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利用卫星观测OLR资料以及海气耦合数值模拟试验结果,从每年波-频分析结果提取了各种传播模态的强度指数序列,分析了热带北半球夏季季节内振荡(BSISO)各种传播模态的年际变化谱特征,探讨了热带各海区海气相互作用对其影响。主要结果如下:赤道外西传波和印度洋北传波以准2 a为显著振荡周期,赤道东传波、南海北传波和西太平洋北传波则都包含准2 a和准5 a两种周期,南海北传波是5种指数中惟一以准5 a为最主要周期振荡的模态。热带印度洋、西太平洋、东太平洋各海区海气相互作用对各指数准2 a振荡、准5 a振荡既有加强作用,也有削弱作用。各海区比较而言,对赤道东传波准2 a和准5 a振荡、南海北传波准2 a和准5 a振荡起最大加强作用的是西太平洋海区海气相互作用;对赤道外西传波准2 a振荡、西太平洋北传波准2 a和准5 a振荡起最大加强作用的是印度洋海区海气相互作用。 相似文献
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利用卫星观测OLR资料以及海气耦合数值模拟试验结果,从每年波-频分析结果提取了各种传播模态的强度指数序列,分析了热带北半球夏季季节内振荡(BSISO)各种传播模态的年际变化谱特征,探讨了热带各海区海气相互作用对其影响。主要结果如下:赤道外西传波和印度洋北传波以准2 a为显著振荡周期,赤道东传波、南海北传波和西太平洋北传波则都包含准2 a和准5 a两种周期,南海北传波是5种指数中惟一以准5 a为最主要周期振荡的模态。热带印度洋、西太平洋、东太平洋各海区海气相互作用对各指数准2 a振荡、准5 a振荡既有加强作用,也有削弱作用。各海区比较而言,对赤道东传波准2 a和准5 a振荡、南海北传波准2 a和准5 a振荡起最大加强作用的是西太平洋海区海气相互作用;对赤道外西传波准2 a振荡、西太平洋北传波准2 a和准5 a振荡起最大加强作用的是印度洋海区海气相互作用。 相似文献
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用59年Ishii再分析温度资料,讨论了热带西南印度洋(SWTIO)上升流区的季节和年际变化以及与上升流区有关的温度距平的变化,同时分析了其与热带印太海气系统的关系,结果显示SWTIO 上升流在南半球冬、夏季比较强,春季最弱。它的范围在5°~1°S,在东西向从50°E可以伸展到90°E。该上升流区的变化与温跃层的温度距平有密切的关系,并存在明显的5 a振荡周期。SWTIO上升流区温度距平的5 a周期振荡是由热带东印度洋温度距平在最大垂直温度距平曲面(MTAL)上向西沿着11.5°~6.5°S传播过来的,它与热带太平洋的温度距平传播方式不同。SWTIO上升流是热带印太海气系统的一个重要组成部分,印度洋偶极子 超前SWTIO上升流区温度变化5个月,最大相关系数达到0.57,NINO3区指数超前SWTIO上升流区指数2个月达到0.49。当热带印太区域的大气风场改变,影响热带太平洋和印度洋表层SSTA,出现ENSO和DIPOLE,进一步向西传播到SWTIO次表层,导致SWTIO上升流区出现改变。 相似文献
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ENSO冷暖事件期间海气潜热通量特征分析 总被引：3，自引：0，他引：3
利用1981-2002年OAFlux逐月海气潜热通量资料,探讨了与ENSO冷暖事件相对应的全球海气潜热通量的时空演变特征.结果表明,与ENSO冷暖事件相对应的赤道中、东太平洋地区特别是Ni(n)o3区的海气潜热通量差异最为显著,且这种差异全年都存在,而其他海区潜热通量差异的季节变化比较显著;更值得注意的是,文章还发现与ENSO冷暖事件相对应的海气潜热通量"东南太平洋异常型"的存在,该异常型出现于东南太平洋地区,在夏季最为明显,其正负异常中心呈南北向,由赤道东太平洋地区向南伸展到东南太平洋中高纬一带.此外,结合逐月合成分析和个例分析对海气潜热通量"东南太平洋异常型"作了进一步的研究,发现海气潜热通量"东南太平洋异常型"在ENSO冷暖事件中具有明显的季节变化和年际变化特征,其逐月演变过程明显,并且其强度和范围在不同的El Ni(n)o事件和La Ni(n)a事件中均有所不同. 相似文献
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太平洋海气界面净热通量的季节、年际和年代际变化 总被引：9，自引：0，他引：9
根据 COADS资料 ,使用经验正交分解 (EOF)等分析方法 ,研究了北太平洋海气热通量的季节、年际和年代际变化特征。分析结果表明 :北太平洋海洋夏季净得热 ,冬季净失热 ,且黑潮及其延伸体区失热最大。净热通量年际变化较明显 ,北太平洋西部模态水形成区冬季净热通量和副热带失热区春季净热通量的年际变化都主要依赖于潜热和感热通量的年际变化。夏季净热通量的低频变化中心在热带 ,冬季低频变化中心在黑潮及其延伸体区。冬季赤道东、西太平洋净热通量异常的年际变化相反 ;在热带北太平洋中部年际变化达到最大。夏季热带太平洋是净热通量异常的年际变化最大的海域 ,沿赤道两侧在 16 5°E处呈偶极子型分布。 相似文献
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近百年西北太洋热带气旋频数变化特征与ENSO的关系 总被引：4，自引：0，他引：4
本文根据西北太平洋近106年(1899～2004年)热带气旋系列资料,分析了热带气旋年频数多年变化的统计特征.结果表明:西北太平洋台风频数既存在明显的短周期的年际变化也存在明显长周期的年代际变化,是一种短周期与长周期相互作用的多时间尺度的变化.年际变化与ENSO有明显关系,ENSO事件的当年9月到次年8月冷事件年相对与暖事件年会有更多的台风生成和登陆.在年代际尺度上,106年的台风活动可以分为几个明显的活跃期和不活跃期,这种年代际的变化可能与海气耦合的经向模态调制有关系. 相似文献
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El Niño-Southern Oscillation（ENSO）是热带太平洋海气作用最强的年际信号，其变化会引起全球气候异常，对东亚季风具有重要影响。2000年后中部型El Niño频繁发生，掀起了ENSO多样性研究热潮；El Niño的复杂性也对ENSO理论研究和预测提出了新的挑战。为进一步理解并深入研究ENSO物理机制，本文总结了近年来对两类ENSO的最新认识；特别对副热带太平洋通过海气界面“大气桥”和太平洋副热带-热带经向环流圈的内部经向翻转环流这一“海洋通道”与热带太平洋建立联系的相关成果进行了阐述，并对存在的关键问题进行了展望。 相似文献
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大气和海洋是影响地球气候系统的两个重要因素，它们之间的相互作用是海洋和大气研究的重要课题，海气耦合模式则是研究海气相互作用的重要工具，而海气耦合模式重点考虑的参数是海气通量。针对传统的大尺度海气耦合模式缺少湍流尺度分析的问题，本文使用并行大涡模拟海气耦合模式（The Parallelized Large-Eddy Simulation Model，PALM），在小尺度上探究风速对海气通量及湍流动能收支（Turbulence Kinetic Energy Budget，TKE Budget）的影响，设置了5、10和15m/s三种地转风速度对大气边界层（Atmospheric Boundary Layer，ABL）和海洋混合层（Oceanic Mixed Layer，OML）进行海气耦合模拟。研究表明：海气通量的分布与风速大小密切相关，风速越大，净热通量和浮力通量相对越大，由于温度上升导致海水蒸发加剧，使得大气的淡水通量增大；海洋湍流动能收支各项在近海面处受风速影响较大，且随着深度加深而逐渐减弱。本研究初步展示了小尺度海气耦合模式在海气通量研究中的应用，对进行小尺度海气相互作用研究具有一定的意义。 相似文献
