Deep sea navigation techniques     

K. G. Robertson 《Marine Geophysical Researches》1990,12(1-2):3-8

Accurate navigation forms an essential part of all research at sea and the deep ocean imposes it's own unique problems. This chapter discusses several of the techniques in current use on the research vessels of the Natural Environment Research Council (NERC), concentrating on those systems which provide global navigation facilities, as opposed to the more localised, coastal aids. Whilst most of the systems rely on surface propagation of radio waves, the use of acoustics and sea-bed mapping instruments constitute accurate alternatives for some sub-sea applications.  相似文献   

我国海洋软相底质底栖经济贝类的可持续利用探讨   总被引：1，自引：0，他引：1  

吴进锋  梁超愉  陈利雄  陈素文  李夏 《海洋湖沼通报》2005,(2):93-98

分析了海洋软相底质底栖贝类的资源特性和我国的资源利用现状及存在问题．并从规模化苗种生产、海区增殖、高效养殖模式开发及增养殖环境保障与产品无公害生产等方面对该资源的可持续利用进行了探讨。  相似文献   

Sea ice characteristics between the middle Weddell Sea and the Prydz Bay, Antarctica during the austral summer of 2003   总被引：1，自引：0，他引：1  

TANG Shulin  KANG Jiancheng  ZHOU Shangzhe  LI Zhijun 《海洋学报(英文版)》2005,24(2):9-15

The antarctic sea ice was investigated upon five occasions between January 4 and February 15, 2003. The investigations included: (1) estimation of sea ice distribution by ship-based observations between the middle Weddell Sea and the Prydz Bay; (2) estimation of sea ice distribution by aerial photography in the Prydz Bay; (3) direct measurements of fast ice thickness and snow cover, as well as ice core sampling in Nella Fjord; (4) estimation of melting sea ice distribution near the Zhongshan Station; and (5) observation of sea ice early freeze near the Zhongshan Station. On average, sea ice covered 14.4% of the study area. The highest sea ice concentration (80%) was observed in the Weddell Sea. First-year ice was dominant (99.7%-99.8%). Sea ice distributions in the Prydz Bay were more variable due to complex inshore topography, proximity of the Larsemann Hills, and/or grounded icebergs. The average thickness of landfast ice in NeUa Fjord was 169.5 cm. Wind-blown snow redistribution plays an important role in affecting the ice thickness in Nella Fjord. Preliminary freezing of sea ice near the Zhongshan Station follows the first two phases of the pancake cycle.  相似文献   

Simulations of Annual Cycle of Phytoplankton Production and the Utilization of Nitrogen in the Yellow Sea     

Tian?TianEmail author  Hao?Wei  Jian?Su  Changsoo?Chung 《Journal of Oceanography》2005,61(2):343-357

A nutrient dynamic model coupled with a 3D physical model has been developed to study the annual cycle of phytoplankton production in the Yellow Sea. The biological model involves interactions between inorganic nitrogen (nitrate and ammonium), phosphate and phytoplankton biomass. The model successfully reproduces the main features of phytoplankton-nutrient variation and dynamics of production. 1. The well-mixed coastal water is characterized by high primary production, as well as high new production. 2. In summer, the convergence of tidal front is an important hydrodynamic process, which contributes to high biomass at frontal areas. 3. The evolution of phytoplankton blooms and thermocline in the central region demonstrate that mixing is a dominant factor to the production in the Yellow Sea. In this simulation, nitrate- and ammonium-based productions are estimated regionally and temporally. The northern Yellow Sea is one of the highly ranked regions in the Yellow Sea for the capability of fixing carbon and nitrogen. The annual averaged f-ratio of 0.37 indicates that regenerated production prevails over the Yellow Sea. The result also shows that phosphate is the major nutrient, limiting phytoplankton growth throughout the year and it can be an indicator to predict the bloom magnitude. Finally, the relative roles of external nutrient sources have been evaluated, and benthic fluxes might play a significant role in compensating 54.6% of new nitrogen for new production consumption.  相似文献   

海洋环流模式中不同近似假设下的海表高度   总被引：1，自引：1，他引：1  

李薇  张学洪  金向泽 《海洋科学进展》2003,21(2):132-141

Boussinesq近似是现代海洋环流模式中经常采用的假设，但随着海洋模式的不断发展完善以及气候研究应用的需要，有必要估算Boussinesq近似造成的模式误差。分别利用一个非Boussinesq近似的海洋模式与另一个结构相同且采用Boussinesq近似的模式计算海表高度，并同时利用模式预报的温度、盐度资料计算了比容异常高度。分析结果显示，这3种不同定义的海表高度无论空间结构，还是时间演变，都基本类似，尤其在热带海区最接近，差值≤1cm。Boussinesq近似意味着在模式中以体积守恒代替质量守恒，通常的做法是对其进行简单的质量补偿来保持质量守恒。比较说明，以质量补偿方法进行的高度订正对减小Boussinesq近似带来的误差没有本质的意义。  相似文献   

