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1.
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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西天山托木尔峰南麓大型山谷冰川冰舌区消融特征分析 总被引：4，自引：3，他引：1
基于对托木尔峰南麓托木尔型山谷冰川的野外考察和典型冰川的定位观测,对冰面被表碛广泛覆盖的所谓“托木尔型”冰川冰舌区表碛与冰面消融的关系进行了研究. 结果表明：表碛对冰面消融、冰川水文过程、冰川变化等均具有重要影响,当表碛厚度超过3 cm时,表碛对冰面消融就产生明显抑制作用,且随着厚度增加,冰面消融显明减弱. 科其喀尔冰川表面的观测表明,由末端向上,表碛厚度逐渐减薄. 受表碛影响,科其喀尔冰川区最大的消融量出现在海拔3 800~3 900 m之间、表碛物厚度小于10 cm的区域内;冰川消融强度由此向上随着海拔的升高而下降,向下随表碛厚度的增大而减弱. 冰面湖的发育是表碛覆盖冰川的又一主要特征,湖水对冰面的融蚀和快速排泄成为冰面产汇流的主要过程. 科其喀尔冰川研究表明,两三个冰面湖排泄形成的融蚀冰量就相当于冰川末端退缩造成的冰量损失. 因此,冰面湖等热喀斯特地形的形成、扩张融蚀、融穿排泄、形成湖区低地,这一周而复始的过程不仅是其主要消融方式之一,而且也强烈的影响着冰川水文及冰川变化. 托木尔峰南麓地区大型冰川变化主要以厚度减薄为主,而不是像大多数冰川显著的变化主要表现在末端和面积减少方面. 相似文献
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天山南坡科其卡尔巴契冰川度日因子变化特征研究 总被引：14，自引：7，他引：7
度日模型是估算冰川消融的一种简单而有效的方法.根据科其卡尔巴契冰川2003年的观测资料,分析了该冰川度日因子的空间变化规律及其影响因素.研究表明:各高度上的度日因子,介于2.0～9.7mm·℃-1·d-1之间变化,平均值为5.7mm·℃-1·d-1,与青藏高原各冰川及其它地区冰川相比较小;随着海拔的增高,度日因子随之递增;随平均气温的升高而随之递减.由于冰面状况复杂,度日因子变化幅度较大,裸冰区的度日因子明显大于表碛覆盖区.人为测量误差、反照率、地形等对度日因子的影响也不容忽视. 相似文献
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Thermal regime of a supraglacial lake on the debris-covered Koxkar Glacier, southwest Tianshan, China 总被引：1，自引：0，他引：1
A supraglacial lake was surveyed on the Koxkar Glacier in southwest Tianshan from July to September 2007 and July to September 2008, and the temperature variation characteristics of the lake, debris and debris-free ice were analyzed at different depths to determine the thermal regimes. In addition, the discrepancies of temperature variation characteristics were investigated for different geomorphic units of the ablation zone of the Koxkar Glacier. It was found that daily temperature variation curves for deep water are V-shaped because meltwater from the glacier surface at temperatures of around 0°C feeds the lake and mixes with the relatively high-temperature surface water during the day. As the water temperature rises to approximately 4°C, the mixed water sinks and forms a low-temperature trough in the deep water of the lake in the middle of the day. The vertical lapse rate of the lake water temperature against depth (?0.33°C/m) has a magnitude lower than that of the debris (?4.29°C/m) and that of the debris-free ice (?0.38°C/m) in the Koxkar Glacier??s ablation zone. The temperature curve for the surface water largely varied between the temperature curves for the debris at depths of 0.2 and 0.5?m. The surface thermal condition of the ablation zone is significantly affected by the daily weather, and there is a limited influence in debris at a depth of 1?m and in the lake at a depth of 5?m. 相似文献
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Using radio echo sounder, ice thickness of Keqikaer Glacier tongue was measured in 1981 and 2004. Data obtained by comparing
topographical maps, aerial and satellite photographs at different times, illustrates changes of the thickness and advance/retreat
of Keqikaer Glacier. Keqikaer Glacier has been in intensive retreat since the 1990s and become thinner since the 1980s. Measured
thickness of the ice tongue indicates reducing with a speed of 0.5–1.5 m a−1 since 1981. The shrinkage of the glacier terminus is less than 2% of the total length during the last 30 years; however,
the retreat of terminus position and the thinning of the ice thickness provides significant information that these glaciers
on the south slope of Mt. Tuomuer are in an intensively decreasing phase in recent time. 相似文献
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近30a来托木尔峰南麓科其喀尔冰川冰舌区变化 总被引：7，自引：6，他引：1
20世纪80年代中期以来,托木尔峰南麓地区冰雪融水量明显增加,冰川处于强烈的消融退缩状态.根据对科其喀尔冰川冰舌区不同海拔探测表明,近30 a来冰川厚度明显减薄,冰舌区平均厚度减薄在0.5~1.5 m·a-1之间.对科其喀尔冰川末端位置研究表明,科其喀尔冰川进入20世纪90年代以来处于比较强烈的退缩状态.相对于1974年的冰川位置,冰川退缩了380 m左右.科其喀尔冰川的全面退缩,标志着托木尔峰地区冰川处于全面的负物质平衡状态. 相似文献
