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白令海和鄂霍次克海的海冰偶极子及其对大气环流的影响 总被引：3，自引：0，他引：3
基于海冰历史资料的分析表明,白令海和鄂霍次克海的海冰密集度分布在某些年份表现出反位相变化的特征,尤其以冬季最为明显.合成分析的结果表明这种偶极子型海冰异常可能对大气环流(气温和位势高度)产生一定的影响.利用大气环流模式,在给定理想化的白令海、鄂霍次克海偶极子型海冰异常的情况下,通过20个冬季(1-2月)大气环流模式的集合强迫试验,研究了大气环流对这种偶极子型海冰异常的响应特征,数值试验结果与基于观测资料的合成分析比较一致:低空气温对于偶极子型海冰强迫表现为比较明显的对称性响应,气温变化具有垂直斜压的结构,气温变化主要集中在低空;高空大气温度和各层的位势高度的变化均具有显著的非对称性特征,位势高度的变化具有垂直正压结构.参考已有的理论和模拟研究结果,指出高纬地区低空大气的温度变化受直接热力学调整过程的影响明显,对称性响应分量明显,而高层大气温度和各层的大气位势高度变化是由直接热力学调整和间接动力过程响应所共同控制,非对称分量占主导. 相似文献
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采用美国NCEP-CFSR数据库资料,提取了1979—2010年的海平面大气要素场,在中国南海区域(0°～25°N、105°～125°E)和黄岩岛附近点(15°N、118°E),按日、月、年统计了32 a间海平面气压、海面2 m气温、海面2 m相对湿度、海面10 m风场基本气象要素特征。分析发现:黄岩岛及邻近中国南海区域属于赤道带、热带海洋性季风气候,其气候特征是:(1)海平面气压呈北高南低、冬季高夏季低的分布形势;黄岩岛日平均海平面气压冬季约为1 012 hPa,其他季节约为1 008 hPa,年平均海平面气压变化具有准5 a的周期;(2)全年平均气温较高,分布呈现北低南高,大陆低海面高,冬季低夏季高的特点;黄岩岛海面2 m气温日变化较小,年平均值约为27～28℃,年际变化上具有整体增加的趋势;(3)全年相对湿度较大,基本在60%以上,随季节变化明显,冬季较小,夏季较大;黄岩岛日平均相对湿度为80%,总体也具有略微增大的年际变化趋势;(4)受季风影响明显,冬季盛行东北季风,平均风速约为10～12 m/s,夏季盛行西南季风,平均风速约为4～8 m/s;黄岩岛海面风速的变化具有2.5～5 a的变化周期,年平均风速在5.3 m/s上下波动。 相似文献
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北半球中高纬度大气环流主模态的季节演变及其与北极海冰变化的联系 总被引：2，自引：0，他引：2
利用31a(1979—2009)气候月平均的海平面气压(SLP)资料,提出1种与北半球中高纬度环流转变相适应的分季法。并根据这个客观分季方法,通过SEOF分析,发现大气环流主模态的季节演变有着典型的北极涛动(AO)空间结构,其时间系数在1990年代中期发生转型。500hPa上纬向波的涡度有着南北反位相的分布特征,冬季正涡度的区域对应着气旋性环流,其覆盖范围广,而夏季正涡度区域更偏北,可见AO在冬季增强,夏季减弱。北半球SLP异常的EOF分解第一模态为北极涛动(AO),第二模态是偶极异常(DA);将这2个模态称之为北半球中高纬度大气环流异常的优势模态。通过计算优势模态与海冰面积的超前滞后相关性,发现AO依然是控制海冰变化的前期大气环流异常的模态,而DA则可能是海冰快速变化后期大气环流的主导模态。 相似文献
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《中国海洋大学学报(自然科学版)》2020,(Z1)
本文采用经验正交函数分析、线性回归、相关性分析等方法对1982—2017年乌拉尔阻塞(UB)与巴伦支-喀拉海(BKS)海冰季节特征及其相关关系进行分析发现,UB活动频率与BKS海冰密集度均有较强的季节性周期变化,且不同季节BKS海冰与UB相关性不同。进一步对秋季UB与冬季BKS海冰的相关关系分析发现:秋季UB频率在BKS及其周边区域增多的年份里,秋季到冬季结冰期内,局地BKS海域500hPa位势高度持续增加、低层大气温度持续升高;同时,秋季BKS海域海表面温度异常增暖持续至冬季。上述海洋、大气条件不利于结冰期BKS海冰的冻结,因此这些年份里冬季BKS海冰密集度减少。此外,秋季BKS海冰减少也伴随着冬季UB高纬度频率增加。 相似文献
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台湾以东黑潮流量变异与冬季西北太平洋海洋-大气相互作用 总被引：5，自引：1，他引：5
通过对历史资料进行奇异值分解、合成分析及相关分析,揭示了对应冬季台湾以东黑潮流量增强(减弱)时,西北太平洋海区异常失热(得热),北太平洋(北纬20°N以北)上空500hPa位势高度负异常(正异常);进一步证实了冬季西北太平洋海洋-大气相互作用是一个正反馈过程;发现了冬季台湾以东黑潮的暖平流作用可能是维持该正反馈过程进行的一个必要条件;通过超前和滞后相关及合成分析,提出从10月开始,台湾以东黑潮流量异常形成的暖平流作用会对冬季西北太平洋海区海洋-大气相互作用有贡献。 相似文献
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本文主要通过相关统计分析,研究了7月各海区海冰与同期上空500hPa高度场的关系及其与后期翌年1月北半球500hPa大气环流的联系,对翌年1月亚洲中高纬地区气温趋势的可能影响在此也作了讨论。结果表明:7月北极海冰与其同期上空500hPa高度存在着较好的负相关关系。其中,尤以Ⅰ、Ⅱ海区负相关关系更好。在北极各海区中,以7月第Ⅲ海区海冰与后期翌年1月北半球500hPa大气环流联系较为密切。主要表现为,7月Ⅱ海区海冰M指数高(即冰情重)时,翌年1月北欧低槽及东亚大槽偏弱,并多伴随着乌拉尔山阻塞形势的破坏过程。7月Ⅱ海区海冰M指数低(即冰情轻)时,翌年1月北欧低槽及东亚大槽偏强,多伴随着乌拉尔山阻塞形势的建立过程。7月Ⅱ海区冰情重时,亚洲中、高纬地区1月气温多偏低,反之多偏高。 相似文献
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福建春季降水量场预测模型研究 总被引：2，自引：0，他引：2
利用1960—2000年福建春季(2—4月)降水量场资料，分析了经验正交函数(EOF)展开得出的特征向量，以反映降水的空间分布特征。研究了前三种分布型的时间系数与前期北半球500hPa、100hPa月高度距平场和北太平洋海温距平场之间的关系，针对不同的分布型分别找出了不同的前期预测信号，以此为预测因子，构建出福建春季降水量场短期气候预测模型。利用该模型对2001、2002年福建春季降水量场进行试预测，取得了较满意的结果。 相似文献
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基于欧洲中期天气预报中心(ECMWF)的ERA_interim全球再分析数据集,利用客观算法识别和追踪温带气旋,分析了1979—2014年冬季(12月—次年2月)北太平洋(120°E~120°W,20°N~80°N)的温带气旋活动特征及其变化,探讨了冬季风暴路径与秋季北极海冰异常的关系。北太平洋温带气旋活动的气候态显示为自日本以东洋面至阿拉斯加湾北部的风暴路径。对30°N以北气旋活动频率异常的EOF分析显示其第一模态为太平洋气旋活动的南北向偶极子结构,表示风暴路径南北摆动的变化特征,且有向北偏移的趋势。第二模态的空间分布表现为40°N~60°N之间的大陆沿岸和太平洋洋面上呈相反的分布形势。时间系数的回归分析显示,冬季太平洋风暴路径的南北摆动与秋季(9—11月)东西伯利亚海-波弗特海海冰的异常显著相关。该海区秋季海冰减少导致冬季阿留申低压区呈高压异常,西风急流北移,45°N~75°N之间的大气斜压性增强而45°N以南大气斜压性减弱,从而使风暴路径向45°N以北偏移。 相似文献
