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1.
The wind-induced water exchange between the ria of Ferrol (NW Spain) and the adjacent shelf is analyzed by means of a three-dimensional hydrodynamic model (MOHID2000). Since thermohaline measurements indicate that the estuary can be considered vertically homogeneous a barotropic version of the model has been used. Real in situ wind measurements have been used for model calibration and further analysis. The approach to study the wind effect on water exchange through the ria strait consisted in subtracting the signal calculated with only tidal forcing (Ts) from the one with wind and tidal forcing (WTs). This shows the existence of a residual circulation, with water flowing in wind direction along surfaces layers and a counter current flowing in the opposite direction at bottom layers. The flux across the strait of Ferrol has shown to increase linearly on wind strength, with a correlation larger than 96% and reaching values close to 20 m3 s−1 under real wind forcing.  相似文献   

2.
An internal gravity wave model was employed to simulate the generation of internal solitary waves(ISWs) over a sill by tidal flows. A westward shoaling pycnocline parameterization scheme derived from a three-parameter model was adopted, and then 14 numerical experiments were designed to investigate the influence of the pycnocline thickness, density difference across the pycnocline, westward shoaling isopycnal slope angle and pycnocline depth on the ISWs. When the pycnocline thickness on both sides of the sill increases, the total barotropic kinetic energy, total baroclinic energy and ratio of baroclinic kinetic energy(KE) to available potential energy(APE) decrease, whilst the depth of isopycnal undergoing maximum displacement and ratio of baroclinic energy to barotropic energy increase. When the density difference on both sides of the sill decreases synchronously, the total barotropic kinetic energy, ratio of baroclinic energy to barotropic energy and total baroclinic energy decrease, whilst the depth of isopycnal undergoing maximum displacement increases. When the westward shoaling isopycnal slope angle increases, the total baroclinic energy increases whilst the depth of turning point almost remains unchanged. When the depth of westward shoaling pycnocline on both sides of the sill reduces, the ratio of baroclinic energy to barotropic energy and total baroclinic energy decrease, whilst the total barotropic kinetic energy and ratio of KE to APE increase. When one of the above four different influencing factors was increased by 10% while the other factors keep unchanged, the amplitude of the leading soliton in ISW Packet A was decreased by 2.80%, 7.47%, 3.21% and 6.42% respectively. The density difference across the pycnocline and the pycnocline depth are the two most important factors in affecting the characteristics and energetics of ISWs.  相似文献   

3.
《Oceanologica Acta》2002,25(2):51-60
A new composite model, which consists of a generation model of the internal tides and a regularized long wave propagation model, is presented to study the generation and evolution of internal solitary waves in the sill strait. Internal bores in the sill strait are first simulated by the generation model, and then the internal tidal field outside of the sill region is given as input for the propagation model. Numerical experiments are carried out to study the imposing tide, depth profile, channel width and shoaling effect, etc., on the generation and evolution of internal solitary waves. It is shown that only when the amplitude of internal tide at the forcing boundary of the propagation model is large enough that a train of internal solitary waves would be induced. The amplitude of the imposing tide in the generation model, shoaling effect, asymmetry of the depth profile and channel width have some effects on the amplitude of the induced internal solitary wave. The imposing tidal flow superimposed on a constant mean background flow has a great damping effect on the induced internal waves, especially on those propagate against the background flow direction. The generation and propagation of internal solitary waves in three possible straits among the Luzon Strait are simulated, and the reasons for the asymmetry of their propagation are also explained.  相似文献   

