Spatiotemporal variations of the surface Kuroshio east of Taiwan Island derived from satellite altimetry data

Spatiotemporal variation of the surface Kuroshio east of Taiwan Island is investigated by quantitatively analyzing 23-year(1993–2015)sea surface Absolute Dynamic Topography data.The annual mean state of the Kuroshio is shown,with a flow width ~136 km and surface transport ~7.75×10~4 m^2/s.The corresponding standard deviations of these are 28 km and 2.14×10~4 m^2/s.Results of power spectrum analysis indicate that the primary periods of Kuroshio surface transport east of Taiwan Island are 1 and 2.8 years,respectively.Spatially,the Kuroshio surface transport southeast of Taiwan Island has greater variability than that to its northeast.That transport showed strong seasonality,with a maximum 8.8×104 m^2/s in summer and minimum 7.5×10~4 m^2/s in winter,which was mainly caused by local monsoon winds.A linear long-term upward trend of Kuroshio surface transport during 1993–2015 was found,during which the mean,southeast,and northeast of the Kuroshio east of Taiwan Island increased by 0.30×10~4,0.22×10~4 and 0.36×104 m^2/s,respectively.Correlation and composite analysis show that the Philippines-Taiwan Oscillation(PTO)is important in the interannual variability of the Kuroshio.PTO-induced relative intensity of anticyclonic and cyclonic eddies is the dominant influence on the interannual variability of the Kuroshio east of Taiwan Island.

Sediment source and environment evolution in Taiwan Island during the Eocene–Miocene

Taiwan Island’s outcropping strata can provide important insights into the sedimentary environment and source development of the southeast China margin.This research is based on the Eocene–Miocene strata of the Tsukeng area in the central Western Foothills,northeast shoreline of Taiwan Island and two sites of the East China Sea Shelf Basin(ECSSB),using petrology and detrital zircon U-Pb age for the analysis.Results show that central and northeast Taiwan Island experienced a transformation from continental to marine facies during the Eocene–Miocene,and the sandstone maturity changed with time.Source analysis shows that sediments from the Eocene–early Oligocene strata mainly originated from near-source Mesozoic rocks,whose zircon age is consistent with the igneous rock in the surrounding area and coastal Cathaysia,showing 120 Ma and 230 Ma peaks in the age spectrum diagram.Since the late Oligocene,peaks of 900 Ma and 1800 Ma are seen,indicating that deposition of matter from the old block began.The sediments could be a mixture of the surrounding Mesozoic volcanic and fewer pre-Cambrian rocks sourced from the coastal river and sporadic old basement in the ECSSB instead of longdistance transportation.

A dipole wind curl pattern induced by Taiwan Island and its effect on upper stratification in the northeastern South China Sea

Using hydrographic data sampled during four successive late summer-early autumn cruises in 2004-2007, vertical stratification along transects in the lee of Taiwan Island was analyzed to investigate upper ocean responses to orographically induced dipole wind stress curl (WSC). Results indicate that mixed-layer depth (MLD) and its relationship with thermocline depth varied under different local wind forcings. Average MLD along the transects from the 2004 to 2007 cruises were 18.5,30.7,39.2 and 24.5m, respectively. The MLD along the transects deepened remarkably and resulted in thermocline ventilation in 2005 and 2006, whereas ventilation did not occur in 2004 and 2007. Estimates indicate that frictional wind speed was the major factor in MLD variations. To a large degree, the combined effects of frictional wind speed and Ekman pumping are responsible for the spatial pattern of MLD during the cruises.

Morphological characteristics in the area off eastern Taiwan Island and their tectonic implications

On the basis of bathymetric data and other geological and geophysical data obtained during the first survey conducted by Chinese Mainland in the area off eastern Taiwan Island from May to June in 2000, the morphological features of the region, the tectonic control to the seafloor topography and their tectonic implication are studied and discussed. The results have revealed that both the slope zone of the Ryukyu arc and the Ryukyu Trench present a typical morphotectonic characteristics controlled by the trench-arc system in the West Pacific Ocean. At the slope of eastern Taiwan Island the isobathic lines parallel to the coastline and distribute densely in nearly N-S direction and the slope gradient of topography is large. Such a unique feature is attributed to the collision of the Luzon arc and Eurasia continent. In the Huatung Basin, turbidity fans and submarine canyons are well developed, the formations of which are mainly related to the steep topography of the slope of the Luzon arc and the abundant supply of sediments. These submarine canyons are controlled by basement highs and strike-slip faults. On eastern side and western side of the Gagua Ridge, both the water depth and morphological features are different, but the basement of Gagua Ridge belongs to the Huatung Basin. The eastern side of the Gagua Ridge (123°12' E) corresponds to the boundary of two plates with different ages. In the West Philippine Basin, linear ridges and troughs in a NW trending are identified, which are dissected by a NE trending transform fault. According to the seafloor topography features, the direction of the transform fault and the magnetic anomaly lineations, the seafloor of this region was formed during 60-45 Ma B.P when the West Philippine Basin was spreading along NE-SW relative to the present orientation.

