The Impact Of Extreme Summer Melt on Net Accumulation of an Avalanche Fed Glacier,as Determined by Ground‐Penetrating Radar

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.     

乌鲁木齐河源1号冰川2009年出现物质正平衡

自1997年以来,乌鲁木齐河源1号冰川消融极为强烈,物质平衡呈大幅度亏损,连续12 a都处于强负平衡状态,平均物质平衡达-708 mm,且在2008年物质平衡达到历史最低值-999 mm,然而2009年出现了物质正平衡,物质平衡63 mm,年际变化量达1 062 mm。以2008-2009年物质平衡实测资料为基础,根据该地区的气温和降水资料分析,结果表明,造成这种现象的主要原因是夏季气温（5～8月）的降低,较2008年低1.8℃,致使冰川消融期的开始时间推迟至了7月份,结束时间提前到8月份,大大削弱了冰川的消融强度,其次是2005年以来逐渐增多的连续性降水,增加了冰川的积累量。     

Effective Sample Size for Glacier Mass Balance

Correlograms from multiple time series of point mass balance, measured on White Glacier (Axel Heiberg Island, Canada) and Abramov Glacier (Alai Range, Kirgizia), show that the correlation decreases with the difference in elevation between the points. The correlogram is used to calculate an integral spatial scale or effective sample area which, when divided into the area of the glacier, yields an estimate of the number of degrees of freedom in a stake-based estimate of the whole-glacier balance. This number – the 'effective sample size'– is a small fraction of the number of point measurements; indeed, it is independent of the number of measurements. Estimates of average balance for elevation bands are at one remove from raw stake measurements, but they are amenable to a principal component analysis which confirms that the effective sample size is very small. The small effective sample size means that uncertainty in a typical measurement of whole-glacier mass balance cannot be much less than the large value implied by the conservative assumption that stakes are perfectly correlated. One way around this difficulty would be to increase the role of prior physical understanding by seeking to model the spatial variability of mass balance. A successful model would need only a few parameters, and would allow for the joint estimation of both magnitude and uncertainty; the uncertainty in mass balance could be derived objectively from the uncertainty in the parameters. This, however, would require good estimates of the variability of mass balance at the elevation-band scale, which might in turn require that many measurement networks be redesigned.     

2000—2014年喀喇昆仑山音苏盖提冰川表面高程变化

喀喇昆仑山区冰川由于存在正物质平衡或跃动、前进现象,被称之为"喀喇昆仑异常",不过该地区冰川变化差异显著,尤其是大型表碛覆盖冰川,呈现与其他类型冰川明显的差异性响应,为理解喀喇昆仑冰川异常的机理,冰川尺度的详细变化研究十分必要。音苏盖提冰川位于喀喇昆仑山乔戈里峰北坡,是中国面积最大的冰川,是典型的大型表碛覆盖冰川。通过应用TanDEM-X/TerraSAR-X(2014年2月)与SRTM-X DEM(2000年2月)的差分干涉测量方法计算音苏盖提冰川表面高程变化,并结合冰川表面流速对冰川表面高程变化和跃动进行分析和讨论。结果表明:2000—2014年音苏盖提冰川表面高程平均下降了1.68±0.94 m,即冰川整体厚度在减薄,年变化率为-0.12±0.07 m·a^-1。冰川表面高程变化分布不均,其中南分支(S)冰流冰川整体减薄较为显著,冰川南分支冰流运动速度较快,前进/跃动的末端占据了冰川的主干,阻滞原主干冰川物质的向下运移(跃动),导致原主干冰舌表面高程上升;冰川厚度减薄随着海拔升高先下降后保持稳定,同时呈现一定的波动性;低海拔表碛区域消融大于裸冰区,可能存在较薄...     

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.     

