共查询到20条相似文献，搜索用时 31 毫秒
1.
2.
《Ocean Modelling》2008,20(2):134-156
This paper reviews current approaches to the lateral open boundary condition problem for nested regional primitive equation ocean numerical models and proposes a new approach that considers a scale decomposition of the nesting field variables for the barotropic lateral velocity boundary conditions. The Flather [Flather, R.A., 1976. A tidal model of the north-west European continental shelf. Memories de la Societe Royale des Sciences de Liege 6 (10):141–164] open lateral boundary condition is derived from mass conservation considerations and we use this approach to derive a generalized lateral open boundary condition for barotropic velocities. In addition we do a scale selective decomposition of the generalized Flather obtaining new and general lateral scale dependent boundary conditions. The performance of the new lateral boundary conditions have been evaluated in two kinds of experiments: (1) idealized and (2) realistic frameworks. In the idealized framework, as well as the realistic case, the results confirms that the scale selective open boundary conditions improves the solution almost everywhere but in particular in the shallow depth parts of the model domain. In the realistic case the assessment is more difficult and it is connected also to the capability of the nesting and nested model to reproduce the dynamics contained in the observations. 相似文献
3.
Numerical modeling of coastal circulation encompassing the nearshore requires forcing by tide, surface gravity waves, and possibly other factors. In the nearshore, the wave-induced longshore current and setup are dominant hydrodynamic processes, and lateral boundary conditions representing tide and oceanic forcing typically do not include surface-wave contributions. Without proper boundary conditions, significant gradients in current and water level can occur that contaminate the solution in the internal domain. A standard strategy is to place the boundaries far from the site of interest, but this strategy greatly increases computational demands, and it may not be appropriate for long-term simulations. This paper describes a wave-adjusted boundary condition that accounts for wave-induced water level and current acting in combination with tidal forcing. The wave-adjusted boundary condition is demonstrated for an idealized case of a parallel-contour beach and for an engineering application at Ocean City, MD. 相似文献
4.
The paper analyzes the effect which prescribed errors in the cross-shore boundary conditions for a computational domain along a beach have on the flow field predicted inside the domain. This problem is relevant because errors in boundary conditions are unavoidable when modeling limited domains of a nearshore region. For simplicity, we consider a longshore uniform plane beach with monochromatic, obliquely incident waves, and assume depth uniform currents. It is then studied analytically and numerically how small perturbations of the boundary conditions along both upstream and downstream cross-shore boundaries spread inside the computational domain. It is found that the errors at the upstream cross-shore boundary tend to spread over a long distance downstream of the boundary, while the influence of the errors in the downstream boundary condition is limited to the adjacent upstream area of the computational domain. Both the numerical and analytical solutions show that the errors introduced at the upstream boundary decay exponentially in the surf zone at a rate proportional to the bottom friction. A simple formula is developed to estimate the influence distance of the upstream errors. If we consider the mismatch in the volume flux at the upstream boundary, the error merely redistributes in the cross-shore direction to conserve volume. In the case of excessive flux or velocity specified at the cross-shore boundaries, a circulation cell tends to appear in the offshore region where the errors caused by the boundary mismatch increase with the cross-shore width of the model domain. 相似文献
5.
采用三维浅海湖波定解方程组,建立番禺附近海域的三维潮流数值模型来计算潮流和潮位变化情况,开边界采用调和常数计算的水位来驱动,潮流和潮位验证结果较好,模拟结果较真实的反应了番禺附近海域的潮流和潮位情况.在潮流模拟验证正确的前提下,建立溢油预测数值模型,采用欧拉-拉格朗日追踪方法,对油膜中心轨迹进行预测,并预测出油膜的平均... 相似文献
6.
In this paper , we present a novel Kalman filter approach to combine a hydrodynamic model-derived lowest astronomical tide (LAT) surface with tide gauge record-derived LAT values. In the approach, tidal water levels are assimilated into the model. As such, the combination is guided by the model physics. When validating the obtained “Kalman-filtered LAT realization” at all tide gauges, we obtained an overall root-mean-square (RMS) difference of 15.1 cm. At the tide gauges not used in the data assimilation, the RMS is 17.9 cm. We found that the assimilation reduces the overall RMS difference by ～ 31% and ～ 22%, respectively. In the Dutch North Sea and Wadden Sea, the RMS differences are 6.6 and 14.8 cm (all tide gauges), respectively. Furthermore, we address the problem of LAT realization in intertidal waters where LAT is not defined. We propose to replace LAT by pseudo-LAT, which we suggest to realize similarly as LAT except that all water level boundary conditions and assimilated tidal water levels have to be enlarged by a constant value that is removed afterward. Using this approach, we obtained a smooth reference surface for the Dutch Wadden Sea that fits LAT at the North Sea boundary within a few centimeters. 相似文献
7.
