共查询到17条相似文献，搜索用时 234 毫秒
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探地雷达是一种利用电磁波的反射原理探测地下介质分布特征的地球物理勘探技术，在冰川研究中发挥了重要作用。在天山一号冰川上用探地雷达进行了探测，获得了能够清晰地分辨冰一岩界面的雷达剖面。根据这些雷达剖面读出冰厚值，再结合最新的冰川地形图，作出了天山一号冰川的冰厚等值线图和冰下地形图；并由天山一号冰川最新的表面积数据推算了冰储量。 相似文献
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探地雷达因其快速、准确、无损、高分辨率等优势而被广泛应用于冰川学领域。以天山托木尔峰青冰滩72号冰川为例,着重介绍了探地雷达在冰川厚度及冰下地形探测中的应用。通过对雷达图像的处理和解译,获取了高精度的冰川厚度数据,恢复了冰下地形,计算了冰储量,并分析了冰川厚度变化对气候变化的响应。结果表明:冰舌厚度为0～148 m;冰储量为0.055 860 km3,折合成水为0.050 274 km3。近50年来,该冰川呈现强烈消融,与冰川区气温快速上升有直接关系,雷达探测为研究此响应机制提供了定量化的科学依据。 相似文献
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冰川雷达探测主要采用调制脉冲雷达系统。其基本原理是向冰川发射载波频率为几十至几百兆周的无线电波,接收来自冰川内部或底部反射的回波,藉此来测定冰川的厚度,研究冰川的内部构造、温度和运动状况等。由于冷性冰川冰对电磁波的吸收率很小,吸收系数一般小于几分贝/100米,相对介电常数也较稳定,一般为3.2左右;冰川体(尤其是冷性冰川)一般较均匀。因此,有利于雷达探测技术的应用。六十年代初,首先在极地冰川上使用雷达探测技术,成功地取得了冰层厚度的资料。此种方法适合在飞机上测量,具有快速、经济、准确的特点。目前,已成为冰川学研究的重要技术手段之一。一九七九年五月,我们首次在祁 相似文献
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探地雷达作为一种高精度无损探测新技术，已广泛应用于工程勘察各领域，具有探测速度快、定位准确、轻便灵活、可实现连续透视扫描以及二维彩色图像实时显示等优点。不同的地质条件，探地雷达将表现为不同的波谱特征。文章在分析了探地雷达的分辨率与地层介质、探测深度、天线频率的基础上，例举了其在第四系地质、活动断裂、滑坡、土体性质等不同地质条件下的探测效果。 相似文献
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结合上林湖区域水体电性参数测量结果,开展了探地雷达水下考古试验探索。在上林湖指定水域用机动木船承载雷达仪器和工作人员进行了水下情况调查,通过对比试验,分析了频率为100 MHz、200 MHz、400 MHz的雷达天线对不同深度水域及水底地层的反射特征,在此基础上,对探地雷达数据进行处理及解释。探地雷达探测结果清楚地显示了古水坝、窑炉遗址、陶瓷废墟、古河道和码头堤岸等多种不同的水下考古目标,并可对湖底地层中的局部隐伏异常实现高精度成像。经过潜水探摸,进一步核实了本次探地雷达的调查结果。 相似文献
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简要介绍了探地雷达工作原理及其探测地下空洞的方法技术，以广州某地基勘察中地下空洞的检测为例，分析了地下空洞的雷达波组特征，总结了探地雷达时深剖面图的异常特征。指出该方法具有速度快、探测精度高、可获得连续结果等特点。经开挖验证，探地雷达异常特征与地下空洞实际位置相吻合。 相似文献
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祁连山八一冰川雷达测厚与冰储量分析 总被引：12，自引：7，他引：5
基于2006年5月利用探地雷达对祁连山八一冰川厚度的系统测量资料,绘制了该冰川冰厚度分布等值线图,计算出了该冰川的平均厚度为54.2 m,冰储量为0.153 km2.这几乎是我国第一次冰川编目资料中给出的八一冰川平均厚度(30 m)和冰储量(0.0843 km3)数据的1倍.由此可见,准确评估我国冰川的冰储量是冰川水资源研究亟待解决的重要问题.将八一冰川冰面地形图与冰厚度分布图相结合,绘制了该冰川的冰床地形图,结果表明:其崎岖不平的冰床地形与其相对平缓的冰面地形形成了显明的对比,显示了冰帽冰川的形貌特征. 相似文献
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探地雷达在淡水区浅水域的探测试验 总被引：1，自引：0，他引：1
通过堤防护岸水域抛石探测、水下砼格及碎石层探测、江边堆场滑坡水域探测三个案例,说明探地雷达在淡水区浅水域探测效果。重点分析了探测对象所处环境的电导率、介电常数和探测所采用天线频率对探测效果的影响。探地雷达填补了浅水域工程勘察空白,研究成果对非水域探地雷达探测与检测具有借鉴意义。 相似文献
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南极地区自然界现存的冰雪体,是南极冰川学研究的对象。南极冰雪体及其变化对全球水体的分布和循环以及气候、环境演变具有十分重要的影响,因而使南极冰川学研究不仅在南极科学中处于主要地位,而且在全球变化研究中举足轻重。 南极冰盖巨厚的冰雪内保留有数十万年乃至上百万年地球环境和气候变化的详细记录,冰芯综合研究受到高度重视。目前,南极冰川学正在向大尺度宏观方向和冰体内部微观方向两个方面迅速发展,涉及的学科更加广泛。其热点为:1、冰盖的物质和动态平衡——海平面和气候变化;2、冰芯综合研究。 中国南极研究起步较晚,南极热的兴起仅是最近十年的事情,总体水平与国际先进水平相比存在较大差距。为此,笔者提下列几点建议:1、南极冰川学是一门国际性很强的学科,其研究工作只能从横向与各国同行相比,要求研究内容具有国际水平;2、为接近和达到国际水平,需要培养一批年富力强、德才兼备的南极冰川学科研骨干队伍;3、抓紧建设南极冰川学实验室的建设;4、切实加强国内各部门、各学科之间的联系和合作。 相似文献
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We investigate the accuracy and robustness of one of the most common methods used in glaciology for finite element discretization of the ??