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31.
Li Dashan Shen Ying Ren Rushu Chen Yao
Senior Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing Associate Professor Hohai University Nanjing Master Hohai University Nanjing 《中国海洋工程》1997,(1)
In this paper,the characteristics of density current under the action of waves are describedwith the help of flume experiment and theoretical analysis.The study shows that turbid water under the ac-tion of the waves can present three types of motion,i.e.significant stratification,fragile stratification andstrong mixing.The motion of turbid water presents significant stratification when(H/D)/△ρ/ρ~(1/2)≤4.5,generally this state is known as density current.The formulas of motionvelocity,thickness,and discharge of density current moving on horizontal bottom are derived by use of ba-sic equations such as momemtum equation,equation of energy conservation and continuity equation offluid.The time-average velocity and the thickness of density current under the action of waves have a rela-tionship with such parameters as relative density(△ρ/ρ),wave height(H),and water depth(D).Whenthese parameters are determined,the time-average thickness and motion velocity of density current are al-so determined.The relat 相似文献
32.
波浪作用下异重流运动特性研究 总被引:3,自引:0,他引:3
本文通过水槽试验和理论分析手段对波浪作用下异重流运动特性进行了研究,应用流体运动基本方程推导了异重流在水平底面运动时的运动速度、厚度和流量表达式。结果表明,计算结果与水槽试验较一致 相似文献
33.
结合近年来参与有关水下工程检测和项目监理的实践体验 ,从总结水下工程项目的基本特征着手 ,分析了水下工程项目监理的主要任务 ,并结合对于实施水下工程项目监理必备装备条件的探讨 ,介绍了国内外现有水下监测技术装备的开发应用状况 相似文献
34.
对渤、黄海14个主要海湾的原始验潮记录进行了分析,从中筛选出水位变化幅度大于或等于50cm的54个假潮个例,着重分析了伴随假潮过程的天气形势,把可能引发假潮的天气形势归纳为4种基本类型。分析结果显示:绝大多数(92%)引发假潮的天气个例都与锋面活动有关;所有个例中低层大气基本上都是弱静力稳定,且都具有较强的垂直风速切变。根据观测事实和稳定度理论分析认为,低层大气的弱静力稳定层结构以及由垂直风速切变引起的剪切不稳定性,是假潮气象学成因的一种必要条件和物理机制。 相似文献
35.
南海罗斯贝变形半径的地理及季节变化 总被引:3,自引:1,他引:3
根据南海 1°× 1°网格的标准层季节平均温、盐度资料 ,在未引入Boussinesq近似条件下 ,采用改进的Thompson Haskell算法求解线性化斜压海洋水平大尺度波的垂直结构方程 (重力内波方程 ) ,从而得到了南海各网格点的第一斜压重力波相速度和相应的罗斯贝变形半径 ,并探讨其地理分布和季节变化特征 ,以期有助于南海环流和中尺度涡旋以及有关海洋侧边界效应的研究。 相似文献
36.
37.
Ching-Hui Tsai Shu-Kun Hsu Yi-Ching Yeh Chao-Shing Lee Kanyuan Xia 《Marine Geophysical Researches》2004,25(1-2):63-78
Magnetic data suggest that the distribution of the oceanic crust in the northern South China Sea (SCS) may extend to about 21 °N and 118.5 °E. To examine the crustal features of the corresponding continent–ocean transition zone, we have studied the crustal structures of the northern continental margin of the SCS. We have also performed gravity modeling by using a simple four-layer crustal model to understand the geometry of the Moho surface and the crustal thicknesses beneath this transition zone. In general, we can distinguish the crustal structures of the study area into the continental crust, the thinned continental crust, and the oceanic crust. However, some volcanic intrusions or extrusions exist. Our results indicate the existence of oceanic crust in the northernmost SCS as observed by magnetic data. Accordingly, we have moved the continent–ocean boundary (COB) in the northeastern SCS from about 19 °N and 119.5 °E to 21 °N and 118.5 °E. Morphologically, the new COB is located along the base of the continental slope. The southeastward thinning of the continental crust in the study area is prominent. The average value of crustal thinning factor of the thinned continental crust zone is about 1.3–1.5. In the study region, the Moho depths generally vary from ca. 28 km to ca. 12 km and the crustal thicknesses vary from ca. 24 km to ca. 6 km; a regional maximum exists around the Dongsha Island. Our gravity modeling has shown that the oceanic crust in the northern SCS is slightly thicker than normal oceanic crust. This situation could be ascribed to the post-spreading volcanism or underplating in this region. 相似文献
38.
Profiles observed by Sea-Wing underwater gliders are widely applied in scientific research. However, the quality control(QC) of these data has received little attention. The mismatch between the temperature probe and conductivity cell response times generates erroneous salinities, especially across a strong thermocline. A sensor drift may occur owing to biofouling and biocide leakage into the conductivity cell when a glider has operated for several months. It is therefore critical to design a mature real-time QC procedure and develop a toolbox for the QC of Sea-Wing glider data. On the basis of temperature and salinity profiles observed by several Sea-Wing gliders each installed with a Sea-Bird Glider Payload CTD sensor, a real-time QC method including a thermal lag correction, Argo-equivalent real-time QC tests, and a simple post-processing procedure is proposed. The method can also be adopted for Petrel gliders. 相似文献
39.
Shigenao Maruyama Koutaro Tsubaki Keisuke Taira Seigo Sakai 《Journal of Oceanography》2004,60(3):563-568
Deep seawater in the ocean contains a great deal of nutrients. Stommel et al. have proposed the notion of a “perpetual salt fountain” (Stommel et al., 1956). They noted the possibility of a permanent upwelling of deep seawater with no additional external energy source. If
we can cause deep seawater to upwell extensively, we can achieve an ocean farm. We have succeeded in measuring the upwelling
velocity by an experiment in the Mariana Trench area using a special measurement system. A 0.3 m diameter, 280 m long soft
pipe made of PVC sheet was used in the experiment. The measured data, a verification experiment, and numerical simulation
results, gave an estimate of upwelling velocity of 212 m/day.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
40.