A singular evolutive extended Kalman filter to assimilate ocean color data in a coupled physical–biochemical model of the North Atlantic ocean     

V. Carmillet  J. -M. Brankart  P. Brasseur  H. Drange  G. Evensen  J. Verron 《Ocean Modelling》2001,3(3-4)

Within the European DIADEM project, a data assimilation system for coupled ocean circulation and marine ecosystem models has been implemented for the North Atlantic and the Nordic Seas. One objective of this project is to demonstrate the relevance of sophisticated methods to assimilate satellite data such as altimetry, surface temperature and ocean color, into realistic ocean models. In this paper, the singular evolutive extended Kalman (SEEK) filter, which is an advanced assimilation scheme where three-dimensional, multivariate error statistics are taken into account, is used to assimilate ocean color data into the biological component of the coupled system. The marine ecosystem model, derived from the FDM model [J. Mar. Res. 48 (1990) 591], includes 11 nitrogen and carbon compartments and describes the synthesis of organic matter in the euphotic zone, its consumption by animals of upper trophic levels, and the recycling of detritic material in the deep ocean. The circulation model coupled to the ecosystem is the Miami isopycnic coordinate ocean model (MICOM), which covers the Atlantic and the Arctic Oceans with an enhanced resolution in the North Atlantic basin. The model is forced with realistic ECMWF ocean/atmosphere fluxes, which permits to resolve the seasonal variability of the circulation and mixed layer properties. In the twin assimimation experiments reported here, the predictions of the coupled model are corrected every 10 days using pseudo-measurements of surface phytoplankton as a substitute to chlorophyll concentrations measured from space. The diagnostics of these experiments indicate that the assimilation is feasible with a reduced-order Kalman filter of small rank (of order 10) as long as a sufficiently good identification of the error structure is available. In addition, the control of non-observed quantities such as zooplankton and nitrate concentrations is made possible, owing to the multivariate nature of the analysis scheme. However, a too severe truncation of the error sub-space downgrades the propagation of surface information below the mixed layer. The reduction of the actual state vector to the surface layers is therefore investigated to improve the estimation process in the perspective of sea-viewing wide field-of-view sensor (SeaWiFS) data assimilation experiments.  相似文献   

Modelling effects of fishing in the Southern Benguela ecosystem   总被引：2，自引：0，他引：2  

Shannon  Lynne J.; Cury  Philippe M.; Jarre  Astrid 《ICES Journal of Marine Science》2000,57(3):720-722

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喀斯特荒漠化是一种地质—生态灾难   总被引：23，自引：0，他引：23  

杨汉奎 《海洋地质与第四纪地质》1995,15(3):137-147

ＫＤＮ是一种ＧＥＯＬ－ＥＣＯＬ灾难,是发生潮湿的碳酸盐岩区的土壤侵蚀、土地退化与生态系统凋萎,致使人类很难生活在其中。ＫＤＮ是我国四大ＧＥＯＬ－ＥＣＯＬ灾害中最难整治、最难摆脱贫困的地区。本文按国际公认的原则为准,认定“石山化”≠ＫＤＮ,从地质结构性气候、物候和生态系统多因子厘定了ＫＤＮ术语,认定人为扰动与人口超载是其产生的序参量。其过程最迟也是３００多年前明清朝代屯垦开始,近半个世纪加速衰竭,森  相似文献   

天津港南部海区水体富营养化水平评价   总被引：1，自引：0，他引：1  

曹佳莲  刘宪斌  刘占广  聂利红  纪明航 《海洋湖沼通报》2007,(Z1)

根据2006年3月和7月的调查数据,对天津港南部海区海水的营养水平及动态变化进行了评价。考虑到水质状况和水体营养水平是水体中多项指标分析评价的综合结果.本文先通过单项指标评价法和营养指数法进行评价。然后又通过集对分析方法,选择化学需氧量(COD)、无机磷(DIP)、无机氮(DIN)、叶绿素a(Ch1—a)等作为评价指标,对该区海水富营养化水平进行了综合评价。评价结果表明集对分析方法更能反映海水的实际富营养化状况,计算结果显示天津港南部海域两期调查中除21,26.27和29站位在7月呈富营养化状态其余站位海水均在中营养(Ⅳ)及以下水平状况,未达到富营养化水平,水质状况较好。  相似文献   

