Sea surface temperature record from the north of the East China Sea since late Holocene

Using the alkenone paleotemperature index U37^k, a high-resolution sea surface temperature （SST） record since 3600 a BP was reconstructed from the mud area in the north of the East China Sea. Combining with the grain size distribution curve of sensitive grain size group, which may reflect the East Asia Winter Monsoon activity, the palaeoenvironmental evolution cycle throughout the late Holocene in the area was obtained. The marine environment evolution during the last 3600 years displays a five-stage trend. （1） Temperature descending period from 0.85 cal. ka BP to present. The maximum temperature decrease amplitude is 2℃. The winter monsoon intensified and ＇Little Ice Age＇ were recorded in this period. （2） Warming period from 1.90 to 0.85 cal. ka BP. The mean temperature increase amplitude is 0.8℃. The Sui-Tang warming period was recorded at about 0.85--1.35 cal. ka BP and a prominent cooling event was recorded at 1.4 cal. ka BP in this period. （3） Temperature descending period from 2.55 to 1.90 cal. ka BP. Temperature cooling amplitude is 0.9℃. This period is coincident with an integrated temperature circle recorded in the Antarctic ice core, with the temperature changes from a slow cooling stage to a rapid warming stage. （4） Temperature comparatively stable with a little ascending period from 3.2 to 2.55 cal. ka BP. Temperature warming amplitude is 0.3℃. This period is coincident with the temperature fluctuant ascending period recorded in Antarctic ice core. （5） Temperature comparatively stable with little descending period from 3.6 to 3.2 cal. ka BP. This period corresponds with the temperature fluctuant cooling period recorded in Antarctic ice core. Basically, those five periods were coincident with the Antarctic ice core record. During the global cooling stage, the SST change in the continental shelf sea can be adjusted simultaneously.     

基于耦合气候系统模式的中全新世黄、东海海表通量分析

对中全新世(6,ka时期)海洋和气候的研究可加深人们对现阶段气候变化和海洋环境的认识,为预测未来海洋与气候环境变化提供一个重要参照.文章分析一个耦合气候系统模式FGOALS-s2.0的模式结果,首先对其工业革命前(0,ka时期)东亚地区夏季降水及冬、夏季10,m风场的模拟结果进行评估,然后进一步对中全新世和工业革命前黄、东海海表大气强迫的季节变化进行了对比.结果显示:模式模拟出0,ka时期东亚夏季降水从东南洋面至西北内陆减少的空间分布特点,冬、夏季10,m风场亦与观测大体一致;6,ka时期夏季,黄、东海风速较0,ka时期增大约0.8,m/s,16%左右;黄海风应力旋度值为正,东海为负,与0,ka时期相比旋度绝对值均增大;同时,两海区接收的太阳短波辐射较0,ka时期均增加,短波辐射的差异是中全新世夏季黄、东海海表的净热吸收增加的主要因子.6,ka时期冬季,黄、东海北风加强,东海增加量在0.5~1.0,m/s,幅度约为10%,较黄海更为明显;两海区在冬季的净热释放也较0,ka时期增大,东海释放更甚;冬季黄、东海风应力旋度较0,ka时期则无太大差别.研究表明,由于6,ka时期太阳辐射季节循环的改变,造成了黄、东海夏季风增强,海表净热通量也发生相应变化,该时期大气强迫场的变化可能会使黄、东海表层水温分布趋势发生较大改变,进而影响陆架环流格局.     

黄、东海沿岸海表温度变化与厄尔尼诺的关系

利用黄、东海沿岸8个长期水文观测站多年海表温度资料,分析黄、东海沿岸海表温度的季节和年际变化特征,重点分析在1982—1983年和1997—1998年两次厄尔尼诺年期间的异常变化,以及ENSO影响黄、东海沿岸海表温度的可能机制。结果表明,在厄尔尼诺发生年,夏季风较弱,鄂霍次克海高压加强,西太平洋副高位置偏南,强度偏强,江淮流域及长江中下游降水偏多,黄、东海沿岸海表温度偏低。黄、东海沿岸海表温度受到ENSO和PDO(太平洋年代际振荡)的影响和调制,在厄尔尼诺发生的前冬半年及当年,黄、东海沿岸海表温度偏低;在厄尔尼诺发生次年,黄、东海沿岸海表温度偏高。厄尔尼诺对黄、东海沿岸海表温度变化的影响通过海洋和大气2个通道,1982—1983年海表温度异常以负异常为主,1997—1998年海表温度异常以正异常为主;ENSO期间,北赤道流减弱,黑潮流量减少,海表温度降低。海表温度受局地气温影响显著,如果ENSO期间东亚气温升高,则黄、东海沿岸海表温度偏高。     

