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1.
Storm surges are abnormal rises in sea level along coastal areas and are mainly formed by strong wind and atmospheric depressions.When storm surges coincide with high tide,coastal flooding can occur.Creating storm surge prediction systems has been an important and operational task worldwide.This study developed a coupled tide and storm surge numerical model of the seas around Taiwan for operational purposes at the Central Weather Bureau.The model was calibrated and verified by using tidal records from seas around Taiwan.Model skill was assessed based on measured records,and the results are presented in details.At 3-minute resolution,tides were generally well predicted,with the root mean-square errors of less than 0.11 m and an overall correlation of more than 0.9.Storms(winds and depressions) were introduced into the model forcing by using the parameter typhoon model.Five typical typhoons that threatened Taiwan were simulated for assessment.The surges were well predicted compared with the records.  相似文献   

2.
Oceanic pycnocline depth is usually inferred from in situ measurements. It is attempted to estimate the depth remotely. As solitary internal waves occur on oceanic pycnocline and propagate along it, it is possible to retrieve the depth indirectly in virtue of the solitary internal waves. A numerical model is presented for retrieving the pycnocline depth from synthetic aperture radar (SAR) images where the solitary internal waves are visible and when ocean waters are fully stratified. This numerical model is constructed by combining the solitary internal wave model and a two-layer ocean model. It is also assumed that the observed groups of solitary internal wave packets on the SAR imagery are generated by local semidiurnal tides. A case study in the East China Sea shows a good agreement with in situ CTD (conductivity-temperature-depth) data.  相似文献   

3.
A storm surge is an abnormal sharp rise or fall in the seawater level produced by the strong wind and low pressure field of an approaching storm system.A storm tide is a water level rise or fall caused by the combined effect of the storm surge and an astronomical tide.The storm surge depends on many factors,such as the tracks of typhoon movement,the intensity of typhoon,the topography of sea area,the amplitude of tidal wave,the period during which the storm surge couples with the tidal wave.When coupling with different parts of a tidal wave,the storm surges caused by a typhoon vary widely.The variation of the storm surges is studied.An once-in-a-century storm surge was caused by Typhoon 7203 at Huludao Port in the north of the Liaodong Bay from July 26th to 27th,1972.The maximum storm surge is about 1.90 m.The wind field and pressure field used in numerical simulations in the research were derived from the historical data of the Typhoon 7203 from July 23rd to 28th,1972.DHI Mike21 is used as the software tools.The whole Bohai Sea is defined as the computational domain.The numerical simulation models are forced with sea levels at water boundaries,that is the tide along the Bohai Straits from July 18th to 29th(2012).The tide wave and the storm tides caused by the wind field and pressure field mentioned above are calculated in the numerical simulations.The coupling processes of storm surges and tidal waves are simulated in the following way.The first simulation start date and time are 00:00 July 18th,2012; the second simulation start date and time are 03:00 July 18th,2012.There is a three-hour lag between the start date and time of the simulation and that of the former one,the last simulation start date and time are 00:00 July 25th,2012.All the simulations have a same duration of 5 days,which is same as the time length of typhoon data.With the first day and the second day simulation output,which is affected by the initial field,being ignored,only the 3rd to 5th day simulation results are used to study the rules of the storm surges in the north of the Liaodong Bay.In total,57 cases are calculated and analyzed,including the coupling effects between the storm surge and a tidal wave during different tidal durations and on different tidal levels.Based on the results of the 57 numerical examples,the following conclusions are obtained:For the same location,the maximum storm surges are determined by the primary vibration(the storm tide keeps rising quickly) duration and tidal duration.If the primary vibration duration is a part of the flood tidal duration,the maximum storm surge is lower(1.01,1.05 and 1.37 m at the Huludao Port,the Daling Estuary and the Liaohe Estuary respectively).If the primary vibration duration is a part of the ebb tidal duration,the maximum storm surge is higher(1.92,2.05 and 2.80 m at the Huludao Port,the Daling Estuary and the Liaohe Estuary respectively).In the mean time,the sea level restrains the growth of storm surges.The hour of the highest storm tide has a margin of error of plus or minus 80 min,comparing the high water hour of the astronomical tide,in the north of the Liaodong Bay.  相似文献   

