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1.
2015年9月台风“灿鸿”经过黄海海域的QF111浮标,该浮标观测到黄海海洋的温度和流速响应。受台风影响,黄海海表温度有明显的下降,降温幅度在2~4°C,且在台风路径右侧形成了海表面温度低于20°C的低温斑块。流速的响应主要表现为台风过境期间流速增强,达1.2~1.5 m/s,呈现出全水深强化的特征。风一直对海洋有能量输入,且在台风过境期间风输入海洋的能量最大,旋转功率谱的分析结果表明台风输入海洋的能量向海洋内部传播。黄海海域由台风激发出的近惯性振荡衰减较快,近惯性振荡e折时间尺度约为2 d。 相似文献
2.
基于锚碇观测资料，本文分析了南海西北部陆坡区上层海洋对台风“杜苏芮”的动力学和热力学响应特征。在动力学响应方面，台风“杜苏芮”期间上层流速显著增强，混合层纬向流速可达1.20 m/s；“杜苏芮”经过后上层海水运动以近惯性振荡为主(流向顺时针旋转周期在36～40 h之间)。近惯性能量在垂向分布上存在两个高值中心，分别位于混合层和温跃层深度上。近惯性能量耗散过程的e折时间尺度约为3.7 d，我们认为能量的向下传播在局地近惯性能量衰减过程中起主要作用。对能量谱的分析表明，“杜苏芮”作用期间近惯性频率能量相对于其作用前增大了约29.4倍，而全日和半日频率(K1和M2)能量有所减弱。此外，能量谱显示近惯性频率存在明显的“蓝移”现象，即对于纬向和经向流速分量在400 m以浅平均的近惯性振荡频率分别为1.167 f0和1.170 f0(f0为局地惯性频率)。蓝移与近惯性内波的向下传播及正的相对涡度的输入有关。在热力学响应方面，上层海洋在台风的搅拌作用下，40～250 m深度均出现较小增温，最大增温幅度接近1°C；此外70 m以浅盐度的降低可能与台风过境时的降水相关，而Ekman抽吸引起的上升流则可能对70～100 m深度盐度的升高具有重要作用。 相似文献
3.
上层海洋对台风"凯萨娜"(2009)的响应特征 总被引：1，自引：1，他引：0
本文利用多源卫星遥感数据和Argo浮标数据对2009年台风"凯萨娜"过后,南海上层海洋的物理和生态响应特征进行了分析。结果表明,"凯萨娜"引起的上升流流速最大可以达到1.6×10~(–3)m/s,台风过后,海表面温度(SST)下降显著,最大降温幅度可以达到6℃,海表面高度降低,先前存在的中尺度冷涡进一步加强。台风过后,沿着台风路径,叶绿素浓度升高,最大值可以达到2 mg/m~3以上,初级生产力升高到台风过境前的5倍。SST的最大降温中心与海面高度下降区域以及叶绿素浓度升高的区域一致。Argo数据表明台风诱发了强烈的垂向混合和艾克曼泵吸,不同位置处,垂向混合和艾克曼泵吸的强度不一样。通过混合和泵吸过程,台风可以把海洋内部的营养盐输送到海洋表层,对整个南海的物理和生态过程有重要影响。 相似文献
4.
本研究利用三维物理-生物耦合模型模拟了大气氮沉降对南黄海主要初级生产过程的影响,并通过数值实验区分了不同季节大气氮沉降的贡献。模拟结果显示,大气氮沉降明显增大了南黄海表层溶解无机氮的浓度,近岸海域增加量较大,可以达到3.0 mmol/m^3,且由近岸海域到黄海中部海域有明显的递减趋势,这主要是由于近岸海域无机氮来源众多,导致浓度较高,大气沉降的氮不会被浮游植物生长吸收,出现氮累积。大气氮沉降明显促进了黄海中部春季表层水华和夏季次表层叶绿素最大值两个重要初级生产过程,春季表层叶绿素增加量最大,可达0.20 mg/m^3,夏季次表层叶绿素浓度增加最显著,可达0.10 mg/m^3,分别约为峰值浓度的10%和6%。不同季节大气氮沉降对初级生产过程的贡献不同,冬季氮沉降可以存留下来影响春季水华过程,但作用小于春季氮沉降;夏季,由于水体层化较强,本季的氮沉降对次表层叶绿素最大值的促进作用并不明显,反而冬季氮沉降的影响大于春季和夏季的氮沉降。同时,大气氮沉降也促进了氮循环的各个过程,包括浮游植物生长吸收、呼吸释放和矿化过程。 相似文献
5.
