Meltwater input to the southern ocean during the last glacial maximum

Three records of oxygen isotopes in biogenic silica from deep-sea sediment cores from the Atlantic and Indian sectors of the Southern Ocean reveal the presence of isotopically depleted diatomaceous opal in sediment from the last glacial maximum. This depletion is attributed to the presence of lids of meltwater that mixed with surface water along certain trajectories in the Southern Ocean. An increase in the drainage from Antarctica or extensive northward transport of icebergs are among the main mechanisms that could have produced the increase in meltwater input to the glacial Southern Ocean. Similar isotopic trends were observed in older climatic cycles at the same cores.     

The Indian Ocean experiment: widespread air pollution from South and Southeast Asia

The Indian Ocean Experiment (INDOEX) was an international, multiplatform field campaign to measure long-range transport of air pollution from South and Southeast Asia toward the Indian Ocean during the dry monsoon season in January to March 1999. Surprisingly high pollution levels were observed over the entire northern Indian Ocean toward the Intertropical Convergence Zone at about 6 degrees S. We show that agricultural burning and especially biofuel use enhance carbon monoxide concentrations. Fossil fuel combustion and biomass burning cause a high aerosol loading. The growing pollution in this region gives rise to extensive air quality degradation with local, regional, and global implications, including a reduction of the oxidizing power of the atmosphere.     

Zonal temperature-anomaly maps of Indian ocean surface waters: modern and ice-age patterns

Maps of sea surface temperature anomalies in the Indian Ocean in modern and ice-age times reveal striking changes in its surface circulation. During the last glacial maximum (18,000 years before the present), the Indian Ocean had colder average zonal surface temperatures, a cooler and less extensive Agulhas Current, a distinct eastern boundary current, and decreased upwelling and a weaker southwest monsoon in its northwestern region.     

Ecologic and Paleoclimatic Implications of Morphologic Variation of Orbulina universa in the Indian Ocean

Multivariate cluster analysis of various morphologic indices of Orbulina universa populations from the Indian Ocean indicate the existence of two major groups whose geographic distribution corresponds to the equatorial and central water masses. An abrupt change in shell porosity between populations of this planktonic foraminiferal species in plankton as well as sediment samples occurs within or near the 10 degrees S Hydrochemical Front. Orbulina universa is an excellent indicator of oceanographic conditions in the Indian Ocean today, and may be used as an independent check on shifts in water masses during the last glaciation.     

基于Cytb基因的东印度洋鸢乌贼系统发育关系和种群遗传结构

通过测定东印度洋北部、赤道、南部3个鸢乌贼（Sthenoteuthis oualaniensis）群体的线粒体DNA细胞色素b（Cytb）基因序列,分析了东印度洋鸢乌贼的系统发育关系。研究表明,东印度洋鸢乌贼整体具有高单倍型多样性（h=0.939）和高核苷酸多样性（π=0.015）。3个鸢乌贼群体间的F_st值为0.661,群体间遗传分化水平很高,具有明显的遗传分化现象,可分为以东印度洋北部群体为主的谱系1（东印度洋北部谱系）和主要由东印度洋赤道与南部群体组成的谱系2（东印度洋南部谱系）,且谱系2经历过群体扩张。东印度洋巨大的南北水文差异可能是鸢乌贼产生南北谱系分化的原因,在东印度洋鸢乌贼资源的利用和管理方面应考虑南北谱系的差异和特点。     

南海—北印度洋SST变化趋势及周期分析

利用来自NOAA的SST（海袁温度）资料,计算了近半个世纪以来（1950～2009年）南海—北印度洋SST的整体变化特征,主要计算了整体变化趋势、变化趋势的区域性差异、季节性差异、变化周期.结果表明,近半个世纪以来,南海—北印度洋大部分海域的SST表现出显著的逐年线性递增趋势,其中北印度洋的递增趋势强于南海,印度洋赤道中东部海域的递增趋势尤为明显,可达0.014℃/a以上;南海—北印度洋海域的SST以0.011 5℃/a的速度显著性逐年线性递增,在夏季的递增趋势强于冬季,冬季和夏季分别以0.010 6、0.012 2℃/a的速度显著性逐年线性递增;该海域的SST具有显著的2.4 ～2.9、3.1 ～5.7年的显著性变化周期,以及40年以上的长周期震荡.     

