首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
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   

2.
We present a glaciological and climatic reconstruction of a former glacier in Coire Breac, an isolated cirque within the Eastern Grampian plateau of Scotland, 5 km from the Highland edge. Published glacier reconstructions of presumed Younger Dryas‐age glaciers in this area show that equilibrium line altitudes decreased steeply towards the east coast, implying a arctic maritime glacial environment. Extrapolation of the ELA trend surface implies that glaciers should have existed in suitable locations on the plateau, a landscape little modified by glaciation. In Coire Breac, a 0.35 km2 cirque glacier existed with an equilibrium line altitude of 487 ± 15 m above present sea level. The equilibrium line altitude matches closely the extrapolated regional equilibrium line altitude trend surface for Younger Dryas Stadial glaciers. The mean glacier thickness of 24 m gives an ice volume of 7.8 × 106 m3, and a maximum basal shear stress of c. 100 kPa?1. Ablation gradient was c. –0.0055 m m?1, with a mean July temperature at the equilibrium line altitude of c. 5.1°C. The reconstruction implies an arctic maritime climate of low precipitation with local accumulation enhanced by blown snow, which may explain the absence of other contemporary glaciers nearby. Reconstructed ice flow lines show zones of flow concentration around the lower ice margin which help to explain the distribution of depositional facies associated with a former debris cover which may have delayed eventual glacier retreat. No moraines in the area have been dated, so palaeoclimatic interpretations remain provisional, and a pre‐Lateglacial Interstadial age cannot be ruled out.  相似文献   

3.
Glacier advance and recession are considered key indicators of climate change. Understanding the relationship between climatic variations and glacial responses is crucial. Here, we apply archival digital photogrammetry to reconstruct the decadal scale glacial history of an unmonitored Alpine valley glacier, the Haut Glacier d'Arolla, Switzerland, and we use the data generated to explore the linkages between glacier recession and climate forcing. High precision digital elevation models were derived. They show continual recession of the glacier since 1967, associated with long‐term climatic amelioration but only a weak reaction to shorter‐term climatic deterioration. Glacier surface velocity estimates obtained using surface particle tracking showed that, unlike for most Swiss glaciers during the late 1970s and early 1980s, ice mass flux from the accumulation zone was too low to compensate for the effects of glacier thinning and subsequent snout recession, especially during the rapid warming that occurred through the 1980s. The results emphasise the dangers of inferring glacier response to climate forcing from measurements of the terminus position only and the importance of using remote sensing methods as an alternative, especially where historical imagery is available.  相似文献   

4.
In the centre of the highly glacierized Oetztal valley, mass balance is determined for the three neighbouring glaciers Hintereisferner, Kesselwandferner and Vernagtferner, applying the direct glaciological method, related to the 'fixed date' system. The diverging behaviour of the three glaciers due to slightly varying local climatic conditions as well as to different topoclimatological and physiographic features gave reason to analyse the Vernagtferner mass balance separately for three easily discernible sections, i.e. Schwarzwand, Taschachjoch and Brochkogel, each showing characteristic aspect and elevational distributions of area respectively.
The cumulative mass balance of the Vernagtferner for the period 1968/69, when separate mass balance computations for the three sections were started, until 1996/97 amounted to −8.7 m water equivalent (w.e.). The mass loss of the western Schwarzwand section as the part with the largest share of low elevation area was −13.3 m w.e., in contrast to the central Taschachjoch section which lost only −6.6 m w.e. The remaining eastern Brochkogel section with a loss of −8.5 m w.e. fits best the mass balance of the total Vernagtferner although its physiographic characteristics differ markedly from those of the entire glacier. The equilibrium line altitude (ELA) dependence on specific net mass balance ( b ) is slightly different for the three sections, whereas the dependence of the accumulation area–total area ratio (AAR) on b is characterized by nearly identical sensitivities. Moreover, AAR correlates better with b than ELA, therefore AAR is regarded as a more representative parameter for the Vernagtferner than ELA.  相似文献   

