2008年夏季楚科奇海余流分布特征

根据2008-08-05-09-07在楚科奇海布放的一套浅水潜标系统(71°40′1.4″N,167°58′54.6″W)获得的海流剖面资料及温盐资料,采用Lanczos余弦滤波的方法,研究了楚科奇海中央水道余流剖面及温盐时间序列的结构和变化特征,对表层余流与风场的关系及影响温盐结构的因素进行了分析。结果表明,余流的方向和大小在垂直方向上存在明显的差异:表层余流全流呈现西向流态,平均流速为19.6cm/s,方向为257.4°,受表层风场影响显著;中、下层的余流全流平均流速为6.6cm/s,流向为29.6°,呈现东北偏北方向。在整个观测期间,温度时间序列表现出剧烈的震荡,振幅达到3.7℃以上,而盐度序列变化缓慢,波动区间相对较小,为32.0～32.8,并表现出逐渐降低的趋势;温盐序列的变化受底层余流分布的影响较弱。     

2012年夏季楚科奇海浮游动物垂直迁移及上升流对其生物量的影响

The diel vertical migration(DVM) of zooplankton and the influence of upwelling on zooplankton biomass were examined using water column data of current velocity and mean volume backscattering strength(MVBS)collected by moored acoustic Doppler current profilers(ADCPs) deployed in the southeastern Chukchi Sea during the 5th Chinese National Arctic Research Expedition(CHINARE) in summer 2012, combined with the satellite observational data such as sea surface temperature(SST), wind, and chlorophyll a(Chl a). Hourly acoustic data were continuously collected for 49-d in the mooring site. Spectral analysis indicated that there were different migrating patterns of zooplankton, even though precisely classifying the zooplankton taxa was not available. The prevailing 24-h cycle corresponded to the normal DVM with zooplankton swimming upwards at sunrise and returning to deep waters at sunset. There was a clear DVM in the upper 17 m of the water column during the period with distinct day-night cycles, and no active DVM throughout the water column when the sun above the horizon(polar day), suggesting that light intensity was the trigger for DVM. Also there was a second migrating pattern with 12-h cycle. The upwelling event occurring in the northwest of Alaskan coastal area had important influence on zooplankton biomass at the mooring site. During the upwelling, the SST close to the mooring site dropped significantly from maximal 6.35°C to minimal 1.31°C within five days. Simultaneously, there was a rapid increase in the MVBS and Chl a level, suggesting the aggregation of zooplankton related to upwelling.     

楚科奇海夏季潮流和余流观测研究

根据2008年8月5日至9月7日在楚科奇海布放的一套锚碇潜标观测系统(71°40.024′N,167°58.910′W)获得的海流剖面资料研究了该海区的海流分布特征,重点探讨了潮流的垂向结构、余流剖面特征及海流的斜压性.结果表明:(1)该海域主要分潮为半日潮M1,S2和N2,近日分潮O1,天文分潮MM和MSF,其中以M...     

2012年楚科奇海及其邻近海域浮游植物现存量和初级生产力粒级结构研究

通过2012年夏季第五次北极科学考察期间在楚科奇海及其邻近海域现场调查所获得的数据分析研究了海域的粒度分级叶绿素a浓度和初级生产力。结果表明,叶绿素a浓度和初级生产力的高值均出现在楚科奇海陆架区,并且远高于深海区。去程时调查海域水层平均叶绿素a浓度的变化范围为0.32~15.66mg/m3,平均(2.77±3.96)mg/m3,高值区出现在南部邻近白令海峡海域、北部阿拉斯加巴罗近岸和冰缘区;初级生产力的范围为50.11~943.28mg/(m2d),高值出现在冰缘水华区。返程时水层平均叶绿素a浓度的变化范围为0.07~1.52mg/m3,平均(0.41±0.40)mg/m3,高值仍出现在陆架区,但比去程时低了一个数量级;初级生产力的分布范围为12.31~41.35mg/(m2d),高值出现在陆架区。浮游植物粒度分级测定结果表明,在生物量较低的深海区,叶绿素a浓度和初级生产力的粒级结构以微微型浮游生物(Pico级份)占优势(其贡献率分别为46.1%和56.9%),小型(Net级份)和微型(Nano级份)对总叶绿素a浓度的贡献差异极小,分别为26.6%和27.3%,对总初级生产力的贡献分别为23.8%和19.3%;而在生物量较高的水深小于200m的陆架区,Net级份叶绿素a浓度所占百分比最高,Pico级份次之,Nano级份最低,分别为59.8%、27.9%和12.3%,初级生产力的粒级结构中叶绿素a浓度所占百分比由高到低同样是Net、Pico和Nano,所占百分比分别为60.6%,32.2%和7.2%。     

