Finite difference analog of the Coriolis force in papers by Endoh

A wrong finite difference form is used for the rotation of the Coriolis force in the vorticity equation with bottom topography in a series of papers byEndoh.     

The effect of horizontal Coriolis force on internal wave-mean flow interaction

-In this paper, an improvement and revision of the theory of Miiller (1974, 1976), has been made under two conditions: (1) the horizontal component of the Coriolis force has been taken into account in the equations of motion for the internal wave field; and (2) the role of internal waves with frequencies close to the inertial frequency has been considered. The values of the viscosity coefficients and the diffusivity coefficients obtained in this paper are: Theappearance of the cross-diffusion (vc) of momentum is a natural result from the effect of the horizontal Coriolis force. Therefore the role of the horizontal shear of the mean flow cannot be absolutely separated from that of the vertical shear. So far in testing Muller's theory, the approximation of effective wave stress obtained by Ruddick and Joyce (1979) was extensively used, but it has to be revised under the conditions of this paper. The revised approximation shows that the internal waves with low frequencies close to the inertial frequency pl     

Tide simulation using the mild-slope equation with Coriolis force and bottom friction

Since the mild-slope equation was derived by Berkhoff (1972),the researchers considered various mechanism to simplify and improve the equation,which has been widely used for coastal wave field calculation.Recently,some scholars applied the mild-slope equation in simulating the tidal motion,which proves that the equation is capable to calculate the tide in actual terrain.But in their studies,they made a lot of simplifications,and did not consider the effects of Coriolis force and bottom friction on tidal wave.In this paper,the first-order linear mild-slope equations are deduced from Kirby mild-slope equation including wave and current interaction.Then,referring to the method of wave equations’ modification,the Coriolis force and bottom friction term are considered,and the effects of which have been performed with the radial sand ridges topography.Finally,the results show that the modified mild-slope equation can be used to simulate tidal motion,and the calculations agree well with the measurements,thus the applicability and validity of the mild-slope equation on tidal simulation are further proved.     

地转及均匀背景流场对混合层深度SAR遥感反演的影响

以考虑了地转和均匀背景流场影响的两层流体界面内波频散关系模型为基础,得到新的利用SAR遥感图像计算混合层深度的方法。利用该方法对一幅南海北部SAR内波图像进行了实例研究,并且和时空同步的CTD资料进行了对比。结果表明,加入地转和均匀背景流场影响的模型更为合理,为更准确地反演混合层深度奠定了基础。     

Interpretation of GLORIA side-scan sonar imagery for the Coriolis Troughs of the New Hebrides backarc

The Coriolis backarc troughs in southern Vanuatu are elongate, rhomboidal depressions with steep walls and flat floors, formed by extension. The Futuna Trough is relatively immature and, like Erromango Basin, shows no recent volcanism. Vate Trough is most developed, and its floor is largely covered by lava fields. Between Vate and Banks Islands, the backarc has three distinct characters: in the south it is sediment-draped; centrally, either lava projects through sediment cover or the area is covered by slide debris; in the north, a steep escarpment may result from collision of the arc with the D'Entrecasteaux Ridge.     

Theoretical analysis of equatorial near-inertial solitary waves under complete Coriolis parameters

An investigation of equatorial near-inertial wave dynamics under complete Coriolis parameters is performed in this paper. Starting from the basic model equations of oceanic motions, a Korteweg de Vries equation is derived to simulate the evolution of equatorial nonlinear near-inertial waves by using methods of scaling analysis and perturbation expansions under the equatorial beta plane approximation. Theoretical dynamic analysis is finished based on the obtained Korteweg de Vries equation, and t...     