5.
The Debeli Namet glacier in the Durmitor massif, Montenegro, is one of the lowest altitude glaciers (2050–2300 m) at this latitude (42–44°N) in the northern hemisphere. The glacier survives well below the climatological equilibrium line altitude because of substantial inputs from avalanching and windblown snow. The glacier survived two of the hottest summers on record in 2003 and 2007, although it experienced significant retreat. However, during the intervening years (2004–2006) the glacier increased in size and advanced, forming a new frontal moraine. This rapid advance was primarily in response to much cooler summer temperatures, close to or cooler than average, and a marked increase in winter precipitation. The rapid growth and decay of the Debeli Namet glacier in response to inter‐annual climate variability highlights the sensitivity of small cirque glaciers to short‐term climate change.  相似文献   

6.
Glacier mass balance is more sensitive to warming than cooling, but feedbacks related to the exposure of previously buried firn and ice in very warm years is not generally considered in sensitivity studies. A ground‐penetrating radar survey in the accumulation area of Rolleston Glacier, New Zealand shows that five years of previous net accumulation was removed by melt from parts of the glacier above the long‐term equilibrium line altitude during a single negative mass balance year. Rolleston Glacier receives a large amount of accumulation from snow avalanches, which may temporarily buffer it from climate warming by providing additional mass that has accumulated at higher elevations, effectively increasing the elevation range of the glacier. However, glaciers reliant on avalanche input may have high sensitivity to climatic variations because the extra mass is concentrated on a small part of the glacier, and small variations in avalanche input could have a large impact on overall glacier accumulation. Further research is needed to better estimate the amount and spatial distribution of accumulation by avalanche in order to quantify the climate sensitivity of small avalanche‐fed glaciers.  相似文献   

7.
We present a radiocarbon data set of 71 samples of wood and peat material that melted out or sheared out from underneath eight presentday mid‐latitude glaciers in the Central Swiss Alps. Results indicated that in the past several glaciers have been repeatedly less extensive than they were in the 1990s. The periods when glaciers had a smaller volume and shorter length persisted between 320 and 2500 years. This data set provides greater insight into glacier variability than previously possible, especially for the early and middle Holocene. The radiocarbon‐dated periods defined with less extensive glaciers coincide with periods of reduced radio‐production, pointing to a connection between solar activity and glacier melting processes. Measured long‐term series of glacier length variations show significant correlation with the total solar irradiance. Incoming solar irradiance and changing albedo can account for a direct forcing of the glacier mass balances. Long‐term investigations of atmospheric processes that are in interaction with changing solar activity are needed in order to understand the feedback mechanisms with glacier mass balances.  相似文献   

8.
THE 'LITTLE ICE AGE': RE-EVALUATION OF AN EVOLVING CONCEPT   总被引：4，自引：0，他引：4  
ABSTRACT. This review focuses on the development of the ‘Little Ice Age’ as a glaciological and climatic concept, and evaluates its current usefulness in the light of new data on the glacier and climatic variations of the last millennium and of the Holocene. ‘Little Ice Age’ glacierization occurred over about 650 years and can be defined most precisely in the European Alps (c. AD 1300–1950) when extended glaciers were larger than before or since. ‘Little Ice Age’ climate is defined as a shorter time interval of about 330 years (c. AD 1570–1900) when Northern Hemisphere summer temperatures (land areas north of 20°N) fell significantly below the AD 1961–1990 mean. This climatic definition overlaps the times when the Alpine glaciers attained their latest two highstands (AD 1650 and 1850). It is emphasized, however, that ‘Little Ice Age’ glacierization was highly dependent on winter precipitation and that ‘Little Ice Age’ climate was not simply a matter of summer temperatures. Both the glacier‐centred and the climate‐centred concepts necessarily encompass considerable spatial and temporal variability, which are investigated using maps of mean summer temperature variations over the Northern Hemisphere at 30‐year intervals from AD 1571 to 1900. ‘Little Ice Age’‐type events occurred earlier in the Holocene as exemplified by at least seven glacier expansion episodes that have been identified in southern Norway. Such events provide a broader context and renewed relevance for the ‘Little Ice Age’, which may be viewed as a ‘modern analogue’ for the earlier events; and the likelihood that similar events will occur in the future has implications for climatic change in the twenty‐first century. It is concluded that the concept of a ‘Little Ice Age’ will remain useful only by (1) continuing to incorporate the temporal and spatial complexities of glacier and climatic variations as they become better known, and (2) by reflecting improved understanding of the Earth‐atmosphere‐ocean system and its forcing factors through the interaction of palaeoclimatic reconstruction with climate modelling.  相似文献   

