共查询到20条相似文献，搜索用时 15 毫秒
1.
A. V. Leonov V. M. Pishchal’nik V. S. Arkhipkin O. V. Chicherina 《Water Resources》2010,37(4):528-564
This study has no analogues in terms of methodology, as it uses three electronic instruments for studying the oceanographic
regime of Tatar Strait. GIS “Sakhalin Shelf” was used to reconstruct annual variations in hydrological and hydrochemical characteristics
of the marine environment at standard horizons of oceanographic stations in fixed geographic coordinates. An adapted version
of the Oceanic Model created in Bergen University was used to reconstruct the spatial and temporal distribution of seawater
temperature and salinity, to calculate the density and the circulation rate of water masses and water exchange parameters
between the strait and nearby water areas and between regions within the strait. The hydroecological CNPSi-model was next
used to assess the annual dynamics of concentrations of biogenic element compounds; the biomasses, biohydrochemical activity,
and bioproductivity of microorganisms (heterotrophic bacteria, three phytoplankton and two zooplankton groups), involved in
transformation of biogenic substances, as well as the internal fluxes of biogenic substances, governed by microorganism activity
and the external load onto the marine ecosystem. Analysis of calculation results made it possible to reveal new features in
water circulation in the strait (including those for winter) and, for the first time, to analyze the transport regime of biogenic
substances through the external boundaries of Tatar Strait and through the boundaries of three regions identified within the
strait. 相似文献
2.
The conditions of transformations of biogenic substances and the redistribution of their concentrations in the shelf water
of Sakhalin Island are studied. Preliminary works have given the results for the water area of La Perouse Strait and Aniva
Bay (the Sea of Okhotsk), while this paper gives such results for Tatar Strait (the Sea of Japan). Three electronic instruments
of oceanographic studies are applied: an adapted version of Bergen Oceanic Model (for the reconstruction of the space and
time distribution of seawater temperature, salinity, and density; the circulation intensity of water masses; and water exchange
parameters with nearby water areas and within the strait); GIS “Sakhalin Shelf” (for the reconstruction of annual variations
in thermohaline characteristics on a standard grid and horizons of oceanographic stations, and the parameters of the aquatic
environment); hydroecological CNPSi-model (for studying the annual dynamics of biogenic element compounds, the biomasses,
biohydrochemical activity and bioproduction of microorganisms—bacteria, phytoplankton, and zooplankton, taking part in transformation
of biogenic substances and petroleum hydrocarbons, as well as the internal fluxes of biogenic substances governed by the activity
of microorganisms and the external load on the marine ecosystem). The results of modeling the spatial transport of biogenic
substances through the outer boundaries of Tatar Strait water area and the boundaries of the three areas identified within
it are presented and discussed. 相似文献
3.
The dynamics of Bonifacio strait (south of Corsica) are investigated in a comprehensive study at long term from two set of data. First, by moored ADCP put in middle of the strait during six weeks (4 November 2004 to 7 January 2005), at a depth of 40 m and at few Kilometers from coast. Second, by velocity profiles obtained with a 314.4 kHz Acoustic Doppler Current Profiler (ADCP) during seven cruises (Cyrce) covering entirety strait. From moored ADCP data, a study is made on time correlation between wind stress and current. Shipboard ADCP data permits to obtain a general view in totality of strait and mostly to observe spatial variability. This study shows that the circulation is governed both by wind stress and by general circulation of Mediterranean Sea. 相似文献
4.
The ecohydrodynamics of the Gibraltar Strait and the Western Alboran Sea is investigated using a 3-D, two-way nested, coupled
hydrodynamic/plankton ecosystem model, exploiting the MEDATLAS climatological database. A high-resolution model (~1 km) of
the Gibraltar/Western Alboran region embedded within a coarse-resolution model of the West Mediterranean (~5 km) is implemented.
The model seasonal climatology of the 3-D circulation and the flow characteristics at the Gibraltar Strait and the Alboran
Sea are discussed, and their impact on the plankton ecosystem evolution is explored. An important ecohydrodynamic feature
produced by the model is a permanent upwelling zone in the northwestern part of the Alboran Sea in agreement with observations.
Model results show that both horizontal and vertical current intensity of the Atlantic Jet increases progressively at the
strait to obtain maximum values in the northeastern Mediterranean entrance, inducing an upward displacement of the nitracline.
The nutrient-rich water transport through the strait along with the generation of cyclonic vorticity in the northwestern Alboran
Sea result in the accumulation of nutrients there and thus induce a permanent fertilisation of this area. 相似文献
5.
