吕宋海峡Ekman输运和南海SST的相关性分析

在利用1950—2009年NCEP(National Center for Environmental Prediction)资料分析风场数据的基础上,计算吕宋海峡的Ekman输运,研究表明其存在显著的季节变化,除了夏季外,其它季节均为由太平洋向南海输运。分析吕宋海峡Ekman输运和南海海盆表征上层热力状况的海表面温度SST(Sea Surface Temperature)之间的关系发现:在年内时间尺度上,两者不存在显著的同期相关,Ekman输运对SST的影响开始于一个月之后,从北部向南扩展,第二个月最为明显,并扩展至整个海盆,第三个月开始衰减,第四个月影响消失,且相关性为正;在年际尺度上,吕宋海峡Ek-man输运的异常同南海SSTA(Sea Surface Temperature Abnormal)的第二模态存在显著的相关联系,并且吕宋海峡Ekman输运和南海SSTA的相关关系在北部为正,南部为负。吕宋海峡Ekman输运调制南海大尺度环流,通过暖、冷平流的作用影响南海SST的变化。     

太平洋—印度洋贯穿流南海分支研究综述

从海洋动力学角度,概述了太平洋-印度洋贯穿流南海分支的主要入流和出流通道—吕宋海峡和卡里马塔海峡的研究现状。太平洋-印度洋贯穿流南海分支是太平洋、南海和印度尼西亚海域进行水体和热盐交换的传输带,对西太平洋、南海、印尼海和东印度洋的环流系统有重要影响。吕宋海峡水交换和卡里马塔海峡贯穿流都呈现冬季大夏季小的季节变化特征,对维持南海的物质、能量和动量平衡起重要作用。太平洋通过吕宋海峡向南海输运水体和热盐,并传递ENSO等气候信号,对南海的环流、水体和海洋环境都产生重要影响。卡里马塔海峡向印度尼西亚海区的水体和热盐输运对印度尼西亚贯穿流有重要意义。太平洋-印度洋贯穿流南海分支和印尼贯穿流的年际变化趋势呈反位相,两者相互调制相互影响,维持了太平洋-印度洋两大洋间的平衡关系,对全球大洋环流的结构和长期的气候变化有重要作用。     

南海南部与外海间的体积和热、盐输运及其对印尼贯穿流的贡献

根据中国近海高分辨率 ( 1 / 6°)环流模式的模拟结果 ,计算了南沙邻近海域与外海之间的海水体积、热量和盐量输运及其对印度尼西亚贯穿流的贡献。研究海域为 0°— 1 4°N的整个南海南部海域。计算得出 ,穿过研究海域流向印度尼西亚海域 ,最终流向印度洋的年平均体积、热量和盐量输运分别为 5 .2Sv( 1Sv =1× 1 0 6m3·s- 1 )、0 .5 7PW和 1 84Gg·s- 1 ,大约占印度尼西亚贯穿流相应输运量的 1 / 4。这一结果表明南海是全球大传送带这一全球海洋最主要热盐环流系统的重要通道之一。从南海流向印度尼西亚海域的通道以卡里马塔海峡为最主要 ,以下依次为巴拉巴克海峡、民都洛海峡和马六甲海峡。大的南向通量主要发生在冬、秋季 ,春末夏初总的通量向北。计算还得出输入本海区的热输运量比输出少 0 .0 64PW ,由这一结果推得 ,通过海 -气界面由大气进入海洋的年平均净热通量约为 30W·m- 2 。     

