2011年1月普里兹湾埃默里冰架附近水文特征

分析“雪龙”号2011年在普里兹湾埃默里冰架外缘24个站位的CTD观测结果,发现有以下一些水文特征：普里兹湾西部,在71°E-72°E范围内,存在一个顺时针运动的中尺度涡。由于这个涡旋存在,冰架水主要扩散方向偏东,在73°30′E附近,流向东北;夏季表层水厚度,东部基本在20m,西部受中尺度涡和其他因素的影响,夏季表层水厚度深达50m左右;在50m以浅的水层内,表面以下温度会出现稍微增大现象,我们称之为逆温层,它是结冰、融冰和海冰覆盖变化造成的;在观测断面西部,在160m～200m水层内,多站出现“静力不稳定”：即上层密度大于下层,厚度有几米,平流混合扩散可能是这一不稳定现象主要原因。     

楚科奇和西伯利亚陆架颗粒有机物的来源：碳、氮同位素的线索

The stable isotopic composition(δ~(13)C and δ~(15)N) and carbon/nitrogen ratio(C/N) of particulate organic matter(POM) in the Chukchi and East Siberian shelves from July to September, 2016 were measured to evaluate the spatial variability and origin of POM. The δ~(13)C_(POC) values were in the range of -29.5‰ to-17.5‰ with an average of -25.9‰±2.0‰, and the δ~(15)N_(PN) values ranged from 3.9‰ to 13.1‰ with an average of 8.0‰±1.6‰. The C/N ratios in the East Siberian shelf were generally higher than those in the Chukchi shelf, while the δ~(13)C and δ~(15)N values were just the opposite. Abnormally low C/N ratios(4), low δ~(13)C_(POC)(almost-28‰) and high δ~(15)N_(PN)(10‰) values were observed in the Wrangel Island polynya, which was attributed to the early bloom of small phytoplankton. The contributions of terrestrial POM, bloom-produced POM and non-bloom marine POM were estimated using a three end-member mixing model. The spatial distribution of terrestrial POM showed a high fraction in the East Siberian shelf and decreased eastward, indicating the influence of Russian rivers. The distribution of non-bloom marine POM showed a high fraction in the Chukchi shelf with the highest fraction occurring in the Bering Strait and decreased westward, suggesting the stimulation of biological production by the Pacific inflow in the Chukchi shelf. The fractions of bloom-produced POM were highest in the winter polynya and gradually decreased toward the periphery. A negative relationship between the bloom-produced POM and the sea ice meltwater inventory was observed, indicating that the net sea ice loss promotes early bloom in the polynya.Given the high fraction of bloom-produced POM, the early bloom of phytoplankton in the polynyas may play an important role on marine production and POM export in the Arctic shelves.     

TOPEX/Poseidon-Jason Comparison and Combination off Nova Scotia

Sea level observations from the tandem TOPEX/Poseidon (T/P) and Jason-1 altimetry missions (2002-2003) are used to study characteristics of sea level and surface currents over the Scotian Shelf and Slope off Nova Scotia. The consistency and error characteristics of T/P and Jason-1 measurements are examined not only in terms of sea level and cross-track current anomalies but also with respect to current anomalies at crossovers, kinematic properties associated with Gulf Stream warm core rings (WCR), and the shelf-edge current transport. Nominal absolute currents are constructed by adding the altimetric geostrophic current anomalies to an annual-mean model circulation field. The concurrent frontal analysis data are analyzed for occurrence of the WCRs and associated kinematic properties are derived from altimetric current anomalies. The comparison of the sea level and cross-track current anomalies from January to July 2002 shows overall good agreement between T/P and Jason, with correlation coefficients different from zero at the 5% significance level at essentially all locations for sea level and at most locations for currents. The cross-track geostrophic current anomalies from January to July 2002 and from September 2002 to December 2003 are further used to calculate the root-mean-square (rms) current magnitude, and the normalized relative vorticity associated with WCRs. The altimetric currents are consistent with each other and complementary to frontal analysis data in deriving the properties of the WCRs. The rms current magnitude is ∼55 cm/s and the normalized relative vorticity is ∼0.15. The model-altimetry combined absolute currents are used to estimate near-surface transport associated with the shelf-edge current, showing good correlation between T/P and Jason estimates and strong seasonal changes. The current anomalies derived from altimetry and moored measurements are significantly (at the 5% significance level) correlated and comparable in the rms magnitude.     