4.
Typhoon-generated waves are simulated with two numerical wave models, the SWAN model for the coastal and Yangtze Estuary domain, nested within the WAVEWATCHIII (WW3) for the basin-scale East China Sea domain. Typhoon No. 8114 is chosen because it was very strong, and generated high waves in the Estuary. WW3 was implemented for the East China Sea coarse-resolution computational domain, to simulate the waves over a large spatial scale and provide boundary conditions for SWAN model simulations, implemented on a fine-resolution nested domain for the Yangtze Estuary area. The Takahashi wind model is applied to the simulation of the East China Sea scale (3-hourly) and Yangtze Estuary scale (1-hourly) winds. Simulations of significant wave heights in the East China Sea show that the highest waves are on the right side of the storm track, and maxima tend to occur at the eastern deep-water open boundary of the Yangtze Estuary. In the Yangtze Estuary, incoming swell is dominant over locally generated waves before the typhoon approaches the Estuary. As the typhoon approaches the Estuary, wind waves and swell coexist, and the wave direction is mainly influenced by the swell direction and the complex topography.  相似文献   

5.
Based on the three-dimensional zeroth-order model of the ultra-shallow water storm surge theory proposed by Chin and Feng (1975), a numerical investigation of the Bohai Sea wind surges is made. As a preliminary numerical experiment the model wind fields are designed for computations. Computational results are compared with the principal characteristics of observations as well as with some conclusions of the classical theories on storm surges presented by P. Groen (1962) and others.  相似文献   

6.
The influences of tropical cyclone paths and shelf bathymetry on the inducement of extreme sea levels in a regional bay are investigated. A finite volume coastal ocean model(FVCOM) has been configured for the Gulf of Thailand-Sunda Shelf. A parametric wind model is used to drive the FVCOM. The contributions of the tropical cyclone characteristics are determined through a scenario-based study. Validation based on a historical extreme sea level event shows that the model can resolve the oscillation mechanism well. The intensification of severe storm surges in the region highly depends on four factors including phase propagation of the storm surge wave determined by the landfall position, funnel effect caused by locality of the coastline, and shelf bathymetry determined by the state of mean sea level and coastline crossing angle of the storm path. The coexistence of these factors can cause particular regions e.g. the Surat Thani Bay, inner Gulf of Thailand and Ca Mau Peninsular to experience a larger surge magnitude. These areas are found to be highly related to monsoon troughs that develop during the onset and early northeastern monsoon season(October–November).  相似文献   

7.
A new three-dimensional numerical model is derived through a wave average on the primitive N-S equations, in which both the"Coriolis-Stokes forcing" and the"Stokes-Vortex force" are considered. Three ideal experiments are run using the new model applied to the Princeton ocean model (POM). Numerical results show that surface waves play an important role on the mixing of the upper ocean. The mixed layer is enhanced when wave effect is considered in conjunction with small Langmuir numbers. Both surface wave breaking and Stokes production can strengthen the turbulent mixing near the surface. However, the influence of wave breaking is limited to a thin layer, but Stokes drift can affect the whole mixed layer. Furthermore, the vertical mixing coefficients clearly rise in the mixed layer, and the upper ocean mixed layer is deepened especially in the Antarctic Circumpolar Current when the model is applied to global simulations. It indicates that the surface gravity waves are indispensable in enhancing the mixing in the upper ocean, and should be accounted for in ocean general circulation models.  相似文献   

8.
Based on the third-generation oceanic wave prediction model (WAVEWATCH Ⅲ) ,the third-generation nearshore wave calculation model (SWAN) and the mathematical tide, tidal current and cyclone current model, which have been improved, interconnected and expanded, a coupled model of offshore wave, tide and sea current under tropical cyclone surges in the South China Sea has been established. The coupled model is driven by the tropical cyclone field containing the background wind field. In order to test the hindcasting effect of the mathematical model, a comparison has been made between the calculated results and the observational results of waves of 15 cyclone cases, water levels and current velocities of the of 7 cyclones. The results of verification indicate that the calculated and observed results are basically identical.  相似文献   