4.
Numerical experiments with two-dimensional nonhydrostatic model have been performed to investigate tidally generated internal waves at the Dewakang sill at the southern Makassar Strait where two large-amplitude “bumps” of relatively shallow water exist. We investigate the effect of these features on vertical mixing, with emphasis on the transformation of the Indonesian throughflow (ITF) water properties. The result shows that large-amplitude internal waves are generated at both bumps by the predominant M2 tidal flow, even though the condition of the critical Froude number and the critical slope are not satisfied. The internal waves induce such vigorous vertical mixing in the sill region that the vertical diffusivity attains a maximum value of 6 × 10−3 m2s−1 and the salinity maximum and minimum core layers characterizing the ITF thermocline water are considerably weakened. Close examination reveals that bottom-intensified currents produced mainly by the joint effect of barotropic M2 flow and internal tides generated in the concave region surrounding both bumps can excite unsteady lee waves (Nakamura et al., 2000) on the inside slopes of the bumps, which tend to be trapped at the generation region and grow into large-amplitude waves. Such generation of unsteady lee waves does not occur in case of one bump alone. Trapping and amplification of the waves in the sill region induce large vertical displacements (∼60 m) of water parcels during one tidal period, leading to strong vertical mixing there. Since the K1 tidal currents are relatively weak, large-amplitude internal waves causing intense vertical mixing are not generated. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

5.
Internal bores are a common feature of tidally modulated two-layer exchange flows through straits and over sills. Even where the forcing changes smoothly, the flow may adjust with sudden jumps in the position of the interface between the two layers. The resulting flow configuration, with a hydraulically controlled exchange flow (at the sill) coupled with a propagating internal hydraulic jump (known as a bore), is investigated with mathematical models and laboratory experiments. The study concentrates on two-dimensional flow in a rectangular channel with a sill. The parameters considered are the depth of the channel compared to the depth over the sill, the depth of the interface before the passage of the bore and the strength of the net flux through the channel.The theory is based on shallow water equations and hydraulic control theory and includes the effects of a steady net flow through the channel (driven, for example, by the tide). Once the depth of the channel is twice the depth over the sill, further changes in geometry have relatively little effect on the flow. The bore velocity and fluxes are strongly affected by the strength of any net flow. The laboratory experiments model pure exchange flows (with no net flow) and give detailed information about the bores themselves. In many cases an undular bore is produced, with a well-defined wave train on the interface behind the front of the bore. The wavelengths and amplitudes of these internal waves are quantified and a brief comparison with similar internal waves observed in the Strait of Gibraltar is presented.  相似文献   

6.
吐噶喇海峡是西北太平洋重要的内潮产生区域,该区域内产生的内潮对于东海陆架和西北太平洋的混合和物质输运有十分重要的作用。水平分辨率为3km的JCOPE-T(JapanCoastalOcean PredictabilityExperiment—Tides)水动力学模式的结果表明,吐噶喇海峡的内潮主要产生在地形变化剧烈的海山和海岛附近,其引起的等密面起伏振幅可达30m。吐噶喇海峡的内潮在垂直于等深线方向分为两支向外传播:一支向西北方向传播,进入东海陆架后迅速减小;另一支向东南方向传播,进入西北太平洋。吐噶喇海峡潮能丰富,其在约半个月内的平均输入的净正压潮能通量为13.92GW,其中约有3.73GW转化为内潮能量。生成的内潮能量有77.2%在当地耗散,传出的内潮能通量为0.84GW,主要通过西北和东南两个边界传出。该区域潮能通量有显著的大小潮变化,大潮期间输入的正压潮净能通量和产生的内潮能通量均约为小潮期间的2倍,但其主要产生区域基本不变,且内潮能量耗散比率均在产生的内潮通量的76%—79%。另外,内潮能通量的传播方向也没有发生变化,仍主要通过西北和东南两个边界传出。因此,大小潮的变化仅影响吐噶喇海峡处产生的内潮能量的大小,不影响其产生区域、传播方向和耗散比率。  相似文献   