河口区治江围涂对杭州湾水动力及海床影响分析   总被引：5，自引：2，他引：5  

倪勇强  林洁 《海洋工程》2003,21(3):73-77

自二十世纪六十年代起，钱塘江河口进行了大规模治江围涂，人类活动对杭州湾水域的影响越来越为人们关注。基于实测资料的分析和潮汐水流数学模型计算，探讨了钱塘江河口区围涂对杭州湾水域潮汐水流和海床的影响。研究成果可为钱塘江河口和杭州湾的进一步开发治理和环境保护提供科学依据。  相似文献   

海沧邻近海域表层沉积物中重矿物研究   总被引：3，自引：0，他引：3  

徐茂泉  沈兴兴  李超  孙美琴  许文彬 《海洋科学》2003,27(11):53-58

对厦门海沧邻近海域表层沉积物中的重矿物(0．063～0．125mm粒级)进行了分析和研究，结果表明该粒级的重矿物共计49种，其优势和特征矿物为磁铁矿、赤铁矿、褐铁矿、绿帘石、铁铁矿、角闪石、锆石、红柱石等；重矿物的平均质量分数为9．56％；根据重矿物的分布和含量，并结合主要标志矿物的颗粒百分含量和分布特征，将该海域划分为5个矿物组合区，根据各区的矿物组合类型分析了该海域的物质来源及影响重矿物分布和组合的因素，进而探讨了九龙江河口湾和厦门西港海湾的沉积环境。  相似文献   

Current status of bacteriological parameters and DOC/POC in Xiamen coastal waters   总被引：2，自引：0，他引：2  

Khalid Maskaoui  Tianling Zheng  Huasheng Hong  Zhiming Yu  Zhong Hu  Yun Tian  Lizhe Cai 《海洋学报(英文版)》2003,22(3):443-451

The surface and bottom waters samples were collected from six locations in Xiamen western sea. The quantified estimation of bacterial production (3H-thymidine method) and observation of bacterial heterotrophic activity (14C-glucose method) have been made in order to have a better understanding of the role of marine bacteria and their activities. The results showed that the mean value of bacterial heterotrophic activity was 9×108 cells/(L.h) in the surface waters and 2.6×108 cells/(L.h) in the bottom waters. The mean value of bacterial production was 38×108 cells/(L.h) in the surface waters and 7.1×108 cells/(L.h) in the bottom waters. The relationship between bacterial production, heterotrophic activity, POC and DOC measured during this survey were discussed. The good understanding of the relationship between bacteria activity and total coliform was addressed.  相似文献   

A Computational Model for Velocity Separation in Shallow Sea   总被引：1，自引：0，他引：1  

SONG  Zhiyao 《中国海洋工程》2002,16(3):407-413

Based on the hydrodynamical feature and the theoretical velocity profiles of tidal flow and vvind-induced flow in shal-low sea, a computational model is established for the first time, which can separate observed velocity into tidal velocity and wind-induced velocity by use of the least square method. With the model, not only the surface velocities of tidal flow and vvind-induced flow are obtained, but also the bed roughness height is determined and the wind velocity above the wa-ter surface is estimated. For verification of the model, the observed velocity in the Yellow River Estuary and the laborato-ry test is separated, then it is applied to the Yangtze River Estuary. All the results are satisfactory. The research results show that the model is simple in method, feasible in process and reasonable in result. The model is a valid approach to analysis and computation of field dala, and can be applied to separate the observed velocity in shallow sea; at the same time, reasonable boundary conditions of th  相似文献   

黄海表面水温场的准周期变化分析     

汤明义  李洪海 《中国海洋大学学报(自然科学版)》1989,(Z1)

本文用能谱方法分析了黄海的海表面水温(SST)场的准周期变化。由分析结果清楚地看出,SST具有高频准周期变化:黄海北部以2.6—3.2,1.4—1.7,3.6—3.8和6.7个月的准周期为主;3.3—3.6,5,1.3—2.3及6.7个月在黄海南部占优势。同时,两个海域都有6.7和3.3年的明显的准周期变化。  相似文献