9.
Measurements and Models of the Mass Balance of Hintereisferner   总被引：1，自引：0，他引：1  
This paper summarizes the methods applied to determine the mass balance of Hintereisferner and several other glaciers in the Tyrolean Alps since 1952. On an annual basis the direct glaciological method was applied with fixed date measurements on 10–15 accumulation pits and 30–90 ablation stakes on 9 km2.
Indirect mass balance determination from equilibrium line altitude, accumulation area ratios or representative stakes, yield fair results and some exceptions could be related to anomalous meteorological conditions.
Monthly or more frequent stake readings supplied time series of ablation at various altitudes and slope aspects that served as basis for the calibration of energy and mass balance models. Of various models developed, two are presented in this paper. Both are based on degree days, one using daily values from a valley station to predict the mean annual balance of the entire glacier, while the other calculates day-to-day changes at 50-m grid points on the glacier.
The geodetic method has been applied for longer periods and yields results consistent with those of the glaciological method. The balance velocity calculated from recent ice thickness soundings and accumulation measurements is significantly less than observed velocity.  相似文献   

10.
  相似文献   

11.
塔里木河源区冰川系统变化趋势预测   总被引：1，自引：0，他引：1  
塔里木河源区是我国冰川分布最集中的地区之一,总面积达17 745.51 km2,占全国冰川总面积的30%;同时本区又属于我国升温幅度最大的地区之一。应用冰川系统变化的功能模型,对塔里木河源区冰川系统在本世纪对气候变化的趋势进行预测。结果表明:到2050年,如气温比1961~1990年高出1.9~2.3℃,本区冰川面积将减少4%~6%,冰川径流将增加22%~34%,零平衡线将上升62~94 m;如此升温率持续到本世纪末,则本区冰川面积将减少10%~16%,冰川径流将会回落,但仍比本世纪初多11%~13%,零平衡线将上升156~233 m。  相似文献   

12.
The service seNorge ( http://senorge.no ) provides gridded temperature and precipitation for mainland Norway. The products are provided as interpolated station measurements on a 1 × 1 km grid. Precipitation gauges are predominantly located at lower elevations such as coastal areas and valleys. Therefore, there are large uncertainties in extrapolating precipitation data to higher altitudes, both due to sparsity of observations as well as the large spatial variability of precipitation in mountainous regions. Using gridded temperature and precipitation data from seNorge, surface mass balance was modeled for five Norwegian glaciers of different size and climate conditions. The model accounts for melting of snow and ice by applying a degree‐day approach and considers refreezing assuming a snow depth depended storage. Calculated values are compared to point measurements of glacier winter mass balance. On average for each glacier, modeled and measured surface mass‐balance evolutions agree well, but results at individual stake locations show large variability. Two types of problems were identified: first, grid data were not able to capture spatial mass balance variability at smaller glaciers. Second, a significant increase in the bias between model and observations with altitude for one glacier suggested that orographic enhancement of precipitation was not appropriately captured by the gridded interpolation.  相似文献   

13.
This paper presents a simple analytical model for estimating rock glacier age by coupling the ratio of frontal advance to total rock glacier length and the ratio of debris volume in the rock glacier to present debris flux in the talus cone–rock glacier transition zone. The model was applied to two rock glaciers at Prins Karls Forland, Svalbard. By assuming volumetric debris contents in the deforming layer of the rock glacier of between 0.3 and 0.4, we obtained age estimates for the rock glaciers of between 12 ka and 24 ka. The corresponding average rockwall retreat rates are between 0.30 and 0.62 mm a‐1. Considering the limitations of the model, we suggest a minimum age of 13 ka for the initiation of rock glacier development. Using this age, rockwall retreat rates for the seven rock glaciers investigated at Prins Karls Forland are between 0.13 and 0.64 m ka‐1 (assuming the volumetric debris content for the whole rock glacier/talus cone is 0.35). The model requires further testing on other datasets, better field estimates of the debris content and depth of the deforming layer, and could also benefit from the inclusion of an unsteady debris supply function in order to refine age estimates.  相似文献   