Three-dimensional numerical calculations of currents east of Taiwan Island in December 1997

Based on the wind and hydrographic data obtained from the cruise of China - Japan Cooper- ative Research on Subtropical Gyre during December 1997, the Kuroshio east of Taiwan Island and the currents southeast of the Ryukyu-gunto are computed by using three-dimensional diagnostic, semidiag- nostic and prognostic models in the a coordinate. The computed results show that: (1 ) The density and velocity fields have been adjusted when time is about 15 d, namely, the solution of semidiagnostic calcu- lation is obtained. The quasi-steady state solution has been reached after 300 d, thus and the results of prognostic calculation got. (2) From the diagnostic calculation, the following main results can be obtained-1) There is a stronger cyclonic eddy with tongue-shaped in the region south of Taiwan Island, and the Kuroshio is located east of this cyclonic eddy. Compared with the results in July 1997, the position of the main axis of the Kuroshio moves eastward. 2) There is an anticyclonic eddy south of Miyako- jima, and there is a cyclonic eddy near the middle of the southern computational boundary. 3) The upwelling dominates in an area of the Kuroshio near Taiwan Island. (3) Comparing the results of diagnostic calculation with those of semidiagnotic and prognostic calculations indicates that the hortizontal velocity fields agree qualitatively, and there is a little difference between them in quantity. For example, the maximun horizontal velocities of the Kuroshio at the sea surface at t = 0 d (diagnostic), 15 d (semiaiagnostic) and 300 d (prognostic) are 88. 6, 98. 0 and 97. 0 cm/s, respectively. As to the distributions of vertical components of velocity, there are some differences between them, which shows that the semidiagnostic and porognostic results can coincide with better the salinity and temperature distributions.

Study of Radiolaria in the surface sediments from the area east of Taiwan Island

The species and characteristics of Radiolaria in the surface sediments were systematcally investigated in the sea east of Taiwan Island. One hundred and seventy-eight species of Radiolaria (including 21 unidentified species) have been identified in the surface sediments, and they belong to 2 orders, 34 families and 101 genera. Among them there are 19 families, 70 genera, 134 species of Spumellaria and 15 families, 31 genera, 44 species of NasseUaria. Of the 178 species of Radiolaria, the individual number of Spumellaria amounts to 88.1% of the total individual number, and that of Nassellaria amounts to 11.9% of the total individual number. It is shown that most of the dominant species belong to the tropical and subtropical dominant species and are brought into the area mainly by the Kuroshio, and some affecting factors including the submarine topography, submarine sediments, upwelling current east of Taiwan Island and carbonate dissolution play a secondary role in forming the Radiolaria distributions.

Numerical study of the influence of Kuroshio Current on the thermocline in the sea area around Taiwan Island

Using P0M97. an oceanic model, we separately do numerical tests to simulate the 3-D struc ture of temperature in the sea area around Taiwan Island with or without effect of Kuroshio (Current). Through contrast analysis. we find that inflow of Kuroshio results in winter mean water temperature of sub-surface layer in the whole sea regions raising 5 - 6℃ more than that without effect of Kuroshio. The existence of Kuroshio does important role on oceanic thermocline of deep water area in the east of Taiwan Island, and has some effect on intensity of seasonal thermocline of Taiwan Strait and its southern shallow water area.

