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1.
文中利用在有限体积近海模型FVCOM基础上拓展开发的全球海洋模型GOCTM(Global Ocean Circulation and Tide Model)进行了海啸波传播过程模拟,GOCTM采用全球无结构三角形网格,避免了开边界条件引入带来的误差,利用德国AWI研究所提供的海啸源作为初始水位场,模拟了2004年12月26日苏门答腊-安达曼Mw 9.2地震引发的海啸传播过程。通过模拟结果与印度沿岸潮位站数据以及海啸发生过程观测到的卫星高度计数据进行了对比,发现模拟结果与观测值相近,相关系数最高达0.82,相关性较好。模拟的海啸波到达苏门答腊岛北部的时间与日本的TUNAMI 模型和德国AWI研究所的TsunAWI模型的模拟结果相符,时间相差不到30 min,证明GOCTM全球模型可以较好地对海啸传播过程进行模拟,结果令人满意,希望本工作可以为我国海啸预报和预警提供参考。 相似文献
2.
R. K. Nayak M. Salim S. K. Sasamal P. C. Mohanthy R. K. Bharadwaj K. H. Rao 《Marine Geodesy》2016,39(5):331-347
The present tidal correction of sea level records of Satellite with ARgoes and ALtimeter (SARAL) is based on the finite element solution (FES) of global tide model FES2012 tidal solution. In this study, we examined the validity of the tidal corrections in the coastal oceans around India using tide gauge measurements and a regional tidal model. Our regional model is based on the barotropic version of the Princeton Ocean Model that is forced by the time-varying tidal levels at the open ocean end based on the global FES99 tidal solution. Tide charts prepared from the simulated tidal levels are very similar to the FES tidal solutions. Comparison with the tide gauge measurement shows close agreement with the regional tidal solutions. On the other hand, the agreement with the FES tide models differ significantly in the Gulf of Khambhat and the Gulf of Kutch on the northwest, and in the Hooghly estuary on the northeast continental shelf. However, the agreement is exceptional in other parts of the study domain. These tidal solutions are used in the SARAL-ALTIKA X-track data to assess the FES tidal correction and to draw some inferences associated with the coastal processes. It is revealed that these corrections are reasonably accurate for the coastal oceans around India except the aforementioned converging channels. 相似文献
3.
西北太平洋的一种潮汐数值同化模型 总被引：1，自引：1，他引：0
利用FVCOM海洋数值模式,在球坐标系统下考虑非线性效应和天体引潮力的影响,基于非结构的三角形网格建立了包括中国近海、日本海、鄂霍次科海和部分西北太平洋海域的高分辨率海洋潮汐数值模型,并采用趋近法同化84个沿岸验潮站的观测资料。模拟结果与175个验潮站的实测结果拟合良好,M2,S2,K1,O1四个主要分潮振幅和迟角的绝对平均误差分别为4.0 cm和5.6°,2.4 cm和7.5°,2.6 cm和6.3°,1.5 cm和5.0°。依据调和分析结果给出了4个主要分潮的同潮图分布,得到8个半日分潮和5个全日分潮的无潮点,证实了宗谷海峡全日潮无潮点的存在,首次模拟得到津轻海峡的全日潮无潮点;还给出了整个计算海域内最大可能潮差和潮汐余水位的分布特征。 相似文献
4.
The wind-induced sea-level variations at Hakata tidal station in winter are reproduced realistically using a one-way nested
model. This nested model is constructed with a structured finite-difference Princeton Ocean Model (POM) for the Tsushima-Korea
Straits, and an unstructured Finite Volume Coastal Ocean Model (FVCOM) for Fukuoka Bay divided into triangular-cell grids.
The correlation coefficient and root-mean-square error between observed and modeled results are 0.742 and 1.88 [cm], respectively.