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新疆哈密是资源性缺水地区,冰川是该区主要的供给水源。为了对该区冰川和水文水资源的现状和未来变化做出合理评价和预估,以榆树沟6号冰川和庙尔沟冰帽为代表,结合野外实测资料以及近年来在冰川变化领域所取得的相关研究成果,综合分析了在气候变暖背景下新疆哈密地区冰川近年来的变化过程及对水资源的影响。结果表明,1972-2011年,榆树沟6号冰川厚度平均减薄20 m,减薄速率约为0.51 m/a,冰川末端退缩254 m,年均退缩约6.5 m。由于强烈消融,冰川表面径流发育明显,且在末端有冰碛湖形成。相比之下,庙尔沟冰帽消融速率相对较小,对气候变暖的敏感度较低,这与冰帽类型和所处海拔较高有直接关系。综合分析发现,流域有无冰川覆盖及覆盖的比率大小,直接造成哈密地区不同流域近期河川径流变化的差异。 相似文献
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Parmanand Sharma Lavkush K Patel Rasik Ravindra Ajit Singh Mahalinganathan K Meloth Thamban 《Journal of Earth System Science》2016,125(3):459-473
As part of the on-going annual mass balance measurements on Batal and Sutri Dhaka glaciers, observations were made during peak ablation (August–September) season in 2013 to understand the response of debris covered and clean-ice (debris free) glacier surface to melting processes. Though, both the Batal and Sutri Dhaka glaciers have almost similar geographical disposition, Batal shows extensive debris cover (90% of the ablation area), while the latter is free from debris (only 5% of the ablation area). The thickness of debris in Batal glacier is inversely proportional to altitude, whereas Sutri Dhaka mostly experienced debris-free zone except snout area. Observation revealed that the vertical gradient of ablation rate in ablation area is contrastingly opposite in these two glaciers, reflecting significant control of debris thickness and their distribution over glacier surface on the ablation rates. While different thickness (2–100 cm) of debris have attenuated melting rates up to 70% of total melting, debris cover of <2 cm thickness has accelerated melting up to 10% of the total melting. Estimated melt ratio reveals that about 90% of the ablation area has experienced inhibited melting in Batal glacier, whereas only less than 5% ablation area of Sutri Dhaka has undergone inhibited melting. Comparison of topographical maps of 1962 with successive satellite images of the area demonstrates a terminus retreat of 373 ± 33.5 m and 579 ± 33.5 m for Batal and Sutri Dhaka glaciers for the period 1962–2013, respectively. 相似文献
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Lavkush Kumar Patel Parmanand Sharma Meloth Thamban Ajit Singh Rasik Ravindra 《Arabian Journal of Geosciences》2016,9(4):309
Complex factors such as climate, glacial geometry, topographical features and debris covers have significant influence on the dynamics of the Himalayan glaciers. Presence of debris covers on the surface of glaciers can significantly alter the surface energy balance and influence the climatic response of glaciers. In this study, the influence of debris covers and its impact on the ablation processes were analyzed from the in situ data collected over the surface of the Batal glacier in Chandra Basin, Western Himalaya. Almost 90 % of the ablation zone of the Batal glacier is covered by debris, 35 % of which is thick debris (>10 cm). Fourteen stakes (depth ～10 m) with increasing altitude and with varying debris thicknesses were installed to cover the whole ablation zone. Among them, four stakes represent thin debris (<2 cm), two stakes represent 2–5 cm debris thickness, two stakes represent 5–25 cm debris thickness, three stakes represent 25–50 cm debris thickness and three stakes represent >50 cm debris thickness. Our study has revealed high surface melting (?2.0 cm. w.e.d?1) in the debris free glacier while low surface melting observed in thick debris covered ice (?0.6 cm. w.e.d?1). Although limited to one season, this observation revealed a significant difference in the rate of surface melting as per the increasing debris thickness. Contrasting to normal ablation pattern over glaciers, Batal has experienced inverse retreat rate of ablation along with increasing altitude. A high degree of negative correlation (r = ?0.82, p < 0.05) between ablation rate and debris thickness in Batal suggest a significant control of debris thickness over ablation rate. 相似文献