以T/P卫星沿迹分析结果为开边界条件的边值解算 总被引：1，自引：0，他引：1
利用球坐标系中的二维潮波方程组,以T/P卫星沿迹分析结果为开边界条件的边值法,计算了黄海中的一个四边形区域.结果证明了此方法的可行性.同时在调试底摩擦系数时,发现其对本方法的影响甚小,说明本方法计算不同区域的潮汐数值模型时,底摩擦系数都可以取为0.0022,省去对底摩擦系数的调试过程. 相似文献
8.
An analytical model with three sub-regions for m2 tide in the yellow sea and the East China Sea 总被引：1，自引：0，他引：1
In this study an analytical tide model of uniform width with three sub-regions is presented. The three-subregions model takes
into account step-like variations in depths in the direction of the channel as a way to examine the M2 tide of the East China Sea (ECS) as well as the Yellow Sea (YS). A modified Proudman radiation condition has been applied
at the northern open head, while the sea surface elevation is specified at the southern open boundary. It is seen that, due
to the presence of an abrupt change in depth, co-amplitude lines of the M2 tide are splitted to the east and west near the end of the ECS shelf region. Variations in depths, bottom friction and the
open head boundary conditions all contribute to the determination of formation of amphidromes as well as overall patterns
of M2 tidal distribution. It is seen that increasing water depth and bottom friction in the ECS shelf results in the westward shift
of the southern amphidrome. There is however no hint at all of the well-known degenerated tidal pattern being formed. It is
inferred that a lateral variation of water depth has to be somehow incorporated to represent the tidal patterns in ECS in
a realistic manner. Regarding the radiation factor introduced by Fang et al. (1991), use of a value larger than one, possibly
with a phase shift, appears to be a proper way of incorporating the reflected waves from the northern Yellow Sea (NYS). Key
words - analytical model, M2 tide, Kelvin wave, Yellow Sea, East China Sea 相似文献
9.
J.O. Blanton A.J. Garrett J.S. Bollinger D.W. Hayes L.D. Koffman J. Amft T. Moore 《Estuarine, Coastal and Shelf Science》2010
A study of tracer transport and retention in a small tidal creek and marsh system located in the southeastern US was conducted using a three-dimensional hydrodynamic model and data from a dye tracer release. The model simulated tidally driven flow, including inundation and drying out of the marshes and the dispersal of the dye tracer. Flow measurements in the tidal creek showed that the simulations appeared to generally duplicate the tidally driven flow into and out of the tidal creeks and marshes. The dye tracer experiment was conducted to test the hydrodynamic model's ability to simulate dispersal of a point release of pollutants into the creek during an incoming tide. The simulations reproduced much of the experimental measurements, but bathymetric errors and lack of resolution of the smallest arms of the tidal creeks affected the ability to faithfully reproduce the initial peak in measured dye tracer concentrations at a sampling location far from the boundary. The lack of the smallest tidal creeks led to some trapping of water and dye in the marshes. Two independent estimates of flushing time yielded values between 1.6 and 2.4 days. An uncertainty analysis indicates that model simulations are sensitive to variations in parameters such as water depth and marsh grass density. On the other hand, omission of the smallest tidal creeks in simulations may be partially offset by decreasing marsh grass density. Further improvements must rely on more accurate and detailed bathymetric data that resolves the smaller arms of the tidal creeks and includes quantitative information about the density and distribution of marsh grass. 相似文献
10.
深圳海域潮汐海啸波耦合数值研究 总被引：3，自引：0，他引：3
以COMCOT海啸模式和TPXO7.1全球潮汐模式为基础,采用三层嵌套网格,建立了南海海啸与潮汐耦合计算模型,分析深圳海域海啸和潮汐相互作用。潮汐计算结果与实测数据吻合较好,高、低潮位平均误差小于15 cm,20 cm;在潮汐验证的基础上,以马尼拉海沟潜在地震海啸源为案例,进行8.0,9.0级地震海啸与潮汐耦合情景模拟计算,计算结果表明,9级地震海啸在深圳海域外海波高为140~150 cm,如先行波为正波发生在高潮时将产生异常高潮位,负波发生在低潮时将产生异常低潮位,线性叠加计算结果偏大,在25.0 cm之内,到达时间差异小于6 min。 相似文献
11.
