Effect of Uncertainties in Measured Variables on the Calculated Mass Balance of storglaciären

Detailed mass balance measurements have been carried out on Storglaciären since 1945, adhering to a fixed system of measurements since the 1960s. Using a geographical information system approach, the effect of parameters such as density conversion model, systematic snow probing error and ablation gradient calculation on the mass balance of the glacier can be investigated. It is evident that the measure of total mass balance of Storglaciären is not sensitive to variations in these parameters. This means that reasonable estimates of the mass balance of a glacier can be made with very little information, given that measurements are distributed over the glacier surface. However, the uncertainty that may result from varying the parameters is c . 0.1 m water equivalent. Hence, reporting mass balance to centimetre or even millimetre resolution is questionable. When considering mass balance measurements as input for flow models, for example, i.e. requiring a distributed balance, the detail necessary in the measurements becomes significantly greater. At this level careful attention must be made to all parameters entering the mass balance calculation. From this it seems evident that any measurements at intermediate complexity do not increase the accuracy of the mass balance in relation to the extra work required and that the choice of method determines the scientific problems to which the data is applicable.     

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.     

Storsteinsfjellbreen: Variations in Mass Balance from the 1960s to the 1990s

When the Norwegian State Power Board decided to plan an extensive water power development in the mountainous areas southeast of Narvik in northern Norway, a large mapping project was started. Detailed maps were constructed at a scale of 1:10 000 from aerial photographs taken in 1960. Several hydrometric stations were installed, and three glaciers were selected for mass balance observations. Storsteinsfjellbreen was the largest of these, and a special glacier map with 10 m contours was printed in four colours, to be used in the field work. Mass balance studies were carried out initially during one 5-year period (1964–68), and also later during another 5-year period (1991–95).
Results from these periods are compared with similar data from the Swedish glacier Storglaciären, about 45 km to the southeast. For all the years except one (1968), the net balance of these glaciers shows a similar pattern: positive years and negative years are synchronous.
A new glacier map was made from a special aerial survey in 1993 at the same scale and of similar accuracy as the first map, so a comparison could be made to calculate the change in glacier volume from 1960 to 1993. From digital terrain models it could be shown that the glacier surface had dropped more than 60 m vertically on the tongue, while the thickness increased above the equilibrium line by up to 20 m. The overall mass loss amounted to 16.8×10⁶ m³ water during 33 years, which corresponds to an extra 2.6 l·s⁻¹·km⁻² (litres per sec. per sq. km) delivered to the river, in addition to the "normal" discharge
due to annual precipitation, which is 36 l·s⁻¹·km⁻² in the area.
A copy of the new glacier map is enclosed with this article.     

Application of Kriging Interpolation for Glacier Mass Balance Computations

In order to compute the specific mass balance of a glacier, point measurements of mass balance need to be integrated and thus interpolated over the entire glacier. In this study kriging was applied as interpolation technique to mass balance data of Storglaciren, a 3 km² valley glacier, focusing on the sensitivity of results to the choice of some kriging parameters. Although the spatial means varied only little in most cases, the spatial distribution of the mass balance quantities was sensitive to the assumption on kriging parameters, suggesting that the kriging parameters need to be carefully optimized for each case if the spatial distribution is of interest.     

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...     

Glaciological investigations in the balance year 1983–84

In mainland Norway, mass balance measurements were carried out on the Hardangerjøkulen and Storbreen glaciers. Both had a small negative net balance. The two glaciers measured in Svalbard, Broggerbreen and Lovgnbreen, also had negative balances as in the previous 19 years. Length fluctuations measured at eight glacier tongues indicate that one was advancing, one in equilibrium, and six were retreating.     

EVALUATION OF GRIDDED PRECIPITATION FOR NORWAY USING GLACIER MASS‐BALANCE MEASUREMENTS

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.     

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.     