Moreover, the results show that the nested model with FVCOM is more accurate than the model in which FVCOM is replaced with
a high-resolution POM for Fukuoka Bay. This indicates that the nested model constructed with structured and unstructured models
works effectively in hindcasting the wind-induced sea-level variations. 相似文献
5.
Dynamical downscaling is developed to better predict the regional impact of global changes in the framework of scenarios. As an intermediary step towards this objective we used the Regional Ocean Modeling System (ROMS) to downscale a low resolution coupled atmosphere–ocean global circulation model (AOGCM; IPSL-CM4) for simulating the recent-past dynamics and biogeochemistry of the Benguela eastern boundary current. Both physical and biogeochemical improvements are discussed over the present climate scenario (1980–1999) under the light of downscaling.Despite biases introduced through boundary conditions (atmospheric and oceanic), the physical and biogeochemical processes in the Benguela Upwelling System (BUS) have been improved by the ROMS model, relative to the IPSL-CM4 simulation. Nevertheless, using coarse-resolution AOGCM daily atmospheric forcing interpolated on ROMS grids resulted in a shifted SST seasonality in the southern BUS, a deterioration of the northern Benguela region and a very shallow mixed layer depth over the whole regional domain. We then investigated the effect of wind downscaling on ROMS solution. Together with a finer resolution of dynamical processes and of bathymetric features (continental shelf and Walvis Ridge), wind downscaling allowed correction of the seasonality, the mixed layer depth, and provided a better circulation over the domain and substantial modifications of subsurface biogeochemical properties. It has also changed the structure of the lower trophic levels by shifting large offshore areas from autotrophic to heterotrophic regimes with potential important consequences on ecosystem functioning. The regional downscaling also improved the phytoplankton distribution and the southward extension of low oxygen waters in the Northern Benguela. It allowed simulating low oxygen events in the northern BUS and highlighted a potential upscaling effect related to the nitrogen irrigation from the productive BUS towards the tropical/subtropical South Atlantic basin. This study shows that forcing a downscaled ocean model with higher resolution winds than those issued from an AOGCM, results in improved representation of physical and biogeochemical processes. 相似文献
6.
The four leading tidal constituents M2, S2, K1 and O1 in the South China Sea are simulated by using POM. The model is forced with tide-generating potential and four leading tidal constituents at the open boundary. In order to simulate more exactly, TOPEX/Poseidon altimeter data are assimilated into the model and the open boundary is optimized. The computed co-tidal charts for M2 and K1 constituents are generally consistent with previous results in this region. The numerical simulation shows that energetic internal tides are generated over the bottom topography such as the Dongsha Islands, the Xisha Islands, the Zhongsha Islands, the Nansha Islands and the Luzon Strait. 相似文献
7.
基于非结构网格半隐式跨尺度海洋模式（semi-implicit cross-scale hydroscience integrated system model,SCHISM）,作者采用非结构三角网格,对全球大洋潮波进行数值模拟。通过调和分析,将196个潮位站的实测数据与模拟结果进行比较验证,两者符合良好,M2、K1分潮同潮图的形态也与TPXO8、FES2014b和NAO.99b模型给出的相似。根据模拟结果,给出了M2、S2、K1、O14个主要分潮的同潮图。结果表明,太平洋中存在8个M2分潮无潮点,大西洋中存在4个M2分潮无潮点,印度洋中存在3个M2分潮无潮点。总体上来说,M2分潮在北太平洋和北大西洋东岸附近海域的振幅大于西岸附近海域的振幅,而在南太平洋和南大西洋情况相反。S2分潮分布特征与M2分潮类似,但振幅较小。太平洋中存在5个K1分潮无潮点,大西洋中存在3个K1分潮无潮点,印度洋中存在2个K1分潮无潮点。K1分潮的振幅普遍较小,在大部分海域不超过30 cm,在北太平洋和南极洲附近海域,由大洋向近岸有增加的趋势。太平洋中存在4个O1分潮无潮点,大西洋和印度洋中各存在2个无潮点。O1分潮在大部分海域不超过20 cm,在北太平洋和南极洲附近海域,由大洋向近岸有增加的趋势。最后,讨论了本模型与对比模型之间误差存在的原因。 相似文献
8.