楚科奇海浮游植物的分布与环境因子的关系

根据1999年7—8月“雪龙”号考察船在楚科奇海采集的样品,运用PRIMER软件分析该区网采浮游植物的分布特征及其与环境因子的关系。结果表明：楚科奇海浮游植物群聚可分为三个生态类群：北极-亚北极类群,主要分布于水深大于2000米且受北冰洋影响较直接的东北部浅水浮冰外缘;北方温带类群,主要分布于水深小于100米的中部浅水浮冰区：广温性类群,主要分布于通过白令海峡与北太平洋进行水交换的南部水域。该区浮游植物平面分布差异大,细胞密度站间变化范围为1．6×10^3～90680．2×10^4,物种多样性指数和均匀度站间变化范围分别为0．07～O．87和0．33～3．82。主成分（PCA）分析表明,对楚科奇海浮游植物分布起支配作用为水温和盐度。此外,由于该海区所处的特殊地理环境,浮冰的位黄及其物理状态（聚集、开裂和消融等）均会增加浮游植物分布的变异。     

加拿大海盆与楚科奇海表层沉积物中硫酸盐还原菌丰度分布状况

对中国第2次北极科学考察海洋表层沉积物(0～1 cm)中硫酸盐还原菌进行4℃、25℃的培养实验,结合首次北极科学考察海洋沉积物硫酸盐还原菌研究成果,研究了研究区硫酸盐还原菌丰度的分布。结果表明,4℃培养得出硫酸盐还原菌丰度为0～2.4×104个/g(湿样),平均3 433个/g(湿样),并呈现有规律的分布趋势:低纬区的高于高纬区的,浅水区的高于深水区的。本区硫酸盐还原菌丰度高于中国东海、南海和黄海部分海区沉积物中的,低于胶州湾以及西北冰洋某些海区中的。25℃培养时硫酸盐还原菌丰度为0～2.4×104个/g(湿样),平均4 062个/g(湿样),在1 880 m以浅水域其丰度与4℃培养时的一致,而在1 880 m以深水域其丰度高于4℃培养时丰度。     

2008年夏季楚科奇陆架海域近底层水温大幅快速变化事件研究

2008年夏季中国第3次北极科学考察期间,利用锚碇潜标对北冰洋楚科奇陆架海域进行了为期33 d的海流剖面、近底层温度与盐度连续观测。观测数据显示楚科奇陆架海域近底层海水温度出现了两次较大幅度的快速升降现象。结合此次科学考察R断面温盐深仪(CTD)观测资料、以及卫星遥感海表温度(SST)和海表风场等资料,综合分析表明:观测到的这种快速升、降温现象不仅发生在近底层;这种快速升、降温现象应该是由海水温度锋面在夏季整体缓慢北移的同时存在短暂南北摆动所导致;温度锋面的季节性北移属于北极气候特征,而温度锋面短暂的南北摆动则与短期天气过程有关。     

夏季楚科奇海河水与海冰融化水组分的空间变化特征

通过对2008年夏季楚科奇海水氧同位素组成的分析,运用S、δ18 O的质量平衡关系计算出河水组分和海冰融化水组分的份额,揭示出楚科奇海河水和海冰融化水组分的空间变化规律,并探讨其影响因素。楚科奇海河水组分的份额介于1.9%~18.4%之间,呈现随深度增加而降低的趋势;河水组分积分高度的变化范围为1.3~16.6m,平均为(4.8±4.0)m。河水组分份额与积分高度均呈现东高西低、北强南弱的特征,与太平洋入流东侧为富含河水组分的阿拉斯加沿岸流、西侧为低河水组分的白令海陆架水,以及北部海域受波弗特流涡埃克曼辐聚作用的影响有关。海冰融化水份额呈现随深度增加而降低的趋势,20~30m以深受到冬季海冰形成时所释放盐卤水的明显影响。海冰融化水积分高度的变化范围为-3.2~1.7m,平均值为(-0.3±1.2)m,其空间分布呈现东低西高、南强北弱的特征,与太平洋入流输入通量的时间变化以及输入路径的西偏有关。     

