基于纹理特征的SAR影像各拉丹冬冰川信息提取     

仲伟凡  唐远彬  殷腾箐 《测绘与空间地理信息》2015,(10):178-180

冰川面积是监测冰川变化信息的重要参数。本文以各拉丹东地区为例,根据冰川区域特有的纹理特征,选取时间间隔为35天的ENVISAT ASAR干涉对,利用灰度共生矩阵提取纹理特征,通过波段组合进行监督分类,进而提取研究区冰川面积。同时以Landsat TM光学影像为依据,评价利用纹理特征提取结果的精度。研究表明:基于纹理特征并利用SAR影像提取冰川面积的方法是可行的,为提取冰川信息提供了又一可靠手段。  相似文献   

Decadal‐Scale Changes of the Ödenwinkelkees,Central Austria,Suggest Increasing Control of Topography and Evolution Towards Steady State          下载免费PDF全文

Jonathan L. Carrivick  Katie Berry  Martin Geilhausen  William H.M. James  Christopher Williams  Lee E. Brown  David M. Rippin  Steve J. Carver 《Geografiska Annaler: Series A, Physical Geography》2015,97(3):543-562

Small mountain glaciers have short mass balance response times to climate change and are consequently very important for short‐term contributions to sea level. However, a distinct research and knowledge gap exists between (1) wider regional studies that produce overview patterns and trends in glacier changes, and (2) in situ local scale studies that emphasise spatial heterogeneity and complexity in glacier responses to climate. This study of a small glacier in central Austria presents a spatiotemporally detailed analysis of changes in glacier geometry and changes in glaciological behaviour. It integrates geomorphological surveys, historical maps, aerial photographs, airborne LiDAR data, ground‐based differential global positioning surveys and Ground Penetrating Radar surveys to produce three‐dimensional glacier geometry at 13 time increments spanning from 1850 to 2013. Glacier length, area and volume parameters all generally showed reductions with time. The glacier equilibrium line altitude increased by 90 m between 1850 and 2008. Calculations of the mean bed shear stress rapidly approaching less than 100 kPA, of the volume–area ratio fast approaching 1.458, and comparison of the geometric reconstructions with a 1D theoretical model could together be interpreted to suggest evolution of the glacier geometry towards steady state. If the present linear trend in declining ice volume continues, then the Ödenwinkelkees will disappear by the year 2040, but we conceptualise that non‐linear effects of bed overdeepenings on ice dynamics, of supraglacial debris cover on the surface energy balance, and of local topographically driven controls, namely wind‐redistributed snow deposition, avalanching and solar shading, will become proportionally more important factors in the glacier net balance.  相似文献   

Changes in the Geometry and Volume of Rabots glaciär,Sweden, 2003–2011: Recent Accelerated Volume Loss Linked to More Negative Summer Balances          下载免费PDF全文

Keith A. Brugger  Latysha Pankratz 《Geografiska Annaler: Series A, Physical Geography》2015,97(2):265-278

Terminus geometry, ice margins, and surface elevations on Rabots glaciär were measured using differential GPS during summer 2011 and compared with those similarly measured in 2003. Glacier length over the eight years decreased by ～105 m corresponding to 13 m a^?1, a rate consistent with ice recession over the last several decades. Measured changes in surface elevations show that between 2003 and 2011 the glacier's volume decreased by ～27.6 ± 2.6 × 10⁶ m³, or 3.5 ± 0.3 × 10⁶ m³ a^?1. This compares favorably with an estimate of ?28.1 ± 2.6 × 10⁶ m³ based on a mass‐balance approach. The rate of volume loss appears, however, to have significantly increased after 2003, being substantially greater than rates determined for the intervals 1959–80, 1980–89, and 1989–2003. This increase corresponds to a sustained interval of more negative summer balances. Previous work suggests that as of 2003 Rabots glaciär had not yet completed its response to a ～1°C warming that occurred c. 1900, and thus the current marked increase rate of ice loss might reflect the effect of recent, or accelerated regional warming that occurred during the last decade superimposed on its continued response to that earlier warming.  相似文献   

