低风速下海面附近气温场对海气动量通量的影响     

程展  吴少华 《海洋预报》1995,12(1):1-6

实用测的海上和层平均风剖面数据和温度剖面数据，通过数据回归和迭代方法计算出了在不同大气稳定情况下的海面阻力系数。得到了与前人理论计算一致的结论：海面阻力系数随海面大气稳定度的增加而减小，另外，我们还发现：在海面风速小于１３ｍ／ｓ时，不能认为气温剖面外推到海面的值与海面水温的是一致的。这样若用海气温差作为衡量海面上方大气的稳定程度，难于得到上面给出了理结论。这一点同前人的理论计算结果是不相同的。  相似文献   

南海带鱼遗传变异及其分类的研究   总被引：4，自引：0，他引：4  

王可玲  刘兰英  尤锋  徐成 《海洋科学》1992,16(2):69-72

带鱼是我国海洋鱼类中最重要的经济鱼类,过去进行了大量的研究,多认为中国近海的带鱼为一个种,而不同的学者分别认为存在3,4和5个种群。从1976年开始,我们试图主要用生化方法并结合形态学资料研究带鱼的分类。1983和1988年报道了我们通过带鱼肌浆蛋白和形态学部分资料的研究认为中国近海带  相似文献   

The optimum control of thruster system for dynamically positioned vessels     

C. C. Liang  W. H. Cheng 《Ocean Engineering》2004,31(1):97-110

An offshore vessel with a dynamic positioning system (DP system) needs fast response to produce thrust to counteract the environmental forces acting on it for the purpose of maintaining its position and heading as close as possible to the working position. Therefore, quick and effective modulation of the thrust is the problem to determine the thrust and the rotation angle of the thruster devices of the ship. This paper presents an effective optimum control for a thruster system, using the sequential quadratic method to achieve economical and effective modulation of the thrust and the direction of the thruster. An optimum control study of a 2280 tons DP coring vessel with five rotary azimuth thruster marine positioning is studied in detail, which can quickly and exactly estimate the thrusts and angles of direction of all the thrusters. The results can provide a valuable thruster system for a dynamically positioned vessel.  相似文献   

A new form of generalized Boussinesq equations for varying water depth   总被引：1，自引：0，他引：1  

M. Zhao  B. Teng  L. Cheng 《Ocean Engineering》2004,31(16):597-2072

A new set of equations of motion for wave propagation in water with varying depth is derived in this study. The equations expressed by the velocity potentials and the wave surface elevations include first-order non-linearity of waves and have the same dispersion characteristic to the extended Boussinesq equations. Compared to the extended Boussinesq equations, the equations have only two unknown scalars and do not contain spatial derivatives with an order higher than 2. The wave equations are solved by a finite element method. Fourth-order predictor–corrector method is applied in the time integration and a damping layer is applied at the open boundary for absorbing the outgoing waves. The model is applied to several examples of wave propagation in variable water depth. The computational results are compared with experimental data and other numerical results available in literature. The comparison demonstrates that the new form of the equations is capable of calculating wave transformation from relative deep water to shallow water.  相似文献   

热带大西洋年际和年代际变率的时空结构模拟   总被引：10，自引：3，他引：10       下载免费PDF全文

赵珊珊  杨修群  朱益民 《海洋学报》2003,25(3):8-19

使用美国夏威夷大学发展的中等复杂程度海洋模式(IOM)在给定表面强迫条件下模拟了热带大西洋上层海洋年际和年代际变率的时空结构.利用NCEP的41a(1958～1998年)逐月平均表面资料作为强迫场,积分海洋模式41a作为控制试验,并利用模式分别做动量(风应力)通量和热量通量无异常变化的平行试验,与控制试验作比较.对3组试验模拟上层海洋变率状况的比较,并按年际和年代际时间尺度分别分析,揭示表面风应力和热通量异常对海表面温度和温跃层深度变化的影响,并比较了其影响的相对重要性.结果表明模式成功地模拟出了热带大西洋上层海洋的变率.模式模拟的海表面温度年际变化主要表现为弱ENSO型,年代际变化表现为南、北大西洋变化相反的偶极子型.在年际时间尺度上,热力强迫和动力强迫对海表温度变化都有贡献,其中赤道外海表面温度异常(SSTA)变化主要由热通量异常引起,而近赤道SSTA的变化主要由动量异常强迫引起.在年代际时间尺度上,热通量强迫的作用远比动量强迫重要.模式不仅能够模拟SST在年际和年代际时间尺度上的变率,还能够模拟温跃层深度在年际和年代际时间尺度上的变率.年际和年代际时间尺度上,温跃层深度的变率主要由动量异常决定,热通量异常强迫的贡献很小.  相似文献   