Characteristics of rainstorm in Fujian induced by typhoon passing through Taiwan Island

Based on the typhoon track and intensity data and the precipitation data of typhoon in China during 1961–2020,the overall characteristics of the rainstorm in Fujian caused by typhoon passing though Taiwan Island were studied.More than 80 percent of typhoons passing though the Taiwan Island can bring heavy rain to Fujian.There are 1.5 events of typhoon rainstorm in Fujian every year,and the average annual impact days are 3.0.In terms of spatial distribution,the frequency and intensity of cross-island typhoon rainstorm decrease rapidly from the coastal areas of Fujian to the inland areas,and Zherong,Changle and Jiu xianshan stations in the coastal areas are the high value centers.The typhoon paths of cross-island typhoon rainstorm in Fujian are mainly divided into three categories:landing-Fujian type(including landing-Fujian northeast turning,landing-Fujian middle northbound and landing-Fujian south westbound),landing-Guangdong and Zhejiang type and offshore turning type,among which landing-Fujian type typhoon has the most significant influence(only the landing-Fujian type appears the rainstorm of≥50 mm·(24 h);),and the rainstorm intensity,influence range and asymmetrical structure of the rainstorm are the strongest,the most extensive and the most significant in the landing-Fujian middle northbound path.Based on the NCEP reanalysis data,the comparative analysis of the environmental fields causing the difference of precipitation intensity between the two typhoons landing-Fujian middle northbound and landing-Fujian south westbound shows that:To the landing-Fujian middle northbound track,strong wind speed area on the north side of the typhoon center leads to strong onshore winds,in the role of mountain terrain,piedmont has better convergence and very strong deep vertical upward movement,with better moisture conditions,it can send low high-energy water vapor to the middle,the precipitation dynamics and water vapor conditions are significantly stronger than the landing-Fujian south westbound track,resulting in more typhoon heavy rain.

An initial note on quasi- stationary, cold-core Lanyu eddies southeast off Taiwan Island

Drifting buoys, satellite altimetry and satellite-derived sea surface thermal images are used to identify the existence of a large cold-core, cyclonic Kuroshio frontal eddy between Hengchun Peninsula and Lanyu, southeast off Taiwan Island around March 1996. The cold eddy accompanies an offshore meander of the Kuroshio near Lanyu, about 70 km and 100 km in horizontal zonal and meridional scales, respectively. The cold eddy is different from normal Kuroshio frontal eddies for its persisting of about 2 months near Lanyu. Supporting evidence suggests that the Kuroshio intruded into the South China Sea (SCS, hereafter) forming a loop-like structure during the persisting period of the cold eddy and that similar eddies occur occasionally in the same location. Compared with the corresponding studies in the Gulf of Mexico, it is suggested that Lanyu cold eddies are SCS analogues of Tortugas eddies found in the southern Straits of Florida. Overshooting of the meandering Kuroshio when it leaves the SCS and effects from conservation of potential vorticity are the possible mechanism of eddy genesis.

Structural control of the Gagua “Wedge” Zone east of Taiwan Island on the southern Okinawa Trough

Based on compositive analysis and interpretation of the observed and historical data, the geophysical field characters and structural properties of the Gagua “Wedge” Zone of the sea area east of Taiwan Island and the primary tectonic stress direction and its variabilities of backarc spreading in the southern Okinawa Trough are studied. It is concluded from the study results that the Gagua “Wedge” Zone is structurally consistent with the Gagua ridge and two fault basins on both sides of the Gagua ridge, and adjusts the moving direction and distance of the western Philippine Sea plate to make the northwestward motion of the plate on its east side change to the northward subduction of the plate on its west side so that the primary tectonic stress direction of the Okinawa Trough changed from NW-SE to nearly N-S, which provided the stress source for the Okinawa Trough to enter the second spreading stage.

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

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克洛玛非法“探险”南沙与中国台湾、菲律宾马尼拉交涉

1956年3月到5月,菲律宾克洛玛等人非法“探险”南沙群岛,引发了台湾地区当局和菲律宾围绕南沙归属问题的交涉。台湾地区当局在交涉之初所具有的优势地位,因海军即将巡弋南沙得到加强,然而受冷战思维的影响,它一开始就采取了妥协态度,这也预示着交涉的最终结果。另外,国内外媒体尤其是中国香港报纸对该事件的报道,在一定程度上有助于还原当时交涉的若干场景。