南海等密度面环流季节变化的数值模拟研究

In this study, we develop a variable-grid global ocean general circulation model(OGCM) with a fine grid(1/6)°covering the area from 20°S–50°N and from 99°–150°E, and use the model to investigate the isopycnal surface circulation in the South China Sea(SCS). The simulated results show four layer structures in vertical: the surface and subsurface circulation of the SCS are characterized by the monsoon driven circulation, with basin-scaled cyclonic gyre in winter and anti-cyclonic gyre in summer. The intermediate layer circulation is opposite to the upper layer, showing anti-cyclonic gyre in winter but cyclonic gyre in summer. The circulation in the deep layer is much weaker in spring and summer, with the maximum velocity speed below 0.6 cm/s. In fall and winter, the SCS deep layer circulation shows strong east boundary current along the west coast of Philippine with the velocity speed at 1.5 m/s, which flows southward in fall and northward in winter. The results have also revealed a fourlayer vertical structure of water exchange through the Luzon Strait. The dynamics of the intermediate and deep circulation are attributed to the monsoon driving and the Luzon Strait transport forcing.     

南海东北部冬季逆风流数值试验

用11种假定情况对南海东北部冬季逆风流（简称冬季逆风流）是否产生进行数值试验。结果表明,除平底、静风假定外,南海东北部大陆坡上均有表层海水辐合带形成;该带是产生冬季逆风流的必要条件。经巴士海峡流入的黑潮水加强大陆坡区辐合带,加速冬季逆风流的形成。风应力、大陆坡是冬季逆风流产生的决定因素。冬季逆风流对风应力曳力系数（CD）及水平涡动系数（AH）的取值相当敏感。     

南海西边界流区域涡旋特征及两类冬季环流对涡致热输运的调制

本文基于观测数据和模式产品,探讨了南海西边界流(South China Sea western boundary current, SCSwbc)区域海洋涡旋的统计特征、涡致热输运并重点探讨了两类冬季环流形态及其风场分布对它们的影响。结果表明研究区域的涡旋气候态上存在旋转速度很强,半径较大,振幅略高于平均值的涡旋统计特征,其中气旋式涡旋(cyclonic eddy, CE)的占比约为56.8%。并且涡旋的生成和消亡主要发生在冬/春季,而涡旋的振幅、半径和旋转速度在夏/秋季发展到顶峰。年际时间尺度上,年平均经向风应力与反气旋式涡旋(anticyclonic eddy,AE)的振幅、半径、旋转速度和消亡均有较好的相关性,但与CE特征的相关性并不好。“O”型冬季环流模态下,风场和南海西边界流显著减弱,冬季环流在越南沿岸发生向东分支。涡旋在“O”模态下吸收平均流能量迅速发展,在越南沿岸东部地区产生了强的涡致热输运(eddy-induced heat transport, EHT)。同时,涡旋内部旋转速度减小且反气旋式涡旋个数减少;“U”型冬季环流模态下,情况则相反。     

太平洋-印度洋贯穿流南海分支在卡里马塔海峡的十年观测回顾

除印度尼西亚贯穿流之外,南海贯穿流也是太平洋向印度洋输送海水的重要分支。尽管基于数值模拟等方法的研究早已指出,南海分支在太平洋-印度洋洋际交换中有重要作用,但是直到2007年之前,南海分支在卡里马塔海峡处的观测几乎是空白。本文回顾了自2007年起,通过中印尼合作项目"南海-印度尼西亚海水交换及对鱼类季节性洄游的影响（SITE）"在卡里马塔海峡开展的近十年观测,以及在此基础上进一步开展的"印度尼西亚贯穿流海域水交换、内波和混合观测及其生态效应（TIMIT）"观测项目,并对SITE和TIMIT观测取得的成果进行了总结。     

吕宋海峡及南海北部海域的水团分析

根据1992年3月和1994年9月台湾海峡两岸科学家对南海北部两次协同调查的CTD资料以及由此计算的重力势资料,对吕宋海峡及南海北部400m以上海水的温盐性质进行分析。结果发现,调查海区基本可划分为两种水团,即黑潮水和南海水。黑潮水主要从吕宋海峡中部和北部进入南海,侵入的黑潮水向西北方向扩展,受到台湾海峡海底地形的阻挡而大部分集中于台湾西南海域,向西的范围基本不超过119°E。虽然两次观测所处的季节不同（分别为春初和夏末）,但黑潮入侵南海的差异并不明显。另外,在二次调查的部分层次上,南海北部陆坡边缘都发现有一团水平尺度约百公里的黑潮性质水。配合重力势的水平分布形式,可以用地转流场的结构解释水团分析的结果。     