Calibration of JASON-1 Altimeter over Lake Erie     

C. Shum  Y. Yi  K. Cheng  C. Kuo  A. Braun  S. Calmant  D. Chambers 《Marine Geodesy》2003,26(3):335-354

This article describes absolute calibration results for both JASON-1 and TOPEX Side B (TSB) altimeters obtained at the Lake Erie calibration site, Marblehead, Ohio, USA. Using 15 overflights, the estimated JASON altimeter bias at Marblehead is 58 ± 38 mm, with an uncertainty of 19 mm based on detailed error analysis. Assuming that the TSB bias is negligible, relative bias estimates using both data from the TSB-JASON formation flight period and data from 48 water level gauges around the entire Great Lakes confirmed the Marblehead results. Global analyses using both the formation flight data and dual-satellite (TSB and JASON) crossovers yield a similar relative bias estimate of 146 ± 59 mm, which agrees well with open ocean absolute calibration results obtained at Harvest, Corsica, and Bass Strait (e.g., Watson et al. 2003). We find that there is a strong dependence of bias estimates on the choice of sea state bias (SSB) models. Results indicate that the invariant JASON instrument bias estimated oceanwide is 71 mm, with additional biases of 76 mm or 28 mm contributed by the choice of Collecte Localisation Satellites (CLS) SSB or Center for Space Research (CSR) SSB model, respectively. Similar analysis in the Great Lakes yields the invariant JASON instrument bias at 19 mm, with the SSB contributed biases at 58 mm or 13 mm, respectively. The reason for the discrepancy is currently unknown and warrants further investigation. Finally, comparison of the TOPEX/POSEIDON mission (1992-2002) data with the Great Lakes water level gauge measurements yields a negligible TOPEX altimeter drift of 0.1 mm/yr.  相似文献   

远区台风“三巴”对长江口波浪动力场的作用机制     

任剑波  何青  沈健  徐凡  郭磊城  谢卫明  朱磊 《海洋科学》2020,44(5):12-23

针对远区台风对河口波浪动力场的影响问题,利用第三代波浪模式SWAN计算了远区台风"三巴"期间长江口波浪动力场分布,分析了陆架至河口区的波浪能量耗散和波致泥沙侵蚀的时空分布,发现波浪由外海向近岸传播过程中,波-波相互作用导致能量由高频向低频转换,周期和波长逐渐增大,近底层轨道流速增大,能量密度增高;阐明白帽破碎是维持深水区波浪能量平衡和限制波高成长的主要机制,底摩擦耗能和水深诱导的破碎耗能是长江口横沙东滩和崇明东滩邻近海域波高衰减的主要原因;提出波浪产生的底部切应力与相对水深有关,当波浪传播到浅水区时,波长和周期越大,波浪切应力越大。研究揭示了与河口相距数百公里的远区台风能够对长江口波浪动力场产生明显影响,河口水下三角洲前缘是最容易受到波浪侵蚀的区域,研究成果弥补了目前关于陆架远区台风对河口波浪动力场影响研究的不足,对深化认识远区台风对长江口动力环境、地貌演变、航运安全和滩涂保护等有重要科学意义。  相似文献   

Numerical Simulation of Dynamic Response of Supple Nets     

朱立新梁振林  黄六一赵芬芳 《中国海洋工程》2006,20(3):443-456

1 .Introduction Owing to the decline of capture fisheries andsaturation of traditional inshorefarms ,sea cage cul-ture as a newtype of aquaculture is developingrapidlyin China .However ,cage culture is a highriskoperation.The practice is vulnerable to natural hazards ,such as strong tides ,storms and typhoons .So,it is necessaryto assess the behavior of a sea cage exposedto waves and current before the designandinstallation of the structure . Computer simulation,due to its many advantages ,ha…  相似文献   

固定化鲅鱼乙酰胆碱酯酶的制备及部分性质测定   总被引：3，自引：0，他引：3  

孟范平  何东海  朱小山  马冬冬  杨正先  YANG Zheng-Xian 《中国海洋大学学报(自然科学版)》2005,35(6):1067-1071

酶的固定化是酶传感器制备过程中重要的1个环节.研究采用直接共价法固定鲅鱼乙酰胆碱酯酶（AChE）.制备方法为：0.1g CNBr活化的Sepharose 4B凝胶用1mmol/L的HCl充分溶胀后,与活力为10U的AChE溶液混合,于4℃下150r/min振荡8h.所制备的固定化酶活力回收率较高（96%）,对pH值和温度变化的适应能力均优于非固定化酶;在3个月保存期内,前者的活力损失13%,而后者的活力则下降89%.这说明固定过程能够大大提高AChE的抗逆性和保持酶活力的稳定,有利于酶传感器的制备.  相似文献   

法国“阿塔郎特”号海洋调查船上的重力取样     

程振波  刘振夏  王揆洋  崔金瑞 《海洋科学进展》1997,(3)

在海洋地质调查中，如何取得好的沉积物样品是每一位海洋地质学家所向往的，而获得好的沉积物样品的关键又很大程度上取决于先进的海洋调查仪器的使用。法国“阿塔郎特”号海洋调查船上的重力取样管不管在性能上，还是安全性上都瞰称世界上比较先进的取样设备。  相似文献