Northern hemisphere controls on tropical southeast African climate during the past 60,000 years

The processes that control climate in the tropics are poorly understood. We applied compound-specific hydrogen isotopes (deltaD) and the TEX(86) (tetraether index of 86 carbon atoms) temperature proxy to sediment cores from Lake Tanganyika to independently reconstruct precipitation and temperature variations during the past 60,000 years. Tanganyika temperatures follow Northern Hemisphere insolation and indicate that warming in tropical southeast Africa during the last glacial termination began to increase approximately 3000 years before atmospheric carbon dioxide concentrations. deltaD data show that this region experienced abrupt changes in hydrology coeval with orbital and millennial-scale events recorded in Northern Hemisphere monsoonal climate records. This implies that precipitation in tropical southeast Africa is more strongly controlled by changes in Indian Ocean sea surface temperatures and the winter Indian monsoon than by migration of the Intertropical Convergence Zone.     

Lower cretaceous sediments from the northwest pacific

The first occurrence of deep-sea Lower Cretaceous (Albian) sediments in the Pacific Ocean is reported from the Shatsky Rise at 31 degrees 51'N, 157 degrees 20'E. Seismic-profile records indicate that the core was taken between the extensive seismic reflectors A and B. Two hundred meters of unconsolidated sediment lies between the core site and basement (B) and suiggests that the sediment just above basement may be at least as old as Middle Jurassic.     

中国夏季降水雨型雨带与印度洋海温变化特征分析

根据1979～1998年中国夏季（6～8月）逐月降水资料和同期的印度洋海温资料,分别运用经验正交函数和奇异值分解的方法,分析了我国夏季降水的时空分布及其与同期印度洋海温之间的联系。结果表明,我国夏季逐月降水存在着几种相对典型的空间分布形态;夏季印度洋海温与同期江淮流域降水之间呈正相关,而与我国其他大部地区降水之间呈负相关。     

我国南方冬季极端降水与印度洋海温的关系

利用我国南方229个站1962～2012年冬季降水量资料和美国国家海洋、大气管理局（NOAA）提供的1961 ～2011年全球逐月扩展重建海表温度（SST）资料,采用EOF分析、合成分析和SVD分解等方法,分析了我国南方冬季极端降水事件的年际异常与印度洋海温的关系.结果表明,我国南方冬季极端降水和印度洋海温均呈上升趋势,且均在1980年左右发生了突变;印度洋存在2个海温关键区（北印度洋、西南印度洋）,影响着我国南方冬季极端降水事件,关键影响时段是前一年12月～当年2月（简称冬季）;北印度洋冬季海温与江南地区、华南地区东部、淮河流域的冬季极端降水量存在显著正相关,西南印度洋冬季海温与江南地区中西部、西南地区东南部、华南地区东部以及江淮地区的冬季极端降水量存在显著正相关.     

基于优势分析法的西印度洋捕捞国和地区渔获量差异初步分析

西印度洋是海洋捕捞作业的重要海域,分析捕捞方渔获种类组成和渔获量是评价渔业资源利用状态的基础,也是确保其资源可持续开发和科学管理的重要支撑。根据FAO提供的1950—2019年西印度洋海域渔获量统计数据,采用优势分析法(dominance analysis)分析了70年间主要捕捞方的渔获种类组成和渔获量,比较不同时间序列下主要捕捞方和捕捞种类对渔获量的贡献率。研究表明,西印度洋海域渔获量整体呈上升趋势,根据突变点检测及渔获量增长趋势可划分为1950—1982年、1983—2005年和2006—2019年3个阶段。各阶段累计渔获量前十的渔获种类、捕捞方不存在显著性差异,长头小沙丁鱼(Sardinella longiceps)累计渔获量最高,鲣(Katsuwonus pelamis)、黄鳍金枪鱼(Thunnus albacores)等种类渔获量对总渔获量的贡献度较高;印度、巴基斯坦和伊朗等是沿海国和地区各阶段渔获量最高的捕捞方,西班牙、法国、日本和中国台湾省等是非沿海国和地区渔获量最高的捕捞方,对各阶段印度洋西部海域总渔获量的贡献度基本都超过10%。研究认为,基于印度洋西部海域渔业资源开发...     