中国西部大陆性冰川与海洋性冰川物质平衡变化及其对气候响应——以乌源1号冰川和帕隆94号冰川为例

为认识全球变暖背景下中国西部大陆性冰川与海洋性冰川物质平衡变化及其对气候响应,本研究以天山乌鲁木齐河源1号冰川和藏东南帕隆94号冰川为例,结合大西沟与察隅站气象资料,对1980 — 2015年两条冰川的物质平衡变化特征及差异进行了分析。结果表明：36 a来乌源1号冰川与帕隆94号冰川物质平衡总体上均呈下降趋势,累积物质平衡达-17102与-8159 mm w.e.,相当于冰川厚度减薄19与9.01 m,且分别于1996、2004年左右发生突变。同期两条冰川所处区域年均温呈显著上升趋势,而降水量却表现出不同的变化态势;二者年内气温分配相仿,但降水分配差异较大。初步分析认为气温上升是导致乌源1号冰川与帕隆94号冰川物质亏损的主要原因,冰川区气温和降水变化幅度的差异和地性因子（坡度、冰川面积）的不同使得乌源1号冰川对气候变化响应的敏感性高于帕隆94号冰川,由于目前海洋性冰川物质平衡监测时段相对较短,为深入研究中国西部冰川物质平衡变化及过程仍需加强对冰川的持续观测。     

Applicability of an ultra-long-range terrestrial laser scanner to monitor the mass balance of Muz Taw Glacier, Sawir Mountains, China

Glacier mass balance is a key component of glacier monitoring programs. Information on the mass balance of Sawir Mountains is poor due to a dearth of in-situ measurements. This paper introduces the applicability of an ultra-long-range terrestrial laser scanner(TLS) to monitor the mass balance of Muz Taw Glacier, Sawir Mountains, China. The Riegl VZ?-6000 TLS is exceptionally well-suited for measuring snowy and icy terrain. Here, we use TLS to create repeated high spatiotemporal resolution DEMs, focusing on the annual mass balance(June 2, 2015 to July 25, 2016). According to TLS-derived high spatial resolution point clouds, the front variation(glacier retreat) of Muz Taw Glacier was 9.3 m. The mean geodetic elevation change was 4.55 m at the ablation area. By comparing with glaciological measurements, the glaciological elevation change of individual stakes and the TLS-derived geodetic elevation change of corresponding points matched closely, and the calculated balance was-3.864±0.378 m w.e.. This data indicates that TLS provides accurate results and is therefore suitable to monitor mass balance evolution of Muz Taw Glacier.     

60-year changes and mechanisms of Urumqi Glacier No. 1 in the eastern Tianshan of China,Central Asia

Worldwide examination of glacier change is based on detailed observations from only a small number of glaciers. The ground-based detailed individual glacier monitoring is of strong need and extremely important in both regional and global scales. A long-term integrated multi-level monitoring has been carried out on Urumqi Glacier No. 1 (UG1) at the headwaters of the Urumqi River in the eastern Tianshan Mountains of Central Asia since 1959 by the Tianshan Glaciological Station, Chinese Acamedey of Sciences (CAS), and the glaciological datasets promise to be the best in China. The boundaries of all glacier zones moved up, resulting in a shrunk accumulation area. The stratigraphy features of the snowpack on the glacier were found to be significantly altered by climate warming. Mass balances of UG1 show accelerated mass loss since 1960, which were attributed to three mechanisms. The glacier has been contracting at an accelerated rate since 1962, resulting in a total reduction of 0.37 km² or 19.3% from 1962 to 2018. Glacier runoff measured at the UG1 hydrometeorological station demonstrates a significant increase from 1959 to 2018 with a large interannual fluctuation, which is inversely correlated with the glacier's mass balance. This study analyzes on the changes in glacier zones, mass balance, area and length, and streamflow in the nival glacial catchment over the past 60 years. It provides critical insight into the processes and mechanisms of glacier recession in response to climate change. The results are not only representative of those glaciers in the Tianshan mountains, but also for the continental-type throughout the world. The direct observation data form an essential basis for evaluating mountain glacier changes and the impact of glacier shrinkage on water resources in the interior drainage rivers within the vast arid and semi-arid land in northwestern China as well as Central Asia.     