In this paper, we use the unstructured grid model SCHISM to simulate the thermohydrodynamics in a chain of baroclinic, interconnected basins. The model shows a good skill in simulating the horizontal circulation and vertical profiles of temperature, salinity, and currents. The magnitude and phases of the seasonal changes of circulation are consistent with earlier observations. Among the mesoscale and subbasin-scale circulation features that are realistically simulated are the anticyclonic coastal eddies, the Sebastopol and Batumi eddies, the Marmara Sea outflow around the southern coast of the Limnos Island, and the pathway of the cold water originating from the shelf. The superiority of the simulations compared to earlier numerical studies is demonstrated with the example of model capabilities to resolve the strait dynamics, gravity currents originating from the straits, high-salinity bottom layer on the shallow shelf, as well as the multiple intrusions from the Bosporus Strait down to 700 m depth. The warm temperature intrusions from the strait produce the warm water mass in the intermediate layers of the Black Sea. One novel result is that the seasonal intensification of circulation affects the interbasin exchange, thus allowing us to formulate the concept of circulation-controlled interbasin exchange. To the best of our knowledge, the present numerical simulations, for the first time, suggest that the sea level in the interior part of the Black Sea can be lower than the sea level in the Marmara Sea and even in some parts of the Aegean Sea. The comparison with observations shows that the timings and magnitude of exchange flows are also realistically simulated, along with the blocking events. The short-term variability of the strait transports is largely controlled by the anomalies of wind. The simulations demonstrate the crucial role of the narrow and shallow strait of Bosporus in separating the two pairs of basins: Aegean-Marmara Seas from one side and Azov-Black Seas from the other side. The straits of Kerch and Dardanelles provide sufficient interbasin connectivity that prevents large phase lags of the sea levels in the neighboring basins. The two-layer flows in the three straits considered here show different dependencies upon the net transport, and the spatial variability of this dependence is also quite pronounced. We show that the blocking of the surface flow can occur at different net transports, thus casting doubt on a previous approach of using simple relationships to prescribe (steady) outflow and inflow. Specific attention is paid to the role of synoptic atmospheric forcing for the basin-wide circulation and redistribution of mass in the Black Sea. An important controlling process is the propagation of coastal waves. One major conclusion from this research is that modeling the individual basins separately could result in large inaccuracies because of the critical importance of the cascading character of these interconnected basins. 相似文献
6.
The problems of flow dynamics in a near-island zone of a shallow channel is considered using as an example the Bjerkezund Strait (eastern Gulf of Finland). Preliminary results of field studies and the results of numerical modeling of water circulation in the strait are given. 相似文献
7.
B. Rudels R. Meyer E. Fahrbach V. V. Ivanov S. Østerhus D. Quadfasel U. Schauer V. Tverberg R. A. Woodgate 《Annales Geophysicae》2000,18(6):687-705
The water mass distribution in northern Fram Strait and over the Yermak Plateau in summer 1997 is described using CTD data from two cruises in the area. The West Spitsbergen Current was found to split, one part recirculated towards the west, while the other part, on entering the Arctic Ocean separated into two branches. The main inflow of Atlantic Water followed the Svalbard continental slope eastward, while a second, narrower, branch stayed west and north of the Yermak Plateau. The water column above the southeastern flank of the Yermak Plateau was distinctly colder and less saline than the two inflow branches. Immediately west of the outer inflow branch comparatively high temperatures in the Atlantic Layer suggested that a part of the extraordinarily warm Atlantic Water, observed in the boundary current in the Eurasian Basin in the early 1990s, was now returning, within the Eurasian Basin, toward Fram Strait. The upper layer west of the Yermak Plateau was cold, deep and comparably saline, similar to what has recently been observed in the interior Eurasian Basin. Closer to the Greenland continental slope the salinity of the upper layer became much lower, and the temperature maximum of the Atlantic Layer was occasionally below 0.5 °C, indicating water masses mainly derived from the Canadian Basin. This implies that the warm pulse of Atlantic Water had not yet made a complete circuit around the Arctic Ocean. The Atlantic Water of the West Spitsbergen Current recirculating within the strait did not extend as far towards Greenland as in the 1980s, leaving a broader passage for waters from the Atlantic and intermediate layers, exiting the Arctic Ocean. A possible interpretation is that the circulation pattern alternates between a strong recirculation of the West Spitsbergen Current in the strait, and a larger exchange of Atlantic Water between the Nordic Seas and the inner parts of the Arctic Ocean. 相似文献
8.