9.
Estimation of Wind Wave Frequency Spectra by Use of the Arcsine Law   总被引:1,自引:0,他引:1  
In the present study,the surface elevation of wind waves oberved in laboratory and in the Bohai Sea are adopted for the estimation of the wind wave frequency spectrum by use of the method of the arcsine law(MAL).The traditional method uses the surface elevation to calculate the correlation and then estimate the frequency spectrum while the MAL,presented by Yu and Lan(1979),uses the time sequence of zero-crossing points of surface elevation rather than directly the surface elevation to calculate the correlation.66 sets of wind wave data obtained in laboratory and 420 sets of data observed in the Bohai Sea are adopted for the examination of the method introduced by Yu and Lan.Results show that the MAL can give reliable estimation of wind wave spectra.Correlation and form of spectra estimated by the MAL are similar to those estimated by the traditional method.The peak frequency and the spectral density in peak frequency by the MAL are close to those obtained by the traditional method.  相似文献   

10.
For settlement of the well-known problem of contemporary radar imaging models, i. e. , the problem of a general underestimation of radar signatures of hydrodynamic features over oceanic internal waves and underwater bottom topography in tidal waters at high radar frequency bands ( X-band and C-band), the impact of the ocean surface mixed layer turbulence and the significance of strat- ified oceanic model on SAR remote sensing of internal solitary waves are proposed. In the north of the South China Sea by utilizing some observed data of background field the nonlinearity coefficient, the dispersion coefficient, the horizontal variability coefficient and the phase speed in the generalized K-dV equation are determined approximately. Through simulations of internal tide transfor- mation the temporal evolution and spatial distribution of the vertical displacement and horizontal velocity of internal wave field are obtained. The simulation results indicate that the maximum amplitudes of internal solitary waves occur at depth 35 m, but the maximum current speeds take place at depth 20 m in this area of the sea (about 20°30'N, 114°E) in August. It was noticed that considering the effects of flood current and ebb current respectively is appropriate to investigate influence of the background shear flow on coefficients of the K-dV equation. The obtained results provide the possibility for the simulation of SAR signatures of internal solitary waves under considering the impact of ocean surface mixed layer turbulence in the companion paper.  相似文献   

11.
渤海一年四季都易受到由温带风暴和热带气旋所致风暴潮的影响。为了缓解风暴潮灾害对海岸地区人员生命财产的影响,十分有必要了解大型风暴潮的发生过程和机制。目前大部分研究主要局限于单一的温带风暴潮或台风风暴潮。本文利用所构建的海气耦合数值模型研究了发生于渤海的两种类型的风暴潮,对发生在渤海的2次典型强风暴潮过程进行了模拟。由WRF模型模拟得到的风场强度和最低海平面气压与实测数据吻合较好,由ROMS模型模拟得到的风暴潮期间水位变化过程与潮位站观测结果也吻合较好。对两种类型风暴潮期间的风场结钩、海面风应力、海洋表面平均流场以及水位分布进行了分析对比,并将耦合模型结果与非耦合模型结果进行了对比。研究表明,渤海两种类型风暴潮期间的风场结钩、海面风应力、海洋表面平均流场以及水位分布等均存在巨大差异。渤海风暴潮的强度主要由海洋表面的驱动力所决定,但同时也受海岸地形地貌的影响。  相似文献   

12.
东海风暴潮与天文潮的非线性相互作用   总被引:1,自引:0,他引:1  
中国东海的风暴潮具有明显的周期性波动。凤暴潮除了决定于风应力和长波效应外,还受到天文潮与风暴潮相互作用的影响。本文利用一个二维数值模式对天文潮与风暴潮相互作用的水位进行了模拟。我们选取了8114号台风加以计算。计算结果与实测资料基本相符,由此说明水位曲线中的潮周期波动主要是由于天文潮与风暴潮之间的非线性相互作用所致。数值实验还表明,如果考虑到天文潮与风暴潮的相互作用可以显著改善水位的预报精度。  相似文献   

13.
采用第三代海浪模式和线性全流风暴潮模式计算封闭海域内风暴潮对风浪的影响。海浪模式中包含水深变化及平均流变化引起的波浪绕射项。计算了不同风速和不同静水深情况下风暴潮引起的风浪波南的变化。计算结果表明:静水深为10m及风速为30m/3时,风暴潮引起的风浪波高的相对变化的最大值达39%;而静水深超过40m时,即使风速为40m/s,风暴潮引起的风浪波高的相对变化的最大值小于5%。  相似文献   