Biogeography and ecological setting of Indian Ocean hydrothermal vents

Within the endemic invertebrate faunas of hydrothermal vents, five biogeographic provinces are recognized. Invertebrates at two Indian Ocean vent fields (Kairei and Edmond) belong to a sixth province, despite ecological settings and invertebrate-bacterial symbioses similar to those of both western Pacific and Atlantic vents. Most organisms found at these Indian Ocean vent fields have evolutionary affinities with western Pacific vent faunas, but a shrimp that ecologically dominates Indian Ocean vents closely resembles its Mid-Atlantic counterpart. These findings contribute to a global assessment of the biogeography of chemosynthetic faunas and indicate that the Indian Ocean vent community follows asymmetric assembly rules biased toward Pacific evolutionary alliances.     

Indian-atlantic transfer of thermocline water at the agulhas retroflection

During November and December 1983, two anticyclonic eddies were observed west of the Agulhas Retroflection, apparently spawned at the retroflection. The western eddy, centered 300 kilometers southwest of Cape Town, has a winter cooled core encircled by warm Indian Ocean water. Between Cape Town and the "Cape Town Eddy" is a net geostrophic transport of Indian Ocean thermocline water (14 x 10(6) cubic meters per second) into the South Atlantic Ocean. This circulation configuration, similar to that observed by earlier researchers, suggests that Indian-Atlantic thermocline exchange is a common occurrence. Such a warmwater link between the Atlantic and Indian oceans would strongly influence global climate patterns. The Indian Ocean water is warmer than the adjacent South Atlantic water and thus represents a heat input of 2.3 x 10(13) to 47 x 10(13) watts into the Atlantic. The large uncertainty arises from the unknown partition between two possible routes for the return flow from the Atlantic to the Indian Ocean: cooler South Atlantic thermocline water or much colder North Atlantic Deep Water. In either case, interocean mass and heat exchange of thermocline water at the Agulhas Retroflection is a distinct likelihood.     

Age of the floor of the eastern Indian ocean

Deep sea drilling in the eastern Indian Ocean shows that the oceanic crust off Western Australia is approximately 140 million years old and becomes younger to the west; this dates the initial opening of the Indian Ocean.     

热带海温的时空变化及其与我国降水的关系

利用1979—2014年的NOAA/NASA海表温度延长重构数据和国家台站的观测数据,采用经验正交函数(EOF)方法,从赤道年平均海温出发,分析热带海温的时空变化特征以及印度洋—太平洋海温对我国年降水量的影响。结果表明,1979—2014年热带地区年平均海温为26℃,海温暖区主要集中在印度洋和西太平洋的赤道地区。热带海温距平时空变化特征:第1特征向量场在印度洋海温表现为全区一致型,太平洋海温表现为弱El Nio(La Nia)现象,时间系数与年降水量主要在新疆、西藏、青海、甘肃和河套地区为显著的正相关关系;第2特征向量场在太平洋海温表现为El Nio(La Nia)现象,印度洋海温表现为偶极子型,时间系数与年降水量在西藏和黄河中游地区为显著的正相关关系,在东北东部和长江以南地区为显著的负相关关系;第3特征向量场在太平洋海温表现为弱El Nio(La Nia)现象,印度洋海温表现为南北型,时间系数与年降水量在西藏、新疆、福建和东北西北部为显著的负相关关系。     