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北方涛动是近几年在北太平洋热带地区发现的一种东西向的大气涛动.本文试图对北方涛动的空间结构和时间变化(包括季节变化和年际变化)的基本特征及其与热带太平洋海温、降水、信风和沃克环流等的联系作进一步的分析研究.经验正交函数(EOF)分析的结果,不仅进一步证实了北方涛动存在的真实性,而且还揭示了它的大尺度特征及其在北太平洋大气环流年际变化中占有头等重要的地位.据延伸的1921-1946年资料的分析表明,北方涛动仍然非常明显,说明它不是某一时期特有的现象,而是北太平洋热带地区大气环流固有的一种低频振荡.北方涛动3-4年的年际振荡与热带太平洋海温、降水、信风和沃克环流关系密切.并且它在这一频带与南方涛动发生强烈的耦合.我们认为,东赤道太平洋之所以是全球热带海洋中海温年际变化最大的地区,以及该区的海气相互作用之所以能够产生世界性年际气候变化最强的信号,可能与它们之间强烈的耦合作用不会没有关系. 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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Coastal inundation associated with extreme sea levels is the main factor which leads to the loss of life and property whenever a severe tropical cyclonic storm hits the Indian coasts. The Andhra and Orissa coasts are most vulnerable for coastal inundation due to extreme rise in sea levels associated with tropical cyclones. Loss of life may be minimized if extreme sea levels and associated coastal flooding is predicted well in advance. Keeping this in view, location specific coastal inundation models are developed and applied for the Andhra and Orissa coasts of India. Several numerical experiments are carried out using the data of past severe cyclones that struck these regions. The simulated inland inundation distances are found to be in general agreement with the reported flooding. 相似文献
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Hoi-Soo Jung Kap-Sik Jeong Yong-Shik Chu Sung-Hyun Park Ki-Hyune Kim 《Marine Georesources & Geotechnology》2001,19(3):181-195
Grain size and water content in box-core sediments from the Clarion-Clipperton fracture zone (C-C zone) in the northeast equatorial Pacific were analyzed in detail to understand the downcore variations across a hiatus between Quaternary and Tertiary layers. Grain-size distributions in the topmost core sediments show two modes: a coarse mode (peaked at 50 μm) and a fine mode (at 2-25 μm). The coarse mode disappears gradually with depth accompanied by the dissolution of siliceous fossil tests, whereas the fine mode coarsens due to the formation of authigenic minerals. Water content increases abruptly across a color boundary between an upper pale brown layer and a lower dark brown layer that is the hiatus between Quaternary and Tertiary layers. Abundant smectites and microvoid molds, which are created by the prolonged fossil dissolution in the underlying sediment, are attributed for the abrupt downcore variation of water content. Overall variations in grain size and water content in the topmost core sediments in the western C-C zone are possibly constrained by the dissolution of biogenic siliceous fossils. Variations in geotechnical properties related to these changes must be considered in the design of nodule collectors. 相似文献
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Shigehisa Nakamura 《Marine Geodesy》2001,24(1):27-33
This article concerns an interrelation between the sea levels and the western boundary flow near a tectonic boundary in a local zone in the Northwestern Pacific. In this zone, sea level variations at stations located on the coast facing the Pacific are studied to find the interrelation between variations of the Kurosio flow as an index of the distance of the flow axis off a specific coast. The result is discussed after data processing of the monthly means of the sea levels, and a notice is taken of variations caused by active crustal upheavals during a seismic event, a local earthquake. 相似文献