A New Approach to High-Order Boussinesq-Type Equations with Ambient Currents   总被引：6，自引：3，他引：6  

王亚玲张洪生  缪国平朱良生 《中国海洋工程》2005,19(1):49-60

A new approach to high-order Boussinesq-type equations with ambient currents is presented. The current velocity is assumed to be uniform over depth and of the same magnitude as the shallow water wave celerity. The wave velocity field is expressed in terms of the horizontal and vertical wave velocity components at an arbitrary water depth level. Linear operators are introduced to improve the accuracy of the kinematic condition at the sea bottom. The dynamic and kinematic conditions at the free surface are expressed in terms of wave velocity variables defined directly on the free surface. The new equations provide high accuracy of linear properties as well as nonlinear properties from shallow to deep water, and extend the applicable range of relative water depth in the case of opposing currents.  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   

Alkaline phosphatase activity and its relationship to inorganic phosphorus in the transition zone of the North-western African upwelling system     

Marta Sebastin  Javier Arístegui  María F. Montero  Jose Escanez  F. Xavier Niell 《Progress in Oceanography》2004,62(2-4):131

The enzymatic activity of alkaline phosphatase (APA) was studied in the transition zone between the African upwelling system and the open ocean waters of the Canary Islands region. This region is recurrently dominated by the presence of upwelling filaments that may transport nutrient-enriched waters out into the open ocean before nutrients become exhausted by plankton. Turnover rates by APA were generally low in the whole region, but detectable in all the measurements carried out. On average, turnover rates were higher in the upwelling stations, and APA in those waters seemed to be mainly generated by heterotrophic bacteria to supply easily assimilable organic C. APA outside the upwelling area showed an inverse hyperbolic relationship with increasing phosphate, suggesting the presence of both constitutive and Pi-inducible APA. In these offshore waters, a threshold of 0.1 μM of phosphate could be defined for the regulatory function of Pi on APA. Thus, APA in nutrient-poor waters seemed to be induced to compensate for Pi-deficiency. Turnover rates in the filaments showed basal (probably constitutive) levels, whereas they increased in the surrounding waters, where phosphate concentration presumably did not satisfy plankton P-demands. The fertilising effect of the filaments and associated cyclonic eddies extended to at least 175 km offshore, where basal alkaline phosphatase activities were still found. The magnitude of this effect depends probably on the intensity of upwelling events and the degree of recirculation of filament water back to the coastal jet.  相似文献   

Plankton size classes, functional groups and ecosystem dynamics: an introduction     

M. Angelica Pea 《Progress in Oceanography》2003,57(3-4):239

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二(甲基环戊二烯)钐氯化物合成和晶体结构研究     

江涛  沈琪 《中国海洋大学学报(自然科学版)》2001,31(2):173-178

作者以 Sm Cl3 与 (CH3 Cp) Na反应分离得到了三价稀土有机配合物 [(CH3 Cp) 2 Sm Cl·THF]2 的单晶 ,X-射线四圆衍射测定 ,该配合物属正交晶系 ,Pbna空间群 ,晶胞参数 a=9.6 6 2 (2 ) ,b=16 .4 76 (9) ,c=2 0 .582 (9) ;α=β=γ=90°,Z=4。并分析比较 [(CH3 Cp) 2 Sm Cl· THF]2 与其他三价稀土一氯化物的结构特点  相似文献   

珠江口东南近海海区污损生物研究   总被引：4，自引：2，他引：4  

严涛  严文侠  董钰  梁冠和  严岩  王华接 《海洋学报》2003,25(6):117-125

为研究珠江口东南近海海区污损生物状况,于1986年5月至1987年6月,在香港东南约114和160km,水深为95和113m处布设了两个生物浮标站,并对距香港约172km,水深为115m处的Marex水文气象浮标上的污损生物群落进行调查.此次调查共采集和鉴定出污损生物78种,其中在浸海只有3个月的试板上,主要有柄蔓足类、水螅和藻类,优势种是细板条茗荷、茗荷和直杯螅.至于浸海时间达6～12个月的浮标(包括沉标)及锚链系统,其上还有相当数量的多种双壳类软体动物、无柄蔓足类和苔藓动物等硬性污损生物附着.在种类垂直分布方面,污损生物群落组成随深度发生明显变化.  相似文献   

