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以三门湾为例,基于经验模态分解方法 (EMD)将原始风暴潮增水过程进行分解,并对各个子模态进行能量谱分析,研究每种波动对应的生成机制。结果表明:半封闭海湾内的风暴潮增水较为严重,造成三门湾内强增水的台风为三门湾南侧的西北向登陆台风。EMD分解结果显示三门湾内的风暴潮增水包含6 h,12 h,20 h左右的波动,其中6 h左右的波动来源于海湾共振,共振的频率是由海湾的形状、水深等固有性质所决定的。12 h的波动是由于天文潮与风暴潮耦合作用导致,20 h左右的波动是由于台风移动过程中外海波动的传入。结果表明EMD方法为风暴潮波动增水特征的精细认知提供了一种新的思路和方法,可以加深对海湾内风暴潮波动增水特征的研究。 相似文献
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近年来随着三门湾内围垦工程规模的不断扩大,三门湾的岸线及水深地形发生了显著变化,有必要重新评估三门湾内的潮汐振幅特征。本研究基于ADCIRC二维潮汐模型,开展了三门湾围垦工程实施前后潮汐振幅变化规律的研究。结果表明:三门湾内以半日潮为主,湾口和湾顶处振幅相差较大。单纯考虑围垦工程引起的岸线变化时,半日潮振幅受到的影响较为明显,振幅以减小为主,M2分潮减小幅度为0. 08～0. 10 m。采用经验公式预测了围垦工程造成的最终回淤量,围垦工程附近平均淤积为1. 5～2. 5 m,深水区附近淤积更加严重。当考虑了回淤导致的地形变化后,围垦工程区附近的潮汐振幅会有显著的减小,半日分潮减小幅度要远大于全日分潮,在围垦区域前沿,M2分潮振幅减小幅度较为明显,然后向外侧逐步减小。与单纯岸线变化相比,水深地形改变导致的潮汐振幅变化幅度要远大于前者。 相似文献
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三门湾潮波运动特征及其与地貌发育的关系 总被引：7，自引：2，他引：7
三门湾位于浙江象山县南田岛和三门县牛头山之间,是一个西北—东南方向的半封闭式海湾,从湾口到湾顶长约40多公里,湾内多数地区宽10多公里,全湾低潮时水域面积约390平方公里。这里除东南方向及通过石浦水道与外海沟通外,其余则为陆地及海岛所包围(图1)。周围都属凝灰岩组成的山体,海湾廓线受到NNE及NNW二组断裂的明显控制,随着时间的推移,泥沙日积月累,湾内目前发育着多条淤泥质舌状滩地,其间又存在着具有良好水深的港汉,这种滩,汉相间的形态构成了浙闽海岸特有的一种港湾淤泥质海岸地貌。本文试图从潮波运动特征出发对由此产生的地貌形态特征及其相互关系作一探讨。 相似文献
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《海洋技术学报》2023,(2)
全球潮汐预报模型在深水大洋具有较高的精度， 但在近岸强潮海区由于地形岸线、模型分辨率等原因精度不一， 难以直接应用。三门湾海域多年平均潮差4 m， 最大潮差可达7 m，是典型的强潮海湾， 为了评估TPXO9.0、TPXO9.0-atlas TOPEX/POSEIDON TIDES）、NAO.99b（National Astronomical Observatory of Japan）与GTM（Global Tide Model） 4 种预报模型在三门湾海域的预报精度， 本文分别通过上述4 个潮汐预报模型提取水动力数学模型开边界进行对比，并利用提取的开边界潮位对二维水动力模型进行驱动。通过计算分析潮位站实测数据与数值模拟结果的误差， 研究4 种预报模型模拟的三门湾潮汐变化得出， NAO.99b 模型在三门湾海域整体预报精度最佳， 分潮振幅、迟角和实测数据误差最小， TPXO9.0-atlas 分潮振幅模拟较好， 但迟角误差较大。对湾内四大分潮进行潮汐调和分析发现， 三门湾海域以半日潮为主， M2、S2 和K1分潮振幅由湾顶向湾口递减， O1分潮相反。 相似文献
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龙口湾是出现假潮比较显著的海湾之一,据统计1972-1981年间,平均每年出现6次40cm以上的振动,1980年9月1日观测到水位振动的最大振幅达293cm,同日的气压波也有7个hPa的起伏.本文用数值模拟的方法,初步探讨了气压扰动和在龙口湾1980年9月1日观测到的假潮之间的定量关系,证实了在龙口湾中出现的大振幅假潮的确是由于移动气压波扰动激起湾外长波,传入湾内发生共振所导致的.直接由气压波扰动很难导致大振幅假潮的发生. 相似文献
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龙口湾大振幅假潮形成的数值模拟 总被引：1，自引：0，他引：1
龙口湾是出现假潮比较显著的海湾之一。据统计,１９７２～１９８１年,平均每年出现６次〉４０ｃｍ的振动,其中１９８０年９月１日观测到水位振动的最大振幅达２９３ｃｍ,同日的气压波也有７ｈＰａ的起伏。用数值模拟方法,初步探讨了气压扰动与１９８０年９月１日 在龙口湾观测到的假潮之间的定量关系,证实,在龙口湾中出现的大振幅假潮的确是由于移动气压波扰动激起湾外长波传入湾内发生共振所引起的。直接由气压波扰动很难引 相似文献
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海湾内外的潮波变形及其不对称性影响海湾内外动力输送和水体交换。利用乐清湾内外共9个测站连续潮位进行调和分析,得到该海湾内外各分潮变化规律,利用潮不对称性偏度计算方法确定湾内外潮汐不对称性时空变化特征,比较了主要分潮组合对潮汐不对称性的贡献度,通过数值研究探讨了湾内偏度比湾外偏度值更小的主要成因,分析了湾内外围垦工程对潮不对称偏度的影响。研究发现:乐清湾内潮汐不对称偏度值为负,表现为落潮占优,同期湾外洞头站偏度值为正,与邻近瓯江、飞云江河口的潮不对称偏度变大、表现涨潮占优的变化规律相反;湾外沿岸各站偏度由东北向西南逐渐增大,由落潮占优向涨潮占优变化;潮汐不对称性偏度呈周期性变化,分析确定M2-M4、M2-S2-MS4分潮组合对潮不对称贡献大,该海域潮汐不对称的强度主要由浅水分潮振幅控制,而相对相位则决定潮汐不对称的方向;数值研究探讨表明,湾内大范围的浅滩地形是其潮汐不对称落潮占优的主要原因,围垦将削弱湾内的落潮占优。 相似文献
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对海洋潮汐共振的理论、方法和各海域共振周期的估算进行了综述。对共振的经典理论介绍了阻尼简谐振动、1/4波长共振和Helmholtz共振的基本理论和共振周期的计算公式。对实际海域共振的数值计算方法方面介绍了Platzman简正模态方法和Webb边值方法的原理。还对这些理论和方法在估计近岸和大洋各海域共振周期中的应用工作做了综合性介绍。在国外海域中,共振特征最明显的是位于加拿大的芬迪湾。在中国近海,许多研究认为北部湾较强的全日潮、仁川湾和台湾海峡较强的半日潮均与海湾共振有关,其中北部湾的共振特征最为明显。 相似文献
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三门湾多个围垦工程的整体影响数学模型研究 总被引：1，自引：1，他引：1