7.
《Marine Geology》2003,201(4):253-267
A series of simple hydraulic calculations has been performed to examine some of the questions associated with the reconnection of the Black Sea to the Mediterranean through the Turkish Strait System during the Holocene. Ryan et al.’s catastrophic flood scenario, whereby the erosive power of the marine in-fluxes, initiated after eustatic sea level reached the sill depth, opened up the Bosphorus, allowing saline water to pour into the Black Sea and filling it on a short time scale, is examined. The calculations show that although it might be possible to fill the palaeo-Black Sea within the order of a decade, a 1–2 year filling time scale is not physically possible. A hydraulic model is also used to examine the more traditional connection hypothesis of (near-)continuous freshwater outflow from the Black Sea, with a slowly increasing saline inflow from the Mediterranean beginning around 8–9 kyr BP. The model considers two forms for the structure of the Bosphorus: a shallow sill as seen today and a deep sill associated with no sediments filling the 100 m gorge above the bedrock in the strait. Sensitivity experiments with the hydraulic model show what possible strait geometric configurations may lead to the Black Sea reaching its present-day salinity of 18 psu. Salinity transients within the Black Sea are shown as a function of time, providing for values that can be validated against estimates from cores. To consider a deep, non-sediment-filled Bosphorus (100 m deep), the entry of Mediterranean water into the Sea of Marmara after 12.0 kyr BP is examined. A rapid entry of marine water into the Sea of Marmara is only consistent with small freshwater fluxes flowing through the Turkish Strait System, smaller than those of the present day by a factor of at least 4. Such a small freshwater flux would lead to the salinification of the Black Sea being complete by an early date of 10.2–9.6 kyr BP. Thus the possibility of a deep Bosphorus sill should be discounted.  相似文献   

8.
The Dardanelles Strait is a remarkable example of a long, narrow, shallow, and strongly stratified strait with bidirectional exchange that is governed by both baroclinic and barotropic forcing with a wide spectrum of variability. A three-dimensional free surface primitive equation model is applied to study seasonal hydrodynamics variability in this strait. The calculated vertical structure of temperature, salinity, and velocity fields agrees well with available survey data. Seasonal monthly values of the volume exchange at the Aegean and Marmara exits are estimated. It is found that the seasonal exchange dynamics is governed by the turbulent friction and entrainment at the Nara Passage area. The mean annual water transport in the upper layer is increased by 80% after the Nara Passage. About 25% of water entering in the Dardanelles bottom layer reaches the Marmara Sea in winter, and 50% reaches it in summer. The estimate of the Dardanelles hydrodynamics according to hydraulic and viscous–advective–diffusive regime classification shows significant deviation from the two-layer hydraulic asymptotic. However, according to three-layer hydraulic theory, the flow is found to be critical in the Nara Passage area.  相似文献   

9.
A high resolution modeling study is undertaken, with a 2.5-dimensional nonhydrostatic model, of the generation of internal waves induced by tidal motion over the ridges in Luzon Strait. The model is forced by the barotropic tidal components K1, M2, and O1. These tidal components, along with the initial density field, were extracted from data and models. As the barotropic tide moves over the Luzon Strait sills, there is a conversion of barotropic tidal energy into baroclinic tidal energy. Depressions are generated that propagate towards the Asian Seas International Acoustics Experiment (ASIAEX) test site on the Chinese continental shelf. Nonlinear effects steepen the depressions, frequency and amplitude dispersion set in, and disintegration into large amplitude solitary waves occurs. The effects of varying the initial density field, tidal component magnitudes, as well as adding a steady background current to represent the occasional excursions of the Kuroshio Current into the strait, are considered.Depressions are generated at each of the two sills in Luzon Strait which radiate away, steepening and evolving into internal solitary wave trains. Baroclinic fluxes of available potential energy, kinetic energy and linear are calculated for various parameter combinations. The solitary wave trains produced in the simulations generally consist of large amplitude wave trains alternating with small amplitude wave trains. During strong tidal flow, Kelvin–Helmholtz type instabilities can develop over the taller double-humped sill. The solitary waves propagating towards the ASIAEX test site have been observed to reach amplitudes of 120–250 m, depending on the tidal strength. ASIAEX observations indicate amplitudes up to 150 m and the Windy Island Experiment (WISE) measurements contain magnitudes over 200 m. The model results yield solitary wave amplitudes of 70–300 m and half widths of 0.60–3.25 km, depending on parameter values. These are in the range of observations. Measurements by Klymak et al. (2006), in the South China Sea, exhibit amplitudes of 170 m, half widths of 3 km and phase speeds of 2.9 m s?1. Model predictions indicate that the solitary waves making up the wave packet each experience different background currents with strong near surface shear.The energy in the leading soliton of the large amplitude wave trains ranges between 1.8 and 9.0 GJ m?1. The smaller value, produced using barotropic tidal currents based on the Oregon State University data base, is the same as the energy estimated to be in a solitary wave observed by Klymak et al. (2006). Estimates of the conversion of barotropic tidal energy into radiating internal wave energy yield conversion rates ranging between 3.6% and 8.3%.  相似文献   

