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   

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   

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  

张文斌  谭家华 《海洋工程》2004,22(2):98-104

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   

波群作用于垂直桩柱的峰力统计性质     

徐立论  陈志军  焦海英 《中国海洋大学学报(自然科学版)》1994,(1)

研究具有窄谱和Ｗｅｉｂｕｌｌ波高分布的波群对非线性桩柱系统作用力的统计性质。求得了桩桩的波浪峰力的各种特征值及其比值。指出这些数值不仅是阻力一惯性力参数ｂＨ的函数，也随着波群因子而变化。本文模式更具广泛性。文中给出了一系列计算图表，可从理论计算波群作用于桩柱的波浪峰力。  相似文献   

我国海水制盐工艺改革的设计研究     

周仲怀  徐丽君  于银亭  王建华  于廷芳  王继业  殷丽 《海洋科学》1997,21(6):43-46

从技术上和工艺上的可能性、可行性和合理性，论证了海水制盐工艺改革的必要性，并且提出了实现海水制盐工艺改革的各种设计方案。它对我国的海水制盐工业的发展将具有深远意义。  相似文献   

Nutrient budgets and trophic state in a hypersaline coastal lagoon: Lagoa de Araruama, Brazil     

Marcelo F. L. Souza  Bjrn Kjerfve  Bastiaan Knoppers  Weber F. Landim de Souza  Raimundo N. Damasceno 《Estuarine, Coastal and Shelf Science》2003,57(5-6):843-858

Lagoa de Araruama in the state of Rio de Janeiro, Brazil, is a hypersaline lagoon with salinity varying spatially from 45 to 56. We collected water samples during monthly cruises throughout the lagoon, and along the streams feeding the system, from April 1991 to March 1992. Nutrients and other water quality parameters exhibited great spatial and temporal variations. Mass balance calculations indicate large amounts of anthropogenic nutrient inputs. The data indicate that the lagoon currently is oligotrophic but is in a state of transition to become a mesotrophic system. Molar dissolved inorganic nitrogen:dissolved inorganic phosphorus (DIN/DIP) varied between 2.2:1 and 659:1 with a volume-weighted average of 22:1. The high DIN/DIP ratio contrasts with that found in nearby lagoons, suggesting that phytoplankton primary production is limited by phosphorus in Lagoa de Araruama. The major loss of DIP is apparently driven by biological assimilation and diagenic reactions in the sediments. Calculations indicate that the lagoon is slightly net autotrophic at +0.9 mol C m⁻² yr⁻¹. This suggests that the biomass of the primary producers is restricted by phosphorus availability. Phosphorus retention in the sediment and the hypersaline state of the lagoon prevent changes in autotrophic communities and the formation of eutrophic conditions.  相似文献   

超过例外氧暴露时限的空气巡回潜水实验中若干生理功能的观察     

陈宝松  荆岩林  郑继昌 《海洋科学》1991,15(1):35-39

17名潜水员安全地进行了55人次超过美国海军例外氧暴露时限1.5—3倍的空气巡回潜水实验。生理功能观察和肺活量测定结果表明,在水深70m以浅,潜水员均保持了相当好的智力和操作能力,在连续3d 3倍氧暴露时限的巡潜后期,只有3人肺活量下降,且在次日测定时已见恢复,表明上述暴露是安全的。美国海军例外氧暴露时限中对于70m以浅空气暴露的相应规定显得保守。  相似文献   

风浪周期分布与谱宽度的关系     

文凡  高志一 《海洋湖沼通报》2006,(3):1-5

本文通过分析实验室风浪周期分布,发现风浪周期累积概率分布曲线低于Longuet-Higgins理论结果,在小概率周期区域实验结果与理论结果的差异明显。对实验结果进一步分析发现,在谱不是很窄时,在小概率处风浪周期累积概率随谱宽度的增大而降低,这与窄谱假定下的理论结果相反,Longuet-Higgins理论结果在小概率处不便于描述周期分布随谱宽度的变化。根据实验结果提出风浪周期的Weibull分布经验公式,Weibull分布中的参数依赖于谱宽度。  相似文献   

嵌入式态势显示系统的设计与开发     

王慧谟  华一新  刘小林  张瑜 《测绘科学》2008,33(1):197-199

嵌入式态势显示系统在机动武器平台上具有重要的应用价值。本文在分析态势显示系统常用的三种开发模式优缺点基础上,改进并设计了一种适合VxWorks特点的开发模式,论述了系统的逻辑结构和功能部件,并以态势符号库管理、态势档案管理等功能模块为重点,介绍了系统的详细设计思想和实现方法。  相似文献   

浅层SH反射波法和多道瞬态面波法 进行联合工程勘察的讨论   总被引：2，自引：1，他引：1  

仇恒永  王治华  王书增  夏学礼 《物探与化探》2008,32(4):451-454

针对目前单一工程物探方法调查浅部地质结构的局限性,提出采用弹性波法勘察中研究浅部地质结构的SH波反射勘察和多道瞬态面波法勘察这2种有效手段进行联合勘探,提高其可靠性和精度,并给出了3个实例,指出了在数据采集和处理时应注意的问题。  相似文献