龙须菜在滩涂贝藻混养系统中的生态作用模拟研究   总被引：4，自引：0，他引：4  

孙伟  张涛  杨红生  刘保忠  周毅  刘鹰 《海洋科学》2006,30(12):72-76

2005年5-7月,在室内采用实验生态学方法对壳长为48.35 mm±4.27 mm文蛤(Meretrix meretrix Linnaeus)成贝和龙须菜(Gracilaria lemaneiformis Weber-van Bosse)的4种配比(生物量配比分别为0∶1、1∶1、2∶1、4∶1)进行了混养实验,每周测定养殖水体中营养盐变化情况以及文蛤、龙须菜的存活和生长情况等。实验表明,加入了大型藻类的文蛤养殖系统,相对于空白对照组,其氨氮、亚硝氮和磷酸盐浓度显著降低,NH4-N从5.52μmol/L降至1.30μmol/L、NO2-N从0.31μmol/L降至0.06μmol/L,而PO4-P从0.48μmol/L降至0.006μmol/L。实验结束后,文蛤及龙须菜生长情况良好,文蛤特定生长率最高达到了0.84%,龙须菜最高则达到了1.79%。本实验条件下,在文蛤成贝养殖系统中加入大型藻类,对养殖水体中的NH4-N、NO2-N、PO4-P有明显的吸收效果,吸收率分别为86%、98%和99%,起到了良好的生态作用。  相似文献   

Atmospheric forcing of the eastern tropical Pacific: A review   总被引：1，自引：8，他引：1  

Jorge A. Amador  Eric J. Alfaro  Omar G. Lizano  Victor O. Magaa 《Progress in Oceanography》2006,69(2-4):101

The increase in marine, land surface, atmospheric and satellite data during recent decades has led to an improved understanding of the air–sea interaction processes in the eastern tropical Pacific. This is also thanks to extensive diagnoses from conceptual and coupled ocean–atmosphere numerical models. In this paper, mean fields of atmospheric variables, such as incoming solar radiation, sea level pressure, winds, wind stress curl, precipitation, evaporation, and surface energy fluxes, are derived from global atmospheric data sets in order to examine the dominant features of the low level atmospheric circulations of the region. The seasonal march of the atmospheric circulations is presented to depict the role of radiative forcing on atmospheric perturbations, especially those dominating the atmosphere at low levels.In the tropics, the trade winds constitute an important north–south energy and moisture exchange mechanism (as part of the low level branch of the Hadley circulation), that determines to a large extent the precipitation distribution in the region, i.e., that associated with the Inter-Tropical Convergence Zone (ITCZ). Monsoonal circulations also play an important role in determining the warm season precipitation distribution over the eastern tropical Pacific through a large variety of air–sea–land interaction mechanisms. Westward traveling waves, tropical cyclones, low latitude cold air intrusions, and other synoptic and mesoscale perturbations associated with the ITCZ are also important elements that modulate the annual rainfall cycle. The low-level jets of the Gulf of California, the Intra-Americas Sea (Gulf of Mexico and Caribbean Sea) and Chocó, Colombia are prominent features of the eastern tropical Pacific low-level circulations related to sub-regional and regional scale precipitation patterns. Observations show that the Intra-Americas Low-Level Jet intensity varies with El Niño/Southern Oscillation (ENSO) phases, however its origin and role in the westward propagation and development of disturbances that may hit the eastern tropical Pacific, such as easterly waves and tropical cyclones, are still unclear. Changes in the intensity of the trade winds in the Caribbean Sea and the Gulf of Mexico (associated with eastern tropical Pacific wind jets) exert an important control on precipitation by means of wind–topography interactions. Gaps in the mountains of southern Mexico and Central America allow strong wind jets to pass over the continent imprinting a unique signal in sea surface temperatures and ocean dynamics of the eastern tropical Pacific.The warm pools of the Americas constitute an important source of moisture for the North American Monsoon System. The northeastern tropical Pacific is a region of intense cyclogenetic activity, just west of the coast of Mesoamerica. Over the oceanic regions, large-scale properties of key variables such as precipitation, moisture, surface energy fluxes and wind stress curl are still uncertain, which inhibits a more comprehensive view of the region and stresses the importance of regional field experiments. Progress has been substantial in the understanding of the ocean and atmospheric dynamics of the eastern tropical Pacific, however, recent observational evidence such as that of a shallow meridional circulation cell in that region, in contrast to the classic concept of the Hadley-type deep meridional circulation, suggests that more in situ observations to validate theories are still necessary.This paper is part of a comprehensive review of the oceanography of the eastern tropical Pacific Ocean.  相似文献   

