共查询到20条相似文献，搜索用时 46 毫秒
1.
《海洋通报》2015,(1)
利用基于客观分析方法重构的Argo网格资料(未同化其他观测资料),分析探讨了2004年1月-2011年12月期间太平洋海域(60°S-60°N、120°E-80°W)盐度气候态分布特征与变化规律。结果表明,分别位于南、北亚热带海域的两个高盐(北部约为35.2,南部为36.4左右)中心,呈马鞍形的双峰分布,对称中心不在赤道,而是偏北12个纬度;在南、北纬40°附近海域,盐度等值线十分密集,形成"极锋";在新西兰东南海域存在低盐水由南向北的入侵现象,且由表层至1 000 m深层终年存在。盐度在亚极地海域每年大致呈一高一低的周期性变化,亚北极海域更明显,最高盐度值出现在每年的4月份,最低盐度值则出现在每年的9月份,高低盐度差在0.30~0.45之间。表层以下,盐度的周期性变化远不如表层明显,至500 m中层,整个太平洋海域的盐度最大变幅不超过0.10。赤道海域的表层盐度在2007年和2010年分别有明显的异常减小,最大振幅约为0.8,年际变化周期约为3年;北副热带和亚北极海域的表层,盐度表现出3-6个月的年际振荡,振幅约为0.2;中层盐度几乎没有明显的异常变化。 相似文献
2.
基于Argo观测的太平洋温、盐度分布与变化（I）：温度 总被引：1，自引：0，他引：1
利用基于客观分析方法重构的Argo网格资料（未同化其他观测资料）,分析探讨了2004年1月-2011年12月期间太平洋海域（60°S-60°N、120°E-80°W）温度气候态分布特征与变化规律。结果表明,在西太平洋赤道附近海域,29℃等温线的包络范围（暖池）,夏季显著增大,位置也明显偏北,且其厚度仅限于约100 m上层;在亚热带海域次表层（约150 m）,形成南北两个高温（南部大于27℃,北部大于24℃）中心,呈马鞍形分布,但并不以赤道为对称中心,而是偏向北半球8个纬度;在南、北纬40°附近海域,等温线十分密集,形成“极锋”;在新西兰东南海域存在低温水舌由南向北的入侵现象,从表层至1000 m深层始终可见,似是终年存在的一个水文特征。温度的年变化规律表层最明显,每年呈一高一低的分布趋势,亚热带海域尤为显著,北半球温度年较差大于9.5℃,南半球约为6.0℃,且北半球的最高、最低温度值分别出现在每年的8月份和2月份,南半球则相反。表层以下,温度的周期性变化远不如表层明显,至500 m中层,整个太平洋海域的温度最大变幅仅为1.0℃。赤道海域表层温度明显存在3年的周期性年际振荡,北亚热带表层也表现为3-6个月的周期性年际变化,中层年际振荡较缓,振幅也较小,而亚南极海域从表层直至500 m中层,均存在不规则年际振荡。 相似文献
3.
利用基于客观分析方法重构的Argo网格资料(未同化其他观测资料),分析探讨了2004年1月-2011年12月期间太平洋海域(60°S-60°N、120°E-80°W)温度气候态分布特征与变化规律。结果表明,在西太平洋赤道附近海域,29℃等温线的包络范围(暖池),夏季显著增大,位置也明显偏北,且其厚度仅限于约100 m上层;在亚热带海域次表层(约150 m),形成南北两个高温(南部大于27℃,北部大于24℃)中心,呈马鞍形分布,但并不以赤道为对称中心,而是偏向北半球8个纬度;在南、北纬40°附近海域,等温线十分密集,形成"极锋";在新西兰东南海域存在低温水舌由南向北的入侵现象,从表层至1 000 m深层始终可见,似是终年存在的一个水文特征。温度的年变化规律表层最明显,每年呈一高一低的分布趋势,亚热带海域尤为显著,北半球温度年较差大于9.5℃,南半球约为6.0℃,且北半球的最高、最低温度值分别出现在每年的8月份和2月份,南半球则相反。表层以下,温度的周期性变化远不如表层明显,至500 m中层,整个太平洋海域的温度最大变幅仅为1.0℃。赤道海域表层温度明显存在3年的周期性年际振荡,北亚热带表层也表现为3-6个月的周期性年际变化,中层年际振荡较缓,振幅也较小,而亚南极海域从表层直至500 m中层,均存在不规则年际振荡。 相似文献
4.
