北极Svalbard地区Austre Lovénbreen和Pedersenbreen冰川表面物质平衡和运动特征分析

对位于北极Svalbard群岛新奥尔松(Ny-lesund)的Austre Lovénbreen和Pedersenbreen冰川首个物质平衡年(2005/06年度)的冰川表面物质平衡及其运动特征进行研究,并阐述了Austre Lovénbreen冰川末端位置的变化状况。结果表明:(1)Austre Lovénbreen和Pedersenbreen冰川净物质平衡分别为-0.44和-0.20m w.e.,年消融量分别为0.99和0.94m w.e.,对应冰川零平衡线高度分别为478.10和494.87m。(2)两条冰川符合Svalbard地区跃动冰川运动的特征模式。运动速度矢量的水平分量表现为:向主流线辐合或平行于主流线。下游运动速度较慢,而在中上游运动相对较快。Austre Lovénbreen冰川表面各观测点的运动速度平均值为2.28m·a-1,运动速度最大值和最小值分别为3.91和0.81m·a-1;Pedersenbreen冰川表面观测点运动速度平均值为6.74m·a-1,运动速度最大值和最小值分别为8.13和5.49m·a-1。运动速度矢量的垂直分量表现为:消融区冰川消融量随海拔升高而减弱,Austr...     

Inferring Glacier Mass Balance Using Radarsat: Results From Peyto Glacier, Canada

The capability of RADARSAT synthetic aperture radar (SAR) for the purpose of snow-line/accumulation area mapping for a temperate alpine glacier is examined. In agreement with other orbital C-band SAR studies, RADARSAT can discriminate between firn and bare ice facies. Limited observations are reported with respect to the electromagnetic variability of the ice facies in the ablation area, but they are inconclusive. Operational considerations are discussed with respect to reconciling the uncertainties of late-summer weather and their possible impact on the dielectric and scattering properties of the glacier surface. Vagaries associated with other glacier settings, mass balance states and their associated facies configurations are discussed including the difficulty of using the transient snow-line to define the equilibrium line and the lower extent of the accumulation area for glaciers where superimposed ice may form.
The radar remote-sensing reconnaissance of equilibrium line altitude (ELA) and accumulation area ratio (AAR) for estimating glacier mass balance requires serious consideration in those instances where traditional ground measurements used in the direct glaciological method are absent. However, with respect to the ELA, such estimates can vary depending on the accuracy of the reference digital elevation information. Moreover, for many glacier configurations, where mass balance variations due to altitude are influenced or in some cases completely masked by local balance variations, defining the ELA may be an irreconcilable problem. Using the AAR may be more robust in this regard. It is further determined that the total error inherent in the reconnaissance method would have serious implications for the confident estimation of mass balance normals and climate-related trends if the method were to be utilized over the longer term.     

Study of annual mass balance(2011–2013) of Rikha Samba Glacier,Hidden Valley,Mustang, Nepal

Although Himalayan glaciers are of particular interest in terms of future water supplies, regional climate changes, and sea-level rises, little is known about them due to lack of reliable and consistent data. There is a need for monitoring these glaciers to bridge this knowledge gap and to provide field measurements necessary to calibrate and validate the results from different remote sensing operations. Therefore, glaciological observations have been carried out by the Cryosphere Monitoring Project(CMP) since September 2011 on Rikha Samba Glacier in Hidden valley, Mustang district in western Nepal in order to study its annual mass balance. This paper presents the first results of that study. There are 10 glaciers in Hidden Valley, named G1, G2, G3, up to G10. Of these, G5 is the Rikha Samba Glacier, which has the largest area(5.37 km2) in this valley and the highest and lowest altitudes(6,476 and 5,392 m a.s.l., respectively). The glacier mass balance discussed in this paper was calculated using the glaciological method and the equilibrium line altitude(ELA). The glacier showed a negative annual point mass balance along the longitudinal profile of its lower part from September 10, 2011 to October 3, 2012. Stake measurements from October 4, 2012 to September 30, 2013 indicated a negative areal average of annual mass balance-0.088±0.019 m w.e. for the whole glacier. Based on these observations, the ELA of the Rikha Samba Glacier is estimated at 5,800 m a.s.l. in 2013. This negative balance may be due to rising air temperatures in the region, which have been incrementally rising since 1980 accompanied by little or no significant increase in precipitation in that period. The negative mass balance confirms the general shrinking trend of the glacier.     