Abrupt variations of the radiolarian fauna at Mid-Pleistocene climate transition in the South China Sea

Based on a detailed study of the radiolarian fauna, the abundance pattern of planktic foraminifera as well as on isotope and sedimentological records, the Mid-Pleistocene climate transition as a multiple transition phenomenon could be recognized at Core 17957-2 from the South China Sea. Distinct changes in the radiolarian/foraminfera ratio, the coarse fraction and the radiolarian assemblages can be related to the global climate cooling observed at the Mid-Pleistocene revolution (MPR) around 900 ka. A pronounced southward shift of the North Equatorial Current that leads to lower sea-surface temperatures in the South China Sea is documented by the shift of tropical to subtropical radiolarian assemblages at 900 ka. Increasing radiolarian abundance after the MPR can be interpreted as a result of stronger upwelling and nutrient supply. These abrupt variations could result from the northern trade wind system and East Asian monsoon circulation.     

气候变化背景下渤黄海海温时空特征分析

【目的】研究渤黄海海温时空变化特征及其与全球海温的关系。【方法】采用相关分析、小波分析等方法,对1985—2015年渤黄海海洋站的海温观测资料进行分析。【结果】渤海是中国内海,沿岸海温受陆地影响显著,变化幅度大,对气温响应快;黄海作为太平洋的边缘海,与外海水体交换通畅,水温变化幅度相对较小,水温变化与渤海相比具有一定的滞后性;各站海温变化周期特征不尽相同,但在2000年以后各站均有较为明显的8年周期;渤黄海海温与全球大部分海域一致,近30年呈现上升趋势,但上升速率与同纬度太平洋和大西洋相比较低,黄海海温上升速率高于渤海。【结论】渤黄海海温具有明显的月际、年际和周期变化特征,受海陆分布等因素影响渤黄海海温对气候变暖的响应低于同纬度太平洋和大西洋。     

Late Holocene paleoenvironmental changes in the southern Okinawa Trough inferred from a diatom record

We analyzed sediment diatoms from core MD05-2908 to infer climate and paleoenvironmental changes in the southern Okinawa Trough (SOT) over the past 1000 years.Because the study area is located in the East Asia monsoon area and beneath the main axis of Kuroshio Current,the climatic and hydrographical conditions are strongly influenced by both of these factors.The species used as environmental indicators,including the Kuroshio Current species (KC species) and freshwater species,were investigated in this paper.Changes in the abundance of the two groups of species revealed significant variations in water temperature and hydrography in the SOT during the Medieval Warm Period (MWP) and the Little Ice Age (LIA).From 950-1500 AD,the abundance of the KC species increased fluctuantly,while the freshwater species decreased,showing that the influence of the Kuroshio Current was intensified at that interval and the precipitation of the study area was relatively low.The KC species decreased remarkably and was maintained at a low abundance during the interval of 1500-1900 AD,which suggests that the impact of the Kuroshio Current on the SOT weakened during the period corresponding to the LIA.Moreover,the high abundance of the freshwater species at the same interval indicates a distinct increase in precipitation in northeastern Taiwan,which may be correlated to the south-detention of the rainfall belt in China caused by the southward migration of the western Pacific subtropical high.     

Records of the East Asian winter monsoon from the mud area on the inner shelf of the East China Sea since the mid-Holocene

AMS¹⁴C dating and analysis of grain size, major elements and clay minerals were applied to Core MZ01 from the mud area on the inner shelf of the East China Sea. Based on the environmentally sensitive grain size, clay mineral and major element assemblages, the history of the East Asia winter monsoon since the mid-Holocene could be reconstructed. These three proxies, mean grain size (>9.71 μm), chemical index of alteration (CIA) and ratio of smectite to kaolinite in particular, show similar fluctuation patterns. Furthermore, 10 extreme values corresponding to the contemporary cooling events could be recognized since the mid-Holocene; these extreme values are likely to have been caused by the strengthening of the East Asia winter monsoon. The cooling events correlated well with the results of the δ¹⁸O curves of the Dunde ice core and GISP2, which therefore revealed a regional response to global climate change. Four stages of the East Asia winter monsoon were identified, i.e. 8300–6300 a BP, strong and unstable; 6300–3800 a BP, strong but stable; 3800–1400 a BP, weak and unstable; after 1400 a BP, weak but stable.     