末次冰期以来巽他陆架东北部陆坡区正构烷烃分布特征及其古植被意义

为了讨论末次冰期以来巽他陆架东北部植被情况及巽他陆架在冰期时的碳循环意义.对位于南海西南部陆坡的18252-3站位岩心柱沉积物中长链正构烷烃组分的平均链长(ACL27-33)、碳优势指数(CPI27-33)、烷烃含量(∑oddC27-C33)、及烷烃比值等指标进行了分析.结果显示:末次冰期以来CPI27-33表现出与海...     

Variability of the subtropical shelf front off eastern South America: Winter 2003 and summer 2004

Hydrographic data collected during surveys carried out in austral winter 2003 and summer 2004 are used to analyze the distributions of temperature (T) and salinity (S) over the continental shelf and slope of eastern South America between 27°S and 39°S. The water mass structure and the characteristics of the transition between subantarctic and subtropical shelf water (STSW), referred to as the subtropical shelf front (STSF), as revealed by the vertical structure of temperature and salinity are discussed. During both surveys, the front intensifies downward and extends southwestward from the near coastal zone at 33°S to the shelf break at 36°S. In austral winter subantarctic shelf water (SASW), derived from the northern Patagonia shelf, forms a vertically coherent cold wedge of low salinity waters that locally separate the outer shelf STSW from the fresher inner shelf Plata Plume Water (PPW) derived from the Río de la Plata. Winter T–S diagrams and cross-shelf T and S distributions indicate that mixtures of PPW and tropical water only occur beyond the northernmost extent of pure SASW, and form STSW and an inverted thermocline characteristic of this region. In summer 2004, dilution of Tropical water (TW) occurs at two distinct levels: a warm near surface layer, associated to PPW–TW mixtures, similar to but significantly warmer than winter STSW, and a colder (T∼16 °C) salinity minimum layer at 40–50 m depth, created by SASW–STSW mixtures across the STSF. In winter, the salinity distribution controls the density structure creating a cross-shore density gradient, which prevents isopycnal mixing across the STSF. Temperature stratification in summer induces a sharp pycnocline providing cross-shelf isopycnal connections across the STSF. Cooling and freshening of the upper layer observed at stations collected along the western edge of the Brazil Current suggest offshore export of shelf waters. Low T and S filaments, evident along the shelf break in the winter data, suggest that submesoscale eddies may enhance the property exchange across the shelf break. These observations suggest that as the subsurface shelf waters converge at the STSF, they flow southward along the front and are expelled offshore, primarily along the front axis.     

东海陆架盆地类型及其形成的动力学环境

东海陆架盆地位于欧亚板块东南缘,处于华南陆块(包括西部的扬子地块和东部的华夏地块)之上.其基底是华夏地块在东海陆架的延伸,也是西太平洋大陆边缘构造域的重要组成部分.从全球板块构造格局分析,东海陆架盆地处于西太平洋三角带区域,是印度-澳大利亚板块和太平洋板块与欧亚板块巨型汇聚的地带,也是全球汇聚中心,其东西两侧分别与特提斯和西太平洋构造域演化息息相关.总体来说,东海陆架盆地是“欧亚板块与太平洋板块之间的碰撞、俯冲、弧后扩张,印度-澳大利亚板块与欧亚板块之间的汇聚、碰撞、楔入的远程效应,以及地球深部动力学作用”共同叠加、复合作用形成的弧后盆地.其形成机制符合被动扩张模式,向东的地幔流和软流圈下降流是导致弧后扩张的主要地球深部动力来源.     

