Study on the interannual variability of the Kerama Gap transport and its relation to the Kuroshio/Ryukyu Current system

An analysis of a 68-year monthly hindcast output from an eddy-resolving ocean general circulation model reveals the relationship between the interannual variability of the Kerama Gap transport(KGT)and the Kuroshio/Ryukyu Current system.The study found a significant difference in the interannual variability of the upstream and downstream transports of the East China Sea-(ECS-)Kuroshio and the Ryukyu Current.The interannual variability of the KGT was found to be of paramount importance in causing the differences between the upstream and downstream ECS-Kuroshio.Additionally,it contributed approximately 37%to the variability of the Ryukyu Current.The interannual variability of the KGT was well described by a two-layer rotating hydraulic theory.It was dominated by its subsurface-intensified flow core,and the upper layer transport made a weaker negative contribution to the total KGT.The subsurface flow core was found to be mainly driven by the subsurface pressure head across the Kerama Gap,and the pressure head was further dominated by the subsurface density anomalies on the Pacific side.These density anomalies could be traced back to the eastern open ocean,and their propagation speed was estimated to be about 7.4 km/d,which is consistent with the speed of the local first-order baroclinic Rossby wave.When the negative(positive)density anomaly signal reached the southern region of the Kerama Gap,it triggered the increase(decrease)of the KGT towards the Pacific side and the formation of an anticyclonic(cyclonic)vortex by baroclinic adjustment.Meanwhile,there is an increase(decrease)in the upstream transport of the entire Kuroshio/Ryukyu Current system and an offshore flow that decreases(increases)the downstream Ryukyu Current.

清代赴琉球册封使的选派

明清鼎革之后,册封使在中琉封贡关系中继续扮演关键角色。清朝八次册封琉球,共计选派十六位册封使远渡重洋,出使琉球,为中琉关系发展作出了重要贡献。清朝十分重视册封使的遴选,主要体现在遴选主体、遴选程序、遴选标准及要求三方面,相较于明代均有较为明显的升格。在册封使派遣方面,对离京前、抵闽后、赴琉球、返国后的全过程,清朝也作了许多规制设计和精密筹划,确保册封使既能顺利完成使命,又能展示“天朝上国”仪度。清代赴琉球册封使选派的日臻完善是明琉封贡关系的延伸,也是清朝重视属国琉球的反映,进一步增强了琉球对中国的向心力,促进了琉球政治、经济、社会的发展,也使琉球更好地履行藩属国义务,满足了清朝对巩固封贡体系的希求。

战后琉球处置及法理争议——基于《旧金山对日和约》领土处置及条约签字权交涉的考察

《开罗宣言》是盟国签订战后对日和约的基础性文件,该宣言的3个条款是一个涵盖了时间和空间两个维度的国际文件,逐层递进,互为补充,意在剥夺日本所有侵夺的领土。基于《开罗宣言》等国际法文件,战后琉球的处置,需要由包括中苏在内的反法西斯盟国共同决定,目前的处置结果存在严重的法理争议。英国内部一度坚持琉球必须从日本领土剥离出去,至于美国所坚持的战略托管,必须经由联合国安理会授权。国民党当局并未默认《旧金山对日和约》的琉球处置条款,而是认为旧金山和约只是一项政治性条约,属于盟国结束对日战争状态的协议,而琉球的处置需要专门的领土条约予以规定。围绕国民党当局《旧金山对日和约》签字权问题的美英交涉,与战后日本领土处置条款的交涉纠缠在一起,影响到了国民党当局对于琉球群岛的处置决策。

明清封舟的航行动力风险及使团预防措施

明清时期,中琉交往频繁,册封琉球使团作为中方构设的官方渠道,数十次横渡东海、互通往来。中琉航路自然环境复杂,使团出行既有海氛未靖之险,更有惊涛骇浪、船破人危之虞。为应对封舟航行中自然动力带来的风险,使团采取提升封舟性能、改进航海技术、遴选贤才能士、储备应急物资等措施预防。在保障航海安全的同时,这些预防措施也对琉球的造船航海技术、文化、农业产生积极影响,推进中琉两国宗藩关系的发展。