东海黄海渤海8个主要分潮的数值模拟

应用球面坐标系下ECOM数值模式,数值模拟了东海黄海渤海的8个主要分潮M₂、S₂、N₂、K₂、K₁、O₁、P₁和Q₁.采用高分辨率网格,计算区域包括东海黄海渤海、东海陆架坡和琉球以东西北太平洋,考虑实际水深和岸线.开边界条件由全球大洋潮汐模式计算的调和常数给出.较成功地模拟出了8个分潮的传播特征,再现了计算区域内半日分潮的5个无潮点和2个蜕化的半个无潮点、全日分潮的3个无潮点.与65个潮位站的观测资料比较,模式计算的M₂、S₂、K1和O₁分潮振幅和位相的均方差分别为7.85 cm和6.81°,5.04cm和8.14°,3.82cm和13.04°,4.34cm和9.33°.与17个潮位站的观测资料比较,N₂、K₂、P₁和Q₁分潮振幅和位相的均方差分别为3.64cm和7.89°,8.47cm和10.51°,1.76cm和7.56°,1.50cm和26.34°.模式模拟的结果可为河口海岸小区域模式提供较为可靠的外海开边界潮汐调和常数资料.     

西北太平洋环流和海温数值模拟

基于Ecom-si建立了一个西北太平洋海洋数值模式,综合考虑了侧边界通量、海表面风应力、热通量、蒸发和降水等因素,模拟并分析了西北太平洋环流和海温的基本特征.模式验证结果表明,模式计算的海温与日本2008年西北太平洋实测温度走航断面资料吻合良好.模式再现了低纬度海区表层自东向西流动的北赤道流、强西边界流黑潮、东海的台湾...     

黄东海多毛类动物种类组成与优势种分析

【目的】探明黄东海区域多毛类Polychaeta物种组成状况。【方法】用0.1 m2 Gray-O’Hara箱式采泥器重复采样2次,对获得的多毛类样品进行准确的分类鉴定,采用优势度计算公式:Y=(ni/N)fi统计得出优势种并分析其空间分布状况。【结果】本次调查黄东海共鉴定出多毛类32个科90种,优势种为背蚓虫Notomastus latericeus Sars,1857和掌鳃索沙蚕Ninoe palmata Moore,1903,其分布没有表现出明显的规律性。【结论】黄东海多毛类种类丰富,优势种随时间变化而改变,而分类学研究应引起重视。     

Southwest monsoon changes indicated by oxygen isotope of ostracode shells from sediments in Qinghai Lake since the late Glacial

The δ 18O records of ostracode shells in sediments of core QH-2000 from Qinghai Lake can be used as a better proxy to reflect monsoon changes. Low monsoon precipitation between 17.5 and 11 cal. ka BP is indicated by positive δ 18O values averaging 2.37‰. A fast shift in δ 18O from positive at 11 cal. ka BP to negative at 10 cal. ka BP indicates sharp increase of monsoon precipitation. An interval of generally high monsoon precipitation is observed between 10 and 6 cal. ka BP with δ 18O values averaging -2.15‰. Decrease of monsoon precipitation between 6 and 2.5 cal. ka BP is indicated by positive δ 18O values. δ 18O keeps positive values averaging 3.0‰ between 2.5 and 0 cal. ka BP suggesting low high monsoon precipitation. The climatic changes indicated by δ 18O records of ostracode shells in sedi- ments of core QH-2000 from Qinghai Lake and our broader regional comparison show that the climate in Qinghai Lake since the late Glacial is probably controlled by southwest monsoon other than southeast monsoon.     

Stalagmite-inferred Holocene precipitation in northern Guizhou Province,China, and asynchronous termination of the Climatic Optimum in the Asian monsoon territory

