北太平洋中尺度涡季节和年际变化的统计分析

依据1993-01-2014-10由卫星高度计资料导出的地转流异常场数据,用几何方法探测识别并追踪了北太平洋的中尺度涡,统计了涡旋的半径、移动距离和移动速率,发现它们近似服从对数正态分布。进一步的分析发现,北太平洋涡旋生成数量存在着显著的季节变化:在冬季涡旋生成的数量最多而夏季生成的数量最少;夏季与冬季相比,涡旋生成数量减少的区域主要集中在15°~35°N。此外,北太平洋涡旋生成数量还存在着显著的年际变化;各个季节对全年变化的方差贡献量值相当。不论是季节变化还是年际变化,涡旋生成数量的变化与SST的变化均是反相,这是因为SST变化改变了上层海洋的层结强度进而影响了涡旋的生成,但该物理机制还需要进一步的分析和验证。     

北太平洋中尺度涡时空特征分析

利用1993~2011年19 a的AVISO卫星高度计资料研究了北太平洋(10°~60°N,120°E~100°W)中尺度涡的时空分布特征,结果表明:北太平洋每年约产生1 800余个涡旋,其中气旋涡稍多。北太平洋东部沿岸、西北沿岸、黑潮延伸体北侧、副热带逆流区是中尺度涡的高发区,春、冬季是涡旋的高发季节。涡极性分布以35°N为界,北部多反气旋涡,南部多气旋涡。涡旋半径以100 km左右为主,并且基本随纬度升高而减小,涡旋数量随着周期增长而急剧下降。反气旋涡的平均半径和周期均大于气旋涡。利用Argo浮标剖面资料分析的6个个例涡旋的垂直结构显示,每个涡旋都有其独特的冷暖核结构,深度不同。研究结果对于分析北太平洋涡动能分布及传输具有一定的参考价值。     

南海及西北太平洋卫星高度计资料分析:海洋中尺度涡统计特征

采用AVISO提供的卫星高度计融合数据,对南海及西北太平洋(5°～35°N,105°～150°E)1993～2009年17a间的中尺度涡活动进行统计分析.结果表明南海中尺度涡活动具有明显的年际变化,每年观测到产生的中尺度涡个数平均为21～22个,标准差约为4个,占年平均值的20%;而西北太平洋中尺度涡个数的年际差异不大,平均每年观测到150～151个中尺度涡产生,标准差约为14个,仅占年平均值的9%.中尺度涡的逐月统计结果表明南海和西北太平洋的中尺度涡活动均有明显季节变化,1993～2009年间的各月南海和西北太平洋分别观测到30～31个和213～214个中尺度涡产生,标准差分别约为6个和41个,均占各自月平均值的19%.中尺度涡主要集中分布在南海东北部、越南东部和黑潮流轴附近海域.涡动能、海面高度距平均方根以及涡度均方根的空间分布大致与涡旋个数分布一致,但在西北太平洋的低纬海区和黑潮延伸体区域则不甚吻合.在相同的涡旋判别标准下,西北太平洋低纬海区(5°～15°N)观测到的中尺度涡个数比中高纬海区要少得多.     

基于1993-2014年高度计数据的西北太平洋中尺度涡识别和特征分析

本文利用22年的AVISO卫星高度计融合数据,基于WA涡旋自动识别方法对西北太平洋的中尺度涡进行了识别追踪,并统计分析了研究区域中尺度涡的空间分布特征、运动属性以及季节和年际变化。研究结果表明:22年间共追踪到生命周期超过30 d的气旋涡3 841个,反气旋涡2 836个,气旋涡数量多于反气旋涡。涡旋大部分向西移动,西向传播的涡旋分布在整个研究区域,而东向传播的涡旋则集中在黑潮及其延伸区。涡旋主要存在15°~30°N的纬度带间;分别而言,气旋涡主要分布在研究区域的北部和南部,而反气旋涡主要分布在副热带逆流区。30°~35°N之间的黑潮延伸区具有明显更高的涡动能和涡振幅,与同纬度区域相比这里的涡旋半径也较高。在季节和年际变化上,春季出现的中尺度涡最多,夏季最少;对涡旋的月生成数目与ENSO指数MEI比较发现,西北太平洋涡旋活动变化并不直接与ENSO现象相关。     