过去44年乌鲁木齐河源一号冰川物质平衡结果及其过程研究

通过1997—2003年度天山乌鲁木齐河源一号冰川物质平衡的观测结果,分析比较了过去44年间一号冰川物质平衡、累积物质平衡的变化过程,以及反映气候一地形要素和冰川发育条件要素的平衡线高度和冰川积累区比率,认为一号冰川负平衡波动期随时间推移而递增,目前处于其观测历史上物质平衡亏损最为强烈的时期。     

Improving local estimations and regional trends of glacier equilibrium line altitudes

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.     

Fifty years of meteo-glaciological change in Toll Glacier,Bennett Island,De Long Islands,Siberian Arctic

Rapid environmental change has been observed in the De Long Islands, Siberian Arctic, where warming has extensively occurred over the area. To quantitatively evaluate glaciological changes since the 1980s, the climate, mass balance, and the equilibrium line altitude (ELA) of Toll Glacier on Bennett Island were analyzed. Air temperature has increased and solid precipitation has decreased since the 1960s, especially after 2000. The cumulative mass balance of Toll Glacier has had a negative trend since the 1960s and reached approximately −20 m water equivalent (w.e.) in 2000, which is one of the largest changes in the Arctic. These changes are much larger than those in the west Russian Arctic. The warming trend is also correlated with the sea ice distribution in the Siberian Arctic and may lead to feedback effects that cause further Arctic warming.     

Glacier balance trends in the Kongsfjorden area, western Spitsbergen, Svalbard, in relation to the climate

For the last thirty years, the mean net balance of two glaciers, Austre Brøggerbreen and Midre Lovénbreen, has been -0.43 and -0.34 m of water equivalent (w.e.). respectively. The mean net balance of Kongsvegen, a tidewater glacier that has been measured since 1987, is 0.11 m w.e. The negative balances of the two first glaciers are driven by the increase in atmospheric temperature which occurred at the end of the Little Ice Age at the beginning of the century. The positive balance of Kongsvegen is due to its higher elevation and larger accumulation area. There is no significant trend in the net balances and no increase of the melting has been detected during the last thirty years.
A correlation coefficient of R = 0.83 has been obtained between the net balance of Lovénbreen and the winter precipitation, together with the summer temperature recorded at the neighbouring station of Ny-Ålesund since 1969. With 14 years of data, the correlation coefficient between the net balance and climatic parameters does not increase consistently by introducing any radiation component, but the coefficient correlation between the summer balance of Austre Brøggerbreen and summer temperature increases from 0.68 to 0.77 when introducing global and long-wave radiation for July and August. Weather conditions and the frequency of their changes influence the balance between global and long-wave radiation and changes in albedo values.     

Present and Late Pleistocene equilibrium line altitudes in Changbai Mountains, Northeast China

According to the glacial landforms and deposits with the optically stimulated luminescence (OSL) dating results, two glacial stages of the last glacial cycle (LGC) and Late Glacial were identified. The Late Glacial stage (Meteorological Station glacier advance) took place about 11 ka (11.3±1.2 ka), and the last glacial maximum (LGM), named Black Wind Mouth glacier advance, occurred at 20 ka (20.0±2.1 ka). Based on the Ohmura’s formula in which there is a relationship between summer (JJA) atmospheric temperature (T) and the annual precipitation (P) at ELA, the present theoretical equilibrium line altitude (ELAt) in Changbai Mountains was 3380±100 m. Six methods of accumulation–area ratio (AAR), maximum elevation of lateral moraines (MELM), toe–to headwall altitude ratios (THAR), the terminal to summit altitudinal (TSAM), the altitude of cirque floor (CF), and the terminal to average elevation of the catchment area (Hofer) were used for calculation of the former ELAs in different stages. These methods provided the ELA for a range of 2250–2383 m with an average value of 2320±20 m during the LGM, which is 200 m higher than the value of previous investigation. The snowlines during the Late Glacial are 2490 m on northern slope, and 2440 m on western slope. The results show that the snowline on northern slope is 50 m higher than that on western slope during the Late Glacial, and the average snowline is 2465m. The ELA △ values were more than 1000 m during the LGM, and about 920 m lower than now during the Late Glacial stage respectively. Compared with Taiwanese and Japanese mountains in East Asia during the LGM, the effect of the uplift on ELA in Changbai Mountains during the glaciations (i.e. 20 m uplift in the LGM and 11 m in the Late Glacial) is not obvious.     

