台风“利奇马”对东中国海表层悬浮物浓度变化的影响

台风过程可使海洋悬浮物浓度的分布在短时间内发生极大变化,并影响海洋生态环境以及海洋资源的分布。受台风期间海洋观测数据的限制,台风过程对海洋悬浮物浓度的影响尚不明确。本文利用GOCI （Geostationary Ocean Color Imager,GOCI）卫星遥感数据,以2019年8月台风“利奇马”为例,对其过境前后东中国海表层悬浮物浓度的时空变化进行了定量研究。结果表明,台风“利奇马”对闽浙沿岸的影响程度最大,使悬浮物质量浓度中高值（≥5 mg/L）覆盖面积和浓度平均值分别增大92%和62%,影响持续时间为4 d;对长江口附近海域的影响程度次之,使悬浮物浓度中高值覆盖面积和浓度平均值分别增大19%和17%,影响持续时间为3 d;对苏北浅滩的影响程度最小,悬浮物质量浓度中高值覆盖面积变化不大,但浓度平均值增大了30%,影响持续时间为4 d。研究结果表明卫星遥感数据可以量化台风过程对东中国海表层悬浮物浓度的影响,弥补极端天气条件下无法进行现场观测的不足。     

Characteristics and origins of middle Miocene mounds and channels in the northern South China Sea

Numerous elongated mounds and channels were found at the top of the middle Miocene strata using 2D/3D seismic data in the Liwan Sag of Zhujiang River Mouth Basin(ZRMB) and the Beijiao Sag of Qiongdongnan Basin(QDNB). They occur at intervals and are rarely revealed by drilling wells in the deepwater areas. Origins of the mounds and channels are controversial and poorly understood. Based on an integrated analysis of the seismic attribute, palaeotectonics and palaeogeography, and drilling well enco...     

Delving into three-dimensional structure of the West Luzon Eddy in a regional ocean model

The three-dimensional structure and associated dynamics of the prominent cold (cyclonic) West Luzon Eddy (WLE) were investigated by a high-resolution regional ocean model. The WLE was horizontally and vertically heterogeneous, exhibiting asymmetric structures in the circulation, vorticity, vertical motion and energy distributions within the eddy. The asymmetry was mainly attributed to the existence of an eddy dipole formed by a coexisting warm (anti-cyclonic) eddy to the south of the WLE. Analysis of the momentum balance revealed that the coexistence of two eddies intensified barotropic pressure gradients in the southern WLE to locally enhance the eastward jet. The positive (negative) vorticity of the jet strengthened (weakened) the eddy in the southern sector (periphery), which, together with the formation of a subsurface density front, intensified (suppressed) the corresponding upward motion and cooling. The baroclinic pressure gradients opposed the dominant barotropic components and spun down the eddy at greater depths with stronger weakening in the southern sector near the front. Asymmetric energy distributions showed that larger mean kinetic energy (MKE) and eddy available potential energy (EAPE) were stored in the southern sector of the WLE. While the larger MKE was directly linked with the stronger barotropic currents, the larger EAPE in the southern WLE was formed by baroclinic energy conversions due to a strong density gradient at the front.     

Taiwan and China: A unique fisheries relationship

Taiwan and China have a long history of sharing marine resources in the China Seas. However, due to political issues, the two sides have yet to formalize collaboration and interaction despite such a close geographical relationship. The lack of formal collaboration means they cannot manage fisheries or conserve resources as a team. The lack of collaboration in the regional fisheries management organizations also means a mutually beneficial situation for the two sides is yet to be achieved. Recognizing this, the two sides began negotiations in 2008 and have since signed agreements on fisheries co-operation projects. This paper discusses the unique fisheries relationship between Taiwan and China, and the characteristics of their fishing industries. The paper also presents the latest update on the collaboration between the two sides. Finally, this paper proposes practical solutions for resolving outstanding issues between the two sides’ fishing industries.     

东海太平洋褶柔鱼角质颚的形态学分析

依据2010年9月及2011年5月、9月东海渔业资源底拖网调查采集的139尾(雌性66尾,雄性73尾)太平洋褶柔鱼(Todarodes pacificus)样本的胴长、体重和角质颚各部分的长度数据,分析了东海太平洋褶柔鱼角质颚的形态学特征。结果表明:(1)太平洋褶柔鱼角质颚上、下颚的喙长(RL)、头盖长(HL)、脊突长(CL)、翼长(WL)、翼宽(WW)等长度差异较大;(2)伴随RL的增长,HL、CL、WL、WW呈现极显著的异速生长特征(P<0.001);(3)各长度指标随胴长、体重的增长呈显著的线性增长趋势;(4)RL/CL、HL/CL的比值非常稳定,随胴长、体重的变化很小,可作为东海太平洋褶柔鱼角质颚形态特征的稳定指标。     

