冲绳海槽有孔虫壳体的微量元素Sr,Nd同位素地球化学   总被引：6，自引：1，他引：6  

孟宪伟  杜德文  程振波 《海洋学报》2001,23(2):62-68

钙质生物壳的微量元素组合和Sr,Nd同位素组成是识别海底混合源沉积物中生物源物质相对贡献的重要参数.冲绳海槽有孔虫壳体强烈富集Sr,P,Mn和Ba,富集Li,U,Th,Sc,Co,Pb,Zn,Cr,Rb,Y,Sb和轻稀土元素,弱富集V,Ga,Zr,Nb,Cd和中稀土元素,相对贫Ge,Mo,In,Sn,Cs,Hf,Ta,W,Tl,Bi和重稀土元素,海水中微量元素的背景含量和生物活动对微量元素的选择性吸收是有孔虫壳体中微量元素发生富集和贫化的主要机制,冲绳海槽有孔虫壳体的稀土元素配分模式与海水和太平洋有孔虫的有明显差异,表现出中稀土元素相对富集,并具有微弱的负Ce异常.有孔虫壳体的Sr,Nd同位素比值也与大洋海水不同,分别为0.709769和0.512162,前者略高于大洋海水,后者略低于大洋海水,表明冲绳海槽海水明显受大陆河水影响.  相似文献   

钙质成岩作用对有孔虫氧同位素的影响     

房殿勇  赵泉鸿  成鑫荣  关平  李洋冰 《海洋地质与第四纪地质》2005,25(2):63-66

通过对南海北部ODPl84航次1148站井深477m之下深海相渐新世浮游有孔虫Globoquadrina压扁壳、次生方解石和充填壳的氧同位素对比，定量分析了钙质成岩作用对壳体氧同位素的影响，结果发现，受成岩作用影响，1148站浮游有孔虫氧同位素显著变轻，这种变化趋势与低纬度开放性大洋明显不同。其原因可能与南海海盆扩张早期，大量陆源物质从较窄陆架可以直接沉积到海底，由于陆源物质氧同位素相对偏负，当与海洋沉积物混合后，引起本区沉积物孔隙水氧离子浓度变轻。而扩张初始，高的沉积速率可能使钙质壳体被快速封存在一个相对孤立的系统中，造成孔隙水离子成为影响壳体氧同位素变化的主要因素。当氧同位素相对较重的有孔虫壳体溶解和重结晶并与孔隙水离子发生交换时，引起壳体δ^18O负向偏移。  相似文献   

黄海鲱鱼的人工孵化及胚胎发育的初步观察   总被引：1，自引：0，他引：1  

姜言伟  程济生 《海洋学报》1981,3(3):477-486

对鲱科鱼类个体发育及早期形态特征的研究,国外早已进行过,尤以苏联和日本的资料最多。  相似文献   

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   

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   

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   

On low-pass digital filters in oceanography   总被引：1，自引：0，他引：1  

Wang Ji  Ralph T. Cheng 《海洋学报(英文版)》1993,12(2):183-196

-Two types of filters are widely used to remove semidirunal and diurnal tidal signals and other high frequency noises in oceanography. The first type of filters uses moving average with weights in time domain, and can be easily operated. Some data will be lost at each end of the time series, especially for the low low-pass filters. The second type of filters uses the discrete Fourier transform filter (DFTF) which operates in the frequency domain, and there are no data loss at the ends for the forward transform. However, owing to the Gibbs phenomenon and the discrete sampling (Nyquist effect) , ringing appears in the inverse transformed data, which is especially serious at each end. Thus some data at the ends are also discarded. The present study tries to find out what causes the ringing and then to seek for methods to overcome the ringing. We have found that there are two kinds of ringings, one is the Gibbs phenomenon, as defined before. The other is the "Nyquist"ringing due to sampling Nyquist critical  相似文献