGOFS-Antarctic Environment and Southern Ocean Process Study (AESOPS) program. The trap locations represent sampling within the Polar Frontal Zone, the Antarctic Polar Front, the Antarctic Zone and the Southern Antarctic Zone. Here we report observations from 1000 m below the sea-surface compared to seafloor and surface water distributions. Sub-sample splits from each trap were obtained and total diatom flux and species composition were determined. The diatom fluxes were quantified using both a dilution and a ‘spike’ method to allow for the rapid repeatability of measurements. Diatom flux was found to be highly seasonal across the ACC particularly at higher latitudes. Marine snow aggregates of intact diatom cells and chains were the major components of the biogenic flux. Siliceous particle size was noted to decrease with increasing latitude, which could be aligned with a shift of the diatom assemblage to small-size species/sea-ice affiliated species. A ‘double-structured’ diatom flux was recorded at the location of the Antarctic Polar Front trap, with a shift in the diatom assemblage from larger to smaller diatoms in the second flux episode. The sediment trap assemblage shows deviations from the surface water assemblage, while surface sediment samples indicate that significant dissolution occurs after 1000 m and at the sediment–water interface. Estimation of diatom biovolumes across the ACC shows that large diatoms have the potential to greatly impact biogenic fluxes to the ocean interior despite their low fluxes. Small species of the genus Fragilariopsis could potentially export as much Corg as Fragilariopsis kerguelensis near the retreating ice edge. However, their low abundance in the surface sediments also suggests that these diatoms are a shallow export species. 相似文献
17.
G. S. Karabashev 《Oceanology》2011,51(1):36-38
Based on the comparative analysis of the characteristics of the early summer maxima of the normalized radiance from the satellite
ocean color data, the seasonal trend of the concentration of the chlorophyll “a,” and the species composition of the phytoplankton
from determinations in water samples from the Black Sea, it is concluded that the summer chlorophyll maximum is due to the
coccolithophorid bloom occurring from late May to mid June in the Black Sea basin. 相似文献
18.
Analysis of characteristics and mechanism of current system on the west coast of Guangdong of China in summer 总被引：1，自引：2，他引：1
On the basis of data of drifting bottles＇ tracks and the current measured in anchored stations, as well as temperature and salinity observed in cruise investigations and coastal stations, ADCP current data and AVHRR surface sea temperature （SST） data on the western coast of Guangdong, synthetic results of analysis showed that the coastal currents in the west of the mouth of the Zhujiang River were mainly westward in summer, which constituted the north branch of cyclonic gyre in the east of the Qiongzhou Straits. Part of its water flowed westward into the Beibu Gulf through the Qiongzhou Straits. The coastal current pattern was not identical with the traditional current system which flowed westward in the Qiongzhou Straits in winter and eastward in summer. The summertime＇s coastal current was always westward, maybe temporarily turning northeast only when the southwest wind was strong. The important characteristics of coastal current on the western coast of Guangdong, in the Qiongzhou Straits and in the north of the Beibu Gulf were analyzed and their mechanisms also were explained. 相似文献
19.
Lihua Wang Benwei Shi Yunxuan Zhou Hui Sheng Yanghua Gao Li Fan Ziheng Yang 《海洋学报(英文版)》2021,40(12):135-147
Ocean currents are a key element in ocean processes and in meteorology, affecting material transport and modulating climate change patterns. The Doppler frequency shift information of the synthetic aperture radar (SAR) echo signal can reflect the dynamic characteristics of the sea surface, and has become an essential sea surface dynamic remote sensing parameter. Studies have verified that the instantaneous Doppler frequency shift can realize the SAR detection of the sea surface current. However, the validation of SAR-derived ocean current data and a thorough analysis of the errors associated with them remain lacking. In this study, we derive high spatial resolution flow measurements for the Kuroshio in the East China Sea from SAR data using a theoretical model of shifts in Doppler frequency driven by ocean surface current. Global ocean multi observation (MOB) products and global surface Lagrangian drifter (GLD) data are used to validate the Kuroshio flow retrieved from the SAR data. Results show that the central flow velocity for the Kuroshio derived from the SAR is 0.4–1.5 m/s. The error distribution between SAR ocean currents and MOB products is an approximate standard normal distribution, with the 90％ confidence interval concentrated between –0.1 m/s and 0.1 m/s. Comparative analysis of SAR ocean current and GLD products, the correlation coefficient is 0.803, which shows to be significant at a confidence level of 99％. The cross-validation of different ocean current dataset illustrate that the SAR radial current captures the positions and dynamics of the Kuroshio central flow and the Kuroshio Counter Current, and has the capability to monitor current velocity over a wide range of values. 相似文献
20.
Besides seasonal variation, instantaneous variation of thermal layer will occur under the effects of tide, tidal current and wind disturbance. In this study the numerical simulation has been first carried out on fluctuation and undulation of thermal layer under influence of tide (simultaneous input of 8 tidal components). The study reveals the geographic distribution of thermal layer fluctuation in the entire study region and temporal and spatial variations of the undulation in tidal period superposing on the fluctuation. Especially, the wave with large amplitude simulated is consistent with observation in the channal and the sea areas with a convex coastline and complex variation of depth, internal relations of tide, tidal current, residual current as well as the factors such as geography, and the fluctuation of thermal layer is induced by residual current due to unsymmetry which occurs as a result of the tidal movement in lower layer influenced by friction and geography, meanwhile, analysis indicates 相似文献