音响驯化技术在鲤养殖中的实验研究     

田涛  张国胜  张旭光  张秀梅 《中国海洋大学学报(自然科学版)》2007,37(1):83-88

探讨淡水养殖尤其是大水域网箱养鱼中由于投饵方式的不当和投饵量过多导致过剩饵料沉积引起水域环境污染的解决方法。本研究利用鱼类的听觉生物学特性,参考音响驯化技术的有关参数,结合投饵用400 Hz正弦波连续音对鲤(Cyprinus carpioLinnaeus)进行了音响驯化实验。结果表明,最初放声时,实验鱼产生惊愕反应,迅速离声源而去;但驯化6 d后,实验鱼在放声后迅速游向声源,摄食时间由最初的150 s缩短到实验后期的60 s。整个实验阶段放声组与对照组摄食时间差异极显著(P<0.01),摄食率和特定生长率无显著差异(P>0.05)。根据实验鱼的生长参数,求得了参考投饵量曲线和方程。本实验结果为音响驯化技术在淡水鱼养殖中的推广应用提供了基础数据。  相似文献   

Zooplankton and the oceanography of the eastern tropical Pacific: A review   总被引：2，自引：5，他引：2  

María Ana Fernndez-lamo  Jaime Frber-Lorda 《Progress in Oceanography》2006,69(2-4):318

We review the spatial and temporal patterns of zooplankton in the eastern tropical Pacific Ocean and relationships with oceanographic factors that affect zooplankton distribution, abundance and trophic relationships. Large-scale spatial patterns of some zooplankton groups show broad coincidence with surface water masses, circulation, and upwelling regions, in agreement with an ecological and dynamic partitioning of the pelagic ecosystem. The papers reviewed and a new compilation of zooplankton volume data at large-scale show that abundance patterns of zooplankton biomass have their highest values in the upwelling regions, including the Gulf of Tehuantepec, the Costa Rica Dome, the equatorial cold tongue, and the coast of Peru.Some of the first studies of zooplankton vertical distribution were done in this region, and a general review of the topic is presented. The possible physiological implications of vertical migration in zooplankton and the main hypotheses are described, with remarks on the importance of the oxygen minimum zone (OMZ) as a barrier to both the vertical distribution and migration of zooplankton in the region. Recent results, using multiple-net gear, show that vertical distribution is more complex than previously thought. There are some well-adapted species that do live and migrate within the OMZ.Temporal patterns are reviewed and summarized with historical data. Seasonal variations in zooplankton biomass follow productivity cycles in upwelling areas. No zooplankton time series exist to resolve ENSO effects in oceanic regions, but some El Niño events have had effects in the Peru Current ecosystem. Multidecadal periods of up to 50 years show a shift from a warm sardine regime with a low zooplankton biomass to a cool anchovy regime in the eastern Pacific with higher zooplankton biomasses. However, zooplankton volume off Peru has remained at low values since the 1972 El Niño, a trend opposite to that of anchoveta biomass since 1984.Studies of trophic relations emphasize the difference in the productivity cycle in the eastern tropical Pacific compared to temperate or polar ecosystems, with no particular peaks in the stocks of either zooplankton or phytoplankton. Productivity is more dependent on local events like coastal upwelling or water circulation, especially in the equatorial countercurrent and around the equatorial cool-tongue. Micrograzers are very important in the tropics as are predatory mesozooplankton. Up to 70% of the daily primary productivity is consumed by microzooplankton, which thus regulates the phytoplankton stocks. Micrograzers are an important link between primary producers, including bacteria, and mesozooplankton, constituting up to 80% of mesozooplankton food. Oceanography affects zooplankton trophic relationships through spatial–temporal effects on primary productivity and on the distributions of metabolic factors, food organisms, and predators. This paper is part of a comprehensive review of the oceanography of the eastern tropical Pacific.  相似文献