To estimate the loading correction, the convolution integral of tidal height with gravity Green's function is usually adopted.
Therefore, two kinds of error sources should be discussed, i.e. errors produced by different earth models and errors due to
the inaccuracy of the cotidal maps.
Thus, the effect of different earth models on tidal correction was estimated by using different loading Love numbers and gravity
Green function obtained on the basis of two different earth models, G-B and 1066 model. We also calculated the error caused
by Schwidersky's cotidal map, by assuming the error of average tidal height to be 5 cm in 1°×1° grids, but yet the effect
coming from the errors of local cotidal maps had not been taken into consideration in this work. In carrying out this calculation,
the results of tidal height errors in adjacent ocean around station, harmonic coefficient errors in open ocean and a truncation
error are discussed respectively. 相似文献
9.
B. A. Kagan E. V. Sofina A. A. Timofeev 《Izvestiya Atmospheric and Oceanic Physics》2010,46(2):224-231
In order to reproduce the diapycnal mixing induced by internal tidal waves (ITWs) in the Arctic Ocean, we use a modified version
of the three-dimensional finite-element hydrothermodynamic model QUODDY-4. We found that the average (over the tidal cycle)
and integral (by depth) baroclinic tidal energy dissipation rate in individual areas of the Siberian continental shelf and
in the straits between the Canadian Arctic archipelago are much higher than in the open ocean and its values on ridges and
troughs are qualitatively similar to one another. Moreover, in the area of open-ocean ridges, the baroclinic tidal energy
dissipation rate increases as it approaches the bottom, but only in the bottom boundary layer; on the Mid-Atlantic and Hawaii
ridges, such an increase is observed within a few hundreds of meters away from the bottom. The average (in area and depth
of the open ocean) coefficient of diapycnal mixing defined by the baroclinic tidal energy dissipation rate is higher than
the coefficient of molecular kinematic viscosity and only a few times lower than the canonical value of the coefficient of
vertical turbulent viscosity, which is used in models of global oceanic circulation. Coupled with the reasoning on the localization
of baroclinic tidal energy dissipation, this fact leads to the conclusion that disregarding the contribution that ITW-induced
diapycnal mixing makes to the ocean-climate formation is hardly justified. 相似文献
10.
11.
The accuracy of GPS data analysis for the vertical component has reached a level where the vertical crustal deformation due to the ocean tidal loading should be taken into consideration. Ocean loading affects in particular the results of the GPS analysis for those observation sets covering less than 24 hours. Especially in these cases, a correction for this phenomenon should be performed during the data analysis. On the other hand, it is possible to estimate the ocean loading effect from GPS data sets. In this way it is possible to validate models for the loading deformation derived from global ocean tide models. 相似文献
12.