为提高我国海洋水色遥感技术和海水环境监测水平,文章根据北海区海水遥感现场监测数据,基于经验算法和荧光基线高度法的回归分析,开展海水表层叶绿素a浓度的遥感定量反演,并选取北黄海近岸海域样本数据进行算法检验。研究结果表明:辽东湾等9个北海区典型海域具有相同或相似海水表层光学特性,适宜建立海水表层叶绿素a浓度遥感定量反演模型;典型海域海水表层叶绿素a浓度与遥感反射率之间的相关关系较强,模型均为简单波段比值模型;二类海水研究区域海水表层叶绿素a浓度与荧光基线高度之间的相关关系不明显;北黄海近岸海域海水表层叶绿素a浓度的最优模型遥感定量反演值的相对误差的平均值为0.669μg/L。 相似文献
6.
2016年夏季黄、渤海颗粒有机碳的分布特征及影响因素 总被引：2，自引：1，他引：1
本文根据2016年6-7月黄、渤海航次获得的调查数据，分析了黄、渤海海域颗粒有机碳（POC）的浓度变化、空间分布特征并结合盐度、叶绿素a、POC/PON、POC/Chl a平面分布特征和相关性分析，探讨了黄、渤海海域POC的来源和影响因素。结果表明:2016年夏季渤海海域POC平均浓度（500.2±226.5）μg/L，北黄海POC平均浓度（358.2±101.5）μg/L，南黄海POC平均浓度（321.0±158.1）μg/L，渤海海域POC浓度高于黄海，整个海域POC浓度表层高于底层。POC的平面分布特征为近岸高，外海低。调查海域表层POC/PON均值为8.89，POC/Chl a均值为182.52；中层POC/PON均值为8.87，POC/Chl a均值为179.56；底层POC/PON均值为9.41，POC/Chl a均值为178.80。黄海海域浒苔衰败对POC/PON与POC/Chl a影响较大。相关性分析结果表明渤海海域盐度、总悬浮物和叶绿素a与POC存在显著的相关性，是影响POC分布的主要控制因素。南黄海除表层POC浓度与盐度、总悬浮物和叶绿素a浓度有很好的相关性外，中层和底层POC浓度与盐度、总悬浮物和叶绿素a浓度不存在显著的相关性。渤海海域POC主要受陆源和浮游植物共同影响，浮游植物是POC的主要贡献者，而黄海海域POC受长江冲淡水、黄海暖流、苏北沿岸流、生物活动和底层沉积物等多种因素影响，其中苏北近岸和青岛外海，有机碎屑为POC的主要贡献者。 相似文献
7.
南黄海秋季叶绿素a的分布特征与浮游植物的固碳强度 总被引：19，自引：5，他引：19
依据2005年10月中下旬对南黄海的调查结果,系统阐述了2005年秋季南黄海叶绿素a的分布特征,并估算了南黄海和东中国近海初级生产力水平及浮游植物固碳强度,分析了控制其变化的生物地球化学机制.结果表明,南黄海表层叶绿素a含量的变化范围为0.11~2.38 mg/m3,平均浓度为0.66 mg/m3,明显高于50 m层的含量.南黄海表层和次表层叶绿素a分布趋势基本一致,均显现出西北高、东南低的趋势,在近岸海域出现显著的高值带,这主要是由于受到陆源输入和沿岸流带来的高营养盐的影响;中部海域的低值区则主要受控于来自东海低营养盐海流的“冲淡”作用.在垂直分布上,叶绿素a最高值基本出现在次表层,与以往发现的该海域次表层溶解氧最大值一致,这显然与南黄海浮游植物及区域水团特性有关.2005年秋季南黄海初级生产力(C)变化在95~1 634 mg/(m2·d),平均为586 mg/(m2·d),其分布趋势显示了海洋初级生产力与海水磷浓度以及水团、海流的关系.应用初级生产力估算的浮游植物固碳强度的结果表明,我国东部近海浮游植物年总固碳量约为222Mt,约占全球近海浮游植物的年固碳量的2.0%,为我国东部近海通过海-气界面总表观碳汇强度每年1 369万t的16.2倍,在不同的海域,浮游植物固碳量是其通过海-气界面总表观碳汇强度的倍数不同(渤海为3.0倍,黄海为6.7倍,东海为81.6倍). 相似文献
8.
