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61.
Comparison among four kinds of data of sea surface wind stress in the South China Sea 总被引:1,自引:0,他引:1
By using remote sensing (ERS) data, FSU data, COADS data and Hellerman & Rosen-stein objective analysis data to analyze the sea surface wind stress in the South China Sea, it is found that the remote sensing data have higher resolution and more reasonable values. Therefore we suggest that remote sensing data be chosen in the study of climatological features of sea surface wind stress and its seasonal variability in the South China Sea, especially in the study of small and middle scale eddies. 相似文献
62.
The Spatial Distribution of Caprellidea (Crustacea: Amphipoda): A Stress Bioindicator in Ceuta (North Africa, Gibraltar Area) 总被引:4,自引:0,他引:4
Abstract. The caprellid (Crustacea: Amphipoda) community associated with the alga Cystoseira usneoides (L.) Roberts 1967 was studied on a spatial scale in relation to the influence of environmental factors on the coast of Ceuta (North Africa) using multivariate analyses. Twenty-two stations were sampled and five environmental factors were tested (hydrodynamics, silting, suspended organic matter, organic matter in silt and suspended solids). The spatial distribution of the caprellid community reflected the physico-chemical conditions of the coast. Phtisica marina Slabber 1769 was the only species present at the stations of the harbour of Ceuta, characterised by the lowest values of hydrodynamics and the highest values of silting, suspended organic matter and suspended solids. The most exposed stations (high hydrodynamics and low values of silting, dissolved organic matter and suspension solids) were mainly dominated by Caprella danilevskii Czerniavskii 1868 and C. penantis Leach 1814. These two species have developed a "parallel" posture that enables them to attach strongly to the substratum and thus inhabit areas subjected to heavy exposure or strong currents. Caprella acanthifera Leach 1814 and Pseudoprotella phasma (Montagu 1804) preferred stations characterised by moderate values of silting and suspended solids, such as those located in the coastal areas in front of the city of Ceuta, but these species were not found at the most stressed harbour stations. 相似文献
63.
将一个三维湍能封闭模型应用于开阔海区的风暴潮,通过数值计算探讨了Taylor底摩擦二次率的拖曳系数随空间的分布及拖曳系数与水深、海底粗糙度、风向和风速等因素的关系。本文对底摩擦二次率的可靠性做了评价。 相似文献
64.
-Based on the calculation model for the floating laying of the offshore oil pipeline, this paper analyses in detail the internal force, and deformation of the pipeline under a definite structural form (pipeline and buoy) and the way of pulling. The obtained results can be used for the buoy deployment, structure design, and the determination of pulling parameters (the pulling force of the cable and its length, etc.), providing an effective analysis method for floating pipeline-laying. A calculation example is given to show the related calculation process and the main results are analyzed and discussed. 相似文献
65.
Sylvie Labroue Philippe Gaspar Joel Dorandeu Oz Zanif F. Mertz Patrick Vincent Denis Choquet 《Marine Geodesy》2004,27(3):453-481
The Jason-1 sea state bias (SSB) is analyzed in depth from the first year of GDR products. Compared to previous missions, this work benefits from two aspects of the empirical determination of the SSB from the altimetric data themselves. First, from a methodological point of view, a nonparametric technique (NP) has been developed and largely tested on TOPEX/Poseidon 1, GFO and Envisat data. The NP estimator has proven to be a useful tool in the SSB estimation, and it is now mature enough to be used for a refined analysis. On the other hand, the SSB can be extracted from three different data sets (crossovers, collinear data, and residuals) with different characteristics. It is then possible to cross calibrate various estimations of the SSB models and to determine the most accurate one. A systematic comparison is made between these different estimates for the Jason-1 altimeter. The collinear and crossover data sets yield very similar estimates despite their difference of spatial and temporal distributions. These SSB models assure consistency with the TOPEX mission when comparing Jason-1 and TOPEX residuals during the tandem phase. Thanks to the present work, the impact of the short wavelengths filtering on the SSB estimation is evidenced. More generally, our understanding of potential errors affecting the sea surface height and their impact onto the SSB estimation is also improved. 相似文献
66.
State Estimation of the North Pacific Ocean by a Four-Dimensional Variational Data Assimilation Experiment 总被引:1,自引:0,他引:1
Toshiyuki Awaji Shuhei Masuda Yoichi Ishikawa Nozomi Sugiura Takahiro Toyoda Tomohiro Nakamura 《Journal of Oceanography》2003,59(6):931-943
A four-dimensional variational data assimilation system has been applied to an experiment to describe the dynamic state of
the North Pacific Ocean. A synthesis of available observational records and a sophisticated ocean general circulation model
produces a dynamically consistent dataset, which, in contrast to the nudging approach, provides realistic features of the
seasonally-varying ocean circulation with no artificial sources/sinks for temperature and salinity fields. This new dataset
enables us to estimate heat and water mass transports in addition to the qualification of water mass formation and movement
processes. A sensitivity experiment on our assimilation system reveals that the origin of the North Pacific Intermediate Water
can be traced back to the Sea of Okhotsk and the Bering Sea in the subarctic region and to the subtropical Kuroshio region
further south. These results demonstrate that our data assimilation system is a very powerful tool for the identification
and characterization of ocean variabilities and for our understanding of the dynamic state of ocean circulation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
67.