Glacier mass balance investigations in the balance years 1984-85 and 1985-86

As in previous years Norsk Polarinstitutt has carried out mass balance investigations on Storbreen and Hardangerjøkulen in mainland Norway and on Broggerbreen and Lovenbreen in Svalbard. More than 20 years of measurements show that the glaciers both in mainland Norway and in Svalbard are retreating.
Both in 1985 and in 1986 the glaciers in Norway had a negative net balance. At Storbreen the mean annual net balance value 1949-86 is -0.30 m in water equivalents, while on Hardangerjflkulen the mean value 1963-86 is -0.02 m.
The two glaciers measured in Svalbard also had negative net balance in 1985 and in 1986. Both measured glaciers have had negative balance nearly all years since the measurements started in 1966. The mean value is close to -40g/cm² or -0.4 m on both.     

极地记录冰川和达尔克冰川流速的遥感监测研究

测定南极冰川的流速 ,对于研究南极冰雪物质平衡、南极环境变化及其对全球环境的影响有重大意义。本文论述了利用多时相卫星遥感影像监测冰川变化的原理和方法 ,通过对英格里特 .克里斯泰森海岸不同时期的遥感影像进行几何纠正和配准及叠加处理 ,测量和计算出极地记录冰川和达尔克冰川的平均流速 ,并对它们的变化特点进行了初步的分析和评价。     

斯瓦尔巴群岛冰川学研究进展与我国北极冰川监测系统建设

北极斯瓦尔巴群岛冰川大多数属于亚极地型(sub-polar)或多热型(polythermal)。Austre Br(?)ggerbreen和Midre Lovénbreen冰川(＜10km~2)长时间系列物质平衡研究显示,自小冰期结束以来几乎所有的观测年中夏季消融比冬季积累更大,导致冰体稳定地减小;而面积更大、海拔高度更高的冰川如Kongsvegen冰川(105km~2)则更加接近稳定态的平衡。斯瓦尔巴群岛冰川流动速率一般较低,但跃动相当频繁,控制跃动型冰川空间分布的因素包括冰川长度、基底岩性和多热场。可通过冰川水文特征、钻孔温度测量和无线电回波探测获取斯瓦尔巴群岛冰川热场的信息。斯瓦尔巴群岛冰川的低流速和多热性结构对冰川上的排水系统相当重要,整个群岛淡水径流的四个主要来源分别是冰川消融、雪融化、夏季降雨和冰崩解,经验回归方法和模式方法用于计算淡水径流量。因夏季融水渗浸作用、采样分辨率低和化学成分分析有限,早期斯瓦尔巴群岛冰芯的准确定年受到严重影响,但最近的研究显示,来自斯瓦尔巴群岛冰帽的冰芯数据仍然能够提供重要的气候和环境信息。通过我国北极黄河站2005年度科学考察,我们已初步建立了Austre Lovénbreen冰川和Pedersenbreen冰川监测系统,并计划在Austre Lovénbreen冰川进行钻孔温度测量、冰川气象要素观测、冰川前缘水文观测以及冰川厚度和内部结构测量,重点开展斯瓦尔巴群岛冰川基本特征和发育条件、冰川表面能量和物质平衡、冰川波动与气候变化关系、淡水径流年际和季节性变化和气/雪/冰界面过程等方面的研究。     

Assessment of the Evolution in Velocity of Two Debris‐Covered Valley Glaciers in Nepal and New Zealand

Feature tracking of orthorectified pairs of Advanced Spaceborne Thermal Emission and Reflection Radiometer satellite images is used to calculate velocities for the Tasman Glacier, New Zealand (2002–2014) and the Khumbu Glacier, Nepal (2001–2008). Velocities in the middle and upper ablation zones of both glaciers show a long‐term decrease of ～10–20%, while the terminus of Khumbu Glacier has remained near stagnation throughout the study period. In contrast, there has been a recent acceleration of the lower terminus of Tasman Glacier, from ～5 m a^–1 in 2002 to 40 m a^–1 in 2014. Both of these glaciers have an extensive supraglacial debris cover across their lower ablation regions, with the Khumbu Glacier terminating on land and the Tasman Glacier terminating in a proglacial lake. The rapid recent increase in velocity of the terminus of Tasman Glacier is closely correlated with the increase in size of its proglacial lake. These results indicate the complex dynamic changes that mountain valley glaciers may undergo in response to long‐term negative mass balance.     

