Circulation on the north central Chukchi Sea shelf   总被引：8，自引：0，他引：8  

Thomas Weingartner  Knut Aagaard  Rebecca Woodgate  Seth Danielson  Yasunori Sasaki  Donald Cavalieri 《Deep Sea Research Part II: Topical Studies in Oceanography》2005,52(24-26):3150

Mooring and shipboard data collected between 1992 and 1995 delineate the circulation over the north central Chukchi shelf. Previous studies indicated that Pacific waters crossed the Chukchi shelf through Herald Valley (in the west) and Barrow Canyon (in the east). We find a third branch (through the Central Channel) onto the outer shelf. The Central Channel transport varies seasonally in phase with Bering Strait transport, and is 0.2 Sv on average, although some of this might include water entrained from the outflow through Herald Valley. A portion of the Central Channel outflow moves eastward and converges with the Alaskan Coastal Current at the head of Barrow Canyon. The remainder appears to continue northeastward over the central outer shelf toward the shelfbreak, joined by outflow from Herald Valley. The mean flow opposes the prevailing winds and is primarily forced by the sea-level slope between the Pacific and Arctic oceans. Current variations are mainly wind forced, but baroclinic forcing, associated with upstream dense-water formation in coastal polynyas might occasionally be important.Winter water-mass modification depends crucially on the fall and winter winds, which control seasonal ice development. An extensive fall ice cover delays cooling, limits new ice formation, and results in little salinization. In such years, Bering shelf waters cross the Chukchi shelf with little modification. In contrast, extensive open water in fall leads to early and rapid cooling, and if accompanied by vigorous ice production within coastal polynyas, results in the production of high-salinity (>33) shelf waters. Such interannual variability likely affects slope processes and the transport of Pacific waters into the Arctic Ocean interior.  相似文献   

Fuzzy Fatigue Reliability Analysis of Offshore Platforms in Ice-Infested Waters   总被引：3，自引：3，他引：3  

方华灿  段梦兰  贾星兰  谢彬 《中国海洋工程》2003,17(3)

1 .IntroductionTheBohaiGulfisinfestedbyiceinthewholewinter,andoffshorestructuresthereexperiencenotonlywind ,waves ,currentsandearthquake ,butalsoiceloadswhicharecomplicatedbecauseofthedynamicinteractionbetweenicesheetsandstructures.Duanetal.( 2 0 0 0 )hadacomprehensivere viewofthelatestadvancesonice inducedvibration ,fatigueandfractureofoffshorestructures ,payingmuchattentiontothedifferencesinicebreakingmodeanddynamicsofstructuresindifferentice in festedwaters .Theypresentedcriticallythelates…  相似文献   

Nonlinear coupled dynamic response of offshore Spar platforms under regular sea waves     

A. K. Agarwal  A. K. Jain 《Ocean Engineering》2003,30(4):492-551

Many innovative floating offshore structures have been proposed for cost effectiveness of oil and gas exploration and production in water depths exceeding one thousand meters in recent years. One such type of platform is the offshore floating Spar platform. The Spar platform is modelled as a rigid body with six degrees-of-freedom, connected to the sea floor by multi-component catenary mooring lines, which are attached to the Spar platform at the fairleads. The response dependent stiffness matrix consists of two parts (a) the hydrostatics provide restoring force in heave, roll and pitch, (b) the mooring lines provide the restoring force which are represented here by nonlinear horizontal springs. A unidirectional regular wave model is used for computing the incident wave kinematics by Airy’s wave theory and force by Morison’s equation. The response analysis is performed in time domain to solve the dynamic behavior of the moored Spar platform as an integrated system using the iterative incremental Newmark’s Beta approach. Numerical studies are conducted for sea state conditions with and without coupling of degrees-of-freedom.  相似文献   

Wave-Current Forces on Vertical Cylinders in Side-by-Side Arrangement for Irregular Waves Combined With Opposing Current     

Li Yucheng Wang Fenglong Professor  Dalian University of Technology  Dalian Senior Engineer  Dalian University of Technology  Dalian 《中国海洋工程》1993,(1)

- The wave-current forces on vertical piles in side-by-side arrangement induced by irregular waves with opposing current are investigated experimentally in this paper. The characteristics in both time and frequency domain of in-line, lift and resultant forces are analyzed. The grouping effect coefficients of inline, lift and resultant forces on piles related to KC number and relative spacing parameters are given. These results are compared with those in the case of irregular waves combined with following currents. It is found that the results in these two cases are quite different. The range of KC number tested is 10- 60, the range of Reynolds number is (0.55-3.43) ×104.  相似文献   