14.
This paper describes the recent evolution of Italian glaciers through an analysis of all available terminus fluctuation data that the authors have entered in a glaciers database (named GLAD) containing 883 records collected on glaciers from 1908 to 2002. Furthermore, a representative subset of data (249 glaciers located in Lombardy) was analysed regarding surface area changes. For the analysis of terminus fluctuations, the glaciers were sorted by size classes according to length. The data showed that during the 20th century Italian Alpine glaciers underwent a generalized retreat, with one distinct and well documented readvance episode that occurred between the 1970s and mid‐1980s, and a poorly documented one around the early 1920s. The rates of terminus advance and retreat have changed without significant delays for the larger glaciers with respect to the smaller ones. However, the smaller the glacier, the more limited the advance (if any) during the 1970s and early 1980s. The behaviour of glaciers shorter than 1 km appears to have changed in the last decade, and between 1993 and 2002 they retreated at a very high rate. The analysis of the subset of data led to a quanti‐fication of surface reduction of c. 10% from 1992 to 1999 for glaciers in Lombardy. Small glaciers proved to contribute strongly to total area loss: in 1999, 232 glaciers (c. 90% of the total) were smaller than 1 km2, covering 27.2 km2 (less than 30% of the total area), but accounted for 58% of the total loss in area (they had lost 7.4 km2).  相似文献   

15.
Glacier mass balance and mass balance gradient are fundamentally affected by changes in glacier 3D geometry. Few studies have quantified changing mountain glacier 3D geometry, not least because of a dearth of suitable spatiotemporally distributed topographical information. Additionally, there can be significant uncertainty in georeferencing of historical data and subsequent calculations of the difference between successive surveys. This study presents multiple 3D glacier reconstructions and the associated mass balance response of Kårsaglaciären, which is a 0.89 ± 0.01 km2 mountain glacier in sub‐arctic Sweden. Reconstructions spanning 101 years were enabled by historical map digitisation and contemporary elevation and thickness surveys. By considering displacements between digitised maps via the identification of common tie‐points, uncertainty in both vertical and horizontal planes were estimated. Results demonstrate a long‐term trend of negative mass balance with an increase in mean elevation, total glacier retreat (1909–2008) of 1311 ± 12 m, and for the period 1926–2010 a volume decrease of 1.0 ± 0.3 × 10–3 km3 yr–1. Synthesising measurements of the glaciers’ past 3D geometry and ice thickness with theoretically calculated basal stress profiles explains the present thermal regime. The glacier is identified as being disproportionately fast in its rate of mass loss and relative to area, is the fastest retreating glacier in Sweden. Our long‐term dataset of glacier 3D geometry changes will be useful for testing models of the evolution of glacier characteristics and behaviour, and ultimately for improving predictions of meltwater production with climate change.  相似文献   

16.
中亚天山山区冰雪变化及其对区域水资源的影响   总被引：8，自引：2，他引：6  
邓海军  陈亚宁 《地理学报》2018,73(7):1309-1323
冰川和积雪是构成山区固体水库的主体,对区域水资源稳定性具有调节功能,但深受气候变化的影响。以中亚天山为研究区域,基于长时间序列的观测数据,分别从冰川、积雪、水储量、径流等方面进行分析,并选取阿克苏河、开都河及乌鲁木齐河3个典型流域,研究天山山区冰雪变化对流域水资源的影响。结果表明：① 冰川退缩速率与面积的函数关系为f（x） = -0.53×x-0.15 （R2 = 0.42,RMSE = 0.086）,说明小型冰川对气候变化的响应更为敏感。同时,中低海拔区域的冰川退缩速率大于高海拔区域;② 2003-2015年天山山区水储量的递减速率为-0.7±1.53 cm/a,天山中部区域的递减速率最大,这一结果与该区域冰川急剧退缩相吻合;③ 近半个多世纪以来,冰雪融水径流增加是这3个典型流域径流量增加的主要原因,其中阿克苏河增幅最大（达0.4×108 m3/a）。但自20世纪90年代中期以来,3个流域的径流量都呈减少趋势,与流域内冰川面积减少、厚度变薄及平衡线海拔升高的关系密切。研究结果揭示了气候变化驱动下的山区固态水体储量变化对流域水资源的影响机制,以期为流域水资源管理提供有价值的决策参考。  相似文献   