海湾内的围垦工程对潮流及冲淤都将产生影响.以三门湾蛇蟠和下洋涂围垦工程为例,设计了3组试验对比的数值模拟计算方案,对比计算结果表明,预测三门湾内2个围垦工程对水动力环境产生的影响,当讨论单一围垦工程时,应把工程前的海湾状态设置为湾内没有任何其它工程,这样才能得出单个围垦工程对湾内环境的真实影响;当讨论2个围垦工程对水动力环境产生影响时,应进行2个围垦工程整体数学模拟计算,考虑2个围垦工程的叠加累积影响,并与海湾原始状态(即假定海湾在围垦前湾内没有任何其它围垦工程)进行比较,才能得出较为科学的预测结果. 相似文献
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Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths. 相似文献
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Shigehisa Nakamura 《Marine Geodesy》2000,23(1):55-61
Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone. 相似文献
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The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics. 相似文献
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《海洋学报(英文版)》2014,(9):F0003-F0003
<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology, 相似文献
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The relationship between the flux of exotic benthic foraminiferal tests (i.e. tests which are supplied from open-sea sources alone) in a tidal inlet and that of bulk sediment was analysed, which can be expressed as two first-order linear equations. According to this relationship, in order to determine net sediment transport directions in the entrance, the test concentration in surficial sediments of the tidal basin can be compared against a ‘ critical level ’. The critical level is determined for the conditions that no net transport of bulk sediment is present within the entrance. If the observed concentration (averaged over the tidal basin) is higher than the simulated critical level, then the net sediment transport is directed to landward. This method is applied to the analysis of net sand transport at Christchurch Harbour, a tidal inlet system located in southern England. In this investigation, concentrations of exotic foraminiferal tests in the surficial sediments of the tidal basin and ebb tidal delta area were obtained from the analysis of sea-bed sediment samples. A series of probable critical levels were calculated based upon the data sets with regard to: (1) sediment discharge from the rivers; (2) magnitude of sediment discharge within the entrance during the ebb; (3) the test concentration outside the harbour; (4) the thickness of the moving layer; and (5) two parameters associated with dispersive processes. The results show that the concentration in the tidal basin sediment is higher than a number of simulated critical concentrations for representative cases. Consequently, the high level of the concentration of exotic benthic foraminiferal tests within the harbour should be explained as a result of landward net transport of sands within the entrance. 相似文献
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Rahul Sharma 《Marine Georesources & Geotechnology》2000,18(3):237-250
Observations on seafloor features from subbottom profiling and seabed photography data show that the undisturbed and natural conditions before the benthic disturbance undergo a substantial change after operation of the disturber. The effects can be seen in the form of deep trenches and grooves, formed by the action of the sleds and the pumping of the sediment along its path, as well as sediment piles on either side of the track. Biological traces such as fecal coils, casts, tubes, burrows, and trails get obliterated in the