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51.
分析了事故统计数据以及传统的以收集事故数据为主的安全数据统计模式的缺陷,提出以收集系统安全影响因素数据为主的安全评价非事故数据统计模式,介绍了该模式思路下建立的海运安全数据库,为提高海运安全评价数据的数量和质量提供理论和实践指导。 相似文献
52.
This article examines the acceptance of aquaculture development by residents and visitors of two islands, Cephallonia and Ithaki, in the Ionian Sea, in western Greece. Aquaculture farms have been established recently in both islands, and processing and packaging units in Cephallonia, generating jobs for the local communities and land rents for the villages in the coastal areas near the fish cages. However, the farms and processing and packaging units entail certain negative impacts on the environment. This study reveals that aquaculture farms have found better acceptance in Ithaki, where aqua culture is a form of development suited to this remote, small, predominantly rural island. The degree of acceptability is higher for locals than for tourists, but also for islanders who do not live in the areas where the processing units are situated. Respondents who consider the pollution of the marine environment by the farms to be high, mostly locals and residents of the villages in the vicinity of the aquaculture infrastructure or the main cities in the islands, are more likely to express a negative attitude toward aquaculture and its further development. 相似文献
53.
Ocean-biogeochemical models show typically significant errors in the representation of chlorophyll concentrations. The model state can be improved by the assimilation of satellite chlorophyll data with algorithms based on the Kalman filter. However, these algorithms do usually not account for the possibility that the model prediction contains systematic errors in the form of model bias. Accounting explicitly for model biases can improve the assimilation performance. To study the effect of bias estimation on the estimation of surface chlorophyll concentrations, chlorophyll data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) are assimilated on a daily basis into the NASA Ocean Biogeochemical Model (NOBM). The assimilation is performed by the ensemble-based SEIK filter combined with an online bias correction scheme. The SEIK filter is simplified here by the use of a static error covariance matrix. The performance of the filter algorithm is assessed by comparison with independent in situ data over the 7-year period 1998–2004. The bias correction results in significant improvements of the surface chlorophyll concentrations compared to the assimilation without bias estimation. With bias estimation, the daily surface chlorophyll estimates from the assimilation show about 3.3% lower error than SeaWiFS data. In contrast, the error in the global surface chlorophyll estimate without bias estimation is 10.9% larger than the error of SeaWiFS data. 相似文献
54.
M. Rouault S. Illig C Bartholomae C.J.C. Reason A. Bentamy 《Journal of Marine Systems》2007,68(3-4):473-488
Warmer than average sea surface temperatures were observed by the Tropical Rainfall Mission Microwave Imager in the Angola Benguela Current system in late austral summer 2001 and persisted for about three months. These coastal anomalies extended offshore by 1 to 4° longitude and were not due to local ocean atmosphere interaction or relaxation of the upwelling favorable southerly winds. Instead, they were remotely forced by ocean atmosphere interaction in the Tropical Atlantic. Satellite remote sensing and a linear ocean model suggest that relaxation of trade winds along the equator triggered Kelvin waves that crossed the basin within a month in early 2001. Westerly wind anomalies were also observed in December 2000 and January 2001 over most of the Tropical Atlantic contributing to a warm preconditioning due to an enhancement of the oceanic annual cycle. This led to abnormal sea level heights near equatorial Africa that propagated southwards along the coast towards the Angola Benguela Frontal zone. This process increased the seasonal penetration of warm and salty water of tropical origin into the Angola Benguela upwelling system. 相似文献
55.
Zooplankton communities were studied in southeastern Beaufort Sea (Arctic Ocean) in September–October 2002. Cluster analysis and non-metric multidimensional scaling revealed three distinct mesozooplankton assemblages. A neritic assemblage occurred on the Mackenzie Shelf and in Franklin Bay, while distinct off-shelf assemblages prevailed in the Cape Bathurst Polynya and on the Beaufort Slope respectively. Over 95% of the mesozooplankton was comprised of eight copepod taxa. Pseudocalanus spp. contributed predominantly to the discrimination of the three assemblages and was the only significant indicator of the Shelf assemblage. Oithona similis, Oncaea borealis, Metridia longa and Calanus hyperboreus were indicators of the Polynya assemblage. Cyclopina sp. and Microcalanus pygmaeus were indicative of the overall off-shelf community (Polynya and Slope assemblages). The importance of omnivores and carnivores increased from the shelf to the polynya and the slope. Station depth and duration of reduced ice conditions during summer (< 50% ice concentration) underpinned the distribution of the assemblages (r2 = 0.71 and 0.45 respectively). The abundance of Pseudocalanus spp. was independent of depth and increased with the duration of reduced ice conditions (rs = 0.438). The abundance of Cyclopina sp., M. pygmaeus and other indicators of the offshore assemblages followed the opposite trend (rs = − 0.467 and − 0.5 respectively). Under continued climate warming, a reduction of the ice cover will affect the biogeography of mesozooplankton on and around the Mackenzie Shelf, to the potential advantage of Pseudocalanus spp. and other calanoid herbivores. 相似文献
56.