Wang Dongxiao Wang Qiang Cai Shuqun Shang Xiaodong Peng Shiqiu Shu Yeqiang Xiao Jingen Xie Xiaohui Zhang Zhiwei Liu Zhiqiang Lan Jian Chen Dake Xue Huijie Wang Guihua Gan Jianping Xie Xinong Zhang Rui Chen Hui Yang Qingxuan 《中国科学:地球科学(英文版)》2019,62(12):1992-2004
The South China Sea(SCS) is a large marginal sea connecting the Indian and Pacific oceans.Under the factors of monsoons,strait transport,and varied bathymetry,the SCS presents a three-layer structure and strong diapycnal mixing which is far greater than that in the open ocean.Theoretical analysis and observations reveal that internal tides,internal solitary waves,and strong winds are the sources of the strong mixing in the northern SCS.A major consequence of the strong mixing is an active mid-deep circulation system.This system promotes exchange of water between the SCS and adjacent oceans,and also regulates the upper layer of wind-driven circulation,making the 3 dimensional SCS circulation clearly different from that in other tropical and subtropical marginal seas.The mass transport capacity of the mid-deep circulation has a substantial impact on marine sedimentation,the biogeochemical cycle,and other processes in the SCS.This paper summarizes the recent advances in middeep sea circulation dynamics of the SCS,and discusses the opportunities and challenges in this area. 相似文献
9.
A high-resolution modelling study of the Turkish Straits System 总被引：2，自引：2，他引：0
High-resolution modelling, for the first time, is used to study the basic hydrodynamics of the Turkish Straits System (TSS). Hydraulic controls in the Bosphorus and Dardanelles Straits are found to be essential in determining the coupled response of the TSS, which directly influences the interaction between the Mediterranean and Black Seas. The mixed baroclinic—barotropic response of the system is investigated as a function of the net barotropic flux and density stratification imposed at external boundaries, in the absence of atmospheric and tidal effects. The intense surface jet issuing from the Bosphorus is found to drive the basin-wide circulation of the Marmara Sea, varying with the net flux. The temporal response of the Bosphorus and Dardanelles Straits picks up rather fast, within a day or two, thanks to hydraulic controls within straits, while the surface currents in the Marmara Sea only approach steady state after a few months. Model stratification and circulation features are validated against independent measurements and a stand-alone model of the Bosphorus. 相似文献
10.
On the dynamics of strait flows: an ocean model study of the Aleutian passages and the Bering Strait
A high-resolution numerical ocean circulation model of the Bering Sea (BS) is used to study the natural variability of the BS straits. Three distinct categories of strait dynamics have been identified: (1) Shallow passages such as the Bering Strait and the Unimak Passage have northward, near barotropic flow with periodic pulses of larger transports; (2) wide passages such as Near Straits, Amukta Pass, and Buldir Pass have complex flow patterns driven by the passage of mesoscale eddies across the strait; and (3) deep passages such as Amchitka Pass and Kamchatka Strait have persistent deep return flows opposite in direction to major surface currents; the deep flows persist independent of the local wind. Empirical orthogonal function analyses reveal the spatial structure and the temporal variability of strait flows and demonstrate how mesoscale variations in the Aleutian passages influence the Bering Strait flow toward the Arctic Ocean. The study suggests a general relation between the barotropic and baroclinic Rossby radii of deformations in each strait, and the level of flow variability through the strait, independent of geographical location. The mesoscale variability in the BS seems to originate from two different sources: a remote origin from variability in the Alaskan Stream that enters the BS through the Aleutian passages and a local origin from the interaction of currents with the Bowers Ridge in the Aleutian Basin. Comparisons between the flow in the Aleutian passages and flow in other straits, such as the Yucatan Channel and the Faroe Bank Channel, suggest some universal topographically induced dynamics in strait flows. 相似文献
11.
We have performed laboratory experiments using a Hele-Shaw cell to model a saturated, porous layer with various sinusoidal upper boundaries. Our intent was to determine the range of conditions over which boundary topography can control the pattern of thermal convection within a porous layer, and thereby take the first step toward understanding why heat flow seems correlated with hypsography in many areas of the ocean floor.These experiments indicate that above the critical Rayleigh number, topography does not control the convection pattern, except when the topographic wavelength is comparable to the depth of water penetration. Scaled to the depth of the layer, the convective wavenumbers are restricted to values between 2.5 and 4.8—a range which brackets π, the natural wavenumber for convection in a porous slab with planar, isothermal, impermeable boundaries. Topographies within this range control the circulation pattern perfectly, with downwelling under valleys and upwelling aligned with topographic highs. Other topographies do not force the pattern, although in some cases, the convection wavenumber may be a harmonic of the topographic wavenumber. Unforced circulation cells wander and vary in size, because they are not locked to the topography.For these experiments we employed eight different topographies with non-dimensional wavenumbers between 1.43 and 8.17, and we studied the flow at Rayleigh numbers between zero and five times the critical Rayleigh number. The amplitude of each topography tapered linearly (over a factor of three to six) from one end of the apparatus to the other, and the mean topographic amplitude was 0.05 times the depth of the layer. Under these conditions, amplitude has only a minor effect on the structural form and vigor of supercritical convection.Our results may apply to submarine geothermal systems, sealed by a thin layer of impermeable sediment draped over the basement topography. In this case, the convection wavelength—as measured perhaps by the spatial periodicity of conductive heat flow—may be a good measure of the depth to which water penetrates the crust. Where the circulation correlates with the bottom topography, it may be because the topographic wavelength is comparable to the depth to which water penetrates the porous crust. 相似文献
12.