浅析宗藩体制下清政府对琉球态度的转变——以“脱清人”的活动为中心

在近代风云变化的东亚地区,随着西方列强的侵入,清朝与琉球的宗藩关系受到了巨大冲击。自明治维新以来,日本侵略的步伐加快,使琉球深陷危机之中。以向德宏、蔡大鼎为代表的“脱清人”在福州、天津和北京等地开展活动以求清政府的援助。清朝作为琉球的宗主国,却对琉球显示出摇摆不定的态度。在“脱清人”的不断努力下,以“分岛改约”事件为节点,清政府对待琉球的态度出现了由轻视到重视的巨大转变,并以强硬的态度与日本谈判。直到甲午战争爆发,华夷秩序完全崩溃,这种以“宗藩体制”为主体的中琉关系最终瓦解。

近世东亚视域下的中琉日关系——以萨摩藩侵略琉球后的三国外交策略为例

17世纪初受到日本挟制的琉球向宗主国明王朝隐瞒了实情并美化日本萨摩藩和德川幕府形象。明王朝改变了对琉态度,下令琉球停止朝贡10年;德川幕府意欲以琉球为媒介重开中日勘合贸易;萨摩藩本想吞并琉球,但在德川幕府的外交政策下改变对琉策略,暗中介入琉球朝贡贸易以从中谋利。萨摩藩入侵后的琉球外交策略与中日两国的对琉政策变化,是17世纪初期东亚区域政治势力的内外冲突和平衡的折射,表明17世纪初期东亚国际区域形势已发生变化。

沟祭证明中国拥有钓鱼岛及其附属岛屿主权

从汪楫开始,清代册封琉球使团持续性地在黑水沟举行了祭祀。然而,由于种种原因,当时的使录和针路对这些活动并不是总能予以切实记载,主要表现为李鼎元在《使琉球记》中对沟祭的歪曲,以及林鸿年和赵新整理的针路对它的忽略。这表明,沟祭作为惯例在实际上得到册封使团的长期遵行,沟祭作为钓鱼岛及其附属岛屿属于中国的历史证据是有效与可信的。

《使琉球录》中的“清廉”

《使琉球录》详尽记录了明代嘉靖、万历年间三次册封琉球的史实。每次册封,面对琉球国王的七场宴会款待和“一宴一酬金”的礼节,中国册封使只参加重要的几场宴会,推辞其余宴请,拒收所有礼金。册封使的却金之举,展现了中华大国风范和使臣的高风亮节,那霸的却金亭见证了中琉友好交往的历史和中国使臣清廉高尚的品格。

清代前中期旅外文献考略

清代前中期的旅外文献虽然在数量上、涉及范围上均无法与晚清时期相比,但在一定程度上也能反映清代前中期对外交往的格局,以及清人对周边世界的观察。出于册封等原因,清代前中期的旅外文献主要为清廷使臣及随行人员撰写,涉及的区域为琉球、安南与朝鲜等。除个人行纪、诗文外,此类旅外文献还涉及域外国家的风俗、制度等。它们所记的世界在地理上虽是域外,但文化层面上仍是域内。

朱仕玠海洋书写与宦台情志探析

中国台湾独特的海洋环境及其内涵特质,引发宦台文人朱仕玠的文学想象与浪漫遐思,并深刻影响其内在情志及外在探奇行为。朱仕玠对台湾海洋的观察与书写,往往在真实与想象、现实与神话之间交织错杂,折射出清代宦台文人独特的生命意识与海洋文化认知。

古代琉球舞蹈文化功能研究

本文以环太平洋西岸琉球舞蹈为例,运用文化人类学家马林诺夫斯基的文化功能理论与方法,对环太平洋西岸的琉球舞蹈种类形式、琉球舞蹈对琉球人的基本生存需要、衍生需要及综合需要的文化功能进行了分析。经研究发现,舞蹈作为人类精神文化的一个类型,能够对人类不同时期的需要而发挥其独有的功能。时代发展到今天,世界面临着各种挑战。琉球舞蹈能够为满足琉球人的互联互通、资源共享、合作共赢与要和平、不要战争、构建人类命运共同体的综合需要方面,发挥其组织社会力量的功能。