基于GIS 的南海中尺度涡旋典型过程的特征分析

以具有复杂时空演变过程的海洋中尺度涡旋为研究对象,以定量表达和组织涡旋典型过程案例为前提,基于Global NLOM(Naval Research Laboratory Layered Ocean Model)所得的SSH(Sea Surface Height)、SST(Sea Surface Temperature)和表层海流场,对海洋中尺度涡旋进行综合辨认和动态跟踪。以南海为例,通过提取涡旋典型过程中的典型状态,建立中尺度涡旋典型案例库。然后以库中所有过程案例为对象对涡旋进行GIS(Geographic Information System)时空特征分析。所得结果为:(1)南海中尺度涡旋整体上呈东北-西南向分布,涡旋水平移动速度为3~16 cm/s,平均速度为8.4 cm/s。(2)大部分涡旋向西移动。春夏季涡旋主要向西北方向移动,秋冬季涡旋主要向西南方向移动。(3)南海东北部涡旋主要集中在9~10月以及次年的1~2月发生,涡旋先向西北方向移动,后又转向西南方向移动,大部分中尺度涡旋不能西移太远。南海中部气旋涡主要发生在冬、春两季。一部分涡旋沿陆坡向西南运动,其中一些反气旋涡沿南海海盆向西运动。南海东南部在研究期内只有反气旋涡出现,向西或西北偏西运动,这里的涡旋比较弱,但移动距离较长,也有较长的生命周期。南海西南部夏季出现的涡旋多于冬季,且夏季的绝大部分涡旋以偶极子结构出现,该区域涡旋移动的距离较小。该研究引入GIS技术,基于大量时空数据对具有复杂时空特征的中尺度涡旋的信息进行组织、存储,以期通过对涡旋生消过程的时空分析来揭示其演变规律,为进一步研究海洋涡旋的空间推理预测奠定了坚实的基础。     

夏季副热带西北太平洋地区大气涡旋空间分布特征的初步研究

应用1985—2002年夏季欧洲中期天气预报中心(ECMWF)的40a再分析资料,初步分析了副热带西北太平洋区域温带气旋、热带气旋和高空冷涡三种涡旋的三维结构及其时空分布特征。结果指出:(1)不同种类的涡旋具有不同的三维结构特征;(2)温带气旋和热带气旋主要分布在400hPa以下,涡旋分布的高值区位于近海海区,向内陆方向或向远海方向分布减少。副热带高空冷涡分布在太平洋上空的400~100hPa,呈东西向带状分布;(3)三种涡旋的个体强度有不同的年际变化特征。     

黑潮延伸体邻近区域中尺度涡特征统计分析

本文利用20年的卫星高度计资料,对黑潮延伸体邻近海区(25°—45°N,135°E—175°W)中尺度涡的统计特征以及季节变化进行了统计研究。基于涡旋自动识别方法,共识别出本区域3006个气旋涡轨迹和2887个反气旋涡轨迹,其平均周期分别为9.99周和11.00周,平均半径分别为69.5km和71.8km。长生命周期涡旋的平均半径、涡度、涡动能(EKE)和涡旋能量密度(EI)在生命周期内大致都经历了增大-基本保持不变-减小这三个阶段。绝大多数涡旋沿纬线向西移动,经向移动距离较小,气旋涡和反气旋涡在西向传播过程中都具有明显的向南(赤道)偏离趋势。涡旋的生成数量与总数量均在春夏季达到最多,且这一时期涡旋的平均涡度、EKE、EI处于较高水平。     

北太平洋爆发性气旋的统计特征

利用FNL(Final Analyses)全球格点资料,对2000—2015年冷季(10月至来年4月)发生于北太平洋(20°N~65°N,110°E~100°W)的爆发性气旋进行了分析研究。依据爆发性气旋的空间分布特征和高时间分辨率的资料,将爆发性气旋定义修订为海表面中心气压(地转调整到45o N)12h平均加深率达到1hPa/h以上的气旋。根据爆发性气旋最大加深率的大小,在强度上将其划分为4类:弱、中、强和超强。日本海、西北太平洋、中西太平洋、中东太平洋和东北太平洋为北太平洋爆发性气旋的5个多发区域,发生于各区域的爆发性气旋依次称之为:JOS(Japan-Okhotsk Sea)、NWP(Northwestern Pacific)、WCP(West-Central Pacific)、ECP(East-Central Pacific)和NEP(Northeastern Pacific)爆发性气旋。北太平洋爆发性气旋发生频数自西向东逐渐减少,呈现出"西多东少"的分布特征。爆发性气旋的统计特征因发生区域不同而呈现出较大差异,NWP爆发性气旋多发生于冬季和早春,而NEP爆发性气旋多发生于秋季和早春;相对于NEP爆发性气旋,NWP爆发性气旋发展较为剧烈,中心最低气压较低,爆发史长和发展史长较长。NWP爆发性气旋的移动路径多为西南-东北向,随着爆发强度的增强,其移动路径更趋于集中。NEP爆发性气旋的移动路径因生成位置的不同而呈现出较大差异,在中西太平洋和中太平洋海域生成的NEP爆发性气旋,其移动路径前期多为偏东向,后期折向西北;而在中东太平洋海域生成的NEP爆发性气旋,其移动路径多为西南-东北向。海洋暖流为NWP和NEP爆发性气旋的急剧发展提供了有利的海洋物理环境场。     