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祁连山老虎沟12号冰川退缩对细菌优势种群影响的初步研究 总被引：1，自引：1，他引：0
随着全球冰川正在越来越多的地区融化, 冰川微生物资源很可能会由于冰川退缩而未被人类所发现就已受到生存的威胁而濒危.以祁连山老虎沟12号冰川消融区和末端雪样及末端土样为研究对象, 采用培养方法、分子鉴定, 研究冰川雪样优势菌群在冰川末端土样的分布状况及生理生化指标变化情况, 分析冰川细菌优势菌群在冰川退缩后适应非雪环境的能力.结果表明: 冰川末端雪样优势菌为1BW1和1BW2所代表的Pedobacter, 该属在冰川消融区雪样和冰川末端土样中未分离到; 冰川消融区雪样优势菌为2BW所代表的Acinetobacter, 该属在冰川末端雪样中的数量较少, 在冰川末端土样中的数量更少.不同采样位点16S rRNA序列相似性高的菌株其生理生化特征比相同采样位点的大.因此, 冰川冰退缩可能会引发冰川雪样中的优势种群不能适应新环境而灭绝. 应加强冰川细菌资源利用和保护的研究基础. 相似文献
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中国冰川主要分布在青藏高原及周边地区,在这一广大的区域内分布有冰川46377条。研究表明,中国西部变暖显著,1950年代以来平均气温上升0.2℃/10a,其中1990年代是近千年中最暖的10年;同时,1950s以来西北各省的降水量增加了约18 ％ 。为认识这一气候变化对中国西部冰川的影响,利用遥感和地理信息系统方法,获取了近50a来5000多条冰川的变化状况。结果表明,中国西部82.2 ％ 的冰川处于退缩状态,冰川面积减少了4.5 ％ ,同时也有一些冰川处于前进状态。此外,近数十年中国西部冰川变化表现出明显的区域差异,青藏高原中部和西北部地区的冰川相对稳定,而高原周边山区的冰川物质亏损严重,处于加速退缩状态。 相似文献
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Genesis of the Sveg tills and Rogen moraines of central Sweden: a model of basal melt out 总被引：1，自引：0，他引：1
JOHN SHAW 《Boreas: An International Journal of Quaternary Research》1979,8(4):409-426
Shaw, John 1979 1201: Genesis of the Sveg tills and Rogen moraines of central Sweden: a model of basal melt out. Boreas, Vol. 8, pp. 409–426. Oslo. ISSN 0300–9483. Climatic amelioration in permafrozen regions causes basal melting of Polar glaciers. Supraglacial debris concentrated at the ice surface by ablation at first inhibits the ablation process. When the surface debris is equal in thickness to the active layer no further surface melting occurs. Till deposition processes in permafrozen areas are consequently dominated by melt out from a basal isothermal zone at melting point. The basal melt-out process is influenced by englacial structures and forms which are also largely responsible for the resultant landforms and deposits. Such basal melt out may also occur in areas with less severe climate. A model for deposition largely by basal melt out is documented by field observations in central Sweden. Melt-out tills in areas of former extending or uniform glacier flow show an upward facies change corresponding to poorly attenuated and highly attenuated englacial facies. The till facies are recognised in terms of stratigraphic position, surface form, internal structure, and clast lithology, size, shape, and long-axis orientation and dip. Areas of former compressive flow are characterised by basal melt out of folded and dislocated englacial debris zones in which the stacking of debris produced transverse moraine ridges. The internal structure of the ridges includes folded till bodies dislocated by thrust planes, horizontal, stratified layers cross-cutting the tectonic structures, and characteristic distributions of clast long-axis orientation and dip. The morphology of the ridges at both the macro and micro scales is in accord with the proposed model of formation. The morphological and sedimentological associations produced largely by basal melt out are summarized. An additional implication of the proposed model is that gradual lowering of the supraglacial sediment surface by bottom melting of regionally stagnant ice may be the cause of widespread marine or lacustrine transgression. 相似文献
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表碛下冰面消融模型的改进 总被引：3，自引：2，他引：1