The sensitivity of the North Atlantic gyre circulation to high latitude buoyancy forcing is explored in a global, non-eddy resolving ocean general circulation model. Increased buoyancy forcing strengthens the deep western boundary current, the northern recirculation gyre, and the North Atlantic Current, which leads to a more realistic Gulf Stream path. High latitude density fluxes and surface water mass transformation are strongly dependent on the choice of sea ice and salinity restoring boundary conditions. Coupling the ocean model to a prognostic sea ice model results in much greater buoyancy loss in the Labrador Sea compared to simulations in which the ocean is forced by prescribed sea ice boundary conditions. A comparison of bulk flux forced hindcast simulations which differ only in their sea ice and salinity restoring forcings reveals the effects of a mixed thermohaline boundary condition transport feedback whereby small, positive temperature and salinity anomalies in subpolar regions are amplified when the gyre spins up as a result of increased buoyancy loss and convection. The primary buoyancy flux effects of the sea ice which cause the simulations to diverge are ice melt, which is less physical in the diagnostic sea ice model, and insulation of the ocean, which is less physical with the prognostic sea ice model. Increased salinity restoring ensures a more realistic net winter buoyancy loss in the Labrador Sea, but it is found that improvements in the Gulf Stream simulation can only be achieved with the excessive buoyancy loss associated with weak salinity restoring. 相似文献
12.
B. A. Kagan A. A. Timofeev E. H. A. Rashidi 《Izvestiya Atmospheric and Oceanic Physics》2012,48(4):432-443
To find variations in the dynamics of the surface M 2 tide in the White Sea induced by the spatially inhomogeneity of the resistance coefficient, we use a modified version of the QUODDY-4 three-dimensional finite-element hydrostatic model. This version differs from the original version in that it has a module introduced to calculate the resistance coefficient in the bottom boundary layer (BBL). The resistance coefficient is found from resistance laws for an oscillating rotating turbulent BBL over hydrodynamically rough and partially rough (smoothly rough) underlying surfaces describing the dependence of the resistance coefficient and other integral characteristics of resistance on dimensionless similarity parameters: the sea-bottom Rossby number Ro, the streaming Reynolds number Re, and the relative (normalized to tidal frequency) inertial frequency f/σ. The use of spatial inhomogeneity of the resistance coefficient was shown not to lead to considerable changes in tidal characteristics. The values of these characteristics are several times larger than the instrumental measurement errors for the level and velocity but less than the errors in their calculation. 相似文献
13.
长江口浑浊带核心区北槽水动力特征研究 总被引：4，自引：2，他引：2
本文根据2015年长江口洪季浑浊带水域座底三脚架全水深范围观测数据，对北槽中下段纵横向流、余流结构、边界层特征等进行了深入研究，结果显示:（1）大潮潮流矢量特征在垂向上的变化差异最为显著；北槽中下段水流出现明显的横向输移，指向航槽北面；（2）横向流速在大潮期间的变化（垂线平均）为-0.10~0.39 m/s，小潮期间的变化为-0.13~0.25 m/s；横向平流对于北槽纵向物质输运有显著调整作用；（3）余流垂向差异大，底部几乎为0，小潮期间余流更强；周期性再悬浮的细颗粒泥沙可作为北槽最大浑浊带的重要物质来源；（4）传统六点对数流速拟合法获得摩阻流速误差较大，近底1 m区域高分辨流速剖面是准确获取底边界层参数的有效途径。 相似文献
14.
利用伴随法优化非线性潮汐模型的开边界条件Ⅱ.黄海、东海潮汐资料的同化试验 总被引：12，自引：4，他引：12
本研究基于最优控制理论,采用变分数据同化法,通过建立伴随模型,把观测资料同化到陆架海域潮汐数值模型中去,优化开边界条件,以便提高数值预报的精度.潮汐模型的控制方程为考虑平流项、非线性底摩擦和侧向涡动粘性项的非线性浅水方程组.在第Ⅰ部分建立伴随模型和进行“孪生”数值试验的基础上,给出利用验潮站的水位资料以及TOPEX/Poseidon卫星测高数据在黄海、东海进行变分数据同化试验的数值结果.试验表明利用上述资料对模型进行变分同化校正是可行的. 相似文献
15.
16.
A combination of a three-dimensional hydrodynamic model and in-situ measurements provides the structures of barotropic tides,
tidal circulation and their relationship with turbulent mixing in the Java Sea, which allow us to understand the impact of
the tides on material distribution. The model retains high horizontal and vertical resolutions and is forced by the boundary
conditions taken from a global model. The measurements are composed of the sea level at coastal stations and currents at moorings
embedded in Seawatch buoys, in addition to hydrographic data. The simulated tidal elevations are in good agreement with the
data for the K1 and M2 constituents. The K1 tide clearly shows the lowest mode resonance in the Java Sea with intensification around the nodal point in the central region.