An absolute-dated, bi-decadal-resolution, stalagmite oxygen-isotopic time series from Shigao Cave reveals the evolution of summer monsoon precipitation over the past 9.9 ka BP in northern Guizhou Province, Southwest China. The  18O-inferred climate conditions are divisible into three distinct stages: (1) a maximum humid era from 9.9-6.6 ka BP; (2) a gradual declining precipitation interval between 6.6-1.6 ka BP; and (3) a relatively low precipitation time window after 1.6 ka BP. Consistency of contemporaneous stalagmite Holocene 18O records between Shigao and other caves in the Indian and East Asian monsoon realms support the effect of primary orbital solar forcings on monsoonal precipitation. However, statistical analysis shows a significant spatial asynchroneity of the Holocene Optimum termination in the Asian monsoon territory. The Holocene Optimum ended at 7.2-7.4 ka BP in Oman, located in the Indian monsoon region, and at 5.6-5.8 ka BP in Central China, in the East Asian monsoon zone. In Southwest China, the termination occurred between these periods, at 6.6-7.0 ka BP, and was influenced by both monsoon systems. We propose that this spatially asynchronous ending of Holocene Optimum in Asia may be attributed to sea surface temperature changes in the western tropical Pacific, which is a primary moisture source for the East Asian monsoon.     

南黄海大型底栖动物群落划分及变化

【目的】深入了解南黄海大型底栖动物群落结构,为南黄海生态环境保护提供科学依据。【方法】根据2012年6月、8月和10月3个航次南黄海大型底栖动物的调查资料,采用聚类分析(Cluster analysis,CLUSTER)、非参数多维标度排序(Non-metric multi-dimensional scaling,nMDS)、单因素相似性分析(One-way analysis of similarity,One-way ANOSIM)以及相似性百分比分析(Similarity percentages,SIMPER)对数据资料进行分析。【结果】CLUSTER和nMDS排序发现在20%的相似性水平上,不同月份的大型底栖动物可划分为4~5个群落。One-way ANOSIM分析表明南黄海大型底栖动物群落结构的月份间差异显著。SIMPER分析表明不同群落的贡献种不同,黄海冷水团群落贡献种为棘皮动物和软体动物,其他群落的贡献种以多毛类动物居多。【结论】通过与历史资料对比,发现南黄海大型底栖动物群落在过去半个世纪发生了重大变化,但仍主要以黄海冷水团群落、混合群落和广温性群落为主。棘皮动物浅水萨氏真蛇尾(Ophiura sarsii vadicola)取代软体动物和甲壳动物,成为黄海冷水团群落最主要的优势类群,多毛类动物取代棘皮动物和软体动物,成为混合群落和广温性群落的主要优势类群。     

Changes in sea surface temperature in western South China Sea over the past 450 ka

Sea surface temperature over the past 450 ka was obtained by the unsaturation of molecular fossil-long chain alkenone with a resolution of about 1 ka from the western South China Sea. This is the longest temperature profile in the South China Sea at such high resolution. The U37^κ-SST results revealed similar glacial-interglacial cycles as the δ^18O profile of planktonic foraminifera, with SST variability of 23-25.5℃ for glacial and 25-28℃ for interglacial periods. The highest SST （28.4℃） was recorded at MIS5.5 and lowest SST （22.6℃） during MIS2. The SST record preceded the planktonic foraminiferal δ^18O on five glacial-interglacial transitions. Comparison of temperature records from the Southern and Northern Hemispheres indicated a more Southern Hemisphere-like pattern for the temperature variation in the SCS. Strong precession and semiprecession signals in the spectra of our SST record manifest the tropical phenomena.     

Sea surface temperature and subtropical front movement in the South Tasman Sea during the last 800 ka

Southern Hemisphere mid-latitude westerlies contribute to the ventilation of the deep Southern Ocean (SO), and drive changes in atmospheric carbon dioxide (CO₂) and the global climate. As the westerlies control directly oceanic fronts, the movement of the subtropical front (STF) reflects the westerlies migration. Thus it is important to understand the relationships between STF movement and the weaterlies, ventilation of the deep SO, ice volume and atmospheric CO₂. To this end, we use two new high-resolution records from early Marine Isotope Stage (MIS) 20 (~800 ka) of sea surface temperature (SST) based on Uk’ 37 paleo-thermometer and benthic oxygen isotope (δ¹⁸OB) at Ocean Drilling Program (ODP) Site 1170B in the southern Tasman Sea (STS), to construct linkages between the marine records and atmospheric proxies from Antarctic ice-cores. During the last 800 ka, the average SST (10.2°C) at Site 1170B is 1.8°C lower than today (annual average 12°C). The highest average SST of 11.6°C occurred during MIS 1, and the lowest average SST of 7.8°C occurred during MIS 2. The warmest and coldest records of 14.7°C and 6.2°C occurred in the MIS 5 and MIS 2, respectively. In the glacial-interglacial cycles of the last 800 ka, variability of reconstructed SST shows that the STF moved northward or southward more than 3° of latitude compared with its present location. In the warmest stage MIS 5, the STF shifted to its southernmost location of ~49°S. In contrast, in the coldest stage MIS 2, the STF moved to its northernmost location of ~43°S. In response to orbital cycles, the westerlies movement led ice volume and atmospheric CO₂ changes, but it was in phase with change in Antarctic atmospheric temperature. Ice volume only preceded atmospheric CO₂ only a little at the 23-ka precession band, lagged the atmospheric CO₂ at the 100-ka eccentricity band, and was in phase with atmospheric CO₂ at the 40-ka obliquity band.     