Circulations east of Taiwan and in East China Sea and east of Ryukyu Islands during early summer 1985

A modified inverse method is used to compute the circulations east of Taiwan and in the East China Sec and east of the Ryukyu Islands with hydrographic data obtained during early summer of 1985. The computational region covers an area west of 129°E and from 21°45'N to 35°N. The computed results show that: (1 ) The net volume transport (VT ) of the Kuroshio through 21°45'N Section east of Ta Taiwan and west of 123°E is about 45 × 10￣6 m￣3/sduring early summer of 1985. The Kuroshio has. two current cores. One is located near Taiwan, and its velocity isvery large and its maximum velocity is 226 cm/s at the 100 m level, which is close to the maximum velocity of the beginning of the Kuroshio east of the Philippines. The other is located further to the east, and its maximum velocity is159 cm/s at the 100m level; (2) through a transect northwest Of Miyakojima Island and a transect southwest of Okinawa laaed the volume transports of the Kuroshio in the East China Sea both are about 25 × 10￣6 m￣3/s. The maximumvelocity of the Kuroshio at these two sections is 194 and 128 cm/s, respectively, and both are located on the shelfbreak; (3) beneath and east of the Kurohio there are the countercurrent (4) southeast of Okinawa Island there is anortheastward current, and its VT at Section HI is about 12. 6 × 10￣6 m￣3/s, and it comes from a westward flow at 129° This project was supported by the National Natural Science Foundation of China under contract No. 49476278.(Second Institute of Oceanography, State Oceanic Administration, Hongzhou310012, China) (Institute of Oceanography, Taiwan University, Taipei, China)E Section and the recirculating gyre, and does not originate from the Kuroshio east of Taiwan during early summer of 1985. There is a southwestward abyssal current east of Okinawa Islands (5) there are several different scale eddies in this computational region. For example, there is a meso-scale strong cyclonic eddy east of Miyakojima Island.

Origin and formation of the Ryukyu Current revealed by HYCOM reanalysis

The origin of the Ryukyu Current(RC)and the formation of its subsurface velocity core were investigated using a 23-year(1993–2015)global Hybrid Coordinate Ocean Model(HYCOM)dataset.The volume transport of the RC comes from the Kuroshio eastward branch(KEB)east of Taiwan and part of the North Pacific Subtropical Gyre(p-NPSG).From the surface to 2000m depth,the KEB(p-NPSG)transport contributes 41.5%(58.5%)to the mean total RC transport.The KEB originally forms the subsurface velocity core of the RC east of Taiwan due to blockage of the subsurface Kuroshio by the Ilan Ridge(sill depth:700 m).Above 700m,the Kuroshio can enter the East China Sea(ECS)over the Ilan Ridge,meanwhile,the blocked Kuroshio below 700m turns to the right and flows along the Ryukyu Islands.With the RC flowing northeastward,the p-NPSG contribution strengthens the subsurface maximum structure of the RC owing to the blockage of the Ryukyu Ridge.In the surface layer,the p-NPSG cannot form a stable northeastward current due to frequent disturbance by mesoscale eddies and water exchange through the gaps(with net volume transport into ECS)between the Ryukyu Islands.

Seismic detection of the X-discontinuity beneath the Ryukyu subduction zone from the SdP conversion phase

The X-discontinuity,which appears at the depth of approximately 300 km,is an important seismic interface with positive velocity contrasts in the upper mantle.Detecting its presence and topography can be useful to understand phase transformations of relevant mantle minerals under the high-temperature and high-pressure circumstance of the Earth's interior.In this study,we detect the X-discontinuity beneath the Ryukyu subduction zone using five intermediate-depth events recorded by the dense Alaska Regional Network(AK).The X-discontinuity is successfully revealed from the robust slant stacking of the secondary down-going and converting Sd P phases.From the depth distribution of conversion points,we find that the X-discontinuity's depth ranges between 269 km and 313 km,with an average depth of 295 km.All the conversion points are located beneath the down-dipping side of the Philippine Sea slab.From energy comparisons in vespagrams for observed and synthetic seismograms,the strong converted energy is more likely from a thin high-velocity layer,and the S-wave velocity jumps across the X-discontinuity are up to 5% to 8% with an average of 6.0%.According to previous petrological and seismological studies,the X-discontinuity we detected can be interpreted as the phase transformation of coesite to stishovite in eclogitic materials within the oceanic crust.