areas of disturbance and resedimentation. The smooth, uniform nature of the seafloor observed in predisturbance phase shows microtopographic changes in and around the disturbed area as a result of sediment excavation and resettlement. Vertical mixing as well as lateral transport of sediment alter the geological, biological, physical, and chemical conditions on the seafloor, which need to be monitored over time to assess the process and the time taken for restoration of environmental conditions. 相似文献
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Vance P. Vicente 《Marine Ecology》1989,10(2):179-191
Abstract. Long-term changes in the distributional patterns of commercial sponges ( Spongia spp. and Hippospongia spp.) within the West Indian Region indicates that: 1) commercial sponges had a widespread distribution throughout the whole West Indian Region and were ubiquitous in very shallow water until about the first half of the present century; 2) they were fished commercially not only in the traditional northern Caribbean sites (Florida, Gulf of Mexico, Bahamas) but also in the Greater ( e. g. , Hispaniola, Jamaica) and Lesser Antilles; and 3) they became extinct throughout most of the Lesser Antilles ( e. g. , Puerto Rico, Vieques, St. Thomas) sometime during the first half of this century. Mortalities of spongiids within the Antilles were found to differ from other marine mortalities in that: 1) species disappeared from a large region; 2) species vanished from different habitats and depths; and 3) natural populations never recovered. Species richness patterns suggest that commercial sponge genera ( Spongia and Hippospongia ) evolved under slightly cooler elimatic conditions than those found at present, and that these extinctions occurred as a direct or indirect effect of positive thermal anomalies in sea surface and atmospheric temperatures between 1900–1950. The concept that species diversity is stable on a regional scale is questioned. 相似文献
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The behaviour of an axially pre-loaded cylindrical member of an offshore structure, hit by a supply ship, has been investigated. The effects of axial pre-loading on the dynamic properties of members, the extent of damage and propagation of dynamic instability in the tubular members have also been investigated. Numerical models have been validated using available experimental data from the literature although these are mostly static with no pre-loading. Axial pre-loading was found to change the dynamic characteristics of some cylindrical members quite dramatically while it had no significant effect on others. The study examined whether there was any change in the behaviour between local and global modes when the loading was dynamic rather than static. The effect of damping on the dynamic instability of axially pre-loaded tubes under lateral dynamic loads was also studied. It was observed that for some geometries the quasi-static response can be used to define the boundary between bounded and unbounded dynamic responses. The main contribution of this study, compared with previous investigations reported in the literature, is that both pre-loading and dynamic effects have been included. 相似文献