Tidal data inversion: interpolation and inference 总被引：1，自引：0，他引：1
Gary D. Egbert 《Progress in Oceanography》1997,40(1-4)
Initial efforts in applying inverse methods to studies of ocean tides have focused on making the best use of a small number of observations to map tidal fields in a large area. As such, inversion can be viewed as an objective analysis scheme which uses a dynamically appropriate spatial covariance, derived from the shallow water equations, to interpolate and smooth a sparse data set. Data from recent altimetry missions are not sparsely distributed relative to tidal wavelengths in the open ocean, apparently reducing the need for complicated dynamically based interpolation schemes. Altimetric data sets are also quite large, making application of rigorous inversion methods to global tidal modeling a challenging computational problem. We describe here a new iterative solution scheme which allows us for the first time to fit the full set of TOPEX/Poseidon cross-over differences. The resulting solution (TPXO.3) fits validation tide gauges significantly better than previous inverse solutions. TPXO.3 also reduces residual cross-over variances relative to other recent inverse and empirical solutions, particularly in shallow water where improvements are dramatic. With the new solution approach very significant improvements in global tidal models should be possible in shallow areas and in the vicinity of complex bathymetry, where high-accuracy tidal modeling remains a challenging problem. With the recent improvements in the definition of tidal elevations in the open ocean it should now also be possible to resolve some long unanswered questions about tidal energetics and dynamics. Inverse methods provide a natural framework for addressing these issues, and making inferences about tidal dynamics. In particular, by bringing data and dynamics together in a single solution, we can rigorously test the consistency of the two. We present results of global and local inversions which suggest that over elongated bathymetric features oriented perpendicular to tidal flows, energy dissipation in the open ocean is significantly enhanced, presumably due to conversion of barotropic tidal motions into baroclinic modes. For the M2 tide our preliminary results suggest that perhaps as much as 0.5 TW of energy is dissipated in this manner. However, due to the simplified linear dynamics and limited spatial resolution used for our inversion, there are significant uncertainties associated with these results. A more careful application of inverse methods to make more rigorous inferences about tidal energetics, including use of more reasonable prior dynamics, and the highest possible spatial resolution, should allow for closure of the tidal energy budget within the next few years. 相似文献
13.
Ocean Tide Models Developed by Assimilating TOPEX/POSEIDON Altimeter Data into Hydrodynamical Model: A Global Model and a Regional Model around Japan 总被引：36，自引：0，他引：36
A global ocean tide model (NAO.99b model) representing major 16 constituents with a spatial resolution of 0.5° has been estimated by assimilating about 5 years of TOPEX/POSEIDON altimeter data into barotropic hydrodynamical model. The new solution is characterized by reduced errors in shallow waters compared to the other two models recently developed; CSR4.0 model (improved version of Eanes and Bettadpur, 1994) and GOT99.2b model (Ray, 1999), which are demonstrated in comparison with tide gauge data and collinear residual reduction test. This property mainly benefits from fine-scale along-track tidal analysis of TOPEX/POSEIDON data. A high-resolution (1/12°) regional ocean tide model around Japan (NAO.99Jb model) by assimilating both TOPEX/POSEIDON data and 219 coastal tide gauge data is also developed. A comparison with 80 independent coastal tide gauge data shows the better performance of NAO.99Jb model in the coastal region compared with the other global models. Tidal dissipation around Japan has been investigated for M2 and K1 constituents by using NAO.99Jb model. The result suggests that the tidal energy is mainly dissipated by bottom friction in localized area in shallow seas; the M2 ocean tidal energy is mainly dissipated in the Yellow Sea and the East China Sea at the mean rate of 155 GW, while the K1 energy is mainly dissipated in the Sea of Okhotsk at the mean rate of 89 GW. TOPEX/POSEIDON data, however, detects broadly distributed surface manifestation of M2 internal tide, which observationally suggests that the tidal energy is also dissipated by the energy conversion into baroclinic tide. 相似文献
14.
《Ocean Modelling》2008,20(2):170-182
Most ocean models in current use are built upon structured meshes. It follows that most existing tools for extracting diagnostic quantities (volume and surface integrals, for example) from ocean model output are constructed using techniques and software tools which assume structured meshes. The greater complexity inherent in unstructured meshes (especially fully unstructured grids which are unstructured in the vertical as well as the horizontal direction) has left some oceanographers, accustomed to traditional methods, unclear on how to calculate diagnostics on these meshes. In this paper we show that tools for extracting diagnostic data from the new generation of unstructured ocean models can be constructed with relative ease using open source software. Higher level languages such as Python, in conjunction with packages such as NumPy, SciPy, VTK and MayaVi, provide many of the high-level primitives needed to perform 3D visualisation and evaluate diagnostic quantities, e.g. density fluxes. We demonstrate this in the particular case of calculating flux of vector fields through isosurfaces, using flow data obtained from the unstructured mesh finite element ocean code ICOM, however this tool can be applied to model output from any unstructured grid ocean code. 相似文献
15.