南海海面高度变化及其与太平洋上涛动信号的关系

本文使用循环平稳经验正交函数(CSEOF)方法分析了南海海面高度(SCS-SSH)的时空变化模态,并对它们与太平洋海盆尺度振荡的关系进行了探讨分析。结果表明,SCS-SSH的第一个CSEOF模态是季节变化模态,其变化强度受到一个与厄尔尼诺-南方涛动(ENSO)有关的低频信号的调制,即在厄尔尼诺期间季节变化的幅度减弱(最大可降低30%,1997/98)而在拉尼娜期间季节变化增强。SCS-SSH的第二个CSEOF模态是年际-年代际尺度的低频变化模态,其空间模态的月与月之间的差异微弱,而时间模态和太平洋年代际振荡(PDO)指数高度相关。然后,我们使用独立成分分析(ICA)方法提取了太平洋中的五个主要振荡成分,并检验了它们对SCS-SSH变化的各自影响。分析表明,纯粹的ENSO模态(类似于太平洋东部型ENSO)对SCS-SSH的低频变化的影响比较微弱,而ENSO的红化模态(类似于太平洋中部型ENSO)对SCS-SSH的低频变化具有明显影响。由于ENSO的红化模态是PDO信号的一个主要成分,这一结果解释了为什么在影响SCS-SSH的低频变化上PDO比ENSO更重要。径向鞍型振荡模态、黑潮延伸体处的增温模态、以及赤道的降温模态也由ICA方法提取出来,但它们对SCS-SSH低频变异的影响微弱。进一步的分析表明,太平洋的涛动信号可能以不同的方式来影响南海海面高度变化和海表温度变化。     

Last glacial terrestrial vegetation record of leaf wax n-alkanols in the northern South China Sea: Contrast to scenarios from long-chain n-alkanes

Long-chain n-alkanols and n-alkanes in core sediments from the northern South China Sea (SCS) were measured to make a comparison during terrestrial vegetation reconstruction from ~42 ka to ~7 ka. The results showed that terrestrial vegetation record from long-chain n-alkanes matched well with previous studies in nearby cores, showing that more C₄ plants developed during the Last Glacial Maximum (LGM) and C₃ plants dominated in the interglacial period. However, these scenarios were not revealed by terrestrial vegetation reconstruction using long-chain n-alkanols, which showed C₃ plant expansion during the LGM. The discrepancy during the interglacial period could be attributed to the aerobic degradation of functionalized long-chain n-alkanols in the oxygen-rich bottom water, resulting in poor preservation of terrestrial vegetation signals. On the other hand, the different advantages of functionalized n-alkanols and non-functional n-alkanes to record local and distal vegetation signals, respectively, may offer a potential explanation for the contradiction during the LGM when the SCS was characterized by low-oxygen deep water. Nevertheless, large variations on n-alkyl lipid compositions in C₃/C₄ plants could play a part in modulating sedimentary long-chain n-alkanols and n-alkanes toward different vegetation signals, thereby suggesting that caution must be taken in respect to the terrestrial vegetation reconstruction using long-chain n-alkanes and long-chain n-alkanols.     

南海北部海域表层沉积物底栖有孔虫分布特征及影响因素

有孔虫在海洋环境指示方面具有重要意义,对现代环境中有孔虫的分布及影响因素进行研究有助于利用有孔虫对地质历史时期的沉积环境进行还原。我国南海海域辽阔,南海有孔虫的相关研究很早便有报道。对我国南海北部海域表层沉积物中的底栖有孔虫分布特征进行了描述,研究区以玻璃质壳底栖有孔虫占主导,胶结壳其次,瓷质壳最少。根据底栖有孔虫的分布特征划分了4个底栖有孔虫组合,组合1为Heterolepa subpraecincta - Hanzawaia mantaensis - Rotalinoides gaimardii;组合2为Bulimina marginate - Lagena substriata;组合3为Elphidium advenum - Pararotalia nipponica;组合4 为Recurvoides contortus - Ammodisus cretaceous - Bulimina aculeata。对影响该区域底栖有孔虫分布的环境因素进行了探究,结果表明,温度、盐度、底质类型等对底栖有孔虫的分布均存在一定程度的影响,海流对研究区底栖有孔虫时空分布的影响值得进一步探究。     

Vertical characteristics revealed by biweekly and synoptic variability of upper sea temperature in the northern South China Sea

On the basis of the analysis of the sea temperature data that are observed from the three automatic temperature line acquisition sysem mooring buoys deployed in the central South China Sea (SCS) during South China Sea monsoon experiment, vertical features of biweekly and synoptic variability are discussed. There are five vertical modes, that is, subsurface temperature variability is in phase with,out of phase with, leads to, lags the surface temperature variability, and at depths within the subsurface layer the upper and lower temperature variations are out of phase. The formation of these vertical modes is related to the property of low-level atmospheric forcing and to the background in atmosphere and ocean. Wind stress curl is the main driving factor in forming Modes 1 and 3, and wind stresses in forming Modes 2 and 4.