10.
We report measurements of iron, nutrients, dissolved oxygen, humic-type fluorescence intensity and chlorophyll a concentrations in the coastal waters at the inflow (western) and outflow (eastern) ends of Tsugaru Strait (Japan) in June 2003 and 2004. Two different water masses (intensive eastward flow “subtropical Tsugaru Warm Current Water (TWCw)” and weak westward flow “subarctic Oyashio Water (OW)”) were observed at the eastern end of the strait. TWCw at the southern part of the eastern strait was vertically homogeneous with a uniform concentrations of iron (0.7–1.1 nM for labile dissolved Fe and 14–20 nM for total dissolvable Fe in 2003) as well as other chemical, biological and physical components throughout the water column of 200 m due to strong vertical mixing in the strait. The degree of mixing in the Tsugaru Warm Current (TWC) is predominantly affected by diurnal tidal current, which is strong during the period of tropical tides and weak during the period of equinoctial ones. The especially strong vertical water mixing in 2003 is caused by large dissipation energy input due to the bottom friction of passage-flow through the strait and tidal current. At the northern part of the eastern strait, the fresh surface layer overlying the OW and the deep-bottom waters in 2003 contained large concentrations of dissolved iron, resulting from iron supplied from river runoff and shelf sediments, respectively. These results suggest that the most important mechanism for transporting iron in the strait is the strong vertical water mixing due to the tidal current, and that the iron sources in the coastal waters are the organic-associated, iron-rich freshwater input into the surface water.  相似文献   

11.
The potential role of the tide-induced time-mean flow (the tidal residual current) in determining transport through the Tsugaru Strait (located between the East/Japan Sea and the North Pacific) is investigated using a high-resolution numerical barotropic model. The calculated K1, O1, M2, and S2 tidal fields agree well with available observational records derived from both tide gauge and current meter measurements in the strait and the adjacent seas. The tidal residual current speed reaches 0.3 ms−1 in two narrow “neck” areas where topographic sills are located. This result suggests that tides should be taken into account in estimating the long-term water mass and nutrient transport through narrow regions between the East/Japan Sea and the North Pacific. An interesting aspect of the tidal residual current field is the prediction of several active eddy zones in which sequences of eddy triplets develop in the vicinity of capes. Our vorticity analysis reveals that the interplay of topographic effects arising from both the headland and the sill around capes plays a critical role in the formation of these triple eddy patterns.  相似文献   

12.
The generation mechanism of internal waves by a relatively strong tidal flow over a sill is clarified analytically. Special attention is directed to the role of the tidal advection effect, which is examined by use of characteristics. An internal wave which propagates upstream is gradually formed through interference of infinitesimal amplitude internal waves (elementary waves) emanating from the sill at each instant of time. In the accelerating (or decelerating) stage of the tidal flow, the effective amplification of the internal wave takes place as the internal Froude number exceeds (or falls below) unity because during this period the internal wave slowly travels downstream (or upstream) while crossing over the sill where elementary waves are efficiently superimposed. In fact, the variability in the internal wave field actually observed in a realistic situation (Stellwagen Bank in Massachusetts Bay) is shown to be satisfactorily interpreted in terms of this mechanism. Furthermore, by using this analytical model, the relation between the strength of the tidal advection effect and the resulting internal waveform is clarified. This theory is easily extended to include a vertically sheared steady flow. In this case, although the fundamental generation mechanism is the same as above, the amplitude of the elementary wave varies with time depending on the relative direction of the tidal flow and steady shear flow, so that the internal wave field over the sill differs markedly between the ebb and flood tidal phases. As an example, the internal wave generation process over the sill in the Strait of Gibraltar is qualitatively discussed on the basis of this analytical model. The effect of vertical mixing caused by breaking of these large-amplitude internal waves on the coastal environment is also pointed out. In particular, a brief discussion is made on the control of water exchange by the fortnightly modulation of tidal mixing processes at the sills and constrictions in channels connecting freshwater sources with the ocean.  相似文献   