14.
A coupled wave–tide–surge model has been established in this study in order to investigate the effect of tides, storm surges, and wind waves interactions during a winter monsoon on November 1983 in the Yellow Sea. The coupled model is based on the synchronous dynamic coupling of a third-generation wave model, WAM-Cycle 4, and the two-dimensional tide–surge model. The surface stress generated by interactions between wind and waves is calculated using the WAM-Cycle 4 directly based on an analytical approximation of the results obtained from the quasi-linear theory of wave generation. The changes of bottom friction factor generated by waves and current interactions are calculated by using simplified bottom boundary layer model. The model simulations showed that bottom velocity and effective bottom drag coefficient induced by combination of wave and current were increased in shallow waters of up to 50 m in the Yellow Sea during the wintertime strong storm conditions.  相似文献   

15.
环渤海的历史风暴潮探讨   总被引:4,自引:0,他引:4  
根据地方史志及近现代关于风暴潮的资料,提出在环渤海海域的风暴潮的时空分布,进行了分析与统计,提出环渤海沿岸风暴潮的特点,指出存在发生在夏季的台风潮和发生在春秋两季的风潮两种型式。在风潮的两种型式中,春季风潮占绝对优势,秋季风潮是次要的。三者关系是:台风潮:春季风潮:秋季风潮=60%:30%:10%。此外,还列出了在环渤海沿岸发生的重大历史风暴潮灾表。  相似文献   

16.
Under strong surface wind forcing during winter, direct current observations in the northern Sea of Japan show the existence of strong near-inertial currents in the deep water that is characterized by the extremely homogeneous vertical structures of temperature and salinity. However, the mechanism generating internal waves in the deep water of the northern Sea of Japan has not been well understood. In this study, to clarify the dynamical link between the surface wind forcing and near-inertial currents in the deep water of the northern Sea of Japan, we drive a general circulation model taking into account realistic wind stress, ocean bottom and land topography. In the northern Sea of Japan, the numerical results show that vertically coherent horizontal currents with a speed of ~ 0.05 m s?1 are excited throughout the homogeneous deep water. A two-layer model successfully reproduces the pattern of the horizontal current velocities shown by the general circulation model, indicating that internal waves emanate westward from the northwestern coast of Japan through coastal adjustment to the strong wind forcing event and, while propagating into the ocean interior, they excite evanescent near-inertial response throughout the lower layer below the interface.  相似文献   

17.
A coupled wave–tide–surge model has been developed in this study in order to investigate the effect of the interactions among tides, storm surges, and wind waves. The coupled model is based on the synchronous dynamic coupling of a third-generation wave model, WAM cycle 4, and the two-dimensional tide–surge model. The surface stress, which is generated by interactions between wind and wave, is calculated by using the WAM model directly based on an analytical approximation of the results using the quasi-linear theory of wave generation. The changes in bottom friction are created by the interactions between waves and currents and calculated by using simplified bottom boundary layer model. In consequence, the combined wave–current-induced bottom velocity and effective bottom drag coefficient were increased in the shallow waters during the strong storm conditions.  相似文献   

18.
Simulation of a storm surge caused by Typhoon 9918 in the Yatsushiro Sea, Kyushu, Japan was hindcasted by the synchronous coupled wind-wave-surge model composed of a Meso-scale meteorological model (MM5) for the wind and sea surface pressure, a spectral third-generation wind-wave model (Wavewatch III) for waves, and the coastal ocean model (Princeton Ocean Model). Inclusion of the whitecap wave breaking stresses (whitecap dissipation stress) in the coastal ocean model made it possible to reproduce the extreme surge height in the extremely shallow bay.  相似文献   

19.
夏波  张庆河  蒋昌波 《海洋与湖沼》2013,44(6):1452-1456
本文采用ADCIRC模型和SWAN模型, 建立了一个基于非结构化网格的波流耦合数值模式, 风浪计算和潮汐风暴潮计算均采用同一套三角网格, 对复杂岸线和建筑物布置均有较好的描述, 且避免了模型插值, 提高了计算效率和精度。利用该模型对渤海湾西南海域几次强风过程中的风浪和潮汐风暴潮进行了研究, 通过实测资料对该模型进行了验证, 结果表明该模式具有较高的精度, 能较好地描述风浪、潮汐风暴潮的传播演变及其相互作用, 可应用于风浪与潮汐风暴潮的模拟计算。  相似文献   

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