台湾海峡地区雾形成的天气类型分析

利用 1 980— 1 997年东亚逐日 0 8时地面天气图资料 ,归纳并分析了台湾海峡地区(2 0°— 2 7°N ,1 1 5°— 1 2 5°E)形成雾的 4种天气类型 ,它们分别是冷平流主导型、暖平流主导型、均压场型和台风外围型 ,为台湾海峡地区雾的预报提供天气学参考。     

南印度洋风场时空特征分析

本文根据1950～1995年共46a的南印度洋船舶气象报资料,按1°×1°和5°×5°网格统计的海面风进行分析研究。通过分析每月各要素的等值线分布图,得出南印度洋风场季节变化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,冬季比夏季风强盛,相应的平均风速、6级和8级以上大风频率也较大;全年风场基本相似,10°S以北为季风气候区,而其它海域信风区常年盛行东南风,40°S以南盛行偏西风。本文为船舶远洋交通运输、远洋出访和科学试验等活动,提供了较为详细的风场资料及变化规律。     

中西太平洋金枪鱼围网高产渔区年间变化及其原因分析

金枪鱼类是中西太平洋海域重要的经济鱼种,其中鲣产量约占到总产量的50%。本研究利用1995-2010年16年的中西太平洋（20°S~20°N,120°E~155°W）鲣围网生产统计数据和Niño3.4海区（5°S~5°N,120°~170°W）海表温度异常数据,对这16年鲣产量最高的十大渔区（5°×5°）进行时空格局分析,讨论渔场分布差异及CPUE与ENSO指数的关系。结果表明:16年间十大作业渔区主要分布在5°S~5°N、130°~175°E区域,这十大渔区产量占总产量的比重达47.5%,其中5°S~0°、155°~160°E,0°~5°N、130°~135°E,0°~5°N、135°~140°E及5°S~0°、160°~165°E等4个渔区产量占高产渔区产量的比重均超过10%,是中西太平洋重要的鲣产区。高产渔区的分布受海表温度影响较大,在厄尔尼诺时期,高产渔区分布明显偏东,主要分布在155°~180°E海域;在拉尼娜时期,高产渔区分布明显偏西,主要分布在130°~160°E海域。     

长江口区化学耗氧量的分布特征

根据“三峡工程对长江河口区生态与环境的影响和对策”的研究要求,为掌握工程兴建前长江口环境状况,我们于1985年8月一1986年5月,对122°-124°E,30°45′-32°00′N海域及受潮汐影响的江段进行了调查。本文根据5个航次的调查资料阐述了长江口海域化学耗氧量(COD)的分布特征。     

南印度洋中国中山站至澳大利亚费里曼特尔断面海洋锋位置及其年际变化

根据中国第18次南极科学考察队2002年1～3月在南印度洋从中山站外普里兹湾到澳大利亚费里曼特尔断面的走航XBT/XCTD资料和CTD资料及1998年1月、1999年2月和2000年3月等其他航次的调查资料,分析了该航线上海洋锋的位置及其年际变化:(1)在75°～78°E南极陆坡锋的位置在645°～655°S;在84°～100°E范围极地锋在535°～543°S附近;在96°～103°E亚南极锋在46°S～470°S附近;在110°E附近亚热带锋在372～380°S之间;(2)在南极极锋区存在显著等温线、等盐线的上凸和下凹,不同年份发生位置有变化;(3)在亚南极锋北侧,等温线、等盐线呈垂直排列的状态,温度、盐度垂直方向上分布均匀一致;(4)与1979,1991和1992年该区域同期的资料相比,近4a观测到的极地锋显著偏南1个纬距以上.     

台湾周边海区的海浪特点

本文收集了1960～1990年的国际气象船舶报资料,以台湾岛为中心,范围为20°～28°N、116．5°～124°E的海区,并将整个海区划分为台湾海峡、台湾东部、台湾北部、巴士海峡四个海域。按1°×1°网格逐月进行统计,并将统计结果绘制成海面风、海浪玫瑰图,以及平均波高、平均周期、大浪大涌(≥2．5m)频率、小于等于1．2m波高和各类波长频率分布图。通过分析得出全年的海浪特点及其分布规律,这对发展国民经济、航海和军事活动具有重要意义。     

南大西洋海面风场时空特征分析

本文根据 1950 年~1995 年共 46a 的南大西洋船舶气象报资料,按 1°×1°和 5°×5°网格统计的海面风进行分析研究。通过分析每月各要素的等值线分布图,得出南大西洋海面风场季节变化不如北大西洋显著,但仍有较明显的季节变化,冬季比夏季强盛,相应的平均风速较大,6、8 级大风频率也较高。位于赤道和 25°S 之间的信风区,主要盛行东南风;副热带高压带,风速小,风向变化不定;35°S 以南的西风带风力较强。对这些规律的总结归纳,为该地区的各种活动提供了较为翔实的海面风场变化规律。     

南太平洋风场时空统计特征分析

南太平洋风场时空统计特征对船舶远洋交通运输、远洋出访、南极考察和科学试验等活动有重要实用价值。本文根据 1 950～ 1 995年共 46a的南太平洋船舶气象报资料 ,按 1°× 1°和5°× 5°网格统计的海面风进行分析研究。通过分析每月风各要素的等值线分布图 ,得出南太平洋风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 ,冬季比夏季风强盛 ,相应的平均风速 6级和 8级以上大风频率也较大 ;全年风场基本相似 ,低纬度地区 (2 5°S以北至赤道 )为信风区 ,常年盛行东至东南风 ;2 5°S～ 35°S的广大海域上 ,风力较小 ,风向变化最大 ;40°S以南盛行偏西风 ,风力最强。     

中太平洋西部毛颚类的分布

分析1979年1～2月、4～5月在中太平洋西部水域(0°～5°N,160°～165°E)调查所采集的浮游动物样品,共记录毛颚类种类15种,并根据现场实测的水文资料,对该区毛颚类的种类组成、数量分布与海区环境因子的相关性进行初步探讨.     

欧亚大陆阻塞高压的统计特征及其与中国东部夏季降水的关系

该文利用美国 NCEP再分析资料 2 4年 (1976～ 1999年 )的逐日 12 h欧亚大陆 (0°E～15 0°E,2 0°N～ 90°N) 5 0 0 h Pa位势高度场资料 ,对阻塞高压 (简称阻高 )的活动进行了统计分析。结果表明 ,阻高主要发生在乌拉尔山地区。阻高活动有明显的季节性变化 ,春夏季阻塞形势发生得最多 ,持续时间最长 ,秋季最少且持续时间短。小波分析和离散功率谱分析都表明阻高发生的频数存在明显的年际变化 ,主要包含 3～ 4年和准 8年的周期振荡。进一步研究表明 ,乌拉尔山附近 (5 0°N～ 80°E)的阻高活动与夏季江淮流域的降水有着很好的正相关 ,与华南、华北、东北区域的降水有着很好的负相关 ;而贝加尔湖附近 (80°E～ 12 0°E)的阻高与中国东部的降水关系则正好相反。冬春季 (1～ 3月 )阻高活动对当年夏季的降水有着一定的中长期预报意义。     

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin

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.     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

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.     

A Review of Some Environmental Issues Affecting Marine Mining

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.     

Increased Particle Fluxes at the INDEX Site Attributable to Simulated Benthic Disturbance

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.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

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。     

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.     

Determination of In Situ Sediment Shear Strength from Advanced Piston Corer Pullout Forces

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.     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

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.     

《Acta Oceanologica Sinica》Vol. 33(2014) contents

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