VOLCANIC ACTIVITY IN TAIWAN

A group of A-Kr dating data of volcanic rocks in Taiwan Island is listed in thes paper, which clarifies the data of volcanic activity. And according to changes of plate movement in East Asia, a basic regularity of the volcanic activity in Taiwan can be obtainted, i.e. it is closely related with plate movement. The volcanic activity in Taiwan has always been moving about since Mesozoic, as the island lies in a special place of plate tectonic in East Asia, and the volcanic activity zone has changed with variations of plate motion. The paleo-Pacific plate launched a subduction toward the west in Cretaceous. Kula plate took a subduction toward the north from Cretaceous to Eogene. In Oligocene, the direction of the subduction of the Pacific plate changed from northward to westward. Taiwan Island has been the first to be affected by this change since Miocene Epoch. Therefore, volcanic activity occurs in the middle and the east of Taiwan Island. In addition, as the border of subduction moved eastward, the volcanic activity zone moves toward the east, too.Penglai movement in the period ranging from Tertiary to Quatemary is the most magnificent transformation in geological history of Taiwan. As the subduction movement of the Philippine Sea plate was replaced by the collision with Taiwan crust, the volcanic activity in the east of Taiwan Island ceased. Only the northem island and some offshore islands constitute a part of the Quatemary volcanic arc where the signs of volcanic activiy has been still displayed by now. However, the volcanic activity of the Penghu Island Group fell into the same category as that in Quatemary which was caused by the fracture activations in the eastem coast of China.

A Preliminary Analysis of Geologic & Seismologic Conditions for an Undersea Tunnel across the Taiwan Strait

The Taiwan Strait tunnel, as a great project, has been studied for a long time and met many challenges from the beginning of the feasibility study that has attracted attention among scientists and engineers on both sides of the Taiwan Strait and around the world as well. The key question is whether this undersea tunnel can be constructed with present technologies under such complex geologic and seismologic conditions. Results of current researches indicate that the sea floor of the Strait is covered with a horizontal layer composed of both the Pleistocene and the Holocene sandstone and shale with a thickness of about 200～300 m, without any large fault belt or fold.This can serve as a good bearing and impermeable layer for constructing such an undersea tunnel. The Penghu Islands and Penghu terrace, which are composed of hard basaltic rock over a wide area of 70 km (NS)×40 km (EW), might be connected each othar by a bridge instead of an undersea tunnel, and serve as a construction site. Although there are several geologic units separated by faults under the upper horizontal layer, these faults do not cut through the upper layer. Only the NE offshore fault along the Fujian coast and that along the west coast of Taiwan should be noticed, between which a suspension tunnel instead of an undersea tunnel can be constructed. Therefore it is judged that the tunnel beginning from Amoy, through the Jinmen Island and the Penghu Islands to the Peigang harbour is worth recommendation.

“台独”史观平议

通过系统考察“台独”史观的历史演变、基本观点及社会政治影响,并理性地思考有关应对之策,本文认为“台独”史观与“台独”运动相共生,并在“台独”势力操作下成为中国台湾岛内中国台湾史研究的主流学术话语。近30年来,“台独”史观经历政治化、学术化、社会化过程,严重影响了中国台湾岛内的主流思想意识。“台独”史观不仅促使李登辉、陈水扁、蔡英文等“台独”政客在背弃一个中国原则、分裂国家的“台独”道路上越走越远,而且通过教改与历史教育向中国台湾社会渗透,严重毒害了中国台湾青少年。应对“台独”史观“破”与“立”的两条路径是:一方面,剖析“台独”史观的学理谬误,揭露“台独”史观的社会政治危害;另一方面,坚持马克思主义唯物史观指导,树立正确的中国台湾史观。

过台湾岛的台风所引发的东南沿海地区的暴雨特征分析

利用1961—2020年中国气象局上海台风研究所台风资料和中国台站逐日台风降水资料,对我国东南沿海地区(浙江、福建和广东)过台湾岛台风(以下简称过岛台风)不同量级暴雨的气候特征进行统计分析,并初步探讨造成过岛台风极端降水差异的成因。研究表明:九成过岛台风会给东南沿海地区带来暴雨影响,年均有1.6次过岛台风暴雨事件发生。过岛台风日最大降水量的年际变化有明显增强趋势,特别是自2003年以来暴雨极端事件呈现明显增多增强现象。不同量级日暴雨发生的频次月变化均表现为单峰型,7—9月为高峰季。过岛台风过程日最大降水不同量级发生的频次表明,东南沿海100 mm以上强降水频次随着降水强度的增加而减少,300 mm以上强降水频次明显减少。空间分布上,东南沿海日暴雨频次呈现由沿海向内陆不均匀快速递减特征。过岛台风暴雨对福建北部沿海地区的影响最为突出,其中福建的柘荣站是暴雨极值中心。利用NCEP再分析资料对两组相似台风引发极端降水差异的大尺度环境对比显示:强降水组的台风中心北侧大风速区导致向岸风较大,在山脉地形作用下,山前具有更强的辐合及深厚的强垂直上升运动,配合更有利的水汽条件,将低空高能高湿水汽送至中高层,降水动力和水汽条件均明显强于弱降水组的台风,从而造成更强的台风暴雨。