区域性海洋环流数值模式研究及对南海环流与海峡流量的模拟 总被引：2，自引：0，他引：2
基于MOM模式的物理框架,妥善考虑了开边界的物理过程,改造和发展了一个区域海洋数值模式。本模式不仅可以方便地调整开边界条件,使之满足边界的特定物理条件,而且可以方便地做针对性修改,使模式更加可靠。改进后的模式具有MOM模式物理概念明确、公式便于理解、结果便于表达的全部特点,同时克服了MOM模式边界条件不完整、程序不易调整、参数难以改变的缺点。区域性模式比全球模式的计算速度快很多倍,可以成为区域性研究的有效工具。将此模式应用于南海,利用Hellerman＆Rosenstein气候态风应力驱动模式10a,得到与全球模式效果相当的结果。模式模拟结果展现了南海流场的季节特征,在模式分辨率下表现出了多涡结构。根据模拟的流场计算了南海与其它海域的水交换通量。在年平均意义下,外海水通过吕宋海峡进入南海,南海水通过台湾海峡、民都洛海峡和卡里马塔海峡流出南海。各海峡水通量具有明显的季节变化。 相似文献
16.
采用球面潮波运动基本方程,利用开边界强迫水位条件和考虑天体引潮力,对渤、黄、东海现有的潮波进行数值模拟。模拟包括19个理论系数最大的分潮波,其中半日潮波10个,全日潮波9个,对如此多数目的分潮波进行模拟是第一次尝试。模拟结果与实测资料作了比较。根据模拟获得的调和常数绘制了同潮图,并对潮波运动进行了讨论和分析。 相似文献
17.
Cotidal charts and tidal power input atlases of the global ocean from TOPEX/Poseidon and JASON-1 altimetry 总被引：1，自引：0，他引：1
The global distributions of eight principal tidal constituents, M2 , S2 , K1 , O1 , N2 , K2 , P1 , and Q1 , are derived using TOPEX/Poseidon and JASON-1（T/P-J） satellite altimeter data for 16 a. The intercomparison of the derived harmonics at 7000 subsatellite track crossover points shows that the root mean square （RMS） values of the tidal height differences of the above eight constituents range from 1.19 cm to 2.67 cm, with an average of about 2 cm. The RMS values of the tidal height differences between T/P-J solutions and the harmonics from ground measurements at 152 tidal gauge stations for the above constituents range from 0.34 cm to 1.08 cm, and the relative deviations range from 0.031 to 0.211. The root sum square of the RMS differences of these eight constituents is 2.12 cm, showing the improvement of the present model over the existing global ocean tidal models. Based on the obtained tidal model the global ocean tidal energetics is studied and the global distribution of the tidal power input density by tide-generating force of each constituent is calculated, showing that the power input source regions of semidiurnal tides are mainly concentrated in the tropical belt between 30 S and 30 N, while the power input source regions of diurnal tides are mainly concentrated off the tropic oceans. The global energy dissipation rates of the M2 , S2 , K1 , O1 , N2 , P1 , K2 and Q1 tides are 2.424, 0.401, 0.334, 0.160, 0.113, 0.035, 0.030 and 0.006 TW, respectively. The total global tidal dissipation rate of these eight constituents amounts to 3.5 TW. 相似文献
18.