Snow accumulation, melt, mass loss, and the near-surface ice temperature structure of Irenebreen, Svalbard

This study examines the mass balance, accumulation, melt, and near-surface ice thermal structure of Irenebreen, a 4.1 km² glacier located in northwest Spitsbergen, Svalbard. Traditional glaciological mass balance measurements by stake readings and snow surveying have been conducted annually at the glacier since 2002, yielding a mean annual net mass balance of −65 cm w.e. for the period 2002–2009. In 2009, the annual mass balance of Irenebreen was −63 cm w.e. despite above-average snow accumulation in winter. The near-surface ice temperature in the accumulation area was investigated with automatic borehole thermistors. The mean annual surface ice temperatures (September–August) of the accumulation area were −3.7 °C at 1 m depth and −3.3 °C at 10 m depth. Irenebreen is potentially polythermal, with cold ice and a temperate surface layer during summer. This temperate surface layer is influenced by seasonal changes in temperature. In winter, the temperature of all the ice is below the melting point and temperate layers are probably present in basal sections of the glacier. This supposition is supported by the presence of icings in the forefield of Irenebreen.     

Mass Balance Reconstruction Since 1963 and Mass Balance Model for East Rathong Glacier,Eastern Himalaya,Using Remote Sensing Methods

In this study mass balance, accumulation, ablation, runoff and temperature lapse rate for the East Rathong glacier are estimated for the time period 1963–2011 using remote sensing methods and climate data. A mass balance model is proposed for the glacier that computes mass balance as difference of volumes of consecutive years. Volume estimates of glacier are based on application of volume–area scaling law to glacier area computed from satellite images. It is observed that the glacier is summer‐accumulation type. Time series analysis is applied to the annual mass balance series. The annual mass balance of the glacier is showing a statistically significant negative trend. It is also showing a statistically significant shift in the year 1985. Change in the mean of mass balance before and after the shift year is 0.19 m w.e. Cumulative mass balance suggests that the glacier has lost ～11 m w.e. or 0.047 km³ during the last 48 years.     

Climate， mass balance and glacial changes on small dome of Collins Ice Cap， King George Island， Antarctica

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Map Comparison or Traditional Mass-balance Measurements: Which Method is Better?

A number of Norwegian glaciers were selected in the 1960s for long-term mass-balance measurements, to produce necessary hydrological information for hydropower exploitation. Special large-scale glacier maps were produced for field work and data processing, and some glaciers have been mapped more than once. Thus, comparison of glacier maps can be used to calculate changes in glacier volume for some of the glaciers, provided they are of sufficient accuracy.
Conventional mass-balance measurements were carried out on all the selected glaciers. A cumulative calculation of net balances for a series of years is used to indicate the change in a glacier's volume during that period. However, various errors originate in the field, some of which are systematic, particularly on glaciers with large winter accumulation.
The present study indicates that certain errors are difficult to define and determine, For the maritime glacier Ålfotbreen, a cumulative mass-balance calculation gives a positive total balance (+3.4 m water equivalent in the period 1968–88), whereas the map comparison indicates a total negative balance (−5.8 m water equivalent). This indicates a discrepancy between the methods, which must be accounted for.
Determination of errors in mass-balance measurements is difficult. Sinking of stakes in the accumulation area and the use of sounding sticks (steel probes) in heavy snowlayers cause problems.     

Late Pleistocene climate inferred from the reconstruction of the Taylor River glacier complex, southern Sawatch Range, Colorado

Ice surface topography of a late Pleistocene glacier complex, herein named the Taylor River Glacier Complex (TRGC), was reconstructed on the basis of detailed mapping of glacial landforms combined with analyses of aerial photos and topographic maps. During the last glacial maximum (LGM), the TRGC covered an area of 215 km² and consisted of five valley or outlet glaciers that were nourished by accumulation in cirques basins and/or upland ice fields.Equilibrium-line altitudes (ELAs) for the glaciers of the TRGC were estimated using the accumulation-area ratio method, assuming that ratio to be 0.65 ± 0.05. ELAs thus derived ranged from about 3275 to 3400 m, with a mean of 3340 ± 60 m. A degree-day model (DDM) was used to infer the climatic significance of the LGM ELA. With no appreciable differences in precipitation with respect to modern climate, the ELA implies that mean summer temperatures during the LGM were 7.6 °C cooler than today. The DDM was also used to determine the temperatures required to maintain steady-state mass balances for each of the reconstructed glaciers. The required reductions in summer temperature vary little about a mean of 7.1 °C. The sensitivity of these results to slight (± 25%) changes assumed for LGM precipitation are less than ± 0.5 °C. Even under an LGM climate in which precipitation is assumed to be substantially different (± 50%) than the present, mean summer temperatures must be on the order of 7.0 to 8.5 °C lower to depress equilibrium lines to LGM altitudes. The greater sensitivity of the ELA to changes in temperature suggests that glaciation in the region was driven more by decreases in summer temperature rather than increases in precipitation.     

