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上层海洋通过海气交换影响大气-海洋耦合系统，海浪引起的垂向混合影响上层海洋结构，从而在气候预测过程中发挥着重要的作用。本文基于国家海洋局第一海洋研究所地球系统模式（FIO-ESM），以2016年为例，分别开展了耦合和关闭海浪模式情况下的短期气候预测实验，分析浪致混合对北太平洋海表温度（SST）季节性预测的影响。通过对模式预测的SST异常（SSTA）进行定量评估发现，浪致混合能够显著降低北太平洋高纬度海区预测误差，在（45°N，150°E）附近海区SSTA改善可达1℃，气候模式能够更好地预测SSTA的经向分布特征，特别是能够准确地反映25°~45°N海区SSTA分布特征。通过分析有浪和无浪两个实验的热收支贡献发现，垂向混合是导致上层海洋温度差异的主导影响因子。海浪通过改变垂向混合，使2016年北太平洋SST在高纬度海区大幅降低，在低纬度海区略有升高，最终提升了模式对北太平洋SST的季节性预测能力。 相似文献
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本文利用美国华盛顿数值天气预报中心(KWBC)的3—5天预报的1000hPa等势面的格点高度场(5°×5°)资料,由“海上风的边界层模式”计算的风场,应用“一个参数的大洋波谱模式”,进行了北太平洋海浪数值预报的试验,试验结果表明,尽管输入风场资料存在一定误差,计算的浪场与3─5天后的实测浪场仍有较好的吻合。 相似文献
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南印度洋海浪场时空特征分析 总被引：1，自引：0，他引：1
根据 1950 —1995 年共 46 a 的南印度洋船舶气象报资料，按 5°× 5°网格统计的海浪要素进行分析研究。通过分析每月各要素的等值线分布图，得出南印度洋海浪场季节变化特点不如北半球各大洋显著，但仍有较明显的季节变化，只是季节性差异较小，冬季比夏季海浪强盛，相应的平均波高、大浪大涌频率也较大；盛行风浪传播方向、涌浪传播方向基本一致，10°S 以北为季风气候区，而其它海域则信风区常年盛行 SE 向浪，40°S 以南盛行偏 W 向浪。本文提供了南印度洋海域较为翔实的海浪场资料及变化规律。 相似文献
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西北太平洋风场和海浪场特点分析 总被引：6，自引：1，他引：5
本文根据1950～1995年共46a的西北太平洋气象船舶报资料,按5°×5°网格统计的风、浪要素进行分析研究,阐明了西北太平洋风、浪、涌的特点及其变化规律。该区是世界最典型的季风气候区,季风时期的风向、浪向、涌向基本一致,赤道地区常年盛行东北浪。冬季季风比夏季季风强盛,相应的平均波高、大浪大涌频率也较大。该海域与北印度洋同属季风气候区,但其特点正好相反。本文为船舶在西北太平洋航行、作业和科学试验以及军事活动,提供了较翔实的风场和浪场资料及变化规律。 相似文献
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台湾海区的风浪特点及分布规律 总被引：1，自引：0，他引：1
收集了1960～1990年间的31 a国际气象船舶报资料,以中国台湾周边海区为中心,范围自20°N～28°N,116.5°E～124°E,划分为1°×1°网格单位,对风向、风速、浪向、浪高、周期等要素进行累年逐月统计和作图.通过分析研究,我们发现了该区的风浪特点和分布规律冬季风浪以台湾海峡中部为最大,尤其是澎湖列岛北部地区(风速大于20 m/s,浪高大于3.0m),但在台湾西南部沿岸以高雄为中心,风浪最小;夏季风浪以台湾海峡南口为最大(风速大于13.0 m/s,浪高大于2.0 m),台湾海峡风浪最小(风速小于1.0m/s,浪高小于1.5m).这些新的特点,在以往的2°×2°或5°×5°的大网格分析研究中是显示不出来的. 相似文献
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为了描述北太平洋上空Hadley 环流的纬向结构特征, 利用NCEP 再分析资料(1979～2010 年), 研究了北太平洋上空Hadley 环流纬向结构的季节和年际变化。发现在西太平洋, Hadley 环流季节性上升支呈西北-东南倾斜, 其垂向核心位于对流层中层, 纬向核心在北半球冬季(夏季)位于日界线附近(150°E); 而永久性上升支主要在东太平洋, 其垂向核心位于对流层低层, 且沿经度东移逐渐增强。根据纬向环流结构特征, 北半球冬季环流形态分为3 个区域: 160°E 以西, 主要表现为低层辐合高层辐散;160°E～130°W, 主要表现为高层辐合; 130°W 以东, 表现为低层辐合高层辐散特征。相似地, 北半球夏季环流形态也可沿纬向分为如下3 个区域: 165°E 以西、165°E～165°W 和165°W 以东, 分别对应东亚夏季风主导经圈环流区、过渡区、Hadley 环流主导经圈环流区。在年际变化上, 北太平洋Hadley 环流与ENSO 有很强的相关, 这与前人的研究是一致的。因此北太平洋上空Hadley 环流具有显著的空间性态, 并且对应时间尺度不同, 影响其变化的主要因素也不尽相同。 相似文献
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冬季北太平洋西部上层海洋的热量输送 总被引：1，自引：2，他引：1
用海气界面净热量收支和1950－1979年表层水温资料，计算了冬季北太平洋西部上层海洋热通量散度场，指出冬季北太平洋西部黑潮将大量低纬暖水输送到中高纬度海域，在30－35°N最大；亲潮将极地冷水沿千岛群岛向南输送，在45－50°N最大；两者在40°N附近相遇，混合减弱后沿纬向东传。同时用EOF分析方法对热通量散度距平场分型，前3个主要型分别为：黑潮亲潮偶合型、北太平洋海流型和冷平流优势型。最后还揭示了第一主要型与北太平洋副热带高压之间有意义的相关关系。 相似文献
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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
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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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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
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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
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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
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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
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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
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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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