SURFACE MASS BALANCE AND ITS VARIATION ON THE MIZUHO PLATEAU, ANTARCTICA IN 1987-1988

From the surface mass accumulation data in year of 1987/88, the distribution and variation of annual mass balance on Mizuho Plateau are discussed. The authors also analyze the effects of shortterm climatic and topographical variations on the mass balance. It is found that there are some differences in spatial distribution and annual average state in the year of 1987/88 and other years. Ia the area at elevation lower than 550 m near the coast, the mass balance appears to be negative. The annual mass balance over 80 km distance from S_(16) to inland is 0.84m snow depth. A low mass balance zone from 80 km site to Mizuho Station, is considered to be only 0.14 m snow depth. It is found from the comparison of mass balances that the mass-balance level on the glaciers in West China is 9 times higher than that on Mizuho Plateau, where the massbalance level appears to be low accumulative and low expensive, but inverse in middle and low latitude regions, such as on glaciers in West China. The effects of short-term     

A Small Glacier as an Index of Regional Mass Balance: Baby Glacier, Axel Heiberg Island, 1959–1992

Baby Glacier, Axel Heiberg Island, N.W.T., Canada is a small (0.6 km²), high-latitude (79°N), high-altitude (700–1200 m) glacier with a mass balance record extending from 1959–60 to the present. The record demonstrates shrinkage of the glacier, but a statistically significant trend is not evident. Correlations are strong between the mass balance of Baby Glacier and that of the nearby and much larger White Glacier, and also those of even larger, more distant glaciers. Thus programmes of measurement on small, simple ice bodies such as Baby Glacier can be representative of a large region. However, inter-annual changes are more accentuated for Baby Glacier. Baby Glacier does not meet all of the usual criteria for a representative glacier, but it straddles the regional equilibrium zone, a fact which helps to offset the disadvantages of its small size and limited altitudinal range. The equilibrium zone deserves to be an important focus for studies of high-arctic mass balance, with the aim of facilitating future measurement programmes which will rely on satellite remote sensing.     

近50a来天山博格达峰地区四工河4号冰川表面高程变化特征

基于GIS技术,利用GPS测量数据和1962年地形图分别建立两期DEM,通过对比重点研究了四工河4号冰川1962-2009年冰舌区的表面高程变化特征。结果表明:1962-2009年间,冰舌区平均减薄15±10 m,年均减薄约0.32±0.2 m,冰储量亏损达(14.3±9.5)×10-3km3,折合水当量(12.9±8.6)×10-3km3。不同海拔、坡度区间冰面高程变化差异显著,海拔较低、坡度较缓区域的变化最为强烈。在气候变暖的趋势下,四工河4号冰川发生强烈消融,标志着博格达峰地区的冰川正处于物质严重亏损的状态,直接影响到流域水资源状况。     

Local aspect asymmetry of mountain glaciation: A global survey of consistency of favoured directions for glacier numbers and altitudes

Understanding aspect effects on present-day glaciers provides essential background to the palaeoclimatic interpretation of reconstructed former glaciers or glacial cirques. Several factors influencing glacier mass balance vary with slope aspect: these give more glaciers, lower glaciers and possibly larger glaciers on favoured aspects. Their effects can be measured by either vector analysis of the number of glaciers with each aspect or Fourier regression of glacier altitude or size against aspect. Both approaches are applied here to large data sets from the World Glacier Inventory, for all available regions.Favoured aspect is measured by direction of the resultant vector mean and by the direction of minimum glacier altitude, for 51 regions with a total of 66,084 glaciers. The two directions are broadly consistent in mid-latitudes and in the tropics, but large differences occur in the Arctic and Nepal. Poleward aspects dominate, especially in mid-latitudes: radiation receipt is the major factor, with strong wind effects limited to areas with only moderate relief. Strength of asymmetry is measured by vector strength (from glacier numbers) or by a combination of first Fourier coefficients (from glacier altitudes). Measuring two different facets of degree of asymmetry, they are essentially unrelated. The Fourier measure is the best estimate of local climatic asymmetry, as vector strength is more influenced by topography.     