楚科奇海与加拿大海盆表层沉积物表观特征及其环境指示

通过对中国首次和第二次北极科学考察采集的表层沉积物的观察,根据沉积物的颜色和气味、砾石分布、底栖生物及贝壳分布特征的分析,探讨了该海区表层沉积物表观特征变化与有机质输入、沉积物的氧化还原状态的关系、底栖生物分布范围、冰筏碎屑的分布区域及与海流的关系,指出在研究区软体动物生长的北界位于73．5°N,比浮游动物的北界约低2个纬度。冰筏碎屑的北界可作为融冰水的北界或永久冰区的南界,位置在77°24′N附近。通过对沉积物表观特征的综合分析,结合研究区的海流特征,指出研究区的海流分布对沉积物分布有重要影响,尤其是两股不同性质的海流相遇,对西南部与东部两个区域的沉积物组成及性质具有较强的控制作用。     

西北冰洋楚科奇海台P31孔晚第四纪的陆源沉积物记录及其古海洋与古气候意义

通过对北冰洋西部楚科奇海台P31孔沉积物进行岩性特征和颜色旋回分析、XRF元素扫描、AMS14 C测年、有孔虫丰度统计、筏冰碎屑(IRD)(250和154μm)含量分析以及粒度组成的综合研究,建立了该孔的地层年代框架,其沉积物被划分为MIS 3-MIS 1的沉积序列。自MIS 3以来,楚科奇海台P31孔可以识别出5个IRD事件,它们分别出现在晚MIS 1、MIS 2和早中MIS 3期。这些IRD主要被来自加拿大北极群岛的冰山或者大块冰所携带,随波弗特环流搬运至楚科奇海台并卸载到海底,这不仅反映了晚第四纪冰期-间冰期旋回中北美冰盖的崩塌事件,还反映了波弗特环流的变化历史。粒度组分变化表明,细砂级组分主要来自于冰山或大冰块的搬运,因为其高值对应于IRD的高值,粉砂级组分可能主要来自于海冰的搬运,而黏土级组分主要由波弗特环流和雾状层所搬运。两个敏感组分(5～13和110～176μm)含量的变化呈现明显对称性分布,后者的变化对应于IRD的变化,前者可能指示了物源和沉积作用后期的影响。该孔MIS3-MIS1的沉积速率分别为2.2、0.16和1.6cm/ka,平均沉积速率约为1.2cm/ka。与北冰洋其他海区沉积速率资料对比显示,海冰边缘地区沉积速率较高,而永久性海冰覆盖区沉积速率低较。水深越浅,越靠近陆架物源区,沉积速率越高,纬度越高的门捷列夫-阿尔法脊和加拿大海盆区,沉积速率越低。     

Ocean current observation and spectrum analysis in central Chukchi Sea during the summer of 2008

During the summer of 2008, the third CHINARE Arctic Expedition was carried out on board of Xuelong Icebreaker in the central Chukchi Sea. A submersible mooring system was deployed and recovered at Station CN-01 (71°40.024′N, 167°58.910′W) with 33 days of the current profile records, and continuous observation of temperature and salinity data were collected. This mooring station locates in the blank of similar observation area and it is the first time for our Chinese to finish this kind of long-termmooring work in this area. Thismooring systemfinished integrated hydrological observationswith long-termcontinuous record of the whole profile velocity for the first time. Based on time series analysis of temperature, salinity, velocity and flow direction, we get the following main results. (1) During the observation period, the mean surface current velocity is 70.2 cm/s eastward, and velocity reaches itsmaximumin average at 3mlevelwithmagnitude 90.0 cm/s, direction 206°. (2) In 9-30mlayers, the semidiurnal period variationis themost obvious, the flow direction is quite stable, and the flow is synchronous and consistent vertically. (3) Besides the semidiurnal period variation, the main variation in the upper layer is in 11-d period, with variations in period 5.5, 5.5, and 3.7 d, which reflect the influences of sea surface wind change and maintenance. (4) Near the bottom, the temperature change is correlated and synchronizedwith the conductivity.     

杭州湾南部主水道内温度、盐度、潮流的变化特征

本文基于船载及锚定ADCP、CTD观测,获得了大、小潮时的温度、盐度、浊度、潮位、流速等观测数据,研究杭州湾南部的一个主要弯曲航道——螺头水道内的潮流动力学特性。螺头水道水深超过100 m、最大潮差大于2.5 m。涨潮时,强潮流速出现在水道北岸,落潮时,强潮流速出现在水道南岸,最大流速值分别为约2 m/s和1.8 m/s。受压强梯度、密度梯度、科氏力和离心力影响,涨落潮过渡时在水道的横断面产生较为明显的环流。夏季存在较弱的层化现象,深水处受环流的影响,盐度、温度的混合较强。锚定观测数据表明,温度、盐度的变化频率与潮流的变化频率相似,但存在高于M2分潮频率的谱峰值。因此,笔者认为潮流与横向环流的相互作用,可能导致更高频率的盐度和温度变化。     