13.
We document the accuracy and convergence of solutions for a z-coordinate primitive-equation model of internal tide generation and propagation. The model, which is based on MOM3 numerics, is linearized around a state of rest to facilitate comparison with analytic estimates of baroclinic generation at finite-amplitude topography in a channel forced by barotropic tidal flow at its boundaries. Unlike the analytical model, the numerical model includes mixing of both buoyancy and momentum, and several definitions of “baroclinic conversion” are possible. These are clarified by writing out the energetics of the linearized equations in terms of barotropic kinetic energy, baroclinic kinetic energy, and available potential energy. The tidal conversion computed from the model, defined as the rate of conversion of barotropic kinetic energy into available potential energy, agrees well with analytical predictions. A comparison of different treatments of bottom topography (full-cells, partial-cells, and ghost-cells) indicates that the partial-cell treatment is the most accurate in this application. Convergence studies of flow over a smooth supercritical ridge show that the dissipation along tidal characteristics is, apparently, an integrable singularity. When the ocean bottom is not smooth, the accuracy and convergence of the model depend on the power spectrum of the topography. A numerical experiment suggests that the power spectrum of the resolved topography must roll off faster than k−2 to obtain convergent results from a linear numerical model of this type.  相似文献   

14.
Previous observations in the Gareloch, a Scottish silled fjord, have identified yet failed to explain the baroclinic circulation pattern. Additional fieldwork was carried out in April 2005, showing the loch to be stratified with two distinct layers and currents in each layer 180° out of phase at the M2 frequency. The currents did not display the expected sinusoidal signal that is characteristic of the tide and instead were pulsated and stronger than predicted by barotropic forcing. Fourier analysis showed that the flow was dominated by short period non-linear oscillations that were harmonics of the semi-diurnal tide. Two hydrostatic estuarine models were applied to the Gareloch: a 2D vertical model (SLICE) and a 3D model (ECOMSED). Both models were capable of reproducing the observed (2005) baroclinic circulation at the M2 time scale but failed to simulate the higher frequency, non-linear oscillations. However, each model generated higher harmonics in idealised scenarios. Because lateral motion was negligible and SLICE was an order of magnitude more efficient than ECOMSED, the 2D model was used to simulate the higher harmonics and showed that their generation was attributed to the non-linear distortion of the internal tide. When the internal Froude number (determined by barotropic velocity, stratification and water depth) was increased from a sub-critical value, non-linear advection became more important and higher harmonics were generated. The internal tide was further modified by wave reflection and interaction off steep boundaries, and by flow over the sill.  相似文献   

15.
We have investigated the three-dimensional Lagrangian motion of water particles related with tidal exchange between two basins with a constant depth connected through a narrow strait and the effects of density stratification on the exchange processes by tracking a number of the labeled particles. Tide-induced transient eddies (TITEs), which are similar to those in two-dimensional basin, are generated behind the headlands. Upwelling appears around the center of the eddy and sinking around the boundary. When the basins are filled with homogeneous water, a pair of vortices are produced in the vertical cross section of the strait due to bottom stress, with upwellings along the side walls of the strait and sinking in the center of the strait. These circulations form the horizontally convergent field in the cross-strait direction in the upper layers while the horizontal divergence takes place in the bottom layer. These vertical water-motions produce the three-dimensional distribution of velocity shear and phase lag of the tidal current around the strait, and the Lagrangian drifts of water particles become large. As a result, water exchange through the strait is greatly enhanced: The water exchange rate reaches 94.1% which is much larger than that obtained in the vertically integrated two-dimensional model. When the basins are stratified, the stable stratification suppresses the vertical motion so that a pair of vertical vortices are confined in the lower layers. This leads to a decrease in the exchange rate, down to 88.6%. Our numerical results show that the three-dimensional structure of tidal currents should be taken into account in tidal exchange through a narrow strait.  相似文献   

