共查询到20条相似文献，搜索用时 46 毫秒
1.
2.
3.
卫星重力估计陆地水和冰川对全球海平面变化的贡献 总被引：2，自引：0，他引：2
重力场恢复与气候试验（GRACE）卫星为高分辨率地监测全球海洋质量变化提供了一种新的手段。利用2003年1月至2014年12月Level-2 RL05的GRACE产品，进行去相关误差滤波、高斯滤波和海洋-陆地信号泄漏改正后，得到了全球陆地和海水质量变化，并分析了陆地水和冰川的质量变化对海平面长期变化的贡献。研究表明，全球陆地水和冰川的质量变化对海平面的贡献约为（2.09±0.54）mm/a，与卫星测高扣除海洋温盐数据比热容变化得到的海水质量长期变化（2.07±0.62）mm/a有着很好的一致性，其中全球陆地水储量对全球质量项海平面变化的贡献为（0.15±0.25）mm/a，南极冰盖对全球质量项海平面变化的贡献为（0.59±0.10）mm/a，格陵兰岛冰盖对全球质量项海平面变化的贡献为（0.72±0.12）mm/a，山地冰川对全球质量项海平面变化的贡献为（0.63±0.09）mm/a。并进一步讨论了不同分析中心GRACE重力场系数，一阶项系数和二阶项对质量项海平面变化的影响。结果表明，一阶项对质量项海平面的影响为（0.10±0.08）mm/a，二阶项对质量项海平面的影响为（0.16±0.04）mm/a，美国德克萨斯大学空间研究中心和德国地学研究中心分析结果较为一致，而美国国家航空航天局喷气推进实验室的结果则稍稍偏小。 相似文献
4.
5.
基于数字化海岸分析系统(DSAS)的海岸线变迁速率研究:以黄河三角洲和莱州湾海岸线为例 总被引：3，自引：0，他引：3
海岸线变化对海岸带生态环境改变、滨海土地侵蚀有着极其重要的影响,海岸线的提取和监测对海岸带生态系统的保护和管理具有重要意义。本研究基于数字化海岸线分析系统(DSAS,Digital Shoreline Analysis System),研究了黄河三角洲和莱州湾的海岸线时空变化规律。研究结果表明:通过提取1985-2015年6期的Landsat影像,发现近30年来黄河三角洲和莱州湾地区海岸线均呈现显著的向海方向扩张的趋势,且增长速率逐渐加快。黄河三角洲的终点变化速率(EPR,End Point Rate)约为73.0 m/a、线性回归速率(LRR,Linear Regression Rate)约为75.5 m/a,黄河港-大咀沟增长速度最快(129.2 m/a),受黄河泥沙输送的影响,黄河口和老黄河口岸线的几何形态呈现平滑的变化趋势;莱州湾岸线的EPR和LRR约为139.5 m/a和144.3 m/a,淄脉河河口-白浪河河口段增长速度最快(197.6 m/a),岸线变化较为显著的区域主要集中在港口、圈海堤坝、海水养殖等的地方。DSAS模型在海岸线定量化分析中具有显著优势,利用EPR和LRR指标能够科学有效地模拟岸线在时间和空间上的变化速率。 相似文献
6.
北格陵兰冰上岩心钻探计划(NGRIP)开始于1995年,其目的是研究最近120~130ka以来的古气候。除丹麦和德国外,参与国还有比利时、法国、冰岛、日本、瑞士、瑞典和美国。钻探平台位于格陵兰冰盖的西北部,其地理坐标为75°05′47″N,42°19′41″W,高度为海平面以上2921m。根据雷达研究资料,该地区的冰盖厚度为3085m。最后一次研究工作是于2004年夏季6月份开始的,那时的气温升至-30~-20℃,工作结束于8月份秋季暴风雪来临之前。钻探点的积雪量为195mm/a,而年平均气温则为-32℃。冰川表面缓慢地向北北西方向运动,速度为1·33m/a。科研计划工作量… 相似文献
7.