渤黄东海40年温盐流模拟与初步分析

使用ROMS(regional oceanic modeling system)模式模拟了40年的渤黄东海温盐流,数据包括三维的温度、盐度、流速、流向和海表高度,同时包含了逐小时的潮汐信息。将模拟结果与观测资料和卫星反演数据进行对比,检验了模式准确性。整体上,模式模拟的水位与近岸观测值基本一致,能够准确再现风产生的增水;模式较为准确的再现了渤黄东海的温度分布,在深水区模拟的温盐剖面与观测值基本一致;模式模拟渤黄东海区域的海表高度和海表流与卫星反演结果相比偏小,但分布趋势相近。模式结果可以为研究气候变化对水位的影响和黄海暖舌的扩散过程等现象提供数据支持。     

Sound velocity and related properties of seafloor sediments in the Bering Sea and Chukchi Sea

The Bering Sea shelf and Chukchi Sea shelf are believed to hold enormous oil and gas reserves which have attracted a lot of geophysical surveys. For the interpretation of acoustic geophysical survey results, sediment sound velocity is one of the main parameters. On seven sediment cores collected from the Bering Sea and Chukchi Sea during the 5th Chinese National Arctic Research Expedition, sound velocity measurements were made at 35, 50, 100, 135, 150, 174, 200, and 250 k Hz using eight separate pairs of ultrasonic transducers. The measured sound velocities range from 1 425.1 m/s to 1 606.4 m/s and are dispersive with the degrees of dispersion from 2.2% to 4.0% over a frequency range of 35–250 k Hz. After the sound velocity measurements, the measurements of selected geotechnical properties and the Scanning Electron Microscopic observation of microstructure were also made on the sediment cores. The results show that the seafloor sediments are composed of silty sand, sandy silt, coarse silt, clayey silt, sand-silt-clay and silty clay. Aggregate and diatom debris is found in the seafloor sediments. Through comparative analysis of microphotographs and geotechnical properties, it is assumed that the large pore spaces between aggregates and the intraparticulate porosity of diatom debris increase the porosity of the seafloor sediments, and affect other geotechnical properties. The correlation analysis of sound velocity and geotechnical properties shows that the correlation of sound velocity with porosity and wet bulk density is extreme significant, while the correlation of sound velocity with clay content, mean grain size and organic content is not significant. The regression equations between porosity, wet bulk density and sound velocity based on best-fit polynomial are given.     

The fundamental characteristics of current in the Bering Strait and the Chukchi Sea from July to September 2003

1Introduction TheBeringStraitactsasashallowchannelbe- tweenthePacificandtheArcticOcean(seeFig.1). TheBeringStraitislessthan60mdeepandconnects theChukchiSeatothenorthandtheBeringSeatothe south.TheChukchiSeaisamarginalseaoftheArctic Oceanwithsome50mdeep(Woodgateetal.,2004). TheBeringStraitthroughflowplaysanimportantrole inthestratificationoftheArcticOcean,especiallyin theprimarywaterpropertiesoftheChukchiSea. Aagaardetal.(1985)arguedthatbecauseofthe coastalgeometry,therewerewind-driven…     

Circulation on the north central Chukchi Sea shelf

Mooring and shipboard data collected between 1992 and 1995 delineate the circulation over the north central Chukchi shelf. Previous studies indicated that Pacific waters crossed the Chukchi shelf through Herald Valley (in the west) and Barrow Canyon (in the east). We find a third branch (through the Central Channel) onto the outer shelf. The Central Channel transport varies seasonally in phase with Bering Strait transport, and is 0.2 Sv on average, although some of this might include water entrained from the outflow through Herald Valley. A portion of the Central Channel outflow moves eastward and converges with the Alaskan Coastal Current at the head of Barrow Canyon. The remainder appears to continue northeastward over the central outer shelf toward the shelfbreak, joined by outflow from Herald Valley. The mean flow opposes the prevailing winds and is primarily forced by the sea-level slope between the Pacific and Arctic oceans. Current variations are mainly wind forced, but baroclinic forcing, associated with upstream dense-water formation in coastal polynyas might occasionally be important.Winter water-mass modification depends crucially on the fall and winter winds, which control seasonal ice development. An extensive fall ice cover delays cooling, limits new ice formation, and results in little salinization. In such years, Bering shelf waters cross the Chukchi shelf with little modification. In contrast, extensive open water in fall leads to early and rapid cooling, and if accompanied by vigorous ice production within coastal polynyas, results in the production of high-salinity (>33) shelf waters. Such interannual variability likely affects slope processes and the transport of Pacific waters into the Arctic Ocean interior.