Annual Mass Balance of Blue Glacier, USA: 1955–97

Mass changes of Blue Glacier, USA are calculated from topographic maps made from vertical aerial photography in late summer of 1939, 1952, 1957, and 1987, along with laser altimetry flown in June 1996. Changes in elevation between maps were adjusted for seasonal variations in the snow cover, and to account for the ablation between the date of photography and 1 October. Topography obtained from the laser altimetry was adjusted for snow thickness and glacier motion to estimate topography of 1 October 1995. The mass of Blue Glacier has changed less than 7 m (water equivalent) during this 56 year period which is minor compared with other glaciers in the region and elsewhere in the world. Glacier-average annual mass balances, beginning in 1956, have been calculated either from stake measurements and probing of late-season snow, or from a regression analysis using late-season measurements of the equilibrium line altitude. A comparison with the changes derived from surface maps shows values obtained from field measurements are too positive by about 0.4 m a^?1 , indicating that considerable caution is needed when interpreting time series of mass balance. Two alternative time series of mass balance consistent with the long-term mass changes are created by making simple adjustments: (1) a single constant is subtracted from each value so that the series is consistent with the 1957–95 mass change; (2) one constant is subtracted from each value over 1957–87 and another is subtracted from each value over 1987-95 so that the series is consistent with both the 1957–87 and 1987–95 mass changes. The mass balance of Blue Glacier was generally positive until the mid-1970s and negative since. The fluctuations of mass balance closely resemble those of snowfall on the glacier as estimated from the joint distribution of temperature and precipitation. The climate in western Washington was cooler and wetter during the decade before the mid-1970s, but the trend since has been towards warmer and drier conditions.     

How many Stakes are Required to Measure the Mass Balance of a Glacier?

Glacier mass balance is estimated for South Cascade Glacier and Maclure Glacier using a one-dimensional regression of mass balance with altitude as an alternative to the traditional approach of contouring mass balance values. One attractive feature of regression is that it can be applied to sparse data sets where contouring is not possible and can provide an objective error of the resulting estimate. Regression methods yielded mass balance values equivalent to contouring methods. The effect of the number of mass balance measurements on the final value for the glacier showed that sample sizes as small as five stakes provided reasonable estimates, although the error estimates were greater than for larger sample sizes. Different spatial patterns of measurement locations showed no appreciable influence on the final value as long as different surface altitudes were intermittently sampled over the altitude range of the glacier. Two different regression equations were examined, a quadratic, and a piecewise linear spline, and comparison of results showed little sensitivity to the type of equation. These results point to the dominant effect of the gradient of mass balance with altitude of alpine glaciers compared to transverse variations. The number of mass balance measurements required to determine the glacier balance appears to be scale invariant for small glaciers and five to ten stakes are sufficient.     

Seasonal variability in velocity and ablation of Te Moeka o Tuawe/Fox Glacier, south Westland, New Zealand

Abstract:  Seasonal variations in ablation and surface velocity were investigated on the lower Fox Glacier. Variations occur between summer and winter ablation, with surface velocity also showing marked seasonality. Recent advance has resulted in the glacier gaining around 200 m length since late 2004. Longer term, Fox Glacier appears linked to the Southern Oscillation Index, with positive glacier mass balances associated with negative Southern Oscillation Index (El Niño). An estimated glacier response time of approximately 9–14 years suggests the current terminus advance was linked to mass gains in the mid-1990s. Recent collapses at the terminal face continue to prove a hazard at this busy tourist destination.     

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。     

A Mass Balance Model that Uses Low-altitude Meteorological Observations and the Area–Altitude Distribution of a Glacier

A glacier mass balance model that requires only low-altitude precipitation and temperature observations and the glacier's areaaltitude distribution is presented as an alternative to direct field measurements. Input to the model for South Cascade Glacier are daily weather observations at stations 30–60 km from the glacier and at altitudes 1300 to 1500 m lower than the glacier. The model relies on the internal consistency of mass balance variables that are generated by simulation using the low-altitude weather data. The daily values of such balance variables as snowline altitude, zero balance altitude, glacier balance, balance flux and the accumulation area ratio are correlated throughout the ablation season using two-degree polynomial regressions to obtain the lowest fitting error. When the minimum average error (or maximum R ²) is attained, the generated balances and other variables are considered to be real. A simplex optimization technique is used to determine the optimal coefficient values that are used in algorithms to convert meteorological observations to snow accumulation and snow and ice ablation. The independently produced simulation results for the 1959–1996 period are compared with balances measured at the glacier. The agreement between annual balances for individual years is fair and between long-term volume changes measured by the geodetic method is excellent.     

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.     