台湾以北黑潮水与陆架水的混合与交换

本文根据日本气象厅在台湾以北获得的调查资料及近几年国家海洋局在该海域获得的调查资料,结合卫星图片,分析了夏季和冬季台湾以北海域陆架水与黑潮水的混合与交换过程以及涡旋在水交换过程中所起的作用。结果表明,夏季陆架水从表层向外海方向扩展,与黑潮水进行混合与交换;在陆架底部,黑潮次表层水涌升陆架后与陆架底层水进行混合。冬季由于黑潮表层水大举入侵陆架,低温的陆架水只能沿陆架向南流动,并在台湾西北部转向东沿台湾北岸向东流动,该海域存在的涡旋就象一个旋转泵,在陆架水与黑潮水的混合与交换过程中起了重要的作用。最后,文中还对陆架水与黑潮水的交换量进行了估算。     

A year in the physical oceanography of the Chukchi Sea: Moored measurements from autumn 1990–1991

Year-long time-series of temperature, salinity and velocity from 12 locations throughout the Chukchi Sea from September 1990 to October 1991 document physical transformations and significant seasonal changes in the throughflow from the Pacific to the Arctic Ocean for one year. In most of the Chukchi, the flow field responds rapidly to the local wind, with high spatial coherence over the basin scale—effectively the ocean takes on the lengthscales of the wind forcing. Although weekly transport variability is very large (ca. -2 to ), the mean flow is northwards, opposed by the mean wind (which is southward), but presumably forced by a sea-level slope between the Pacific and the Arctic, which these data suggest may have significant variability on long (order a year) timescales. The high flow variability yields a significant range of residence times for waters in the Chukchi (i.e. one to six months for half the transit) with the larger values applicable in winter.Temperature and salinity (TS) records show a strong annual cycle of freezing, salinization, freshening and warming, with sizable interannual variability. The largest seasonal variability is seen in the east, where warm, fresh waters escape from the buoyant, coastally trapped Alaskan Coastal Current into the interior Chukchi. In the west, the seasonally present Siberian Coastal Current provides a source of cold, fresh waters and a flow field less linked to the local wind. Cold, dense polynya waters are observed near Cape Lisburne and occasional upwelling events bring lower Arctic Ocean halocline waters to the head of Barrow Canyon. For about half the year, at least at depth, the entire Chukchi is condensed into a small region of TS-space at the freezing temperature, suggesting ventilation occurs to near-bottom, driven by cooling and brine rejection in autumn/winter and by storm-mixing all year.In 1990–1991, the ca. 0.8 Sv annual mean inflow through Bering Strait exits the Chukchi in four outflows—via Long Strait, Herald Valley, the Central Channel, and Barrow Canyon—each outflow being comparable (order 0.1–0.3 Sv) and showing significant changes in volume and water properties (and hence equilibrium depth in the Arctic Ocean) throughout the year. The clearest seasonal cycle in properties and flow is in Herald Valley, where the outflow is only weakly related to the local wind. In this one year, the outflows ventilate above and below (but not in) the Arctic halocline mode of 33.1 psu. A volumetric comparison with Bering Strait indicates significant cooling during transit through the Chukchi, but remarkably little change in salinity, at least in the denser waters. This suggests that, with the exception of (in this year small) polynya events, the salinity cycle in the Chukchi can be considered as being set by the input through Bering Strait and thus, since density is dominated by salinity at these temperatures, Bering Strait salinities are a reasonable predictor of ventilation of the Arctic Ocean.     

末次冰期以来巽他陆架的演变及其对南沙群岛海区古环境的影响

通过对南沙群岛海区NS94－93柱样磁组构，矿物成分分析，结合^14C测年，分析了末次冰盛期巽他陆架出露成陆及其后巽他陆架被海水淹没后南沙群岛海区沉积环境的变化，认为巽他陆架在13.2kaB.P。时开始被海水淹没，约经历600a左右趋于稳定，在末次冰期，南沙群岛海区水体封闭，沉积物以陆源物质为主，碳酸盐含量低，13.2-10kaB.P，沉积物以陆源物质为主，碳酸盐含量逐渐增加，至10kaB.P.南沙群岛海区进入全新世，水体交换条件得到较大改善，沉积物中生源物质显著上升，陆源物质明显减少，碳酸盐含量一直维持在较高水平。