利用Argo 浮标资料研究西北太平洋三维声速分布特征

利用西北太平洋海区2002～2009年的Argo浮标剖面温度、盐度资料构建成0.5°×0.5°水平分辨率的三维声速网格化资料,并据此分析该海区声速的空间分布及季节变化特征。研究表明：该海区10 m层等声速线分布的季节变化较为明显,春、冬季的等声速线几乎与纬线平行,黑潮流经区域等声速线呈现一定的弯曲。100 m层等声速线分布的季节变化较小：北赤道流区,等声速线从外海向近岸延伸;吕宋岛东南部沿海,等声速线向南弯曲;吕宋岛、台湾岛东部等声速线呈现偏北方向的弯曲;琉球群岛附近,等声速线朝北偏东方向弯曲。此外,研究海区存在深海声道,声道轴最深的区域主要在吕宋海峡和日本东南部海区,其中吕宋海峡处的声道轴有显著的季节变化特征。可见,利用Argo浮标资料可以初步得到西北太平洋声速的空间分布及其季节变化特征,随着Argo剖面资料的增多,对该海区的声速场认识将会愈加清晰。     

西北太平洋不同寿命中尺度涡统计特征

本研究通过OW（Okubo Weiss）参数和闭合等值线相结合的方法自动识别西北太平洋（0°—45°N,120°—180°E）中尺度涡并跟踪后续中尺度涡,分析了不同寿命中尺度涡的季节变化、年际变化、数量特征以及动力学参数等。研究发现,不同寿命中尺度涡的数量高峰时间在不同程度上晚于气象上最冷月份约1~3个月。与其他寿命中尺度涡不同,中等寿命中尺度涡的气旋涡（33.9 cm/s）比中等寿命中尺度涡的反气旋涡（16.9 cm/s）旋转得更快,季节变化最为显著。冬季更适于西北太平洋中尺度涡的发生与发展,并且在寿命上,更易发展为中等寿命涡旋。不同寿命中尺度涡的月数量变化都存在3个明显的周期性变化（第一主周期、第二主周期、第三主周期）,根据不同主周期的时间尺度长短,它们的影响因子分别可能是太阳辐射、ENSO现象、季节变化。从地理分布看,不同寿命中尺度涡高频区分布并不完全一致。从涡旋平均振幅地理分布看,中等寿命中尺度涡在高频区拥有最大的涡旋平均振幅（15~25 cm）,短寿命中尺度涡次之（15~20 cm）,长寿命中尺度涡的平均振幅最小（10~16 cm）。从涡旋半径地理分布看,长寿命中尺度涡仅在副热带逆流区有较大的平均半径（20~30 km）,中等、短寿命中尺度涡在研究区域北部均有着较大的平均半径（30~45 km）。从动力学参数看,西北太平洋中尺度涡的动力学参数在寿命中期并非是最高值,约在寿命的前三分之一达到第一个高值,然后小幅下降,保持稳定,直到寿命的后三分之一小幅上升,达到第二个高值,然后迅速下降直至数值为零。     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

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.     

A Review of Some Environmental Issues Affecting Marine Mining

This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested.     

Increased Particle Fluxes at the INDEX Site Attributable to Simulated Benthic Disturbance

Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Determination of In Situ Sediment Shear Strength from Advanced Piston Corer Pullout Forces

The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments.     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

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.     

《Acta Oceanologica Sinica》Vol. 33(2014) contents

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INFORMATION FOR AUTHORS

<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,