灰色关联分析法在海洋环境质量评价中的应用   总被引：2，自引：0，他引：2  

付会  孙英兰  孙磊  王翠 《海洋湖沼通报》2007,(3):127-131

介绍了灰色关联分析法的原理,说明了其评价步骤。以青岛某海区海水水质评价为例阐明了该方法在海洋环境评价中的应用,并将评价结果与模糊综合评价结果加以比较,结果表明,两种评价方法的评价结果有着较明显的差别,分析了原因。本文还提出了海水污染防治措施,为海洋环境保护提供依据。  相似文献   

Video assessment of environmental impacts of salmon farms   总被引：1，自引：0，他引：1  

Crawford  C. M.; Mitchell  I. M.; Macleod  C. K. A. 《ICES Journal of Marine Science》2001,58(2):445-452

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Intercomparison of coastal area morphodynamic models     

J. Nicholson  I. Broker  J. A. Roelvink  D. Price  J. M. Tanguy  L. Moreno 《Coastal Engineering》1997,31(1-4)

Five different coastal area morphodynamic models have been set up to run on the same offshore breakwater layout and an intercomparison carried out on the hydrodynamic and morphodynamic output produced by each scheme. In addition, the predicted morphodynamics was checked against available laboratory and field data.It is concluded that the models are capable of producing realistic estimates for the dominant morphodynamic features associated with offshore breakwaters. Coupling of the wave, current and sediment transport components of each scheme is shown to yield bathymetry which attains a state of equilibrium, unlike models which are based on the initial transport field only.  相似文献   

辽东湾北部海域营养状况与趋势评价   总被引：3，自引：0，他引：3  

田金  宋伦  王年斌  周遵春  薛克  吴金浩 《海洋通报》2007,26(6):113-118

根据 1999-2006 年 6-8 月的调查数据,分析辽东湾北部海域的营养水平及变化趋势,以了解辽东湾北部海域营养水平的分布特点及污染状况.由 E 值和 CN/CP 值的总体评价结果来看,辽河口、双台子河口和大凌河口海域的富营养化程度较高,属于磷中等限制潜在性富营养区,而锦州湾海域污染相对较轻,属于中度营养区;在时空分布上,辽东湾北部海域 1999 年与 2006 年污染较为严重,中间年份污染相对较轻.针对辽东湾的具体环境用 CN/CP 值的评价模式更能揭示出营养盐限制对富营养化的影响.  相似文献   

基于模糊综合评判理论的过驳系统效率计算方法     

余建星  谭振东 《海洋技术学报》2003,22(4):40-43

如何计算整个系统的运转效率，特别是受不确定因素影响的系统(如过驳系统)，仍然是一个非常重要的研究课题。文章提出基于模糊综合评判方法的效率计算方法，是一种新的尝试，这种方法较好的避免了人的主观随意性，更符合实际情况，同时又可以弥补统计方法的不足。文章对某沿海地区的一过驳系统进行了效率计算，取得比较好的效果。  相似文献   

Casualties in dry bulk shipping (1963–1996)     

Stephen E. Roberts  Peter B. Marlow 《Marine Policy》2002,26(6)

In recent years, bulk carriers have been identified with high risks of catastrophic structural failure and foundering, and with heavy loss of human life. This study, based upon Lloyd's of London casualty records, identified four risk factors that had significant, independent effect upon the likelihood of a bulk carrier foundering. The risk of foundering increased with the age of the ship, and was related to the ship's flag of registration. Most importantly, however, increased risks were found for heavy cargoes of iron ore and scrap steel or iron, and for trading routes to the Far East and from Europe to North America. Additional safety measures, in particular regarding ship design and high-risk trades, may well be necessary to reduce the high casualty rates.  相似文献