引潮力对海洋环流模式的影响 总被引：2，自引：1，他引：1
The eight main tidal constituents have been implemented in the global ocean general circulation model with approximate 1° horizontal resolution.Compared with the observation data,the patterns of the tidal amplitudes and phases had been simulated fairly well.The responses of mean circulation,temperature and salinity are further investigated in the global sense.When implementing the tidal forcing,wind-driven circulations are reduced,especially those in coastal regions.It is also found that the upper cell transport of the Atlantic meridional overturning circulation(AMOC) reduces significantly,while its deep cell transport is slightly enhanced from 9×106m3/s to 10×106 m3/s.The changes of circulations are all related to the increase of a bottom friction and a vertical viscosity due to the tidal forcing.The temperature and salinity of the model are also significantly affected by the tidal forcing through the enhanced bottom friction,mixing and the changes in mean circulation.The largest changes occur in the coastal regions,where the water is cooled and freshened.In the open ocean,the changes are divided into three layers:cooled and freshened on the surface and below 3 000 m,and warmed and salted in the middle in the open ocean.In the upper two layers,the changes are mainly caused by the enhanced mixing,as warm and salty water sinks and cold and fresh water rises;whereas in the deep layer,the enhancement of the deep overturning circulation accounts for the cold and fresh changes in the deep ocean. 相似文献
19.
This is the first part of a publication that describes the generation of adaptive grids (this part), and simulations with vector-ocean-model (VOM) in unstructured grids resulting from the adaptation (part II). A static vertical adaptive grid in z-coordinates allows improving the approximation of topography and vertical resolution at slopes. Adaptive grids use elements from a set of grid sizes by multiplying a basic smallest cell size with powers of two, as in cell division. Grids with locally isotropic vertical resolution at surface, seabed, and slopes can be generated whereby resolution decreases towards the ocean interior. The adaptation to topography yields unstructured grids that are organised in a one-dimensional vector by column-wise storage of cells, discarding land cells. The vector storage suggested the model’s name. Grids are generated by an iterative procedure that relies on rules, i.e. criteria and directives to control the grid structure in favour of a good representation of physics and smooth numerical operations. The directives govern vertical resolution at sea surface and seabed, and at slopes. For the latter vertical resolution is extended in the horizontal. In the ocean interior horizontal distances between changes in grid size can be controlled for the sake of smooth numerics. The use of a z-grid that avoids transformation errors, the depth-independence of vertical resolution, and the lateral extension of vertical resolution at slopes towards the ocean interior are the most significant differences of adaptive grids in comparison to vertical coordinate transformations. Unstructured grids do not rely on a smoothing of topography and can be used within any of the horizontal Arakawa-grids. For the same topography directives allow creating various grids as demonstrated for a shelf-ocean topography. The number of cells per column in two unstructured grids generated for the North Atlantic may locally well exceed typical layer numbers in conventional model matrices. But the domain average is similar to layer numbers of today’s ocean models. Thus, with the same investment of cells per domain a higher resolution in slope regions can be achieved by unstructured grids as compared to conventional z-grids. 相似文献
20.
内潮耗散与自吸-负荷潮对南海潮波影响的数值研究 总被引：1，自引：0，他引：1
利用非结构三角形网格的FVCOM海洋数值模式,在其传统二维潮波方程中加入参数化的内潮耗散项和自吸-负荷潮项,计算了南海及其周边海域的M_2、S_2、K_1和O_1分潮的分布。与实测值的比较表明,引入这两项对模拟准确度的提高有明显效果。根据模式结果本文计算分析了研究海域的潮能输入和耗散。能量输入计算表明,能通量是潮能输入的最主要构成部分,通过吕宋海峡断面进入南海的M_2和K_1分潮能通量分别为38和29GW;半日周期的自吸-负荷潮能量输入以负值居多,而全日周期的自吸-负荷潮能量输入以正值居多,因而自吸-负荷潮减弱了南海的半日潮,并加强了南海的全日潮。引潮力的作用也减弱了半日潮而加强了全日潮,但其作用要小于自吸-负荷潮。潮能耗散的分析显示底摩擦耗散在沿岸浅水区域起主导作用,内潮耗散则主要发生在深水区域。内潮耗散的最大值出现在吕宋海峡,且位于南海之外的海峡东部的耗散量大于位于南海之内的海峡西部的耗散量。对M_2和K_1分潮吕宋海峡的内潮耗散总值分别达到16和23GW。 相似文献