RECENT GLACIER ADVANCES IN NORWAY AND NEW ZEALAND: A COMPARISON OF THEIR GLACIOLOGICAL AND METEOROLOGICAL CAUSES

ABSTRACT. Norway and New Zealand both experienced recent glacial advances, commencing in the early 1980s and ceasing around 2000, which were more extensive than any other since the end of the Little Ice Age. Common to both countries, the positive glacier balances are associated with an increase in the strength of westerly atmospheric circulation which brought increased precipitation. In Norway, the changes are also associated with lower ablation season temperatures. In New Zealand, where the positive balances were distributed uniformly throughout the Southern Alps, the period of increased mass balance was coincident with a change in the Interdecadal Pacific Oscillation and an associated increase in El Niño/Southern Oscillation events. In Norway, the positive balances occurred across a strong west-east gradient with no balance increases to the continental glaciers of Scandinavia. The Norwegian advances are linked to strongly positive North Atlantic Oscillation events which caused an overall increase of precipitation in the winter accumulation season and a general shift of maximum precipitation from autumn towards winter. These cases both show the influence of atmospheric circulation on maritime glaciers.     

南极冰盖表面冰流速研究综述

冰川表面流速作为南极冰盖物质平衡估算的一项重要内容,对于研究全球变暖背景下的海平面上升具有重要意义。随着技术的进步,南极的冰流速监测方法已经从传统的花杆测量、光学仪器边角测量,发展到先进的GPS测量和遥感观测。南极冰盖冰流速总体特征是:海岸带冰流速快于内陆冰流速,冰架冰流速快于陆地冰流速,西南极冰流速快于东南极冰流速。未来加强对数据稀疏地区的冰流速监测,扩大冰流速研究的时间尺度,开发冰流速研究的新方法以及构建冰流速波动与气候变化相互关系模型等,成为南极冰流速研究的新热点。     

Arctic glacier movement monitoring with GPS method on 2005

During the 2005 Arctic Yellow River Station expedition, the research on monitoring the movement and mass balance of two glaciers around Ny-lesund, Austrelovénbreen and Pedersenbreen, which were selected in the 2004 Yellow River Station expedition were conducted. This paper analyzes the feasibility and advantage in using GPS method to monitor the Arctic glaciers' movement, estimates the precision of first time measured GPS data and discusses the relevant problems in surveying on the Arctic Glaciers with GPS.     

水文气象学方法计算喜马拉雅山北坡冰川流域物质平衡

卡鲁雄曲是喜马拉雅that坡唯一具有长期常规水文气象观测资料的冰川流域.根据中国冰川水文和气候的分布特征,可推导出一组以水文、气象观测数据计算流域冰川平均物质平衡的公式.据此恢复了1983-2006年卡鲁雄曲流域冰川平均物质平衡各分量的逐年值序列,并用SPSS软件对计算结果进行r统计分析.结果表明:1983-2006年的24 a里,卡鲁雄曲流域的冰川消融逐步加剧:多年平均值为-136.3 mm/a,前12 a(1983-1994年)多年平均值为-83.61 mm/a,后12 a(1995-2006年)多年平均值为-188.98 mm/a,且1986、1998和2005年出现较大的波动,冰川物质平衡值分别为:149.19mm、-654.36 mm和-316.43 mm.通过对影响冰川物质平衡动态变化的影响因素进行分析,发现冰川物质平衡变化主要由强烈消融期(5-9月)的平均温度决定,二者的相关系数达到-0.786,并具有很好的线性关系:MB=-331.8T_(5-9)+2683.5.