On the circulation in the East Frisian Wadden Sea: numerical modeling and data analysis     

Emil V. Stanev  Jörg-Olaf Wolff  Hans Burchard  Karsten Bolding  Götz Flöser 《Ocean Dynamics》2003,53(1):27-51

 In this paper we use a combination of numerical modeling and data analysis to gain a better understanding of the major characteristics of the circulation in the East Frisian Wadden Sea. In particular, we concentrate on the asymmetry of the tidal wave and its modulation in the coastal area, which results in a complex pattern of responses to the sea-level forcing from the North Sea. The numerical simulations are based on the 3-D primitive equation General Estuarine Transport Model (GETM) with a horizontal resolution of 200 m and terrain-following vertical coordinates. The model is forced at its open boundaries with sea-level data from an operational model for the German Bight (German Hydrographic Office). The validation data for our model simulations include time series of tidal gauge data and surface currents measured at a pile in the back-barrier basin of the Island Langeoog, as well as several ADCP transects in the Accumer Ee tidal inlet. Circulation and turbulence characteristics are investigated for typical situations driven by spring and neap tides, and the analysis is focused on dominating temporal and spatial patterns. By investigating the response of five back-barrier basins with rather different morphologies to external forcing, an attempt is made to elucidate the dominating physical balances controlling the circulation in the individual sub-basins. It is demonstrated that the friction at the seabed tends to slow down the tidal signal in the shallow water. This leads to the establishment of flood dominance in the shallow sea north of the barrier islands. South of the islands, where the water volume of the channels at low tide is smaller than the tidal prism, the asymmetry of the tidal signal is shifted towards ebb dominance, a feature which is particularly pronounced at spring tide. At the northern open boundary, the tidal wave propagating from west to east generates a sea-level difference of ∼1 m along the boundary, and thereby triggers vigorous alongshore currents. The frictional control in the model is located in the inlets, as well as along the northern boundary. The correlation between velocity and turbulent kinetic energy tends to the establishment of a net southward transport, giving theoretical support to the observed accumulation of sediments on the intertidal flats. Weak turbulence along the northern shores of the barrier islands and the small magnitude of the residual currents there promote accumulation of suspended matter in these areas, although wave action will generally counteract this effect. Received: 29 May 2002 / Accepted: 26 September 2002 Responsible Editor: Jean-Marie Beckers Acknowledgements We are indebted to S. Dick for providing the data from the operational model of BSH and to B. Flemming for the useful discussions. The topography data and Fig. 1 have been prepared in cooperation with F. Meyer. Figure 2 has been prepared by G. Brink-Spalink. We also thank for the comments from an anonymous reviewer which helped to improve our paper.  相似文献   

陆面过程模式的改进及其检验   总被引：11，自引：0，他引：11  

周锁铨  代刊  陈涛  屠其璞  陈万隆 《气象学报》2003,61(3):275-290

文中对陆面过程模式 (BATS)进行了改进 ,改进后的模式能较好地模拟地表物理量的年、季和日变化 ,它有两方面的特点 :采用热扩散方程模拟 7层土壤温度 ,模拟的温度可与实测值进行比较 ;在BATS的地表径流方案中 ,考虑了空间不均匀性的一般地表径流 (GVIC)过程 ,研究结果表明 :⑴模式能很好地模拟各层土壤温度的年、季和日变化。冬季土壤温度下层高于上层 ,而在夏季上层高于下层 ,这种上下层温度的转换时间大约在 4和 10月份 ,这与实测土壤温度的年变化非常一致。较为准确地模拟了各层土壤温度日变化的时滞效应。⑵用南京和武汉站的资料 ,将BATS地表径流方案模拟的地表水分分量与GVIC方案进行比较 ,BATS地表径流方案模拟的地表水分分量 ,与总水量的平衡相差较大 ,而GVIC模拟的效果相对较好 ,地表总水量基本上与降水总量达到了平衡  相似文献   

小波变换在识别储层流体性质中的应用   总被引：16，自引：0，他引：16       下载免费PDF全文

岳文正  陶果 《地球物理学报》2003,46(6):863-869

根据小波变换的特点提出一种识别储层流体的新方法. 本文假设测井所得的信号为地层微观孔隙结构、地层流体性质及岩性和岩相等各部分的综合贡献之和，不同的储层中小波分析的能量谱特征不同，因而通过对已知储层模型进行小波能量谱分析，可得到各种储层的特征能量谱，根据这些储层特征能量谱就可以对待划分的储层段进行储层流体性质判别.  相似文献   

An　Economical　Consistent　Dissipation　Operator　and　Its　Applications　to　the　Improvement　of　AGCM     

王斌  季仲贞 《大气科学进展》1997,(1)

ＡｎＥｃｏｎｏｍｉｃａｌＣｏｎｓｉｓｔｅｎｔＤｉｓｉｐａｔｉｏｎＯｐｅｒａｔｏｒａｎｄＩｔｓＡｐｐｌｉｃａｔｉｏｎｓｔｏｔｈｅＩｍｐｒｏｖｅｍｅｎｔｏｆＡＧＣＭ①ＷａｎｇＢｉｎ（王斌）ａｎｄＪｉＺｈｏｎｇｚｈｅｎ（季仲贞）ＬＡＳＧ，Ｉｎｓｔｉｔｕｔｅ...  相似文献   

