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排序方式: 共有101条查询结果,搜索用时 15 毫秒
91.
92.
A. Alvarez A. Orfila G. Basterretxea J. Tintor G. Vizoso A. Fornes 《Journal of Marine Systems》2007,65(1-4):299
Relatively long term time series of satellite data are nowadays available. These spatio–temporal time series of satellite observations can be employed to build empirical models, called satellite based ocean forecasting (SOFT) systems, to forecast certain aspects of future ocean states. The forecast skill of SOFT systems predicting the sea surface temperature (SST) at sub-basin spatial scale (from hundreds to thousand kilometres), has been extensively explored in previous works. Thus, these works were mostly focussed on predicting large scale patterns spatially stationary. At spatial scales smaller than sub-basin (from tens to hundred kilometres), spatio–temporal variability is more complex and propagating structures are frequently present. In this case, traditional SOFT systems based on Empirical Orthogonal Function (EOF) decompositions could not be optimal prediction systems. Instead, SOFT systems based on Complex Empirical Orthogonal Functions (CEOFs) are, a priori, better candidates to resolve these cases.In this work we study and compare the performance of an EOF and CEOF based SOFT systems forecasting the SST at weekly time scales of a propagating mesoscale structure. The SOFT system was implemented in an area of the Northern Balearic Sea (Western Mediterranean Sea) where a moving frontal structure is recurrently observed. Predictions from both SOFT systems are compared with observations and with the predictions obtained from persistence models. Results indicate that the implemented SOFT systems are superior in terms of predictability to persistence. No substantial differences have been found between the EOF and CEOF-SOFT systems. 相似文献
93.
Christophe Lett Pierrick Penven Patricia Ayn Pierre Fron 《Journal of Marine Systems》2007,64(1-4):189
A Lagrangian model is used to simulate and quantify in the northern Humboldt upwelling ecosystem the processes of enrichment, concentration and retention, identified by Bakun [Bakun, A., 1996. Patterns in the ocean. Ocean processes and marine population dynamics. University of California Sea Grant, California, USA, in cooperation with Centro de Investigaciones Biologicas de Noroeste, La Paz, Baja California Sur, Mexico, 323 pp.] as being important for the survival and recruitment of early life stages of pelagic fish. The method relies on tracking the positions of particles within water velocity fields generated by a three-dimensional hydrodynamic model. Simple criteria for considering particles as participating to enrichment, concentration or retention are used to derive indices of the three processes. We analyse the spatial distribution of and seasonal variability in these indices. The results are discussed in relation to anchovy (Engraulis ringens) eggs and larvae distributions off Peru, and to a comparable study conducted in the southern Benguela upwelling ecosystem. 相似文献
94.
远洋运输业是一个投资大、回收期长的行业。目前我国该行业的成本控制是以单船单航次的成本控制为主线,以计划成本、定额成本等为基础制定成本控制标准,定期分析营运过程中实际成本脱离控制标准所形成的偏差程度。这样在成本管理上存在很多的不足。本文主要通过对财务部门以外的航运技术部门和营销揽货部门,应当如何从自身的管理加强成本的管理进行论述。 相似文献
95.
Yoichi Ishikawa Toshiyuki Awaji Takahiro Toyoda Teiji In Kei Nishina Tomoharu Nakayama Shigeki Shima Shuhei Masuda 《Journal of Marine Systems》2009,78(2):237
A data assimilation system is applied to the integrated monitoring of oceanic states in the northwestern North Pacific by combining a high resolution ocean general circulation model with an adjoint method. A comparison of assimilation results with observations shows that the system is better able to represent synoptic features of ocean circulation than do models or data alone. Furthermore, meso-scale features associated with frontal structures and eddies, which are often seen in the Kuroshio and Oyashio extension regions and the Sea of Japan, are better defined in the assimilation results. These features suggest that our 4D-VAR high-resolution data assimilation system is capable of providing time series data which satisfy the model physics and fit the observations, and hence the ocean state derived from our system has greater information content than that obtained from earlier methods. 相似文献
96.
在蒸气机发明之前的风帆时代,庞大的郑和船队必须依赖季风和洋流的帮助,才能顺利航行。郑和航线所经历的地区是世界上季风现象最显著的地区之一。盛行风的季节性变动,带来了洋流的季节性变化,为郑和航海提供了优越的条件。本文以郑和航海图为基础,结合海洋地理知识,根据郑和出使西洋过程中的航期、航线与航速,分析对季风洋流的认识和利用,并以此侧面反映15世纪中国领先于世界的高超航海水平。 相似文献
97.
The Prince Edward Islands pelagic ecosystem, south Indian Ocean: a review of achievements, 1976–1990
This review summarizes the main research findings of the multi-year oceanographic and biological studies conducted in the vicinity of the Prince Edward Archipelago during the period 1976 to 1990. The Prince Edward Islands represent a flow-through system on the mainstream of the Antarctic Circumpolar Current. Although there are no taxonomic differences between the pelagic communities of the upstream, inter-island and downstream regions, these mesoscale subsystems may operate differently. The mesoscale oceanographic and biological processes appear to be affected by the position of the Subantarctic Front (SAF) in the vicinity of the islands. Both the rich benthic community, which is supported by the local enhancement of primary production, and the strong advection of zooplankton/micronekton from the upstream region provide the food resources necessary for the survival of the huge community of land-based predators present on the islands. Collectively this is termed the ‘life-support system'. Future studies should concentrate on the meridional shifts in the position of the SAF and its influence on background productivity upstream and downstream of the Prince Edward Archipelago. 相似文献
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100.
船舶污染海洋环境"防、救、赔"系统工程的研究 总被引:2,自引:0,他引:2
列举和分析了近几年来我国海事和救捞单位救助遇险船舶防止污染海洋环境的实例,指出目前我国还没有形成一套彻底解决船舶污染造成海洋环境损害问题的机制和措施,提出了建立我国海洋环境的船舶污染“防、救、赔”系统工程理论的构想,以期从根本上解决船舶污染对海洋环境的损害问题。 相似文献