黑潮入侵优化对南海北部中尺度涡旋模拟的影响

基于高分辨率海洋环流模式,通过比较吕宋海峡处地形优化后的黑潮入侵形态和强度不同的试验,我们研究了黑潮入侵优化后对南海中尺度涡模拟的影响。我们发现黑潮入侵的减弱导致了涡旋活动的减弱,这使得模式结果与观测结果更为相近。在这种情况下,模式模拟的吕宋海峡西部及北部陆坡区域的涡动动能明显减弱。模式涡动动能的减弱与模式反气旋式涡数量的减少和气旋式涡强度的减弱有关。涡动动能收支的分析进一步表明,黑潮入侵的优化将通过改变水平速度切变和温跃层斜率来改变涡动动能,而这两个参数分别与正压和斜压不稳定性有关。前者在模式涡动动能减弱中起着更为重要的作用,而黑潮入侵导致的涡动动能的水平输送对吕宋海峡西部区域的能量收支同样起着重要的作用。     

南海南部断裂的分形研究

分形几何作为定量描述自然界中复杂非线性现象的强有力工具,将其应用于南海南部断裂体系的研究中,通过数盒子法计算了断裂分布的分维值。研究结果表明这种方法是可行的,断裂分布的分维值能有效地描述断裂的空间分布特征。南海南部断裂体系在标度区间25～250km内具有很好的统计自相似性,全部断裂的分维值为1．6601,北东向断裂的为1．3875,北西向断裂的为1．2693。根据断裂分维等值线,沿西南海盆扩张轴,两侧断裂呈对称展布;北东向的与北西向的在空间上有一定的互补性,这反映了两组断裂在发育过程中的相互制约性。结合南海的构造演化及南海南部油气盆地的分布,初步探讨了断裂分形特征与南海的构造演化及断裂分形特征与油气盆地分布之间的关系。     

South China Sea wave characteristics during typhoon Muifa passage in winter 2004

The responses to tropical cyclones of ocean wave characteristics in deep water of the western Atlantic Ocean have been investigated extensively, but not the regional seas in the western Pacific such as the South China Sea (SCS), due to a lack of observational and modeling studies there. Since monsoon winds prevail in the SCS but not in the western Atlantic Ocean, the SCS is unique for investigating wave characteristics during a typhoon’s passage in conjunction with steady monsoon wind forcing. To do so, the Wavewatch-III (WW3) is used to study the response of the SCS to Typhoon Muifa (2004), which passed over not only deep water but also the shallow shelf of the SCS. The WW3 model is forced by the NASA QuikSCAT winds and tropical cyclone wind profile model during Typhoon Muifa’s passage from 0000UTC 16 on November to 1200UTC on 25 November 2004. The results reveal the unique features of the SCS wave characteristics in response to Muifa, such as non-decaying, monsoon-generated swell throughout the typhoon period and strong topographic effects on the directional wave spectrum.     

南海海洋环流的诊断计算

利用GDEM温盐资料,采用P矢量方法计算了与温盐资料时间序列相对应的不同季节、不同层深的南海海洋环流及流涡系统,并且得出了相关的结论。     

南海上层环流季节变化的诊断计算

通过一个全球的二维诊断模型,采用Levitus温盐资料和COADS风应力资料,并结合动力计算来研究南海上层环流的季节变化。计算结果与其它模式结果和观测结果非常相似。南海北部(南部)全年存在一气旋式(反气旋式)环流。在冬季气旋式环流几乎占据了整个南海,夏季则以反气旋式环流为主。泰国湾的环流在冬季(夏季)是气旋式的(反气旋的)。南海的西边界流有明显的季节变化,其在冬季从卡里马塔海峡流出南海,夏季部分西边界流从台湾海峡流出南海。越南离岸流在春季就开始出现,其位置比夏季的越南离岸流的位置偏北。     