-Stokes equations: linear equal order finite elements with Galerkin least-squares (GLS) stabilization on anisotropic meshes. Furthermore, we compare the results to other stabilized methods. We find that the vertical velocity component is more sensitive to the choice of GLS stabilization parameter than horizontal velocity. Additionally, the accuracy of the vertical velocity component is especially important since errors in this component can cause ice surface instabilities and propagate into future ice volume predictions. If the element cell size is set to the minimum edge length and the stabilization parameter is allowed to vary non-linearly with viscosity, the GLS stabilization parameter found in literature is a good choice on simple domains. However, near ice margins the standard parameter choice may result in significant oscillations in the vertical component of the surface velocity. For these reasons, other stabilization techniques, in particular the interior penalty method, result in better accuracy and are less sensitive to the choice of stabilization parameter. During this work, we also discovered that the manufactured solutions often used to evaluate errors in glaciology are not reliable due to high artificial surface forces at singularities. We perform our numerical experiments in both FEniCS and Elmer/Ice. 相似文献
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This study is a comparative investigation of the debris layer and underlying ice of the Koxkar Glacier using multi-frequency GPR with antennae having different frequencies. Together with analysis of the fluctuation of the radar signal amplitude and polarity, the debris layer and underlying ice were analyzed on the basis of high-resolution GPR images. It was found that the optimal average velocity in the shallow layer (0–4 m) is 0.06 m/ns. Images obtained with different frequency antennas have different characteristics; and the performance of the 200 MHz antenna for a debriscovered glacier is the best. The interpretation of typical GPR image is validated by using FDTD numerical model. Combining the debris layer thickness and the underlying ice structure, the effect of debris layer on ablation of glacier ice and forecast of the glacier change in the aspect of thickness-thinning and glacier retreat can be estimated. This study can provide as a reference to the formation mechanisms and estimation of the ice volume of glaciers covered by debris. 相似文献
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I. A. Nemirovskaya 《Geochemistry International》2009,47(4):393-404
This paper reports data on the concentrations of organic compounds (organic carbon, Corg; lipids; aliphatic hydrocarbons, AHCs; and polycyclic 0aromatic hydrocarbons, PAHs) in snow, ice, and subice waters from the mouth of the Severnaya Dvina River (2005–2007) and Kandalaksha Gulf (Chupa Bay, 2004) at the end of winter. It was established that organic compounds are accumulated in the snow and upper ice layer near the town of Archangelsk. The distribution of molecular markers indicates that pollution was mainly caused by local fallouts. In Chupa Bay, organic compounds are concentrated in the lower ice layers, which is typical of the Arctic snow-ice cover. The high contents of organic compounds in the snow-ice cover of the White Sea are caused by the pollution of its air and water during the winter season. 相似文献