台湾以北海域浮游桡足类生物海洋学特征的研究Ⅱ.群落特征

在对台湾以北海域浮游桡足类生物海洋学特征进行数量分布方面的研究后的续篇，重点对本海区浮游挠足类的群落结构和群落性质以及与栖区环境条件间的关系作了分析探讨．结果表明，本区桡足类群落结构种类组成复杂，出现种类共２３７种，但周年共有种比例仅占３２％．桡足类群落的多样度和均匀度年均值各为３．７１４和０．６９０，在平面分布上呈外部海区高于近岸海区的大体趋势．本区群落可划分为５个生态类群，其中暖水性外海高温偏低盐类群和热带大洋高温高盐类群可分别指示台湾海峡水和黑潮表层水的季节消长过程．从不同侧面的计算分析均表明，冬季在环境条件上均有异于其他３季．在春、夏、秋季，以普通波水蚤最具优势，盐度是影响群落特征值的主导因子，群落的性质是以暖水性外海种类为主、热带大洋种也占相当比例的亚热带－热带群落结构的特点；在冬季，主要优势种是海洋真刺水蚤，温度是群落特征值的主要制约因子，群落呈现以热带大洋种占支配地位的热带大洋群落结构属性．

海南和台湾蕨类植物多样性及其大陆性特征

海南和台湾是我国南部和东部两个最重要的大陆性岛屿 ,具有极为丰富的蕨类植物多样性 .特有现象揭示着植物区系和植物多样性的历史 ,间断分布揭示着与邻近或相关植物区系的联系 ;特别是在岛屿地区 ,这种现象和意义尤其明显 .海南有蕨类植物区系 5 5科、1 35属、4 6 6种 ,其中特有种有 32种 ,台湾蕨类植物区系 5 7科、1 4 2属、5 99种 ,其中特有种达 6 6种 .在海南与台湾两地 ,有共有属 1 0 4属 ,共有种仅有 1 76种 .台湾海峡出现始于晚白垩世 ,持续至第四纪 ;琼州海峡出现于早第四纪 ,因此 ,两地的特有现象远少于种子植物 台湾有 80 1种 ,海南有 5 0 1种 ,原因与蕨类植物具有更广的散布性相关 ,而且在被子植物中起重要作用的物种生物学障碍 机制 在蕨类是缺乏的 ;形态学的、生殖生物学特征导致蕨类植物具有较缓慢的物种演化历史和较低的灭绝率 Smith,1 972 .海南和台湾蕨类植物区系的比较还表明 。

台湾岛以南海域新近纪的弧—陆碰撞造山作用

台湾岛以南海域(台南滨海)弧—陆碰撞带位于欧亚板块、菲律宾海板块和南海的结合部位,是新近纪弧—陆碰撞研究的理想场所。本文通过对南海973航次在该区域的多道地震剖面的解释,认为台南滨海弧—陆碰撞带增生的火山—沉积楔由恒春海脊和高屏斜坡两部分组成,前者是菲律宾海板块的增生楔,后者是欧亚板块的增生楔,在增生楔体和火山弧之间是作为弧前盆地的北吕宋海槽。自中新世中期以来,南海洋壳开始沿着马尼拉海沟向菲律宾海板块俯冲,形成活动大陆边缘的增生部分———恒春海脊;与此同时菲律宾海板块开始向北西方向移动,前缘的吕宋岛弧距今6.5Ma以来朝着亚洲陆缘斜向汇聚,形成了被动大陆边缘的增生部分———高屏斜坡。由于菲律宾海板块和欧亚板块之间的斜向汇聚,弧—陆碰撞具有穿时性,造山作用首先发生在台湾岛的北部,然后向南部及台南滨海发展。