Mass balance and area changes of four High Arctic plateau ice caps, 1959–2002

Abstract Small, stagnating ice caps at high latitudes are particularly sensitive to climatic fluctuations, especially with regard to changes in ablation season temperature. We conducted mass balance measurements and GPS area surveys on four small High Arctic plateau ice caps from 1999–2002. We compared these measurements with topographic maps and aerial photography from 1959, and with previously published data. Net mass balance (b_n) of Murray Ice Cap was ?0.49 (1999), ?0.29 (2000), ?0.47 (2001), and ?0.29 (2002), all in meters of water equivalent (m w.eq.). The mass balance of nearby Simmons Ice Cap was also negative in 2000 (b_n=?0.40 m w.eq.) and in 2001 (b_n=?0.52 m w.eq.). All four ice caps experienced substantial marginal recession and area reductions of between 30 and 47% since 1959. Overall, these icecaps lost considerable mass since at least 1959, except for a period between the mid‐1960s and mid‐1970s characterized regionally by reduced summer melt, positive mass balance, and ice cap advance. The regional equilibrium line altitude (ELA) is located, on average, above the summits of the ice caps, indicating that they are remnants of past climatic conditions and out of equilibrium with present climate. The ice caps reached a Holocene maximum and were several times larger during the Little Ice Age (LIA) and their current recession reflects an adjustment to post‐LIA climatic conditions. At current downwasting rates the ice masses on the Hazen Plateau will completely disappear by, or soon after, the mid‐21st century.     

Analysis of Difference Between Direct and Geodetic Mass Balance Measurements at South Cascade Glacier, Washington

Net mass balance has been measured since 1958 at South Cascade Glacier using the 'direct method,' e.g. area averages of snow gain and firn and ice loss at stakes. Analysis of cartographic vertical photography has allowed measurement of mass balance using the 'geodetic method' in 1970, 1975, 1977, 1979–80, and 1985–97. Water equivalent change as measured by these nearly independent methods should give similar results. During 1970–97, the direct method shows a cumulative balance of about −15 m, and the geodetic method shows a cumulative balance of about −22 m. The deviation between the two methods is fairly consistent, suggesting no gross errors in either, but rather a cumulative systematic error. It is suspected that the cumulative error is in the direct method because the geodetic method is based on a non-changing reference, the bedrock control, whereas the direct method is measured with reference to only the previous year's summer surface. Possible sources of mass loss that are missing from the direct method are basal melt, internal melt, and ablation on crevasse walls. Possible systematic measurement errors include under-estimation of the density of lost material, sinking stakes, or poorly represented areas.     

基于第二次冰川编目数据的中国冰川高度结构特征分析

主要基于第二次中国冰川编目数据,计算和分析中国西部各个山脉冰川面积随高度分布特征、冰川平衡线高度场的分布规律和积累区比率的分布特征。结果表明：① 各个山脉冰川面积随高度分布呈近似正态分布,冰川最大面积所占总面积的百分比与冰川分布高度差的比值可以作为描述冰川面积随高度分布的形状参数;② 平衡线高度的分布特征受气候和地形影响,由南向北逐渐降低,由东向西逐渐升高;西北和南部高大山脉边缘比较密集,青藏高原内部比较稀疏。③ 冰川积累区比率的分布特征与水汽、地形和物理冰川属性有关。各大山脉外侧和海洋型冰川区积累区比率较小（<0.5）,山脉内侧及高原内陆地区和极大陆型冰川区的积累区比率较大（>0.7）。     

Snow Accumulation on a Small High‐Arctic Glacier Svenbreen: Variability and Topographic Controls

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.     

Modelling Changes in Glacier Mass Balance that may Occur as a Result of Climate Changes

Projections of changes in glacier mass balance caused by climate changes involve modelling present mass balance in terms of climate and then perturbing the climate variables to calculate future mass balance. The simplest model involves linear regression of mass balance time series on temperature and precipitation data at stations close to the glacier but we prefer the degree-day model. This model uses temperature and precipitation to calculate snow accumulation, snow and ice melting, and possible refreezing of meltwater at regular altitude intervals on a glacier. Model parameters are still somewhat uncertain and are established for individual glaciers by tuning the model mass balance as a function of altitude to fit observed data. The model has been applied to 37 glaciers in different parts of the world so far and some details are given for Storglaciären to illustrate the approach. The sensitivity of modelled mass balance to a +1°C temperature increase shows a wide range for the 37 glaciers from about 0.1 to 1.3 m water a⁻¹ . Sub-polar glaciers have lower temperature sensitivities, and maritime and tropical glaciers have higher sensitivities.