Neoproterozoic Trench-arc System in the Western Segment of Jiangnan Orogenic Belt, South China

The Jiangnan orogenic belt is a key to understanding of the Neoproterozoic tectonic evolution of the South China Block. We investigate the mafic-ultramafic suites of lherzolite, pyroxenite, gabbro, pillow basalt and gabbroic diorite as well as red jasper interbedded with marine marbles that are mainly exposed as fault-trapped blocks in the Yuanbaoshan and Longsheng domains of the western Jiangnan belt. The postcollisional granite plutons that intruded the ultramafic-mafic rocks are developed well. Zircons in the gabbro yield crystallization ages of 867±10 Ma, 863±8 Ma, 869±9 Ma and 855±5 Ma whereas those from the granites show ages of 823±5 Ma, 831±5 Ma, 824±5 Ma and 833±6 Ma. The Neoproterozoic serpentinited ultramafic samples display minor REE enriched pattern with depletion of Rb, Ba, Nb, Ta and Ti, similar to those of SSZ type ophiolite. The coeval gabbro shows tholeiitic features and is characterized by negative Ba, Nb, Ta, Zr, Hf and Sr anomalies and LREE enriched patterns, with a minor negative Eu anomaly. Some zircon grains from the Longshen gabbro yield Neoarchean-Paleoproterozoic ages(2859–2262 Ma), suggesting its continental arc setting. Geochemical signature of the maficultramafic rocks is consistent with subduction related setting. The pyroxene-bearing diorite exhibits a distinctive arc affinity. The zircons from the gabbro show positive εHf(t) values ranging from 3.9 to 13.8. The granitoids are typical S–type granites with high ACNK values(1.15–1.40) and negative εHf(t) values(–15.1 to –3.2), and are classified as collision–related granites. Combined with the occurrences of mafic-ultramafic rocks, siliceous marble and red jasper mixed with basalt, our new results suggest the presence of a Tonian(863–869 Ma) SSZ ophiolite system and continental arc-type magmatism in the western Jiangnan orogen.

Validation and Application of Skeletochronology for Age Determination of the Ryukyu Ground Gecko, Goniurosaurus kuroiwae(Squamata: Eublepharidae)

Skeletochronology is a method commonly used for estimating the age of amphibians and reptiles in the wild. However, the number of lines of arrested growth （LAGs） does not necessarily reflect age in some species. We validated the applicability of this method to an endangered eublepharid gecko, Goniurosaurus kuroiwae, then inferred its longevity and age structures in wild populations. We classified young geckos into three groups using previously published data for early growth： Group 1 contained hatchlings before the first winter, Group 2 contained hatchlings after the first win- ter, and Group 3 included yearlings after the second winter. LAG numbers in these groups were then compared. All individuals in Group 1 possessed a single LAG, which was considered as a hatching line. Most individuals in Groups 2 and 3 possessed one and two additional LAGs, respectively （LAG1 and LAG2）, corroborating the notion that LAGs are formed annually. A few geckos exhibited fewer LAGs than expected. Analysis of variations in LAG and marrow cavity diameter demonstrated that in animals with fewer LAGs, endosteal resorption or fusion of hatching line and LAG1 had occurred. LAG2 was never lost by endosteal resorption and was identifiable by its diameter. Thus, the age of adult geckos could be determined by counting LAGs outward from LAG2. Application of this method to wild populations re- vealed that the longevity of this species is not less than 83 months, but that almost all individuals in fragmented habitats die before 50 months, suggesting lower population sustainability in such habitats.