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基于美国国家冰雪数据中心 （NSIDC） 海冰资料、美国国家环境预报中心 （NCEP） 再分析格点数据和黄渤海近岸13个气象站点逐日气温数据，通过相关分析和合成分析，研究了 2007-2018 年黄渤海海冰范围的变化特征，探讨了近 12 年黄渤海海冰范围对近岸陆地气温、大气环流和局地天气过程的响应。结果表明: （1） 黄渤海海冰范围年际振荡明显，近 12 年呈现先增加后减小的趋势，与同期黄渤海近岸气温呈显著负相关关系；每年 1 月下旬至 2 月下旬是一年中海冰范围最大的时期。（2） 海冰范围偏大与偏小年份东亚地区 500 hPa 大气环流形势呈现出近乎相反的分布。 （3） 东亚阻塞形势的建立是黄渤海海冰范围爆发性增大的一个前兆信号，它带来的大风降温天气是造成黄渤海海冰范围爆发性增大的重要原因. 相似文献
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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
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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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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
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Coastal inundation associated with extreme sea levels is the main factor which leads to the loss of life and property whenever a severe tropical cyclonic storm hits the Indian coasts. The Andhra and Orissa coasts are most vulnerable for coastal inundation due to extreme rise in sea levels associated with tropical cyclones. Loss of life may be minimized if extreme sea levels and associated coastal flooding is predicted well in advance. Keeping this in view, location specific coastal inundation models are developed and applied for the Andhra and Orissa coasts of India. Several numerical experiments are carried out using the data of past severe cyclones that struck these regions. The simulated inland inundation distances are found to be in general agreement with the reported flooding. 相似文献
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《海洋学报(英文版)》2014,(9):F0003-F0003
<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology, 相似文献
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Hoi-Soo Jung Kap-Sik Jeong Yong-Shik Chu Sung-Hyun Park Ki-Hyune Kim 《Marine Georesources & Geotechnology》2001,19(3):181-195
Grain size and water content in box-core sediments from the Clarion-Clipperton fracture zone (C-C zone) in the northeast equatorial Pacific were analyzed in detail to understand the downcore variations across a hiatus between Quaternary and Tertiary layers. Grain-size distributions in the topmost core sediments show two modes: a coarse mode (peaked at 50 μm) and a fine mode (at 2-25 μm). The coarse mode disappears gradually with depth accompanied by the dissolution of siliceous fossil tests, whereas the fine mode coarsens due to the formation of authigenic minerals. Water content increases abruptly across a color boundary between an upper pale brown layer and a lower dark brown layer that is the hiatus between Quaternary and Tertiary layers. Abundant smectites and microvoid molds, which are created by the prolonged fossil dissolution in the underlying sediment, are attributed for the abrupt downcore variation of water content. Overall variations in grain size and water content in the topmost core sediments in the western C-C zone are possibly constrained by the dissolution of biogenic siliceous fossils. Variations in geotechnical properties related to these changes must be considered in the design of nodule collectors. 相似文献
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Shigehisa Nakamura 《Marine Geodesy》2001,24(1):27-33