台风Wayne过后南海北部陆架海域的近惯性振荡

1986年8月18日8616号台风维纳(Wayne)在南海中部生成,其后在南海北部迂回盘旋,前后3次穿越巴士海峡,9月4日在海南岛登陆。布放在海南岛东部陆架上的锚系浮标记录了台风中心过境前后风和近表层的海流响应。分析结果表明,台风中心过境造成海水强烈的近惯性运动,其影响大约持续了6—8d,近惯性振荡的频率为0.029 2周.h-1(周期约34.2h),高出当地的惯性振荡频率(0.028cph)4.3%。带通滤波所提取的惯性运动特征显示,台风过境后惯性振荡逐渐衰减,惯性圆逐渐向西南方向偏移。根据这一个例,探讨了台风条件下近表层流速与风速的关系以及台风尾迹中近惯性流流速衰减过程的经验描述,可为近海海洋工程设计提供参考。     

南海北部陆架区两个台风过境时近惯性运动的若干特征

Features of near-inertial motions on the shelf(60 m deep) of the northern South China Sea were observed under the passage of two typhoons during the summer of 2009. There are two peaks in spectra at both sub-inertial and super-inertial frequencies. The super-inertial energy maximizes near the surface, while the sub-inertial energy maximizes at a deeper layer of 15 m. The sub-inertial shift of frequency is induced by the negative background vorticity. The super-inertial shift is probably attributed to the near-inertial wave propagating from higher latitudes. The near-inertial currents exhibit a two-layer pattern being separated at mid-depth(25–30 m), with the phase in the upper layer being nearly opposite to that in the lower layer. The vertical propagation of phase implies that the near-inertial energy is not dominantly downward. The upward flux of the near-inertial energy is more evident at the surface layer(17 m). There exist two boundaries at 17 and 40 m, where the near-inertial energy is reflected upward and downward. The near-inertial motion is intermittent and can reach a peak of as much as 30 cm/s. The passage of Typhoon Nangka generates an intensive near-inertial event, but Typhoon Linfa does not. This difference is attributed to the relative mooring locations, which is on the right hand side of Nangka's path(leading to a wind pattern rotating clockwise with time) and is on the left hand side of Linfa's path(leading to a wind pattern rotating anti-clockwise with time).     

Diagnostic calculation of the circulation in the South China Sea during summer 1998

On the basis of hydrographic data obtained from 12 June to 6 July, 1998, the three-dimensional structure of circulation in the South China Sea (SCS) is computed using a three-dimensional diagnostic model. The combination of sea surface height anomaly from altimeter data and numerical results provides a consistent circulation pattern for the SCS, and the main circulation features can be summarized as follows: In the northern SCS there are a cyclonic eddy C1 near Dongsha Islands and an anti-cyclonic eddy W1 west of Luzon Island. In the central SCS a strong anti-cyclonic eddy W3 and a cyclonic eddy C3 compose a quasi-dipole southeast of Vietnam. A coastal northward jet is present at the western boundary near the Vietnam coast above 300 m level. This northward coastal jet flows northward and turns eastward at about 14°N, and then flows southeastward into the area between eddies W3 and C3. In the southern SCS the current is weaker. The most important dynamic mechanism underlying the circulation in the SCS is the joint effect of the baroclinicity and relief (JEBAR), and the second dynamical mechanism is the interaction between the wind stress and relief (IBWSR). Comparison of the characters of circulation in the SCS during summer 2000 with that during summer 1998 reveals no obvious variability of the main characteristics.     