Paleoproductivity variations in the southern Okinawa Trough since the middle Holocene: Calcareous nannofossil records

Based on 17 AMS 14 C age data,we reconstructed high-resolution records of sea surface primary productivity(PP) in the southern Okinawa Trough(MD05-2908) over the last 6.8 ka BP using the calcareous nannofossil carbon isotope and the relative percentage contents of Florisphaera profunda indexes.The underlying mechanism controlling the sea surface PP was then discussed.The sea surface PP,indicated by the coccolith δ 13 C and %Fp conversional equations,decreased with some fluctuations since 6.8 ka BP.This decrease may be connected to the decreased terrigenous input resulting from the reduced East Asian Summer Monsoon(EASM) precipitation.Both the periods of 4-2 ka BP(PME) and 6.8-4.8 ka BP were characterized by relatively higher PP.The former was mainly controlled by the weakening of the Kuroshio Current,whereas the latter mainly resulted from the greater terrigenous input associated with the stronger EASM.     

Deep sea pollen record during 12－1.6 Ma from the southern South China Sea and its response to envi-ronmental change

Based on deep-sea pollen results (512-76 m) from ODP Site 1143 in the southern South China Sea (SCS),the climate and vegetation evolution sequence on the surrounding islands and the exposed continental shelf are discussed. The pollen records show that the pollen influx was quite low before 8.15 Ma and increased dramatically afterwards. The influx changes can be ascribed,on one side,to tectonics deformations around the southern SCS resulting in rapid uplift of islands and subsequent increase of the sediment rates and pollen influx and on the other side to climate cooling and monsoon enhancement. Around 2.63 Ma was another obvious boundary,the increasing of pollen and spores influx since this time was mainly related to global climate cooling. Spectrum analysis of pollen influx values shows that 2 Ma,0.67 Ma,and 0.19-0.17 Ma cycles existed during 12-3.0 Ma,while 0.1 Ma and 46.9 ka cycles existed during 3.0-2.0 Ma.     

高性能防腐混凝土在黄海大桥项目中的应用

介绍了黄海大桥混凝土结构布置和耐久性设计背景,论述了提高耐久性的技术措施,研究了黄海大桥混凝土的性能。     

Multi-core structure of the main part of the Kuroshio at G-PN section in the East China Sea

Off the east of Taiwan Island the Kuroshio strides over the Ilan Ridge and flows into the East China Sea, where it encounters the continental break. The Ku-roshio then turns right and flows along the Okinawa Trough, where its main axis does not show obvious swaying. This stream continuously flows eastwards in the southwest of Kyushu, and feeds into sea in the south of Japan. This section of the Kuroshio is named“the East China Sea Kuroshio”. Along the East China Sea Kuroshio, there …     

Geological records of marine environmental changes in the southern Okinawa Trough

Indexes of sediment grain size,sedimentation rates,geochemical composition,heavy,minerals,benthic foraminiferal fauna,indicator species of the Kuroshio Current,paleo-SST and carbonate dissolution of core E017 conformably suggest a great marine environmental change occurring at about 10.1-9.2cal.kaBP in the southern Okinawa Trough,which may correspond to the strengthening of the Kuroshio Warm Current and re-entering the Okinawa Trough through the sea area off northeast Taiwan.The invasion of Kuroshio current has experienced a process of gradual strengthening and then weakening,and its intensity became more fluctuation during the last 5000 years.Compared to the transition of sediment grain size,geochemical composition and heavy minerals,the foraminiferal faunas show a 900-year lag,which may indicate that the invasion of Kuroshio Current and the consequent sea surface and deep-water environmental chanages is a gradual process,and fauna has an obvious lag compared to environment altering.The carbonate dissolution of the Okinawa Trough has had an apparent strengthening since 9.2cal.kaBP,and reached a maximum in the late 3000 years,which may be caued by the deep-water environmental changes due to the invasion of Kuroshio Current.