Progress of studies in China from July 2010 to May 2015 on the influence of the Kuroshio on neighboring Chinese seas and the Ryukyu Current

The influence of the Kuroshio on neighboring Chinese seas and the Ryukyu Current is a very important subject of interest in physical oceanography. To deeply explain the research progress made by Chinese scientists from July2010 to May 2015, the following three aspects are reviewed in this paper. The first concerns the Kuroshio intrusion into the South China Sea（SCS） and its circulation around the Luzon Strait. There are two very important points to be explained： the seasonal and inter-annual variation of the Kuroshio intrusion and the mechanisms of the Kuroshio intrusion and the influence of the Kuroshio on currents in the Luzon Strait and circulation in the northern SCS. The second concerns the variability of the Kuroshio and its interaction with the East China Sea（ECS）. There are following four interesting topics to be explained： an overview of studies on the Kuroshio in the ECS; the Kuroshio intrusion into the ECS, water exchange, and dynamic impacts; the downstream increase of nutrient transport by the Kuroshio; and the application of satellite remote sensing on terrestrial material transport by the Kuroshio intrusion into the ECS. Third, the interaction between the Ryukyu Current and Kuroshio in the ECS are also discussed. Finally, the main results are summarized and areas of further study are simply discussed.

The study of the Kuroshio in the East China Sea and the currents east of the Ryukyu Islands

In this study, the inverse method is used to compute the Kuroshio in the East China Sea and southeast of Kyushu and the currents east of the Ryukyu Islands, on the basis of hydrographic data obtained during September-October, 1987 by R/V Chofu Maru. The results show that: (1)A part of the Taiwan Warm Current has a tendency to converge to the shelf break; (2) the Kuroshio flows across the section C3 (PN) with a reduced current width, and the velocity of the Kuroshio at the section C3 increases and its maximum current speed is about 158 cm/s, and its volume transport here is about 26×106m3/s; (3) the Kuroshio has two current cores at the sections C3 (PN) and B2 (at the Tokara Strait); (4) the currents east of the Ryukyu Islands are found to flow northward over the Ryukyu Trench during September-October, 1987. The velocities of the currents are not strong throughout the depths. At the section C2 east of the Ryukyu Islands, the maximum current speed is at the 699 m levei and its magnitude is 25 cm/s, and its volume transport is about 21×06 m3/s; (5) the volume transports of the Kuroshio through the sections B2 (at the Tokara Strait) and C6 (southeast of Kyushu) are 23. 33, 67. 31×106 m3/s, respectively; (6) there are two meso-scale anticyclonic warm eddies between 135° E and the area east of the Ryukyu Islands, and their characters and hydrographic structure are discussed.

WAVENUMBER AND DEPTH PROPERTIES OF TEMPERATURE FINESTRUCTURE IN THE REGION AROUND THE RYUKYU ISLANDS

Forty two CTD profiles gathered in summertime of 1997 were used for finestructure studies around the Ryukyu Islands indicating that finestructure properties varied with depth; and that the wavenumber spectra density is a negative (-3～-4) power function of the wavenumber in the high wavenumber range. The identical finestructure spectral features in different stations indicate considerable water exchange through the Kerama Trench. The wavelet spectrum’s spatial structure and intermittency is related to the vertical mixing of water.

Seismicity and stress field in Okinawa Trough and Ryukyu regions

According to the seismic data (mb≥5. 0) from 1977 to 1991 and the focal mechanisms of 68 earthquakes from 1961 to 1991, the characters of seismicity and stress field in Okinawa Trough and Ryukyu regions are discussed in this paper, and the paper suggests that: ① The Tokara Channel fault belt is a fault belt with seismicity, cutting through lithosphere. ② The different stress state in the both subducting slabs on the both sides of Tokara Channel fault belt are caused by the difference of subducting depth of the both slabs. ③ The seismicity and stress field in the Okinawa Trough and Ryukyu regions are related not only to the subduction of the Philippine Sea Plate but also to the self-expanding action of Okinawa Trough.