南海主要控凹断层活动特征与新生代地壳初始张裂

基于贯穿南海南、北陆缘2条长地震剖面的资料解释,分析了南海海域主要控凹断层的活动特征及其新生代地壳初始张裂特征。南海陆缘大部分断层于新生代张裂期开始发育并强烈活动,控凹断层基本上都发育在凹陷的边界,又称之为控凹边界断层。多数控凹断层早期以断块旋转滑脱、形成铲状断层为特征,北部陆缘主要控凹断层多数还具有幕式断裂的活动特点。控凹断层的初始活动时间主要集中在早始新世—晚渐新世,在南海北部陆缘东部早于西部,东部断层初始活动时间为早始新世甚至更早,西部断层初始活动时间多为晚始新世;南海南部陆缘的控凹断层初始活动时间晚于南海北部陆缘,主要集中在中始新世甚至晚始新世。南海海域地壳新生代初始张裂活动时间具有“东早西晚、北早南晚”的特点。此外,这些控凹断层部分于南海的漂移期继续活动或开始活动,少数断层于中中新世重新活动。     

Signatures of ocean storms on seismic records in South China Sea and East China Sea

Ocean storms on seismic records reveal coupling mechanisms between Earth’s spheres. We analyzed temporal and spatial signatures of ocean storms on seismic records in the South China and East China Seas. The main points are: (1) the landing of ocean storms directly influences spectrum amplitudes of microseisms, showing an “increase-peak-decrease” pattern, whereas they exert no direct influence on Earth’s hum and the high-frequency noise; (2) for microseisms, spectrum amplitudes of short-period double-frequency microseisms are increased greatly during ocean storms’ landing, implying that storms preferably excite short-period ocean swells; (3) while the “increase-peak-decrease” pattern of spectrum amplitudes is observed for both short-period double-frequency microseisms and long-period double-frequency microseisms in South China Sea, the peak arrived and disappeared much earlier for long-period double-frequency microseisms, which can be explained by their causal mechanisms; (4) in East China Sea, only the spectrum amplitudes of short-period double-frequency microseisms show an “increase-peak-decrease” pattern and extraordinary spectrum pulses are observed reflecting thick sediments there; (5) spatial features of microseisms revealed from predominant polarization directions indicate that local coastlines play very important roles in deciding where ocean waves impact; (6) high-frequency noise is caused by local offshore wind-generated ocean waves instead of ocean storms; (7) the influence of ocean storm landing processes on microseisms can propagate through continents and is observed at inland stations; (8) seismic motions are excited more efficiently in horizontal directions when ocean waves impact seafloors. Our work clearly exhibits how effectively local ocean events are coupled with the Earth’s lithosphere in Chinese seas.     

南海北部191柱状沉积物主元素特征及其古环境意义

应用XRF法对南海北部陆坡191柱状沉积物中主元素进行分析,结果显示,全柱沉积物中SiO₂含量最高,其次是CaCO₃,Al₂O₃和CaO。在垂向分布上CaCO₃和CaO含量分布基本一致,SiO₂,Al₂O₃,Fe₂O₃,K₂O,MgO含量变化相似。结合AMS碳-14测年,可将191柱状样划分为5个地球化学层,主元素和MgO与Al₂O₃含量比值在垂向上的旋回变化反映了南海北部氧同位素3期以来末次冰盛期、冰后期、晚冰期的气候变化、海平面波动及陆源物质供应的变化,并对Heinrich事件、格陵兰高频气候振荡(D/O)旋回、新仙女木事件以及普林斜氏虫低值事件等全球性短周期气候事件有很好的对应关系,但受区域影响,在时间上有所滞后。氧同位素3期以来的沉积速率并未显示出南海普遍存在的间冰期比冰期、暖期比冷期的沉积速率低的规律,而是逐渐减小的,这可能是氧同位素3期频繁的冷热干湿气候振荡导致岩石易于风化破碎受侵蚀后被洪水搬运的缘故。     

国家自然科学基金重大研究计划 南海深海过程演变

1研究背景深海是地球表层最晚认识的部分,人类对于深海的知识绝大部分来自最近半个多世纪。1968年开始的深海钻探计划(DSDP),证明洋底在不断扩张;1978年开始的HEBBLE计划,证明几千米海底还有深海风暴;1970年代末发现大洋中脊喷出热液,支持着非光合作用的黑暗食物链;1990年代