Comparing Traditional Mass Balance Measurements with Long-term Volume Change Extracted from Topographical Maps: A Case Study of Storbreen Glacier in Jotunheimen, Norway, for the Period 1940–1997

Storbreen glacier is situated in the western part of Jotunheimen, a mountain area in central southern Norway. Annual mass balance data have been recorded since 1949. In addition, detailed topographical maps at the scale 1:10,000 exist from the years 1940, 1951, 1968, 1984 and 1997. In this paper, volume change calculated from maps is compared with annual mass balance data. The volume change was in reasonable agreement with the measured cumulative mass balance for the periods 1940–1951 and 1968–1984; however, for the periods 1951–1968 and 1984–1997, the mass balance measurements showed larger negative values than obtained from map comparisons. One obvious reason for this is the inaccuracy of the contour lines in the upper areas of the glacier on maps from 1940 and 1951. Other factors influencing the result are tested, and also suggestions are given for improving the techniques for mapping glacier volume changes.     

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.     

The surface velocity feature of Glacier No.1 at the headwater of Urumqi River, Tianshan Mountain

The movement of a glacier can redistribute glacier mass balance and change water and thermal conditions of the glacier.Thus,the glacier can maintain its dynamic balance.Surface velocity of a glacier is a basic feature of glacier movement.With successive monthly observations from 2006 to 2008,we obtained spatial and temporal variations for surface velocity of Glacier No.1 at the headwater of Urumqi River,Tianshan Mountain.Dynamic simulation was used to verify the findings.Results show that altitudinal distribution of glacier velocity was influenced by synthetic effects such as glacier thickness,slope,and bedrock morphology.However,seasonal variation was influenced by changing glacier thickness.     

Glacier Distribution in the Alps: Statistical Modelling of Altitude and Aspect

Mass balance of glaciers in mountain areas varies not only with altitude and regional position but also with aspect, gradient, glacier size, glacier type and detailed topographic position. These factors are combined here in models of how glacier altitude varies, tested with data for the Alps edited from the World Glacier Inventory. An overall northward tendency in glacier numbers (toward 005 ± 4°) and lower altitudes (013 ± 5°) is maintained across a range of glacier sizes, types, altitudes and the major divisions of the Alps. Variation with aspect of glacier altitude (and, by implication, of glacier balance) in the Alps is essentially unimodal, and north‐facing glaciers average 220 m lower in middle altitude than south‐facing: 148 m in the Western Alps, 232 m in the West‐central, 252 m in the East‐central, and 268 m in the Eastern Alps. For smaller subdivisions, confidence intervals on estimates are broader and many differences lack statistical significance. Contrasts are greater in the higher massifs, with greater relief, and lower in cloudy, windward areas. There are small windrelated tendencies east of north along the northern and western fringes, but trends across space are weak: position is thus treated by subdivision into districts and groups. Mid‐altitude averages 2891 m overall and varies from 2552 to 3127 m for 27 glacier districts, and from 2124 to 3209 m for 103 glacier groups. Glacier mid‐altitude varies also with glacier form, nourishment, height range and area, which account for over two‐thirds of variance in combined models.     

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.     

Surface energy balance of Keqicar Glacier,Tianshan Mountains,China, during ablation period

The meteorological data of ablation season in 2005 were recorded by two automatic weather stations on Keqicar Glacier, in the southwest Tianshan Mountains of China. One is operated on the glacier near the equilibrium line with an altitude of 4,265 m (Site A) and another is operated on the glacier ablation area with an altitude of 3,700 m (Site B). These data were used to analyze the meteorological conditions and the surface energy balance (SEB) of Keqicar Glacier. Net radiation was directly measured, and turbulent heat fluxes were calculated using the bulk aerodynamic approach, including stability correction. The ablation value of 0.68 m w.e. derived from four ablation stakes is in close correspondence to the modeled value of 0.71 m w.e. During the observation period, net radiation accounts for 81.4% of the total energy with its value of 63.3 W/m². The rest energy source is provided by the sensible heat flux with a value of 14.4 W/m². Energy is consumed mainly by melting and evaporation, accounting for 69.5% and 29.7% of the total energy with their values of 54.0 and 23.0 W/m², respectively. Radiative energy dominates energy exchanges at the glacier-atmosphere interface, governed by the variation in net shortwave radiation. Net short-wave radiation varies significantly due to the effects of cloudiness and the high albedo caused by solid precipitation. Wind speed influences the turbulent heat fluxes distinctively and sensible heat flux and latent heat flux are much larger in July with high wind speed.