This article concerns an interrelation between the sea levels and the western boundary flow near a tectonic boundary in a local zone in the Northwestern Pacific. In this zone, sea level variations at stations located on the coast facing the Pacific are studied to find the interrelation between variations of the Kurosio flow as an index of the distance of the flow axis off a specific coast. The result is discussed after data processing of the monthly means of the sea levels, and a notice is taken of variations caused by active crustal upheavals during a seismic event, a local earthquake. 相似文献
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This study tests the hypothesis that the in situ void ratio of surficial marine sediments may be predicted from shear wave velocity-depth data with a reliability equal to that of other methods currently available. Shear wave velocity is fundamentally controlled by the number of grain-to-grain contacts per unit volume of material and by the effective stress across those contacts. In this study, three previously established empirical formulae are used to predict void ratio from velocity-depth data. Field data were acquired along a transect off the northern Californian coast across which water depth increased from 35 to 70 m and seafloor sediment type varied from sand to silty-sand, respectively. A towed seafloor sled device was used to collect shear wave refraction data, and a marked, systematic decrease in velocity was observed along the line, ranging from 35-70 m/s for the coarse, near-shore material to 25-40 m/s for the finer, offshore deposits. Void ratios predicted from these velocities were compared with data measured directly from box-core samples. Of the formulae used for prediction, two agree remarkably well with the control data. Both predicted and control values increase from 0.6-0.8 for the sandy material to 1.1-1.5 for the silty-sand. Thus, this study does not disprove the hypothesis set and demonstrates the potential of field shear wave velocity-depth data as a means of delineating spatial variation in void ratio for surficial marine sediments in a remote, nondestructive manner. 相似文献
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Particulate samples were collected from the Changjiang river system during a flood period, in May 1997, and POC, stable isotope and lipids associated with particles were examined. Results showed the decrease (0.84% ～ 1.88%) of organic carbon content from the upper reaches to the estuary.δ13C values of particulate organic carbon was in the range of -24.9×10-3 to -26.6×10-3, which were close to the isotopic signature of continental C3 vegetation. Total particulate n-alkanes concentrations varied from 1.4 to 10.1μg/dm3,or from 23.7 to 107μg/g of total suspended matter. Fatty acids were present in all the samples, from 1.4 to 5.4μg/dm3, with saturated and unsaturated straight-chain and branched compounds in the carbon number range from C12 to C30. Both δ13C and the ratio of carbon content to nitrogen content indicate the predominance of terrestrial inputs (soil organic matter) among the particles. The biomarker approach has been used to identify the relative portion of terrigenous and autochthonous fraction in the particulate samples. The distribution of fatty acids suggests a striking phytoplanktonic and microbial signal in most particle samples. The terrestrial alkanes are used to estimate the contribution of terrestrial inputs along the mainstream. 相似文献