可压二维大气中三类定常基态的稳定性分析     

周江兴  丁一汇  刘益民 《气象学报》1997,55(4):385-397

本文讨论了可压、绝热、无耗散的二维大气中三类定常基态的稳定性问题，并严格证明了这三类定常基态的稳定性性质是由基态的特征矩阵Λ的性质所决定的：ａ．若Λ在域Ｇ＋Γ内处处为正定矩阵，则基态是稳定的；ｂ．若Λ在域Ｇ＋Γ内非处处为半正定矩阵，则基态是不稳定的  相似文献   

THE EFFECTS OF EXTERNAL FORCING,DISSIPATION AND NONLINEARITY ON THE SOLUTIONS OF ATMOSPHERIC EQUATIONS^*     

Li Jianping  Chou Jifan 《Acta Meteorologica Sinica》1997,11(1):57-65

Based on the primitive equations of the atmosphere,we study the effects of external forcing.dissipation and nonlinearity on the solutions of stationary motion and non-stationary motion.The results show that the asymptotic behavior of solutions of the forced dissipative nonlinear system is essentially different from that of the adiabatic non-dissipative system,the adiabatic dissipative system,the diabatic non-dissipative system and the diabatic dissipative linear system,and that the joint action of external forcing,dissipation and nonlinearity is the source of multiple equilibria.From this we can conclude that the important actions of diabatic heating and dissipation must be considered in the models of the long-term weather and the climate.  相似文献   

高粘性牛顿流体粘性耗散的快速计算方法          下载免费PDF全文

陈建军  任彦蓉 《盐湖研究》1997,5(1):76-80

螺旋泵可用来输送高粘性液体，该过程中由于液体的温度升高而粘度降低，因而其粘性耗散不能忽略。本文介绍一种上述情况下计算液体粘度、泵的功率和压力降的近似公式。  相似文献   

The mean and turbulence structure simulation of the monsoon trough boundary layer using a one-dimensional model withe-l ande-ε closures     

Kusuma G. Rao  V. N. Lykossov  A. Prabhu  S. Sridhar  E. Tonkacheyev 《Journal of Earth System Science》1996,105(3):227-260

An attempt has been made here to study the sensitivity of the mean and the turbulence structure of the monsoon trough boundary layer to the choice of the constants in the dissipation equation for two stations Delhi and Calcutta, using one-dimensional atmospheric boundary layer model withe-ε turbulence closure. An analytical discussion of the problems associated with the constants of the dissipation equation is presented. It is shown here that the choice of the constants in the dissipation equation is quite crucial and the turbulence structure is very sensitive to these constants. The modification of the dissipation equation adopted by earlier studies, that is, approximating the Tke generation (due to shear and buoyancy production) in theε-equation by max (shear production, shear + buoyancy production), can be avoided by a suitable choice of the constants suggested here. The observed turbulence structure is better simulated with these constants. The turbulence structure simulation with the constants recommended by Aupoixet al (1989) (which are interactive in time) for the monsoon region is shown to be qualitatively similar to the simulation obtained with the constants suggested here, thus implying that no universal constants exist to regulate dissipation rate. Simulations of the mean structure show little sensitivity to the type of the closure parameterization betweene-l ande-ε closures. However the turbulence structure simulation withe-ε. closure is far better compared to thee-l model simulations. The model simulations of temperature profiles compare quite well with the observations whenever the boundary layer is well mixed (neutral) or unstable. However the models are not able to simulate the nocturnal boundary layer (stable) temperature profiles. Moisture profiles are simulated reasonably better. With one-dimensional models, capturing observed wind variations is not up to the mark.  相似文献   

Pall型摩擦阻尼支撑内力计算方法   总被引：3，自引：0，他引：3  

吴斌  张纪刚  欧进萍 《世界地震工程》2004,20(2):6-11

从Pall摩擦阻尼器四连杆机构的几何非线性变形特征出发，分析框架位移、支撑刚度、阻尼器摩擦力、阻尼器大小、支撑倾角、支撑屈曲力等对一种改进的Pall摩擦阻尼器-T形芯板摩擦阻尼器支撑的受力特点，拟合出可供设计人员使用的实用计算公式。  相似文献   

Seismic tests on reinforced concrete and steel frames retrofitted with dissipative braces     

F. J. Molina  S. Sorace  G. Terenzi  G. Magonette  B. Viaccoz 《地震工程与结构动力学》2004,33(15):1373-1394

Seismic tests have been conducted on two 3‐storey structures protected with pressurized fluid‐viscous spring damper devices. One of the structures was a reinforced concrete frame with clay elements in the slabs, while the other one was a steel frame with steel/concrete composite slabs. The spring dampers were installed through K bracing in between the floors. The tests were performed by means of the pseudodynamic method, which allowed the use of large and full‐size specimens, and by implementing a specific compensation strategy for the strain‐rate effect at the devices. The test results allowed the verification of the adequacy of the attachment system as well as the comparison of the behaviour of the unprotected buildings with several protected configurations, showing the benefits of the application of the devices and the characteristics of their performance. The response of the protected structures was always safer than that of the unprotected ones mainly due to a significant increase of equivalent damping. The increase in the damping ratio depends on the level of deformation. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献