1981—2010年东海及毗邻的西北太平洋表层盐度的气候态分布特征 总被引：1，自引：0，他引：1
使用SODA表层盐度月平均数据,通过计算逐点逐年盐度均值、月际差,绘制等值线分布图,分析在新的30年气候基准期(1981—2010年),东海及毗邻的西北太平洋海域表层盐度场气候态分布特征,为进一步研究该地区长时间序列的气候变化奠定基础。结果表明:(1)在研究区表层平均盐度从西北到东南逐渐升高,形成3个明显的盐度特征场区:东海大陆架海区、东海黑潮海区以及西北太平洋海区;(2)研究区月际表层盐度存在明显的周期性变化,其中,盐度最小值的周期性规律最显著;(3)在月际变化中,1—4月为盐度高值季节,以3月份盐度最高,为27.5psu;5—8月为盐度低值季节,以8月份盐度最低,为22psu;9—12月为盐度上升季节;(4)依据盐度场的分布,结合地形、气候、海流等特征和前人研究,在研究区选取了22个特征点,从特征点看,位于西北太平洋海区的特征点盐度月振幅最小;位于长江入海口附近的D1和位于杭州湾南部的D2盐度月振幅较大,但D1与D2月际变化曲线呈现较为明显的反相关特征,这可能与长江冲淡水水舌夏季北移抑制苏北沿岸流南下和北上的台湾暖流夏强冬弱有关。 相似文献
5.
太平洋次表层海温异常年际变率的信号通道与ENSO循环 总被引：1，自引：1，他引：0
利用SODA海洋同化资料,分析了太平洋次表层海温异常(SOTA)年际信号变异特征与ENSO循环的联系。结果表明,热带太平洋的年际变率表现为以160°W为纵轴的东西向和以6°—8°N为横轴的南北向的跷跷板分布,南太平洋和北太平洋中高纬度海洋的SOTA则与热带西太平洋SOTA同号,但强度较弱,这些变化都与ENSO事件密切相关,是ENSO事件的两个主要模态,具57和44个月显著周期。ENSO循环期间,热带西太平洋SOTA强信号中心沿赤道东传,到达赤道东太平洋后加强并北扩,导致ElNi?o或LaNi?a事件,同时从热带西太平洋有较弱SOTA信号向东北和西南传播,在南、北太平洋中高纬度海域产生弱SOTA;同期位于热带东太平洋反号的SOTA强信号中心沿10°—15°N(平均12°N)西传,至热带西太平洋后加强并南扩,为下次LaNi?a或ElNi?o事件准备条件,同时在北太平洋中高纬度海洋还存在着反号弱的SOTA。如此周而复始,完成ENSO循环。太平洋次表层海温年际变化信号除在赤道及以北的热带太平洋存在一个逆时针方向的传播通道外,同时在热带西太平洋有异常信号向南、北太平洋中高纬度海域传播,并指出ENSO循环期间太平洋次表层海温异常年际变率信号传播的可能通道。 相似文献
6.
本文根据1985—1988年4次考察中140°E断面的温、盐度和海流资料指出,由于1986—1987年E1 Ni(?)o事件的出现,因而原先积聚在西太平洋赤道海域的上层暖水减少,次表层水和中层水显著抬升,从而改变了热带海域的温、盐度场结构。此外,南赤道流几乎消失以及赤道潜流核心层速度的明显减弱,是这次E1 Ni(?)o事件造成的海流方面的重要变化。结合1982—1983年E1 Ni(?)o事件爆发前137°E断面表层动力高度的分布变化,可初步认为西太平洋赤道海域已具备了产生下一次E1 Ni(?)o事件的海洋学条件。 相似文献
7.
本文利用Argo海水盐度资料、海流同化数据和同期大气再分析数据,探讨热带太平洋盐度趋势变化和相关动力过程。Argo资料显示,2015?2017年热带太平洋出现显著的盐度异常(SAE),这是改变长期趋势的主要原因,表现为表层显著淡化和次表层咸化特征。这种盐度异常具有明显的区域性特征和垂直结构的差异,体现在热带太平洋北部海区(NTP)和南太平洋辐合区(SPCZ)表层淡化,盐度最大变幅为0.71～0.92,淡化可以达到混合层底;热带太平洋南部海区(STP)次表层咸化,最大变幅为0.46,主要发生在温跃层附近,期间盐度异常沿着等位密面从西向东扩展。平流和挟卷是与SAE密切相关的海洋动力过程,两者在NTP淡化海域有着持续而较为显著的影响,在SPCZ淡化、STP咸化海域后期贡献也较大,其中盐度平流对热带太平洋海区盐度变化起主要贡献。NTP淡化海区表层淡水通量和STP咸化海区密度补偿引起的混合也是SAE的重要影响因素。 相似文献
8.