16.
The three-dimensional numerical model SUNTANS is applied to investigate river plume mixing in Otsuchi Bay, an estuary located along the Sanriku Coast of Iwate, Japan. Results from numerical simulations with different idealized forcing scenarios (barotropic tide, baroclinic tide, and diurnal wind) are compared with field observations to diagnose dominant mixing mechanisms. Under the influence of combined barotropic, baroclinic and wind forcing, the model reproduces observed salinity profiles well and achieves a skill score of 0.94. In addition, the model forced by baroclinic internal tides reproduces observed cold-water intrusions in the bay, and barotropic tidal forcing reproduces observed salt wedge dynamics near the river mouths. Near these river mouths, vertically sheared flows are generated due to the interaction of river discharge and tidal elevations. River plume mixing is quantified using vertical salt flux and reveals that mixing near the vicinity of the river mouth, is primarily generated by the barotropic tidal forcing. A 10 ms?1 strong diurnal breeze compared to a 5 ms?1 weak breeze generates higher mixing in the bay. In contrast to the barotropic forcing, internal tidal (baroclinic) effects are the dominant mixing mechanisms away from the river mouths, particularly in the middle of the bay, where a narrow channel strengthens the flow speed. The mixing structure is horizontally asymmetric, with the middle and northern parts exhibiting stronger mixing than the southern part of the bay. This study identifies several mixing hot-spots within the bay and is of great importance for the coastal aquaculture system.  相似文献   

17.
Another description of the Mediterranean Sea outflow   总被引：1，自引：0，他引：1  
Papers about the outflow in the Strait of Gibraltar assume that (i) it is composed of only two Mediterranean Waters (MWs), the Levantine Intermediate Water (LIW) and the Western Mediterranean Deep Water (WMDW) from the eastern and western basins, respectively, (ii) both MWs are mixed near 6°W, hence producing a homogeneous outflow that is then split into veins, due to its cascading along different paths and to different mixing conditions with the Atlantic Water (AW).A re-analysis of 1985–1986 CTD profiles (Gibraltar Experiment) indicates two other MWs, the Winter Intermediate Water (WIW) from the western basin and the Tyrrhenian Dense Water (TDW) basically originated from the eastern basin. In the central Alboran subbasin, these four MWs are clearly differentiated, roughly lying one above the other in proportions varying from north to south. Proportions also vary with time, so that the outflow can be mostly of either eastern or western origin. While progressing westward, the MWs can still be differentiated and associated isopycnals tilt up southward as much as being, in the sill surroundings, roughly parallel to the Moroccan continental slope where the densest MWs are. The MWs at the sill are thus juxtaposed and they all mix with AW, leading to an outflow that is horizontally heterogeneous just after the sill (5°45′W) before progressively becoming vertically heterogeneous as soon as 6°15′W. There can be little LIW and/or no WMDW outflowing for a while.An analysis of new 2003–2008 time series from two CTDs moored (CIESM Hydro-Changes Programme) at the sill (270 m) and on the Moroccan shelf (80 m) confirms the juxtaposition of the MWs, their individual and generally intense mixing with AW, as well as the large temporal variability of the outflow composition. Only LIW and TDW were indicated at the sill while, on the shelf, only LIW, TDW sometimes denser there than 200 m below, and WMDW were indicated; but none of the MWs has been permanently outflowing at one or the other place.The available data can be analyzed coherently. Intermediate and deep MWs are formed in both basins in amounts that, although variable from year to year, allow their tracing up to the strait. Four major MWs circulate alongslope counterclockwise as density currents and as long as they are not trapped within a basin, which is necessarily the case for the deep MWs. In the Alboran, the intermediate MWs (WIW, LIW and upper-TDW) circulate in the north while the deep MWs (lower-TDW and WMDW) are uplifted, hence relatively motionless and mainly pushed away in the south. Since both the intermediate and deep MWs outflow at the sill, they are considered as light and dense MWs, the light–dense MWs interface possibly intersecting the AW–MWs interface in the sill surroundings. Considering an outflow east of the sill composed of only two (light–dense) homogeneous layers gives significant results. Across the whole strait, the outflow has spatial and temporal variabilities much larger than previously assumed. The MWs are superposed in the sea and lead at the sill to juxtaposed and vertically stratified suboutflows that will cascade independently before forming superposed veins in the ocean. These veins can have similar densities and hydrographic characteristics even if associated with different MWs, which accounts for the features permanency assumed up to now. The outflow structure downstream of the sill depends on its composition upstream and, more importantly, on that of AW in the sill surroundings where fortnightly and seasonal signals are imposed on the whole outflow.  相似文献   

