Three-dimensional numerical simulation of wind-induced barotropic circulation in the Gulf of Patras   总被引：1，自引：0，他引：1  

Nikolaos Th. Fourniotis 《Ocean Engineering》2010,37(4):355-364

The barotropic, wind-induced circulation, which develops in the Gulf of Patras in Western Greece during the winter, is studied using three-dimensional numerical simulations. The simulations are performed using the numerical code MIKE 3 FM (HD). The Gulf's basin is bracketed between two sills, one on the west at the opening with the Ionian Sea and the other on the east at the Straits of Rio-Antirio at the opening with the Gulf of Corinth. The simulations show that the wind-induced flow creates strong currents near the coasts, which determine the sense of rotation of the gyres that develop in the Gulf. Strong currents are also created at the Rio-Antirio Straits. The wind-induced, barotropic currents do not seem to contribute to the direct replenishment of bottom waters, which recirculate between the two sills. Depending on the wind-speed forcing of the flow, the residence time of the waters in the Gulf of Patras is estimated to range from one week to one month.  相似文献   

Implementation of baroclinic terms in a three-dimensional hydrodynamic model and its application to Anzali Port, Iran     

Ali Khosh Kholgh  Peyman Badiei 《Ocean Engineering》2009,36(11):810-820

Baroclinic terms have been implemented in a three-dimensional fully hydrodynamic model developed by Badiei et al. [2008. A three-dimensional non-hydrostatic boundary fitted model for free surface flows. International Journal for Numerical Methods in Fluids, 56(6), 607-627] modifying its momentum equations to account for density gradients and utilizing the scalar (salinity, temperature, etc.) conservation equation (SCE) and a state equation for the calculation of density. In the solution of advection-diffusion terms of the governing Navier-Stokes equations (NSE) and SCE, a symmetric splitting method was applied to ensure the long-term stability of simulations. Correction terms proposed by Ruddic et al. (1995) were applied to SCE to ensure the conservation of the scalar quantity. In the presence of baroclinic terms, the zero gradient pressure in the vertical direction in the vicinity of surface and bottom boundaries assumed by Badiei et al. [2008. A three-dimensional non-hydrostatic boundary fitted model for free surface flows. International Journal for Numerical Methods in Fluids, 56(6), 607-627] created spurious currents. This problem was solved by assuming a hydrostatic pressure variation at those boundaries. The ability of extended model was validated by comparing its results with an experimental test case. The simulation of hydrodynamic and salt intrusion at Anzali Port located at the southern coasts of Caspian Sea in Iran was carried out by the model with both barotropic and baroclinic modes. The simulated results with baroclinic mode show a better agreement with measured data as compared to the results of barotropic mode that clearly demonstrate the significance of baroclinic terms in the simulation of cyclic intrusion of salt wedge into the Port Basin.  相似文献   

Lateral tidal mixing in the Antarctic marginal seas     

Aike Beckmann  Adriene F. Pereira 《Ocean Dynamics》2003,53(1):21-26

Tidal mixing plays an important role in the modification of dense water masses around the Antarctic continent. In addition to the vertical (diapycnal) mixing in the near-bottom layers, lateral mixing can also be of relevance in some areas. A numerical tide simulation shows that lateral tidal mixing is not uniformly distributed along the shelf break. In particular, strong mixing occurs all along the Ross Sea and Southern Weddell Sea shelf breaks, while other regions (e.g., the western Weddell Sea) are relatively quiet. The latter regions correspond surprisingly well to areas where indications for cross-shelf exchange of dense water masses have been found. The results suggest that lateral tidal mixing may account for the relatively small contribution of Ross Sea dense water masses to Antarctic Bottom Water.  相似文献   

吉林王家店矿区成矿地质特征分析     

亢彬  薄继荣 《地质与勘探》2000,36(6):27-31

在高级变质区会全栈“穹形构造”西缘“线性构造矿源域”基础上,经过古生代,特别是中生代的构造－岩浆作用改造叠加,在王家店花岗岩体风部、边缘、岩体之外,形成岩浆期后热液型金矿,其深部潜在远景有待进一步研究。  相似文献   

Role of barotropic mechanism in the development of a monsoon depression: A MONEX study     

D. Subrahmanyam  M. K. Tandon  L. George  S. K. Mishra 《Pure and Applied Geophysics》1981,119(5):901-912

The role of barotropic processes in the development of a monsoon depression, formed on 5 July 1979 during MONEX observational period, is studied by considering it as a quasi-geostrophic divergent barotropic instability problem of zonal flow of 3 July 1979 at 700 mb level. Numerical solutions are obtained by initial value approach. The preferred wave has a wavelength of 2750 km, an e-folding time of 4.3 days, a period of 6.5 days and an eastward phase speed of 4.9 ms^–1. Structure of preferred wave is found to be in good agreement with the observed horizontal structure of the depression at 700 mb. Poleward momentum transports are found to predominate over equatorward transports.Parts of this paper were presented at the National Symposium on Early Results of MONEX-1979. 9–12 March 1981, in New Delhi, India.  相似文献   