海温距平的ENSO模和类ENSO模的三维结构 总被引：2，自引：0，他引：2
用美国马里兰大学提供的海洋同化(SODA)月平均资料,深入揭示了ENSO模的海洋三维结构及其年际和年代际变率。研究结果指出,ENSO海洋模随深度呈明显规律变化。在热带太平洋,它由热带中东太平洋表层显著海温异常分布型随深度增加逐渐过渡为热带西太平洋次表层显著反号海温异常分布型;在赤道太平洋以赤道西太平洋暖池次表层海温显著异常与赤道中东太平洋表层海温反号显著异常为主要特征。El Nino期间,热带中东太平洋表层为强海温正距平中心,西太平洋暖池次表层为强海温负距平中心,在年际尺度上,160°E以西的西北太平洋副热带海域还存在一个与西太平洋海温异常变化反号、与热带东太平洋同号的区域;La Nina期间正好相反。ENSO循环主要由ENSO年际变率所决定,年际ENSO模具有东部型ENSO事件的海温异常分布特征,其循环是东部型冷暖事件之间的转换,在200m以浅,它具ENSO模相同的三维结构和3-5年的显著年际变化周期;年代际类ENSO模具有中部型ENSO事件的海温异常分布特征,年代际ENSO循环是中部型冷暖事件之间的转换,其影响主要限制在200m以浅的海洋上层,具有ENSO模相似的三维结构和9-23年的显著周期。 相似文献
9.
本文基于实测温盐数据等资料,利用水团的浓度混合分析等方法,揭示了热带中东太平洋海域10°N断面的水团构成自上而下分别为东部赤道–热带水团、北太平洋中央水团、加利福尼亚流系水团、南太平洋中央水团、太平洋亚北极水团和太平洋深层水团。分析发现,受热带辐合带影响,9°～10°N海域常年持续的正风应力旋度诱发上升流出现,北太平洋中央水团、加利福尼亚流系水团、南太平洋中央水团和太平洋亚北极水团4个通风潜沉水团经向运动至该纬度带时被抽吸至次表层和中层,并散布在不同深度。以往研究仅指出上述4个水团在海表通风形成后将潜沉并向赤道方向运动,本研究进一步阐明了4个水团潜沉后向热带海域运动的动力机制及其在热带中东太平洋10°N断面的散布深度。研究成果揭示了热带中东太平洋水团与北太平洋副热带、亚极地和南太平洋副热带海区中上层水团间的循环过程,对认识北太平洋高–中–低纬度间物质和能量的交换和再分配具有重要科学价值。 相似文献
10.
本文利用Argo表层盐度、OSCAR海流等数据,基于盐度收支方程的平流输送项来阐述海洋平流输送对热带印度洋表层盐度的调整作用;利用淡水输运量计算公式揭示6条关键断面海洋平流输送对表层盐度空间结构的调整机制。结果表明,海洋平流将赤道西印度洋和阿拉伯海的高盐水输送到低盐海域的赤道东印度洋和孟加拉湾、安达曼海;将赤道东印度洋和孟加拉湾、安达曼海的低盐水输送到高盐海域的赤道西印度洋、阿拉伯海以及赤道南印度洋海域,起到了调整印度洋盐度基本平衡的作用。断面淡水输运量的分析结果表明,导致苏门答腊岛西部海域的强降水中心与低盐中心不重合,澳大利亚西部海域的强蒸发中心与高盐中心不重合的主要原因是水平环流所致;夏季,来自赤道西印度洋和阿拉伯海的高盐水在西南季风环流的驱动下,入侵孟加拉湾,是导致孟加拉湾夏季表层盐度较高的主要原因。 相似文献
11.
Chandralata Raghukumar G. Sheelu P. A. Loka Bharathi Shanta Nair C. Mohandass 《Marine Georesources & Geotechnology》2001,19(1):1-16
In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance. 相似文献
12.
海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。 相似文献
13.
Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification
An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm. 相似文献
14.
Derek V. Ellis 《Marine Georesources & Geotechnology》2001,19(1):51-63
This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested. 相似文献
15.
G. Parthiban 《Marine Georesources & Geotechnology》2000,18(3):223-235
Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement. 相似文献
16.
17.
18.
Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans 总被引：1，自引：0，他引：1
A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level. 相似文献
19.
The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments. 相似文献
20.
Oedometer tests have been carried out on 70 undisturbed surficial clays (at approximately 250 mm below the mudline), mostly collected by free-fall corers from sites widely scattered throughout the deep-sea North Atlantic. Acoustic measurements were also made, initially on contiguous samples and ultimately on the same sample using a geophysically instrumented oedometer which also collected electrical resistivity data. Apart from those quiescent areas below the carbonate compensation depth, such as north of the West Indies where very fine clays exist, most of the samples are silty clays whose geotechnical-geophysical properties are dependent on the type of clay minerals present (and their ability to take in moisture), the sand-size fraction, and the quantity of carbonate present. Thus the pure clays have high compressibilities which decrease on the addition of coarse particles, while the converse is true for the acoustic parameters, these increasing with the sand fraction. Using the notion of the intrinsic compression line for all samples, and comparison to it of the measured compression curves, it is clear that, contrary to some previously held ideas, most deep-sea clays are normally consolidated; the addition of carbonate has the effect of creating an open, stronger sediment skeleton. Interestingly, where information is available, the variation with depth of a sample's acoustic velocity follows the void ratio pressure relationship of the compression curve. This allows the construction of an in-situ sediment compression curve using the in-situ geophysical observations. 相似文献