针对已有的表碛下冰面消融模型的缺点,通过对模型算法、模型假设和模型结构等方面进行改进,在模型的易用性和模拟精度上有了较大的提高.科其喀尔冰川的实例研究表明,改进模型对于表碛区不同试验点上地温的模拟是较好的,变化趋势基本一致,变化幅度也相当.但也存在模拟值与实测值之间变化相位差异的突出问题,实际操作可以通过适当的校正程序得以较好的解决.模型中对表碛热参数的常数化处理不会产生较大的模拟误差,此外计算开始时均一表碛温度的假设不会对表碛温度的整体模拟效果产生较大的影响.通过地温模拟得到的冰面消融速率与利用实测表碛热通量计算的冰面消融速率的比较说明,模型思路合理且算法可行. 相似文献
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Neogene fjordal sedimentation on the western margin of the Lambert Graben, East Antarctica 总被引：5，自引：0，他引：5
The Lambert Graben is occupied by the world’s largest fjord system, through which flows the Lambert Glacier, the Amery Ice Shelf and their tributaries. Along the western margin of the graben, in the northern Prince Charles Mountains, remnants of uplifted Miocene and Pliocene strata of the glacigenic fjordal Pagodroma Group total more than 800 m in thickness. These sediments provide evidence for a dynamic East Antarctic ice sheet during the Neogene Period. Each of the four Pagodroma Group formations defined from this region rests unconformably on either Proterozoic or Permo‐Triassic rocks. The unconformity surfaces represent parts of the walls and floors of Neogene fjords. For these surfaces to have been eroded, the ice must have been grounded out as far as the continental shelf in Prydz Bay. The Pagodroma Group was deposited by wet‐based glaciers discharging into a fjordal setting and includes lithofacies that are quite different from those produced by modern Antarctic ice masses. The principal lithofacies are massive diamicts and soulder gravels, deposited both close to a calving, grounded glacier terminus and from icebergs. The few stratified diamicts are the product of more distal iceberg sedimentation. An ice‐transported gravel lithofacies includes rockfall debris derived from palaeofjord walls and mixed with subglacially derived diamicts. Some lithofacies contain evidence of subaquatic slumping and gravity flowage. Volumetrically minor lithofacies include laminites, with some exposures exhibiting large ice‐rafted clasts. The laminites represent less proximal, mainly ice‐free fjordal sediments, resulting either from tidal‐current sorting of suspended sediment originating from subaquatic glaciofluvial discharge, or from turbidity currents derived from unstable subaquatically deposited glacigenic sediment. The Pagodroma Group provides a record of multiple glaciation by dynamic, sliding glaciers carrying large amounts of both basal and supraglacial debris. The closest modern analogues, in terms of the thermal and dynamic characteristics of the Neogene Lambert Glacier, appear to be the fast‐flowing tidewater glaciers of East Greenland. These glaciers originate from the interior ice sheet and discharge large volumes of icebergs; the resulting lithofacies are predominantly diamicts. 相似文献
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基于分形的冰塔林形态模拟初探 总被引：1，自引：1，他引：0
冰塔林在低纬度高海拔地区的大型冰川上发育广泛, 如何评估其对冰川总体积的贡献意义显著.对冰塔林的形态特征进行了初步探讨, 结果表明: 东绒布冰川冰塔林呈现出分形特点, 其盒维数在1.3～1.9之间, 无标度区间约为40～160 m. 通过构建冰塔林消融模型, 认为冰塔林区域的整体消融率(约50%)不依赖于其地形参数的变化; 估计珠峰东绒布冰川冰塔林体积对冰川总体积的贡献率约为3.7%, 可以忽略. 相似文献
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大陆型冰川与海洋型冰川物质平衡对比研究——以天山和阿尔卑斯山典型冰川为例 总被引：8，自引：6，他引：2
物质平衡是冰川对气候变化最直接的响应,是冰川变化的重要参数.大陆型冰川与海洋型冰川发育在不同的水热环境下,它们对气候变化的响应程度、过程和机理存在很大差异,因此在全球变暖背景下对这两类不同性质冰川物质平衡变化特征及其机理做一全面的对比研究意义重大.以东、西天山的乌鲁木齐河源1号冰川和图尤克苏冰川以及阿尔卑斯山东、中、西部的欣特雷斯冰川、Caresèr冰川和Sarennes冰川为参照冰川,在对比分析这五条参照冰川近60 a来物质平衡变化幅度差异和阶段性差异基础上,对大陆型冰川与海洋型冰川物质平衡变化特征及其机理进行了对比研究.结果表明:在物质平衡阶段性变化上,阿尔卑斯山参照冰川物质平衡变化具有相似的阶段性,而天山和阿尔卑斯山参照冰川之间以及天山内部两条参照冰川之间物质平衡阶段性变化存在很大的差异,可见,无论不同性质冰川还是同一性质的不同冰川,其物质平衡的阶段性变化都可能存在差异,这与不同冰川所处环境水热变化的时间差异有关,而与冰川性质无关;在物质平衡变化幅度上,海洋型冰川变化幅度明显大于大陆型冰川,原因是不同性质冰川发育的水热环境及其对气候变化敏感性差异;在前人对冰川加速消融机理的研究基础上,本文也讨论了大陆型冰川与海洋型冰川物质平衡变化的机理及其异同. 相似文献