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991.
Glacial features in the geological record provide essential clues about past behavior of climate. Of the numerous physical systems on earth, glaciers are one of most responsive to climate change, especially small glaciers, their direct marginal response taking only a few years or decades to be expressed. Accelerating recession of modern glaciers raises the issue of the climate’s impact on water runoff. Data based on topographic maps and Advanced Spaceborne Thermal Emission and Radiometer (ASTER) imagery sho... 相似文献
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1974—2010年雅鲁藏布江源头杰玛央宗冰川及冰湖变化初步研究 总被引:9,自引:5,他引:4
青藏高原冰川和冰湖是气候变化敏感的指示器.基于1974年的地形图及其生成的DEM数据、1990年和2000年的TM影像、2005年和2010年的ETM+影像、以及2010年和2009年的GPS实测数据,应用3S技术分析了1974—2010年37a来雅鲁藏布江源头杰玛央宗冰川和冰湖的变化特征.结果表明:冰川面积减小了5.02%(21.78km2减小至20.67km2)、冰川末端退缩了768m(速度为21m.a-1);冰湖面积增加了63.7%(0.70km2增加至1.14km2),冰湖体积扩大约9.8×106 m3.普兰县气象站的观测资料表明,近37a来气温呈快速上升趋势,而降雨量明显减少,气候暖干化是杰玛央宗冰川和冰湖变化的主要原因.若该区气候的暖干趋势进一步加剧,必然导致杰玛央宗冰川退缩进一步加剧,冰湖溃决的可能性将会增大. 相似文献
995.
Glaciers in the Altai Mountains of Mongolia provide an estimated 11% of the total water resources within the country. Yet, their number and area in inconsistent. Using satellite imagery acquired from Landsat 4, 5, and 7, and SRTM digital elevation model (DEM) data, we present here an intuitive, robust, and inexpensive methodology to map the exposed ice of glaciers in the Altai Mountains for the period 1989 to 2011. The total glacierized area was 515 km2 in 1989/1991, 428 km2 in 1998/2001, and 372 km2 in 2010/2011; it decreased by 17% from 1989/1991 to 1998/2001, 13% from 1998/2001 to 2010/2011, and 28% for the entire period 1989/1991 to 2010/2011. In analyzing a sub‐sample of 260 glaciers, 6% advanced, 11% were stable, and 83% receded from 1989 to 2011. The glacier dataset is available to the public free of charge at the Global Land Ice Measurements from Space (GLIMS) website. 相似文献
996.
Kay Helfricht Michael Lehning Rudolf Sailer Michael Kuhn 《Geografiska Annaler: Series A, Physical Geography》2015,97(4):721-736
Snow deposition and redistribution are major drivers of snow cover dynamics in mountainous terrain and contribute to the mass balance of alpine glaciers. The quantitative understanding of inhomogeneous snow distribution in mountains has recently benefited from advances in measuring technologies, such as airborne laser scanning (ALS). This contribution further advances the quantitative understanding of snow distribution by analysing the areas of maximum surface elevation changes in a mountain catchment with large and small glaciers. Using multi‐annual ALS observations, we found extreme surface elevation changes on rather thin borders along the glacier margins. While snow depth distribution patterns in less extreme terrain have presented high inter‐annual persistence, there is little persistence of those extreme glacier accumulations between winters. We therefore interpret the lack of persistence as the result of a predominance of gravity‐driven redistribution, which has an inherently higher random component because it does not occur with all conditions in all winters. In highly crevassed zones, the lidar‐derived surface elevation changes are caused by a complex interaction of ice flux divergence, the propagation of crevasses and snow accumulation. In general, the relative contribution of gravitational mass transport to glacier snow cover volume was found to decrease for glaciers larger than 5 km2 in the investigated region. We therefore suggest that extreme accumulations caused by gravitational snow transport play a significant role in the glacier mass balance of small to medium‐size glaciers and that they may be successfully parameterized by simple mass redistribution algorithms, which have been presented in the literature. 相似文献
997.
Snow Accumulation on a Small High‐Arctic Glacier Svenbreen: Variability and Topographic Controls 下载免费PDF全文
Jakub Małecki 《Geografiska Annaler: Series A, Physical Geography》2015,97(4):809-817
One of the main controls on the net mass change of land‐terminating Arctic glaciers is the magnitude and distribution of snow accumulation. In Dickson Land, region of Svalbard with the greatest distance to the sea, the issue has not been receiving much scientific attention for decades. In this paper, new snow accumulation data are presented from Svenbreen in Dickson Land from end‐of‐winter surveys. The measured winter balance was 0.42 ± 0.15 m w.e. in 2010, 0.50 ± 0.10 m w.e. in 2011 and 0.62 ± 0.10 cm w.e. in 2012. Snow depth and water equivalent have been analysed in the background of altitude, slope and aspect extracted from the digital elevation model of the glacier. On steep northern slopes (>15°) accumulation was the highest, whereas it was decreased on southern slopes with moderate inclination (9–12°). Elevation, which on many glaciers proved to be highly correlated with snow depth, explained only 17–34% of snow depth variability due to complex interplay between local climate and geometry of a small valley. 相似文献
998.
InSAR由于大范围、高精度、全天候等优势,被广泛应用。但InSAR局限于监测视线向形变,无法观测方位向形变。多孔径干涉测量技术(MAI)作为一种监测方位向形变的有效技术得到广泛应用,其精度可达厘米级。该技术对监测快速,激烈的地表形变更为有效,如冰川流速、同震形变等。文中利用MAI-InSAR技术,选用日本ALOS卫星PALSAR数据,监测玉树Mw=6.9地震的2-D同震形变场,获得有益的结论。 相似文献
999.
利用阈值法进行遥感地物提取效率高、准确率高,但是在阈值的选取方面,传统的手动选取阈值,自动化低,需反复试操作,且易受主观因素影响。文中通过期望最大算法对局部冰川区域归一化雪覆盖指数建立高斯混合模型,去除区域内的混合像元类,再利用高斯混合模型模拟纯净化后的冰川类、非冰川类的NDSI分布情况,根据改进后的高斯混合模型分布情况,自动计算出区域内的冰川提取阈值。本文对不同海拔的3个区域进行算法实验,然后将新疆哈密的哈尔里克山冰川提取边界与冰川编目数据进行对比验证。研究结果表明,该方法自动计算的冰川提取阈值结果可靠、精度高,在差异较大区域仍较稳定,有一定的应用价值。 相似文献
1000.
Researches carried out on the main glacier of the Dovrefjell massif, Scandes Mountains, Norway (62° N; 9° E) point to recent periglacial features which are presently directly developed on the ice. This original location raises the problem of their morphodynamic significance and a hypothesis of ephemeral periglacial activity in a paraglacial context is proposed here. 相似文献