冰心中的气候环境记录与全球变化研究   总被引：1，自引：0，他引：1  

谢树成  殷鸿福 《海洋地质与第四纪地质》1997,17(4):109-113

冰心是高分辨地记录全球变化的主要信息载体之一。本文总结了冰心中提取古气候和古环境信息的系列记录，包括同位素、微量气体、阴阳离子、微粒、生物和有机质等。着重讨论了由这些记录提取的古气候和古环境变化方面的研究进展，并提出了今后的研究重点。  相似文献   

作用于平台桩腿的海冰屈曲破坏冰压力随机过程模型及其参数确定   总被引：2，自引：1，他引：2  

段忠东  欧进萍 《海洋工程》1996,(4)

冰对结构的作用过程是典型的随机过程。本文在冰压力过程为平稳过程的假设下，从渤海海冰对平台桩腿作用的大量实测冰压力数据中，选取了２１条冰屈曲破坏时的冰压力时程曲线，对它们进行谱分析后，得到了单点冰屈曲破坏的压力随机过程的谱密度，并确定了谱参数及其跟环境要素的关系，依据文献［１］中冰压力沿圆柱面的空间分布，建立了绕桩腿的冰压力随机场模型，并得到了作用于桩腿的总冰力随机过程及其谱密度。本文的研究成果为平台结构冰激随机振动和疲劳累积损伤分析提供了荷载基础  相似文献   

Mechanisms controlling the temporal variation of the sea ice edge in the Southern Ocean     

Noriaki Kimura 《Journal of Oceanography》2007,63(4):685-694

This paper examines the mechanism controlling the short time-scale variation of sea ice cover over the Southern Ocean. Sea ice concentration and ice velocity datasets derived from images of the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSM/I) are employed to reveal this mechanism. The contribution of both dynamic and thermodynamic processes to the change in ice edge location is examined by comparing the meridional velocity of ice edge displacement and sea ice drift. In the winter expansion phase, the thermodynamic process of new ice production off the ice edge plays an important role in daily advances of ice cover, whereas daily retreats are mostly due to southward ice drift. On the other hand, both advance and retreat of ice edges in the spring contraction phase are mostly caused by the dynamic process of the ice drift. Based on the above mechanism and the linear relation between the degree of ice production at the ice edge and northward wind speed, the seasonal advance of ice cover can be roughly reproduced using the meridional velocity of ice drift at the ice edge.  相似文献   

北极海冰变化特征分析   总被引：3，自引：0，他引：3  

魏立新  张占海 《海洋预报》2007,24(4):42-48

本文利用NASA的海冰密集度资料(时间为1978年10月～2002年9月,分辨率为1.0×0.25),计算并分析了1978～2002年的北极海冰面积、范围的时间变化趋势以及变化的空间分布。  相似文献   

南极普里兹湾气旋的生消发展   总被引：3，自引：4，他引：3  

解思梅  郝春江  梅山  刘克威  魏立新 《海洋学报》2002,24(6):11-19

利用1989～2000年现场观测的气象资料,特别是自1997年以来在南极考察船上接收的NOAA卫星极轨高分辨的卫星云图,研究了普里兹湾气旋的生消发展;提出了夏季绕极气旋进入普里兹湾内也会发展加强,在湾内东风带里也能生成气旋的新观点,修正了普里兹湾仅是气旋墓地的不全面说法,从而进一步完善了南极西风带绕极气旋和东风带上气旋生消发展的理论;研究了普里兹湾冰-气-海相互作用的机理,解释了气旋发生、发展的物理过程.用整体动力学输送法计算了进入普里兹湾980205号绕极气旋爆发性发展的能量交换,指出气旋在超过冰坝进入冰间湖可以获得巨大的热量,使气旋迅速发展成为具有南极特色的强风暴,风力达12级以上,平均风速为38m/s;瞬时最大风速达100m/s.  相似文献   

Formation of Equilibrium Beach Profile of the Abandoned Yellow River Delta Coast in North Jiangsu     

XU  Min 《中国海洋工程》2001,(1):139-146

The abandoned Yellow River Delta coast is a typical erodible silty and muddy coast in China. The paper analyses the marine dynamic characteristics and the mechanism of beach erosion of this area. Analysis and calculation show that in this sea area wave and tidal current action should be considered. Based on the above analysis, an equilibrium beach profile calculation model is developed, in which the wave-current interaction is considered while sediment supply and sediment re-deposition are neglected. The model consists of four parts: (1) calculation of wave parameters, (2) calculation of velocity due to wave-current interaction at different water depth, (3) calculation of friction velocity and shear stress at different water depths, and (4) calculation of the amount of sediment erosion, erosion intensity and variation of beach profile. Calculated results are in good agreement with observed data. Finally, the evolution tendency is discussed and the equilibrium beach profile of this coast is calculated. B  相似文献