盐度是南海物理环境的重要组成部分之一,盐度的变化对南海的水动力环境有重要影响。利用1972-2010年的SODA数据集的5.01 m层月平均数据,分析南海海域海表面盐度的时空分布特征,采用基于最小二乘法的线性拟合分析南海海表面盐度的长期变化趋势。结果表明南海海域的海表面盐度在39 a间90%以上区域均呈现盐度下降趋势,整个海域SSS则以每年0.005 88 psu的速率下降,春季SSS下降速率最大为0.006 4 psu/a,夏季SSS下降速率在四季中最小为0.005 19 psu/a。 相似文献
8.
河谷型、海岸带、海岛礁以及滩涂等区域地表形变信息的准确获取,迫切且关键。利用25景升轨和28景降轨Sentinel-1A数据,基于SBAS-InSAR技术,获取兰州城区2014年10月~2016年9月的地表沉降速率图和沿视线方向(line-of-sight,LOS)的时相位移量,探讨升降轨数据在河谷型城市地表形变监测中的适用性。结果表明:升降轨Sentinel-1A数据之间的时相位移量具有高度关联性,其中升轨数据在地形起伏较大区体现出良好的干涉性,而降轨数据在平坦区表现出较好的监测能力。兰州城区大部分区域处于稳定状态,但沙井驿、九州、小达坪、东岗、伏龙坪、西客站以及周边区域地表存在沉降趋势,最大沉降速率可达30 mm/年。联合升降轨Sentinel-1A数据监测河谷型、海岸带、海岛礁以及滩涂等区域地面沉降具有可行性和可靠性。 相似文献
9.
库克群岛海域海洋环境因子对长鳍金枪鱼渔获率的影响 总被引：2，自引：0，他引：2
为了提高延绳钓渔业中长鳍金枪鱼(Thunnus alalunga)的渔获率,需了解海洋环境因子对其渔获率的影响。利用2013年9月8日-2013年12月31日库克群岛海域延绳钓渔业调查数据,包括:钓钩作业深度,温度、叶绿素a浓度和海流垂直剖面数据,作业参数,渔获统计数据等,采用逐步回归的方法建立钓钩作业深度预测模型,利用统计和聚类分析的方法分析长鳍金枪鱼渔获率与海洋环境因子的关系。结果表明:在库克群岛附近海域,长鳍金枪鱼渔获率较高的水层、温度、叶绿素a浓度、东西方向、南北方向、垂直方向、水平方向的海流分别为160~200 m、21.0~23.9℃、0.040~0.159μg/L、0~0.1 m/s、0.1~0.2 m/s、0.08~0.10 m/s和0.1~0.2 m/s。在该海域作业时,建议在长鳍金枪鱼渔获率较高的水层、温度、叶绿素a浓度、东西方向、南北方向、垂直方向和水平方向的海流范围内增加钓钩投放数量。 相似文献
10.
莱州湾南岸海岸侵蚀过程与原因研究 总被引：18，自引：0，他引：18
采用历史资料对比分析的方法,对莱州湾南岸1958-2004年的海岸侵蚀进行了研究。结果表明,1958-1984年,莱州湾南岸岸线平均侵蚀后退速率为27 m/a,0 m等深线后退速率为27~65 m/a,岸滩平均蚀低速率为2.1 cm/a。1984-2004年,莱州湾南岸岸线位置基本无变化,岸滩平均蚀低速率为1.04 cm/a,水深5 m以浅的区域表层沉积物变粗。海面相对上升、入海泥沙量减少和风暴潮是研究区海岸侵蚀主要原因,三者对海岸侵蚀影响权重比为3∶5∶2。 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.
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
13.
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
14.
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
15.
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
16.
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
17.
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
18.
19.
20.
《海洋学报(英文版)》2014,(11):161-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