The M2 tide is secondary and propagates westward from the eastern open boundary, along with a counterclockwise amphidromic point
in the western part. The K1 tide produces a major component of tidal energy, which flows westward and dissipates through the node region near the Karimata
Strait. Meanwhile, the M2 tide dissipates in the entire Java Sea. However, the residual currents are mainly induced by the M2 tide, which flows westward following the M2 tidal wave propagation. The tidal mixing is mainly caused by K1 tide which peaks at the central region and is consistent with the uniform temperature and salinity along the vertical dimension.
This mixing is expected to play an important role in the vertical exchange of nutrients and control of biological productivity. 相似文献
17.
Recently, the TOPEX/POSEIDON Science Working Team has recommended the FES95.2.1 and CSR3.0 ocean tide models for reprocessing the TOPEX/POSEIDON Geophysical Data Records. Without doubt, the performance of these models, especially in the deep oceans, is excellent. However, from a comparison of these hydrodynamically consistent models with the purely empirical DW3.2 and DEOS96.1 models, it appears that FES95.2.1 and CSR3.0 are affected by basin boundary related errors which are caused by the basin-wise solution procedure of the FES ocean tide model series. In their turn, the empirical DW3.2 and DEOS96.1 models seem to suffer from significant errors in the Antarctic seas due to the seasonal growth and decay of Antarctic sea ice. Also, bathymetry-induced differences were found between the hydrodynamically consistent models and the empirical models. Concerning these differences, TOPEX/POSEIDON and ERS-1 crossover statistics unfortunately do not provide conclusive results on which models are in error. 相似文献
18.
为了计算的省时性,ＩＡＰ近岸海流数值模式采用了分解算法,即将控制方程分解为３个过程并用不同的时间步长进行积分。文章在此基础上对分解后的控制方程作局地线性化,得到了适合不同过程的开边界条件。对于适应过程,控制方程变换为等价的表示沿不同方向传播波动的特征方程。传出计算区域的波动用特征方程来描述,而传入波动则由无反射边界条件来消除。对于演变过程,求出了解析形式的通解。在流出点上,边界条件可以借助解析解由上一时刻区域内部或边界上的已知值求得;而在流入点上,边值保持定常。对于耗散过程,不需要边界条件。最后对所提出的开边界条件进行了数值检验,结果是令人满意的。 相似文献
19.
The tidal current in Kagoshima Bay is simulated by the two-dimensional subdomain finite-element method. At the open boundary, the sea level is forced to be oscillatory with a linear combination of the four harmonic constituents (M2, S2, K1, O1) of the tide. A calculation having only M2 sea level at the open boundary is also performed and the harmonic constants of M2 are compared with those calculated by the four components.In the calculated velocity vector, a large difference between the two maxima or the two minima in one day appears when the vector is directed to the open sea. On the other hand, when it is directed into the bay, the two extreme velocities are almost equal. In tide-killer residual flow, the flow pattern is almost independent of the tidal age; however, the absolute value of the current velocity depends on the tidal age. The pattern is nearly the same as that calculated by giving only M2 sea level at the open boundary.In relation to the nonlinear interaction, the kinetic energy ratio KER is defined by the ratio of kinetic energy of the induced harmonic components to that of harmonic constituents given at the open boundary. KER is large where the tidal current is disturbed by obstacles,e.g. along the west coast at the mouth of the bay and in the southern sea of Mt. Sakurajima. The distribution of KER seems to be independent of the number of harmonic constituents (one or four) given at the open boundary. The difference of kinetic energy of the M2 tidal constituent between the two calculations.i.e. with the open boundary conditions of four components (M2, S2, K1, O1) and of a single component (M2), is found to be large where the current velocity is large. 相似文献
20.
Numerical Investigation of High Tide Level Due to A Super Typhoon in A Coastal Region 总被引：5，自引：0，他引：5
A numerical model of the coupling between astronomical tide and storm surge based on Mike 21 is applied to the coastal regions of Zhejiang Province.The model is used to simulate high tide levels combined with storm surge during 5 typhoons,including two super typhoons,that landed in the Province.In the model,the atmospheric forcing fields are calculated with parametric wind and pressure models.The computational results,with average computed errors of 13 cm for the high astronomical tide levels and 20 cm for the high storm-tide levels,show that the model yields good simulations.Typhoon No.5612,the most intense to land in China since 1949,is taken as the typical super typhoon for the design of 5 typhoon routes,each landing at a different location along the coast.The possible extreme storm-tide levels along the coast are calculated by the model under the conditions of the 5 designed typhoon routes when they coincide with the spring tide.Results are compared with the high storm-tide levels due to the increase of the central atmospheric pressure at the base of a typical super typhoon,the change of tidal type,and the behavior of a Saomai-type typhoon.The results have practical significance for forecasting and minimization of damage during super typhoons. 相似文献