17.
Abstract Small glaciers have short response times to climate change and therefore offer a powerful means of climate monitoring. Glacier responses to climate, or their mass change, may be suggested by a change in the Equilibrium Line Altitude (ELA). However, regional climatic reconstructions have repeatedly neglected the importance of local variations in ELAs in preference for regional trends. For small glaciers close to the glaciation level, ignoring the importance of local topographic components in mass balance estimates may lead to erroneous climatic reconstructions. Of 510 small valley and cirque glaciers digitised across northern Scandinavia, 284 were objectively deemed suitable for inferring an ELA. The inferred ELA was derived from the median elevation and several local topographic variables using regression analysis. The glacier elevation, area, slope and aspect parameters were found to be the best predictors of the local ELA. ELA estimations improved from 77% up to 94% accuracy when topographic parameters for every grid‐cell within rasters representing glacier surfaces were computed rather than using subjective measurements from topographic maps. Regional ELA trend surfaces, interpolated between the local ELA values, differed in effectively representing the local variability, depending upon the distribution and accuracy of the local ELA values. A second‐order polynomial trend surface most accurately represented ELA variations across the study area, within the initial local measurement accuracy of ±100 m. It is concluded that current subjective topographic map‐based analyses are unlikely to be sufficiently accurate for predicting the regional ELA of small, sensitive and marginal glaciers, unless CIS‐based spatial analyses are made at a reasonable resolution.  相似文献   

18.
中国典型山地温冰川水化学空间分布特征与近期冰川动态   总被引：14，自引：0，他引：14  
从我国玉龙雪玉典型温水王白水１号冰川不同区段表面融水,新近积雪和冰川初给河水采样分析结果表明,雪线以下降水中的稳定同位素的离子含量比雪线以下为高,低海拔河水比高海拨融水的氧同浓度为低,可能在来源上存在着差异,这种分布特征说明本温冰川区局部大气环流情况高度而不同,有可能存在季气候区所特有的“降水量效应”或“季节性效应”。冰川不同水体内离子浓度变化说明,冰川融水与地壳表面接触时间越久,其中的可融性离了  相似文献   

19.
哈尔里克山脉冰川的快速退缩已经影响到吐鲁番坎儿井的水量,先前关于该区冰川研究不够细致,且最新资料报道较为短缺。以哈尔里克山脉冰川为研究对象,基于Landsat TM/ETM+和OLI影像（1992、2002、2010、2016年）,通过比值阈值法、目视解译结合GIS技术,提取了该地区四期冰川边界,同时对研究区周边气温、降水以及日照时数进行线性趋势分析,研究其与冰川的响应关系。结果表明：（1）1992-2016年,哈尔里克山脉冰川总体呈现出持续退缩趋势,面积退缩了13.18%,年均退缩率为0.56%,近年来退缩速率有所减缓。（2）近似估算的冰储量在过去25 a间减少了18.33%,冰川物质亏损将对该区短缺的水资源提供了危险的信号。（3）冰川退缩率与冰川规模呈指数函数变化趋势;低海拔区冰川存在明显的末端升高趋势;N和NW向的冰川占明显优势,但N向退缩率最慢。（4）分形理论分析表明该地区冰川未来退缩将趋于一种稳定状态。该区气温和日照时数的显著上升导致其冰川退缩,同时冰川规模、海拔和坡向分布也是冰川变化的重要因素;对比发现该区冰川退缩速率较天山其他区域慢。  相似文献   

20.
1900-2007年横断山区部分海洋型冰川变化   总被引：12，自引：4，他引：8  
横断山区7条海洋型冰川近百年进退速度变化呈现出以退缩为总趋势的阶段性变化,具体表现为20世纪初至1930s的冰川稳定,1930s-1960s的冰川后退,1970s-1980s的冰川稳定或减速后退,20世纪80年代中期以来的冰川后退,这与我国、北半球及横断山区同期的气候变化呈明显对应,展现出冷干阶段冰川稳定或前进、暖湿阶段后退的态势,但各冰川的变化幅度因纬度位置、坡向、冰川规模、局地环境等而存在明显差异.1982/83年大、小贡巴冰川、海螺沟冰川冰舌段的消融水当量分别为2710mm、3139 mm和5281 mm,1990/91-97/98期间海螺沟冰川冰舌段的年均消融水当量为6157 mm,比1982/83年增加了876 mm.2002年夏季白水1号冰川的积雪消融量由于表碛覆盖较少表现出明显的随海拔升高而降低的特征,平均消融水当量为1086.25 mm,2008.9-19.10.13期间白水1号冰川物质平衡花竿的观测表明,花竿布设区域10月6号左右转入物质积累期.期间日均积累深为1cm,折合水当量5mm.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号