含大地形的准地转正压模式的孤立波解     

陈炯  刘式适 《应用气象学报》1999,10(3):299-306

该文由修正过的含大地形的准地转正压模式方程出发,考虑青藏高原大地形的实际情况,忽略其东西向地形坡度,再利用约化摄动方法,求其孤立波解,并得到结论:当基本气流无切变时,地形是产生Rossby孤立波的必要因子。  相似文献   

正压模式中的非绝热波动     

黄大川  刘式适 《热带气象学报》1999,15(1):26-37

应用含有非绝热因子的正压模式方程组,着重分析了对流凝结加热、蒸发－风反馈和ＣＩＳＫ机制等非绝热因子对低纬Ｒｏｓｓｂｙ波和Ｋｅｌｖｉｎ波的影响。既获得了圆频率的表达式,又分析了波的周期与稳定性。结果表明：非绝热因子的存在不但扩大了绝热波的周期,而且改变了波的稳定性。因此,可以认为：所谓季节内振荡（３０—６０天的周期振荡）等低频振荡实际上是一类非绝热波,这类非绝热波是引起中长期天气变化及短期气候演变的重要因素。  相似文献   

Some theoretical problems of the planetary-scale monsoons     

Chih-Pei Chang 《Pure and Applied Geophysics》1977,115(5-6):1089-1109

Summary Some important theoretical problems of the planetary-scale monsoons which have arisen from recent advances of observational studies are reviewed. These include: (1) the requirement of a strong damping mechanism in the planetary scale vorticity budget of summer monsoon and a similar but weaker requirement for the winter monsoon; (2) the localized barotropic instability of the summer monsoon which is a result of the strong zonal asymmetry of the planetary-scale flow and causes significant nonlinear energy conversions; and (3) the oscillations of the planetary-scale monsoons. It is pointed out that these problems are inter-related and their understanding is also important for the proper simulation of other scales of motion of the monsoon circulation.  相似文献   

纬向切变基流中的非线性正压Rossby波   总被引：2，自引：0，他引：2  

何建中 《气象学报》1994,52(4):433-441

在半地转近似下，用相角函数方法得到了包含纬向基流及其切变的非线性常微分方程。利用常微分方程解的拓扑性质的定性理论，直接得到该方程存在有限振幅的周期波解与孤立波解即非线性正压Ｒｏｓｓｂｙ波解存在的条件，由此分析了纬向切变基流对波解存在的影响。最后利用函数逼近法求得了非线性正压Ｒｏｓｓｂｙ波解的显式表达式。结果表明，纬向切变基流对波的影响不仅表现在波的存在方面，而且还表现在波的形态方面，反映了波的非线性特点和基流对波动的作用。  相似文献   

The influence of the coast on the dynamics of upwelling fronts: Part II. Numerical simulations     

Pascale Bouruet-Aubertot  Vincent Echevin 《Dynamics of Atmospheres and Oceans》2002,36(1-3)

We investigated the dynamics of upwelling fronts near a coast. This work was first motivated by laboratory experiments [Bouruet-Aubertot, Linden, Dyn. Atmos. Oceans, 2002] in which the front is produced by the adjustment of a buoyant fluid initially confined within a bottomless cylinder. It was shown that cyclonic eddies consisting of coastal waters are enhanced when the front is unstable near the coast (the outer vertical boundary). The purpose of this paper is to provide further insights into this process. We reproduced the experimental configuration using a three-dimensional model of the primitive equations. We first show that for coastal fronts more potential energy, in terms of the maximum available potential energy, is released than for open-ocean fronts. Therefore, waves of larger amplitude are generated during the adjustment and the mean flow that establishes has a higher kinetic energy in the former case. Then as baroclinic instability starts and wave crests reach the boundary, cyclonic eddies are enhanced as in the laboratory experiments and in a similar way. However, in contrast to the laboratory experiments, offshore advection of cyclonic eddies can occur in two stages, depending on the spatial organization of the baroclinic wave. When the baroclinic wave consists of the sum of different modes and is thus highly asymmetric, the offshore advection of cyclonic eddies occurs just after their enhancement at the boundary, as in the laboratory experiments. By contrast, when a single-mode baroclinic wave develops, neighboring cyclonic eddies first merge before being advected offshore. Very different behavior is observed for open-ocean fronts. First a mixed baroclinic–barotropic instability grows. Then the eddies transfer their energy to the mean flow and the barotropic and baroclinic instabilities start again. An excellent agreement is obtained with the main result obtained in the laboratory experiments: the ratio between growth rates of surface cyclonic and anticyclonic vorticity increases as the instability develops nearer to the coast.  相似文献