Ocean circulation influences nearly all aspects of the marine ecosystem. This study describes the water circulation patterns on time scales from hours to years across Torres Strait and adjacent gulfs and seas, including the north of the Great Barrier Reef. The tridimensional circulation model incorporated realistic atmospheric and oceanographic forcing, including winds, waves, tides, and large-scale regional circulation taken from global model outputs. Simulations covered a hindcast period of 8 years (i.e. 01/03/1997–31/12/2004), allowing the tidal, seasonal, and interannual flow characteristics to be investigated. Results indicated that the most energetic current patterns in Torres Strait were strongly dominated by the barotropic tide and its spring-neap cycle. However, longer-term flow through the strait was mainly controlled by prevailing winds. A dominant westward drift developed in summer over the southeasterly trade winds season, which then weakened and reversed in winter over the northwesterly monsoon winds season. The seasonal flow through Torres Strait was strongly connected to the circulation in the north of the Great Barrier Reef, but showed little connectivity with the coastal circulation in the Gulf of Papua. Interannual variability in Torres Strait was highest during the monsoon period, reflecting variability in wind forcing including the timing of the monsoon. The characteristics of the circulation were also discussed in relation to fine sediment transport. Turbidity level in Torres Strait is expected to peak at the end of the monsoon, while it is likely to be at a low at the end of the trade season, eventually leading to a critically low bottom light level which constitutes a severe risk of seagrass dieback. 相似文献
13.
We describe the solutions of a numerical two-layer primitive equation model of an idealized Strait of Gibraltar and an adjacent eastward basin. The quasi-steady circulation pattern in the basin features an anticyclonic gyre southward of the strait exit and an eastward boundary current attached to the southern boundary of the basin. A variation of the initial upper-layer depth and the target interface height at the eastern boundary causes minor changes of the upper-layer circulation in a basin with rectangular coastline and larger changes when a cape is added to the coastline of the southern boundary. 相似文献
14.
Almudena Fontán Manuel González Neil Wells Michael Collins Julien Mader Luis Ferrer Ganix Esnaola Adolfo Uriarte 《Continental Shelf Research》2009,29(8):998-1007
The Basque coastal area, in the southeastern Bay of Biscay, can be characterised as being more influenced by land climate and inputs, than other typically ‘open sea’ areas. The influence of coastal processes, together with the presence of irregular and steep topography, complicate greatly the water circulation patterns. Water movement along the Basque coastal area is not well understood; observations are scarce and long-term current records are lacking. The knowledge available is confined to the surface currents: the surface water circulation is controlled mainly by wind forcing, with tidal and density currents being weak. However, there is a lack of knowledge available on currents within the lower levels of the water column; likewise, on the main time-scales involved in the water circulation. This study quantifies the contribution of the tidal and wind-induced currents, to the overall water circulation; it identifies the main time-scales involved within the tidal and wind-induced flows, investigating difference in such currents, throughout the water column, within Pasaia Bay (Basque coast). Within this context, extensive oceanographic and meteorological data have been obtained, in order to describe the circulation. The present investigation reveals that the circulation, within the surface and the sub-surface waters, is controlled mainly by wind forcing fluctuations, over a wide range of meteorological frequencies: third-diurnal, semidiurnal and diurnal land–sea breezes; synoptic variability; frequencies, near fortnightly periods; and seasonal. At the lower levels of the water column, the main contribution to the water circulation arises from residual currents, followed by wind-induced currents on synoptic time-scales. In contrast, tidal currents contribute minimally to the overall circulation throughout the water column. 相似文献
15.