18.
For a vertical two-dimensional field with a sill at a bay entrance, the tidal exchange mechanism is discussed.The schematic model is proposed as follows. The tidal trapping effect which is detected at the entrance section,i. e., the material transport due to the phase difference between the tidal periodic constituent of material concentration and tidal current at the entrance section, results because the oscillatory tidal flow at the sill entrance induces a gravitational flow along the sill slope inside the entrance. Accordingly, the tidal trapping effect depends largely upon the difference in water density between the bay and open sea and the density stratification in the bay.This model is supported by the observations at Kabira Cove (Okinawa Pref.) and Lake Hamana (Shizuoka Pref.) in 1976 through 1984. In addition, based on this model, in the case of Lake Hamana, the activity of the tidal exchange is inferred to change seasonally.  相似文献   

19.
莫桑比克海峡及其邻近海区是全球海洋潮流和潮能耗散最强的海区之一。文章利用高分辨率通用环流模式对该海区的正压潮流进行模拟, 并对该海区潮能通量和潮能耗散特征进行分析。结果表明, 莫桑比克海峡及其邻近海区的潮波主要是半日分潮占主导地位, 全日分潮可忽略不计, M2分潮形成1个左旋潮波系统和1个右旋潮波系统, S2分潮形成1个左旋潮波系统。莫桑比克海峡和马达加斯加岛南部等绝大数区域的M2和S2半日潮流是逆时针旋转, 在马达加斯加岛顶部等局部区域是顺时针旋转, 而且在海峡通道等复杂地形处潮流流速量级较大。潮能通量矢量主要来自东边界, 大部分潮能通量沿马达加斯岛北部传入莫桑比克海峡区域, 其中经过马达加斯加岛北部和进入莫桑比克海峡的M2 (S2)分潮的潮能通量分别为156.86GW (40.53GW)和148.07GW (36.05GW), S2分潮潮能通量的量级大约为M2分潮的1/5~1/4。底摩擦耗散主要发生莫桑比克海峡和马达加斯加岛南北部, 其中莫桑比克海峡M2 (S2)分潮的底摩擦耗散为1.762GW (0.460GW), 占其底部总耗散的43.74% (39.72%)。  相似文献   

20.
The effect of seawater movement through the Kerch Strait for extreme deviations in the level and speed of currents in the Sea of Azov caused by the action of climate wind fields has been studied using the Princeton ocean model (POM), a general three-dimensional nonlinear model of ocean circulation. Formation of the water flow through the strait is caused by the long-term action of the same type of atmospheric processes. The features of the water dynamics under conditions of changing intensity and active wind direction have been studied. Numerical experiments were carried out for two versions of model Sea of Azov basins: closed (without the Kerch Strait) and with a fluid boundary located in the Black Sea. The simulation results have shown that allowance for the strait leads to a significant change in the velocities of steady currents and level deviations at wind speeds greater than 5 m/s. The most significant effect on the parameters of steady-state movements is exerted by the speed of the wind that generates them; allowance for water exchange through the strait is less important. Analysis of the directions of atmospheric circulation has revealed that the response generated by the movement of water through the strait is most pronounced when a southeast wind is acting.  相似文献   

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