高山冰川多时相多角度遥感信息提取方法   总被引：1，自引：0，他引：1  

都伟冰  李均力  包安明  王宝山  王双亭 《测绘学报》2015,44(1):59-66

提出一种多角度遥感影像的冰川信息提取方法。通过"全域—局部"的阈值分割方法获取短时期内不同时相的遥感影像的冰雪边界,结合地形信息和多时相遥感影像的太阳角度信息,联合消除山体阴影对冰川的遮挡,并以多期影像的最小冰雪边界作为最佳冰川边界。以托木尔峰西侧冰川为研究对象,采用2009—2010年4个时相的遥感影像提取冰川信息。结果表明多角度遥感提取的冰川边界效果好,能有效地排除积雪与山体阴影的干扰。  相似文献   

Seasonal evolution of meltwater generation,storage and discharge at a non‐temperate glacier in Svalbard     

Richard Hodgkins 《水文研究》2001,15(3):441-460

In glacierized catchments, meteorological inputs driving surface melting are translated into runoff outputs mediated by the glacier hydrological system: analysis of the relationship between meteorology and diurnal and seasonal patterns of runoff should reflect the functioning of that system, with the role of meltwater storage likely to be of particular importance. Daily meltwater storage is determined for a glacier at 78 °N in the Svalbard archipelago, by comparing inputs calculated from a surface energy balance model with measured outputs (proglacial discharge). Solar radiation, air temperature, wind speed and proglacial discharge are then analysed by regression and time‐series methods, in order to assess the meteorology–discharge relationship and its variation at diurnal and seasonal time‐scales. The recorded discharge time‐series can be divided into two contrasting intervals: up to early August, proglacial discharge was high and variable, mean hydrographs showed little indication of diurnal cycling, ARIMA models of discharge indicated a non‐seasonal, moving‐average generating process, and there was a net loss of meltwater from storage; from early August, proglacial discharge was low and relatively invariable, but with clearer diurnal cycles, regression models of discharge showed substantially improved correlations with air temperature and solar radiation, ARIMA models indicated a non‐seasonal, autoregressive generating process, and eventually a seasonal component, and there was a net gain in meltwater storage. The transition between the two periods is brief compared with the duration of the melt season. The runoff response to meteorology therefore lacks the strongly progressive element previously identified in mid‐latitude glacierized catchments. In particular, the glacier hydrological system only appears responsive to diurnal forcing following the depletion of the seasonal snowpack meltwater store. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Flow modelling in a high mountain valley equipped with hydropower plants: Rio Zongo Valley,Cordillera Real,Bolivia     

Yvan Caballero  Pierre Chevallier  Robert Gallaire  Ramiro Pillco 《水文研究》2004,18(5):939-957

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Development and Conservation of Glacier Tourist Resources —— A Case Study of Bogda Glacier Park   总被引：3，自引：0，他引：3  

LIU Xuling YANG Zhaoping XIE Ting 《中国地理科学(英文版)》2006,16(4):365-370

1 Introduction As a special kind of tourism, glacier tourism is popular to tourists all over the world owing to its meeting tourists’ needs for seeking after freshness, difference, surprise and risk. Differing from conventional tourism, glacier tour- ism has its special characters while there is little literature on it. It is of great significance to study its characters and seek after the harmonious development in exploitation and protection of glacier tourism resources. Glacier tourism refe…  相似文献   

Critical Approach to Methods of Glacier Reconstruction in High Asia and Discussion of the Probability of a Qinghai-Xizang （Tibetan） Inland Ice     