航空矢量重力测量中科里奥利加速度对测速精度要求分析

首先论述了航空矢量重力测量中科里奥利加速度的计算模型,给出了科里奥利加速度改正对水平、垂直速度要求的分析模型。数值表明,在低纬地区欲达到1mGal的科里奥利加速度的精度,要求速度的精度为5cm／s左右;依据实测数据,目前GPS测得的载体速度精度为0．3mm／s,完全能够满足航空矢量重力测量对科里奥利加速度改正的要求。     

The symmetry and stability of unstructured mesh C-grid shallow water models under the influence of Coriolis

The symmetry and stability properties of two unstructured C-grid discretisations of the shallow water equations are discussed. We establish that a scheme in which the circumcentres of the mesh triangles are used as the surface elevation points has advantageous symmetry properties and derive a Coriolis discretisation which preserves these properties. It is shown that the resulting scheme is conservative in a discretised energy norm. We then establish that schemes in which the water surface elevations are stored at the mesh triangle centroids do not share these advantageous symmetry properties. Finally we show examples which demonstrate that the centroid based scheme is subject to unstable growing modes, particularly in long timescale, Coriolis dominated problems; while the energy conservative circumcentre based scheme suffers from no such limitation. We conclude that unstructured C-grid methods using the triangle circumcentres and the conservative Coriolis scheme derived here therefore have advantages for this sort of problem over those schemes based on centroids.     

On the Theory of Symmetric Instability of Time-Periodic Flows with a Complete Account for the Coriolis Force

Izvestiya, Atmospheric and Oceanic Physics - The symmetric (inertial) parametric instability of time-periodic flows with a linear velocity profile has been investigated, with a complete account for...     

Finite differencing of the advection term

The advection term in the finite difference diffusion equation can give rise to the false computational oscillation unless the ratio of the grid size to the coefficient of eddy diffusivity is smaller than a critical value. The slightly uncentered differencing scheme is useful for the advection term.     

The role of Coriolis in sandbank formation due to a headland/island system

Tidal flow past a headland was modelled and the resulting sandbank formation due to bedload transport by eddy systems was examined with particular emphasis on the role of Coriolis. The headland configuration was extended to the more complex case of a headland with a detached island and the role of Coriolis in sandbank formation was again examined. In the headland case, the contribution of Coriolis resulted in the expected change in bed level at the centre of the residual eddies (positive contribution for the cyclonic eddy and negative change for the anticyclonic eddy). In the headland/island case, the role of Coriolis in the resulting bed level change was a function of eddy shedding from the island, defined by the island wake parameter. When eddy shedding occurred, the inclusion of Coriolis had a large magnitude effect on creating flood/ebb sandbank asymmetry. When eddies remained attached to the island, Coriolis had a minor role in the magnitude of this asymmetry.     

A force source of tectonic movement-A secondary mass center restoring force

The earth system discussed in this paper is composed of two secondary particle systems: a water body and a base body. The base body shows different behaviours under the actions of long term and short term effects of its rheologic character and viscoelasticity. The short term effects result in a secondary particle system to deviate from its original position, and produce a secondary mass center restoring force directly proportional to the deviating distance. The long term effects result in the earth's material producing a secondary mass center restoring motion under the action of the secondary mass center restoring force.     

4D analogue modelling of transtensional pull-apart basins

Scaled sandbox models were used to investigate the 4D evolution of pull-apart basins formed above underlapping releasing stepovers in both pure strike-slip and transtensional basement fault systems. Serial sectioning and 3D volume reconstruction permitted analysis of the full 3D fault geometries. Results show that very different pull-apart basins are developed in transtension compared to pure strike-slip. Both types of models produced elongate, sigmoidal to rhomboidal pull-apart systems, but the transtensional pull-apart basins were significantly wider and uniquely developed a basin margin of en-echelon oblique-extensional faults. Dual, opposing depocentres formed in the transtensional model whereas a single, central depocentre formed in pure strike-slip. In transtension, a distinct narrow graben system formed above the principal displacement zones (PDZs). Cross-basin fault systems that linked the offset PDZs formed earlier in the transtensional models.Sequential model runs to higher PDZ displacements allowed the progressive evolution of the fault systems to be evaluated. In cross-section, transtensional pull-aparts initiated as asymmetric grabens bounded by planar oblique-extensional faults. With increasing displacement on the PDZs, basin subsidence caused these faults to become concave-upwards and lower in dip angle due to fault block collapse towards the interior of the basin. In addition, strain partitioning caused fault slip to become either predominantly extensional or strike-slip. The models compare closely with the geometries of natural pull-apart basins including the southern Dead Sea fault system and the Vienna Basin, Austria.     