基于台风最佳路径资料和20a的Argo浮标资料,采用一种合成分析方法,得到了西北太平洋上层海洋的温度、盐度、溶解氧等三维要素场对台风的平均响应特征,结果表明:台风移动路径右侧海表面温度呈明显的负异常,即具有"右偏性",次表层在"热泵"和"冷抽吸"共同影响下,温度异常呈正负相间的分布,次表层以下大部区域以温度负异常为主,但"右偏性"已不明显;表层至1 000 m深度,各层占主导的盐度异常值呈"正-负-正"的垂向分布,次表层以下,各层的盐度异常在平行和垂直于台风路径方向上的分布较为均匀,不具有明显的各向性差异;表层至1 000 m深度层,溶解氧浓度呈"小-大-小"的垂向分布,各层的平面分布特征较为相似,均在平行于台风路径-2～2 R50范围存在一带状高值区域;温度、盐度、溶解氧浓度等要素对台风的平均响应深度可达到1 000 m以上. 相似文献
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浮游植物作为食物链的基础,对海洋生态系统具有重要影响。黄海作为我国重要的渔场,渔业资源面临枯竭的危险,因此对该区浮游植物进行研究具有重要意义。叶绿素a浓度是反映浮游植物生物量的重要指标。利用谷歌地球引擎平台对2002-2018年的MODIS Aqua叶绿素a浓度数据进行处理,并研究其时空分布与变化特征,然后结合区域气候、水文与地理特征以及海洋表面温度、风速、盐度、光合有效辐射和混合层厚度数据分析了其分布与变化的原因。研究发现:受陆源营养物质输入、近岸上升流以及黄海中央冷水团影响,叶绿素a浓度分布呈现由近岸向黄海中部递减特征;在季风、气候、水文的控制下,受风速、海洋表面温度、光合有效辐射、中央冷水团的影响,叶绿素a浓度的最大值出现在4月份,而最小值出现在6、7月份;受苏北沿岸海域海水污染和水体富营养化影响,沿岸海域盐度明显增加,海州湾叶绿素a浓度增速较大;影响黄海叶绿素a浓度变化的环境因子较复杂,除了部分月份存在显著的相关影响因子外,在全年和各季中不存在主导影响因子。 相似文献
10.
黄海在有无潮作用下对“布拉万”不同响应的数值模拟研究 总被引：2，自引：0，他引：2
黄海是典型的强潮驱动的陆架浅海。为了研究黄海对台风的响应特点,本文利用区域海洋模式(Regional Ocean Modeling Systems,ROMS)分别模拟了在有潮和无潮作用下黄海对台风"布拉万"的响应过程。结果表明,不管潮存在与否,"布拉万"经过黄海后都引起了海表面降温和流速的近惯性振荡响应,这种响应主要分布于黄海中部较深区域,带通滤波提取的近惯性流速具有垂向第一模态特征。同时,研究发现强背景潮流能显著地影响黄海对"布拉万"的响应过程。主要结论如下:一方面,由于潮的存在,近岸垂向混合均匀的较暖水体与远岸较冷水体之间会形成潮混合温度锋面,"布拉万"过后,暖水发生了明显的离岸扩张,尽管路径右侧的混合层降温更显著,但是左侧即黄海西岸的暖水扩张更明显;另一方面,潮的存在减弱了布拉万产生的近惯性振荡响应,半日潮流在黄海仍然占据主导地位。在混合层中潮流的作用减弱了"布拉万"产生的近惯性能量,但也使其更易穿过跃层传入黄海内部。 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.
Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths. 相似文献
13.
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
14.
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
15.
Shigehisa Nakamura 《Marine Geodesy》2000,23(1):55-61
Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone. 相似文献
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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
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19.
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
20.
The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics. 相似文献