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海冰在全球气候系统中扮演着重要角色。在中国第二次北极科学考察中，使用3D雷达探测结合冰钻进行海冰测量。雷达剖面上可清楚识别冰-水界面，与冰钻测量结果较好地吻合。雷达3D图像清晰显示了冰底界面在3D方向的起伏变化以及冰内构造的空间展布情况。对三维探测区域内海冰厚度统计显示，所测冰盘的平均厚度为4．15m，较厚的区域位于左下角，最大厚度约为6．4m，较薄的区域是在中央和左上角区域，最小的厚度小于3．0m。经过进一步计算可提供如海冰上下表面面积、海冰体积等参数，为遥感和数值模拟提供地面校核数据，也为海冰形成机制和动力作用过程研究提供佐证和依据。 相似文献
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Internal structure and trend of glacier change assessed by geophysical investigations 总被引：1，自引：1，他引：0
Ground-penetrating radar (GPR) is a useful tool for mapping the thickness, morphology and structure of alpine glaciers. Englacial information obtained during a field survey of the Koxkar Glacier in Tian Shan, China, in June 2008 was retrieved from GPR profile data. At least four specific types of structures can be identified from the GPR reflection image: (1) hyperbolae from point sources, (2) irregular linear distributed features, (3) a dense chaotic return zone above a clearly defined bed reflection and (4) linear reflection within the ice body. The interpretation of a typical GPR image was validated using waveform analysis and a finite-difference time-domain numerical model. Through a series of data analyses, these types of reflection characteristics were strongly related to englacial melting. Considering also the GPR result of the debris thickness distribution at the terminus, it is concluded that strong glacial ablation does not occur at the terminus but at a position higher than the terminus where there is a thin layer of debris and relatively high temperatures. Meanwhile, there are many lakes receiving mostly englacial discharge that greatly erode the ice body through melt-water discharge in some regions, and a thick layer of debris insulating the ice body at the terminus; these features may differentiate the retreat of the Koxkar Glacier from the general retreat of glaciers. In the future, with the ablation of glaciers, the central positions of intense ablation may be disconnected and there may be a dead zone at the terminus. 相似文献
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A database comprising some ～5200 individual striation measurements on bedrock surfaces across the island of Ireland was used to produce maps of flowsets corresponding to individual ice flow events during the last (late Devensian) glacial cycle. These flowsets were identified on the basis of regional-scale correspondence between striae orientations which, when linked together spatially, are able to identify consistent ice flow vectors. Four main chronological stages are identified on the basis of this evidence: (i) incursion of Scottish ice into Ireland; (ii) glacial maximum conditions; (iii) ice retreat and dissolution; and (iv) development of localised ice domes. Striae-based reconstructions of the glaciology of the last Irish ice sheet are qualitatively different from those based on bedform (mainly drumlin and ribbed moraine) evidence. Significant differences are apparent in upland areas which have fewer preserved bedforms and a higher concentration of striae. Combining bedform and striae datasets will enable a better understanding of the temporal evolution of the ice sheet. It is likely that both datasets record a snapshot of ice flow direction and subglacial conditions and environments immediately prior to preservation of this directional evidence. 相似文献