Evaluation of methods to remove inertial force from measured model wave impact force signals

The subject of wave impact on offshore structures and their components is important to vessel designers and operators for many reasons. They are often required to quantify these impact loads. Standard methods for wave load prediction will underestimate the forces on these structures due to intermittent loading. This necessitates the use of physical model tests to establish wave impact loads. The model measurement systems are designed to have high stiffness. This ensures that the natural frequency of the structure is above the wave frequency. However, it is widely believed that impacting waves contain high-frequency energy components that cause the structure to vibrate at its modal frequencies. This impact-induced vibration is recorded by the measuring system as a force (inertial force), and corrupts the actual applied force measurement. Before scaling can occur, the inertial force must be removed from the measured signal.A number of techniques for removing inertial force from measured signals are described in the published literature. Three methods are discussed, implemented and compared in this paper. The algorithms and procedures are presented. Each technique contains inherent and unique problems, while some are common to all methods.Neither of the techniques produced results that are fully satisfactory. The main problem is unwanted high-frequency content after the application of the methods. While neither method offers the perfect solution, the use of digital filtering techniques is recommended based on their relative performance and ease of implementation.     

A study of Coriolis effects on long waves propagating in an unbounded ocean, channel and basin

The effects of Coriolis force on long waves have been discussed based on gravity waves propagating in an unbounded ocean, channel and basin. In case of ocean, results show that the Coriolis effect will be significant and negligible, when the wave period is comparable to 2π/f and much shorter, respectively. Results also show in a channel, the wave amplitude and water particle velocity decrease exponentially in the positive y direction in the northern hemisphere (where f is positive). Moreover, in a basin, the Cotidal lines have been found as curves and rotate counterclockwise around the origin.     

Managed retreat: a natural analogue from the Medway estuary,UK

A comparison between open marshes (un-reclaimed) and breached reclaimed land is made for sites within the Medway estuary, UK, in order to determine the effectiveness of these natural retreat sites in protecting the hinterland, and to use these findings as an analogue for modern managed retreat schemes. Two sites, who’s defences were breached at the turn of the century are studied to show rates of erosion experienced by the post-breach marsh, and compared to open marshes in the same system. This has shown that the rates of loss are greater in the open marshes over the same period of time, and that as an analogue for contemporary managed retreat sites, the breached sites have provided significant coastal protection to the hinterland for over 71 years, and, it could be argued, have survived natural erosive processes more effectively than open marshes.     

High-resolution central difference scheme for the shallow water equations

1 IntroductionThe shallow water equations (SWE) are frequent-ly used as a mathematical model for water flows incoastal areas, lakes, estuaries, etc. Thus, they are animportant tool to simulate a variety of problems relat-ed to coastal engineering, environment, ecology, etc.(Bermúdez et al., 1998). On the basis of solving theone-dimensional (1D) SWE, Hu et al. (2000) have de-veloped a model capable of simulating storm wavespropagating in the coastal surf zone and overtopping asea wall. Ano…     

近岸多波束测量中的GPS-RTK差分技术及其受影响的因素

分析了近岸多波束测量中应用GPS-RTK差分技术对船只导航与定位,对在受波浪影响的多波束测量中,船只所受潮汐、换能器吃水的动态变化量等诸影响因素的改正以及船只的运动姿态纠正等问题进行了讨论。使用GPS-RTK系统可以有效地解决潮汐(水位)、波浪影响和换能器吃水的动态变化量对多波束测量精度综合影响的问题,如果使用"一加三"的GPS-RTK接收机,还可以实现船只姿态的高精度综合修正。同时,对4个影响GPS-RTK差分技术系统能力的主要因素应引起重视,采取措施加以解决,使近岸的多波束测量工作更加富有成效。