基于渔获量平均营养级的西印度洋渔业资源利用评价

西印度洋是世界上重要的作业海域,评价渔业资源利用状态是实现其资源科学管理和可持续开发的重要基础。本研究根据FAO提供的1950-2018年西印度洋海域渔获量数据,结合渔获种类的营养级(Trophic Level, MTL),分析了69年间西印度洋海域渔获物平均营养级(Mean Trophic Level, MTL)和营养级平衡指数(Fishing in Balance index,FiB)的变动情况,以此评价渔业资源的开发利用情况。研究表明,1950-2018年西印度洋海域渔获量呈上升趋势,按其渔获量增长趋势可划分为1950-1982年、1983-2005年和2006-2018年三个阶段,其中长头小沙丁鱼渔获量最高。渔获物MTL呈先下降后上升再稳定的变动趋势,按渔获量划分的按个阶段,其MTL平均值分别为3.49±0.14、3.71±0.06、3.71±0.03,高营养级渔获物(TL>3.25)的MTL平均值分别为4.04±0.04、4.09±0.04、4.13±0.01,高营养级渔获物(TL>3.25)的平均营养级与总渔获物的平均营养级变化趋势相似(P<0.001)。FiB指数总体呈现上升趋势,三个阶段的平均值分别为0.0998±0.1659、0.8041±0.1849、0.9782±0.0670。分析认为,1950-1982年西印度洋海域早期渔获量相对较低,并随着长头小沙丁鱼等低营养级渔获量的增加,MTL和FiB呈波动下降趋势；1983-2005年,随着高营养级渔获量的增加,MTL和FiB呈逐渐升高趋势；2006-2018年,MTL和FiB相对稳定处在一个高位值。研究表明,目前西印度洋海域渔业资源状况良好,生态系统结构和功能稳定,该海域仍具有较大的开发潜力。     

Osmium isotopic evidence for ancient subcontinental lithospheric mantle beneath the kerguelen islands, southern indian ocean

Upper mantle xenoliths found in ocean island basalts are an important window through which the oceanic mantle lithosphere may be viewed directly. Osmium isotopic data on peridotite xenoliths from the Kerguelen Islands, an archipelago that is located on the northern Kerguelen Plateau in the southern Indian Ocean, demonstrate that pieces of mantle of diverse provenance are present beneath the Islands. In particular, peridotites with unradiogenic osmium and ancient rhenium-depletion ages (to 1.36 x 10(9) years old) may be pieces of the Gondwanaland subcontinental lithosphere that were incorporated into the Indian Ocean lithosphere as a result of the rifting process.     

The agulhas current during the late pleistocene: analysis of modern faunal analogs

Analysis of micropaleontologic evidence in a deep-sea core in the south-west Indian Ocean indicates that the Agulhas Current was not a dominant feature of this region during glacial intervals. Interpretation of the fossil record, based on the analysis of modern faunal analogs, indicates that during glacial intervals the Agulhas Current was not the strong, year-round current that it is today. Evidence shows that during summer months a weak tropical current was present. During winter months the current was replaced by cool, high-salinity waters. This interpretation suggests that seasonal changes in circulation may have been more pronounced in the southwest Indian Ocean during glacial intervals than today.     

Continuity of Mid-Oceanic Ridge and Rift Valley in the Southwestern Indian Ocean Confirmed

The existence of a continuous, rifted, mid-oceanic ridge in the southwestern Indian Ocean, previously predicted by us, has been confirmed by soundings taken by the research vessel Vema during the expedition now in progress.     

A major ecosystem shift in the northern Bering Sea

Until recently, northern Bering Sea ecosystems were characterized by extensive seasonal sea ice cover, high water column and sediment carbon production, and tight pelagic-benthic coupling of organic production. Here, we show that these ecosystems are shifting away from these characteristics. Changes in biological communities are contemporaneous with shifts in regional atmospheric and hydrographic forcing. In the past decade, geographic displacement of marine mammal population distributions has coincided with a reduction of benthic prey populations, an increase in pelagic fish, a reduction in sea ice, and an increase in air and ocean temperatures. These changes now observed on the shallow shelf of the northern Bering Sea should be expected to affect a much broader portion of the Pacific-influenced sector of the Arctic Ocean.