P. Pondaven C. Fravalo D. Ruiz-Pino P. Trguer B. Quguiner C. Jeandel 《Journal of Marine Systems》1998,17(1-4)
A coupled 1D physical–biogeochemical model has been built to simulate the cycles of silicon and of nitrogen in the Indian sector of the Permanently Open Ocean Zone of the Southern Ocean. Based on a simplified trophic network, that includes two size classes of phytoplankton and of zooplankton, and a microbial loop, it has been calibrated by reference to surface physical, chemical and biological data sets collected at the KERFIX time-series station (50°40′S–68°25′E). The model correctly reproduces the high nutrient low chlorophyll features typical of the studied area. In a region where the spring–summer mixed layer depth is usually deeper than 60 m, the maximum of chlorophyll never exceeds 1.5 mg m−3, and the annual primary production is only 68 g C m−2 year−1. In the surface layer nitrate is never exhausted (range 27–23.5 mmoles m−3) while silicic acid shows strong seasonal variations (range 5–20 mmoles m−3). On an annual basis 71% of the primary production sustained by nanophytoplankton is grazed by microzooplankton. Compared to North Atlantic, siliceous microphytoplankton is mainly prevented from blooming because of an unfavourable spring–summer light-mixing regime. Silicic acid limitation (high half saturation constant for Si uptake: 8 mmoles m−3) also plays a major role on diatom growth. Mesozooplankton grazing pressure excerpts its influence especially in late spring. The model illustrates the efficiency of the silica pump in the Southern Ocean: up to 63% of the biogenic silica that has been synthetized in the photic layer is exported towards the deep ocean, while only 11% of the particulate organic nitrogen escapes recycling in the surface layer. 相似文献
57.
L. Goeyens M. Semeneh M.E.M. Baumann M. Elskens D. Shopova F. Dehairs 《Journal of Marine Systems》1998,17(1-4)
The separation in Southern Ocean provinces of silicate excess at nitrate exhaustion and of nitrate excess at silicate exhaustion was already introduced by Kamykowski and Zentara (Kamykowski, D., Zentara, S.J., 1985. Nitrate and silicic acid in the world ocean: patterns and processes. Mar. Ecol. Prog. Ser. 26, 47–59; and Kamykowski, D., Zentara, S.J., 1989. Circumpolar plant nutrient covariation in the Southern Ocean: patterns and processes. Mar. Ecol. Prog. Ser. 58, 101–111) and our investigations of the silicate to nitrate uptake ratios confirm the earlier distinction. Oligotrophic antarctic waters mainly exhibit proportionally higher silicate removal what induces a potential for nitrate excess. The nitrogen uptake regime of such areas is characterised by low absolute as well as specific nitrate uptake rates throughout. Maximal values did not exceed 0.15 μM d−1 and 0.005 h−1, respectively. Corresponding f-ratios ranged from 0.39 to 0.86. This scenario contrasts strikingly to the more fertile ice edge areas. They showed a drastic but short vernal increase in nitrate uptake. Absolute uptake rates reached a maximum value of 2.18 μM d−1 whereas the maximal specific uptake rate was 0.063 h−1. In addition to an optimal physical environment for bloom development, accumulation of ammonium stimulated nitrate uptake in a direct or indirect way. Since ammonium build-up in surface waters traces enhanced remineralisation, release of other essential compounds during degradation of organic matter might have been the main trigger. This peak nitrate utilisation during early spring led to the observed potential for silicate excess. With increasing seasonal maturity the nitrate uptake became inhibited by the presence of enhanced ammonium availability (up to 8% of the inorganic nitrogen pool), however, and after a short period of intensive nitrate consumption the uptake rates drop to very low levels, which are comparable to the ones observed in the area of nitrate excess at silicate exhaustion. 相似文献
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60.
Aceh, located in the northernmost area of Sumatra Island, is one of the regions that suffered the most damage from the Indian Ocean tsunami in 2004. The process of reconstruction after a large-scale disaster is considered an opportunity to create a safer society, especially for developing countries, however the accumulation of knowledge about how to improve reconstruction is insufficient. The affected areas have diverse social and economic characteristics and unprecedented restoration efforts have been made. The Indian Ocean tsunami disaster, therefore, provides numerous research opportunities, and many surveys and other researches have been conducted to better understand what happened and how the reconstruction process could be improved. However, the majority of such research has focused on housing reconstruction, rebuilding livelihoods and community rehabilitation and there has been only limited research on transportation-related issues. Thus, there is significance in evaluating the reconstruction of Aceh from a transportation perspective, a dimension that has yet to be examined systematically. As a first step in the effort to evaluate various aspects of the reconstruction of Aceh from a transportation perspective, this research aims to present three transportation-related issues within the reconstruction process—1) the road network in the Banda Aceh coastal area, 2) mobility in relocation sites, and 3) reconstruction of the Banda Aceh–Meulaboh road—and to conduct a preliminary analysis of these issues by adding the viewpoint of disaster management and reconstruction, the authors' area of specialization. For conducting a preliminary analysis, existing information such as research papers, articles and reports and data collected through interviews and field reconnaissance conducted by the authors were utilized as much as possible, and such “qualitative data” was analyzed by applying the “interpretive approach”, considered an appropriate analytical framework for qualitative data. 相似文献