Matthias Kuhle 《山地科学学报》2007,4(2):91-124

This overview discusses old and new results as to the controversy on the past glacier extension in High Asia, which has been debated for 35 years now. This paper makes an attempt to come closer to a solution. H.v. Wissmann's interpretation (1959) of a small-scale glaciation contrasts with M. Kuhle's reconstruction (1974) of a large-scale glaciation with a 2.4 million km2 extended Qinghai-Xizang (Tibetan) inland glaciation and a Himalaya-Karakorum icestream network. Both opinions find support but also contradiction in the International and Chinese literature (Academia Sinica). The solution of this question is of supraregional importance because of the subtropical position of the concerned areas. In case of large albedo-intensive ice surfaces, a global cooling would be the energetical consequence and, furthermore, a breakdown of the summer monsoon. The current and interglacial heat-low above the very effective heating panel of the Qinghai-Xizang (Tibetan) Plateau exceeding 4000 m, which gives rise to this monsoon circulation, would be replaced by the cold-high of an inland ice. In addition, the plate-tectonically created Pleistocene history of the uplift of High Asia — should the occasion arise up to beyond the snowline (ELA) —would attain a paleoclimatically great, perhaps global importance. In case of a heavy superimposed ice load, the question would come up as to the glacio-isostatic interruption of this primary uplift. The production of the loesses sedimentated in NE-China and their very probable glacial genesis as well as an eustatic lowering of the sea-level by 5 to 7 m in the maximum case of glaciation are immediately tied up with the question of glaciation we want to discuss. Not the least, the problems of biotopes of the sanctuary-centres of flora and fauna, i.e., interglacial re-settlement, are also dependent on it. On the basis of this Quaternary- geomorphological-glaciological connection, future contributions are requested on the past glaciation, the current and glacial permafrost table and periglacial development, the history of uplift, and the development of Ice Age lakes and loess, but also on the development of vegetation and fauna in High Asia.  相似文献   

Suspended sediment dynamics in a steep,glacier‐fed mountain stream,Place Creek,Canada     

G. Richards  R. D. Moore 《水文研究》2003,17(9):1733-1753

This study examined suspended sediment concentration (SSC) during the ablation seasons of 2000 and 2001 in Place Creek, Canada, a steep, glacier‐fed mountain stream. Comparison of stream flow in Place Creek with that in an adjacent, almost unglacierized catchment provided a rational basis for separating the ablation seasons into nival, nival–glacial, glacial and autumn recession subseasons. Distinct groupings of points in plots of electrical conductivity against discharge supported the validity of the subseasonal divisions in terms of varying hydrological conditions. Relationships between SSC and discharge (Q) varied between the two study seasons, and between subseasons. Hysteresis in the SSC–Q relationship was evident at both event and weekly time‐scales. Some suspended sediment released from pro‐glacial Place Lake (the source of Place Creek) appeared to be lost to channel storage at low flows, especially early in the ablation season, with re‐entrainment at higher flows. Multiple regression models were derived for the subseasons using predictor variables including Q, Q², the change in Q over the previous 3 h, cumulative discharge over the ablation season, total precipitation over the previous 24 h and SSC measured at 1500 hours as an index value for each day. The models produced adjusted R² values ranging from 0·71 to 0·91, and provided tentative insights into the differences in SSC dynamics amongst subseasons. Introduction of the index value of SSC significantly improved the model fit during the nival–glacial and glacial subseasons for both years, as it adjusts the model to the current condition of sediment supply. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Surface sediment analysis of a rock glacier     

B. M. Yarnal 《Mathematical Geology》1982,14(4):371-386

Three trend surface techniques are used to evaluate the nature and distribution of the surface sediments of a rock glacier. Trend surface analysis, vector trend analysis, and most predictable surface (MPS)mapping suggest that long-term rock glacier creep causes the highly variable debris cover to display crude sorting and orientation patterns. Poorly sorted and randomly oriented surface materials may be the result of insufficient time for slowly evolving rock glacier sediment distributions to be established and/or the site of glacial erosion or deposition.  相似文献