Seasonal succession of cyanoprokaryotes in a hypereutrophic oligo-mesohaline lagoon from the South of France 总被引:2,自引:0,他引:2
Nicolas Chomrat Robert Garnier Cline Bertrand Arlette Cazaubon 《Estuarine, Coastal and Shelf Science》2007,72(4):591-602
The Bolmon lagoon (South of France) is an oligo-mesohaline coastal lagoon that has undergone intense eutrophication in the past decades, resulting from a strong concentration of human activities in its drainage basin. Consequently, it exhibits some characteristics typical of an advanced trophic state; namely, the disappearance of submerged vegetation, the permanently intense phytoplankton growth and the recurrence of cyanoprokaryote blooms. As cyanoprokaryote dominance in south-temperate saline lagoons is little reported, we carried out this study in order to understand the seasonal variations in the phytoplankton composition and biomass, and to analyse the influence of environmental parameters such as salinity, nutrients and climate on the seasonal succession of species. In this lagoon, the phytoplankton was permanently dominated by cyanoprokaryotes, probably because of high availability of nutrients, low light penetration in the water column and frequent turbulent mixing induced by wind. The two most abundant species Planktothrix agardhii (in winter–spring) and Pseudanabaena limnetica (in summer) have low light requirements and are well adapted to a high mixing frequency, which defines the S1 functional group in Reynolds' typology for phytoplankton. Although widely studied in north-temperate lakes, blooms of these typically freshwater species are almost unreported in the Mediterranean area, especially in brackish ecosystems that are not their normal habitat. In the Bolmon lagoon, all their requirements for nutrients, light and mixing are satisfied and they seem to cope with a moderate presence of salt but P. agardhii was less competitive than P. limnetica at highest salinities, the latter being probably more halophytic. Contrary to the observations in lakes located at higher latitudes, the Mediterranean climate seems to induce a typical seasonal pattern of succession characterised by the dominance of P. agardhii (winter) – Chroococcales (spring) – Pseudanabaenaceae (summer) – P. agardhii (autumn, winter). The warm temperatures seemed to have a major influence on the phytoplankton succession, being responsible for the survival of Planktothrix during winter and its rapid and intense development in early spring. Intense mixing and high irradiance in summer promoted the development of Pseudanabaenaceae, as reported in another south-temperate lagoon, the Albufera of Valencia (Spain). The ecological success of Oscillatoriales observed in the Bolmon lagoon is a perfect example of a shift to the “turbid stable state” as proposed for freshwater shallow lakes only. Our work demonstrated that hypereutrophic Mediterranean lagoons can function very similarly to shallow lakes at higher latitudes; but the warmer climate and higher irradiances are probably responsible for differences in the seasonal pattern of species dominance. 相似文献
68.
塔里木盆地的构造演化 总被引:6,自引:0,他引:6
从地震大剖面显示,塔里木盆地发育为手风琴式的演化史。大体上形成有3层“断-坳”结构:①震旦系的“断”,古生界-三叠系的“坳”;②侏罗系的“断”,上白垩系的“坳”;③古近系的“断”,新近系的“坳”。断陷与坳陷分别由拉张与挤压应力场所致,这种应力场的变化是由相邻洋壳板块俯冲倾角由小到大的变化所引起的。由于地壳的多旋回运动,多次发生构造沉积演变,构成了多套生储盖组合,多领域、多种圈闭类型的油气藏,从震旦系-古生界-中生界-新生界,各断陷-坳陷结构的盆地都有可能形成油气藏的地质条件。 相似文献
69.
土工布充砂袋的应用及其研究进展 总被引:10,自引:1,他引:10
对土工布充砂袋技术和国内外的应用进行了介绍。鉴于土工布充砂袋属于一种新兴起的土工新材料和新技术,在设计和工程实际中还存在着许多急待解决的问题,着重对各种典型状态和典型环境下的土工布充砂袋的变形、应力和土工布充砂袋堆的稳定性研究进展进行综述,最后提出进一步研究的思路。 相似文献
70.
An embedded cylinder is a large-diameter cylinder embedded in a soil foundation. The state of failure of such an embedded cylindrical structure shows large deflection instead of slide and overturn of the traditional gravity type of structure placed on a rubble base or foundation base. The critical value of deflection of the embedded cylindrical structure, which is the maximum allowable deflection for stability calculation of the cylinder, is a vital control value. Through investigation on deflection and soil pressures on an embedded cylinder by model experiments, the variations of the angle of rotation θ of a cylinder with effective anti-overturning ratio η and moment MH of thrust are discussed. On the basis of experimental study, the critical value of deflection of the cylindrical structure is proposed in the paper. Meanwhile, the formulas for calculating deflection of cylinders are derived. 相似文献