The state of the marine environment (the temperature, light intensity, transparency, biogenic load) in Tatar Strait was assessed
based on mean annual data from literary sources and with the use of GIS “Sakhalin Shelf.” The entire strait was divided into
three regions (northern, southwestern, and southeastern), and water exchange between them for each month was estimated by
using Bergen Oceanic Model. The information about the state of the marine environment and water exchange characteristics was
used as input data for a hydroecological model, which enabled the assessment of annual variations of biogenic substance concentrations
and biomasses of microorganisms (heterotrophic bacteria, three groups of phytoplankton, and two groups of zooplankton) in
the strait regions chosen. The development conditions of microorganism biomasses within the year can be characterized by their
activity indices (specific growth rates), the values of internal fluxes of biogenic substances, and calculated bioproductivity
values. The calculated biogenic substance concentrations and phytoplankton bioproductivity values showed good agreement with
the estimates for the Sea of Japan and Tatar Strait available from the literature. 相似文献
16.
Dynamics of the circulation in the Sea of Marmara: numerical modeling experiments and observations from the Turkish straits system experiment 总被引：4，自引：3，他引：1
During September 2008 and February 2009, the NR/V Alliance extensively sampled the waters of the Sea of Marmara within the
framework of the Turkish Straits System (TSS) experiment coordinated by the NATO Undersea Research Centre. The observational
effort provided an opportunity to set up realistic numerical experiments for modeling the observed variability of the Marmara
Sea upper layer circulation at mesoscale resolution over the entire basin during the trial period, complementing relevant
features and forcing factors revealed by numerical model results with information acquired from in situ and remote sensing
datasets. Numerical model solutions from realistic runs using the Regional Ocean Modeling System (ROMS) produce a general
circulation in the Sea of Marmara that is consistent with previous knowledge of the circulation drawn from past hydrographic
measurements, with a westward meandering current associated with a recurrent large anticyclone. Additional idealized numerical
experiments illuminate the role various dynamics play in determining the Sea of Marmara circulation and pycnocline structure.
Both the wind curl and the strait flows are found to strongly influence the strength and location of the main mesoscale features.
Large displacements of the pycnocline depth were observed during the sea trials. These displacements can be interpreted as
storm-driven upwelling/downwelling dynamics associated with northeasterly winds; however, lateral advection associated with
flow from the Straits also played a role in some displacements. 相似文献
17.
Ｃｈａｒａｃｔｅｒｉｓｔｉｃｓ ａｎｄ ａｎａｌｙｓｉｓ ｏｆ ｔｈｅ ｇｅｏｍａｇｎｅｔｉｃ ｖａｒｉａｔｉｏｎｓ ｉｎ ｒｅｇｉｏｎｓ ａｒｏｕｎｄ ｔｈｅ Ｑｉｏｎｇｚｈｏｕ Ｓｔｒａｉｔ（范国华）（姚同起）（顾左文）（朱克佳）（陈伯舫）（冯戬... 相似文献
18.
Study on the transverse structures across Taiwan Strait 总被引：3，自引：0，他引：3
The mountain ranges are almost NE- or NNE-trending in mainland and Taiwan island across the strait. But a number of correspondent
transverse structures across Taiwan Strait have been identified on the basis of morphology, surface structure, deep seismic
survey and gravity field etc. Moreover, it is inferred from the square or/and rectangular shape of the isoseist maps of 8
M≥ 6 earthquakes occurring in the western foothill plain of Taiwan that there is an apparent segmentation of the Taiwan Island
along the N-S orientation. This has been verified from the GPS’s results of the ground motions measured during the Chi-Chi
earthquake in 1999. As a matter of fact, the transverse structures within the Taiwan Island could be correlated with more
salient NW- and EW-trending structures in the mainland of Fujian than in Taiwan. The investigation of the transverse structures
across Taiwan Strait is conducive to realizing the geology within the strait. Hence, the tectonic sketch map of the strait
as well as mainland and island drawn in this context shows NW- and EW-trending structures for the study area. 相似文献
19.
Ocean Dynamics - We present research on the excitation of ocean surface wind waves in non-homogeneous situations, for the case of a deep water strait in the presence of a constant wind, blowing... 相似文献
20.
琼州海峡裂谷成因的火山活动标志 总被引：4，自引：0，他引：4
张虎男 《地震地磁观测与研究》1996,(4)
根据雷琼地区存在大规模火山活动以及新生界明显地由断陷的南、北侧向海峡急剧增厚的事实，结合近年来海峡地区的物探成果，论证了琼州海峡的裂谷成因，是上地幔物质上涌的结果。该地区的高热流值、高地热增温率和强震活动都说明，琼州海峡是现今仍具有一定活动性的裂谷构造。 相似文献