Hydrogeochemistry of the Chhota Shigri glacier meltwater,Chandra basin,Himachal Pradesh,India: solute acquisition processes,dissolved load and chemical weathering rates

The chemical compositions of various ions in meltwater of the Chhota Shigri glacier were analysed during the observation period from May to October 2010. Total 164 samples of meltwater were collected in two times a day at 8.0 a.m and 6.0 p.m. Bicarbonate and calcium were the dominant anion and cation in meltwater of the investigation area. High ratios of (Ca + Mg) versus TZ⁺ and (Ca + Mg) versus (Na + K) demonstrate that hydrogeochemistry of the study area was mainly governed by carbonate type weathering. The average sulphate mass fraction of meltwater was computed to be 0.31 ± 0.12, showing dominancy of bicarbonate over sulphate. This excess bicarbonate would be generated by an alternative proton supply mechanism due to biological activities in the bed rock lithology and sulphide oxidation may be about the same as carbonation as a driver of chemical weathering at Chhota Shigri glacier. In general, major ions and total dissolved solid concentrations showed decreasing trend with increasing discharge from the study area. The average daily mean dissolved load of this glacier was much lower than that of the Gangotri glacier, which may be due to low meltwater runoff and lithology of the investigation area. The cation weathering rates of study area for early, peak and late melt seasons were computed to be 694, 1631 and 481 meq m^?2 a^?1, respectively. The average value of chemical denudation rates of the Chhota Shigri glacier meltwater was found lower than that of the Dokriani glacier.     

北半球冰川物质平衡变化的若干特征及其气候意义

根据北半球连续观测的４０多条冰川物质平衡资料，分析了目前冰川物质平衡状态及影响它们的地形因互。冰川物质平衡的变化在区域间存在着一定的联系：斯堪的纳维亚、落基山和天山地 区冰川物质平衡的变化在大多数时间内存在着对应联 系，而与阿尔卑斯山冰川物质平衡的变化具有不同程度的反向波动特征。     

Terminal environment, topographic control and fluctuations of West Greenland glaciers

Glaciers are commonly regarded as sensitive indicators of climatic change, but iceberg calving can partially decouple glacier oscillations from climatic forcing. Recent fluctuations (1942–85) of 72 West Greenland outlet glaciers were studied using aerial photographs, and nine of them examined in the field. Despite similar climatic forcing, variable glacier behaviour is apparent. Eighty-four percent of the land terminating glaciers have been retreating or stable during the period, whereas more than half the tidewater and lake terminating glaciers have been advancing. The calving glaciers exhibit much greater variability in frontal behaviour. Patterns of change suggest that the land-terminating glaciers are controlled dominantly by variations in summer temperature, but that calving dynamics have caused the tidewater and lake-calving glaciers to respond to climatic change in non-linear ways. Dynamic and response contrasts are apparent between freshwater and tidewater glaciers. Trough geometry is of great significance in controlling the nature and magnitude of frontal change of calving glaciers; in particular, topographic 'pinning points' represent potentially stable locations within the fjord at which stillstands almost invariably occur, irrespective of climatic change or regional trends.     

1980-2015年青藏高原东南部岗日嘎布山冰川变化的遥感监测

基于地形图、航空摄影相片和Landsat OLI遥感影像,对青藏高原东南部岗日嘎布山1980-2015年间的冰川变化进行了研究。结果表明： 1980-2015年,岗日嘎布山冰川面积减少679.50 km²（-24.91%）,年平均面积退缩率为0.71%·a^-1,末端海拔平均抬升了111 m。研究区范围内有10条冰川处于前进状态,冰川长度平均增加566.17 m;其余冰川均处于退缩状态,冰川长度平均减少823.49 m。与中国其他山系冰川相比,岗日嘎布山冰川面积年平均退缩速率较大,冰川长度变化速率最大,是冰川退缩最强烈的地区之一。岗日嘎布山冰川变化与气候变化关系密切,对研究区附近三个气象站5-9月平均气温和降水变化分析表明,自1980年以来,岗日嘎布山5-9月平均气温显著上升,降水变化不明显,是导致该区域冰川呈现快速退缩的主要原因。     

1973—2020年阿尔金山冰川面积变化及其对气温变化的响应

研究冰川面积变化对气温变化的响应模式,对于冰川资源的保护和利用具有重要意义。利用Landsat MSS、TM和OLI影像,采用比值阈值法结合目视修正,提取了阿尔金山地区1973—2020年8个时期的冰川边界信息,分析了冰川的时空变化特征,并结合距离阿尔金山较近的且末、若羌、茫崖和冷湖等四个气象站点的气象数据,分析了冰川变化对气温变化的响应规律。主要结论如下：1973—2020年阿尔金山地区冰川整体处于退缩状态,面积减少了（64.89±12.36） km²（19.21%±2.90%）;1973—1990年冰川退缩较快,年均退缩率为（0.49±0.07）%·a^-1;1990—1995年和1995—2000年这两个时期冰川退缩最快,年均退缩率分别为（1.07±0.08）%·a^-1和（1.08±0.08）%·a^-1;2000年后,冰川退缩速率较慢,比较稳定,年均退缩率均低于0.2%·a^-1。气温是影响阿尔金山地区1973—2020年冰川变化的主要气候因子。阿尔金山地区冰川对不同气温变化阶段的响应模式为：气温升高阶段,冰川消融,冰川面积减少;气温稳定阶段,冰川逐渐进入新的动态均衡状态,冰川面积也相对稳定;气温降低阶段,因冰川运动的滞后性,冰川面积在短时间内无明显变化。     

Role of debris cover to control specific ablation of adjoining Batal and Sutri Dhaka glaciers in Chandra Basin (Himachal Pradesh) during peak ablation season

As part of the on-going annual mass balance measurements on Batal and Sutri Dhaka glaciers, observations were made during peak ablation (August–September) season in 2013 to understand the response of debris covered and clean-ice (debris free) glacier surface to melting processes. Though, both the Batal and Sutri Dhaka glaciers have almost similar geographical disposition, Batal shows extensive debris cover (90% of the ablation area), while the latter is free from debris (only 5% of the ablation area). The thickness of debris in Batal glacier is inversely proportional to altitude, whereas Sutri Dhaka mostly experienced debris-free zone except snout area. Observation revealed that the vertical gradient of ablation rate in ablation area is contrastingly opposite in these two glaciers, reflecting significant control of debris thickness and their distribution over glacier surface on the ablation rates. While different thickness (2–100 cm) of debris have attenuated melting rates up to 70% of total melting, debris cover of <2 cm thickness has accelerated melting up to 10% of the total melting. Estimated melt ratio reveals that about 90% of the ablation area has experienced inhibited melting in Batal glacier, whereas only less than 5% ablation area of Sutri Dhaka has undergone inhibited melting. Comparison of topographical maps of 1962 with successive satellite images of the area demonstrates a terminus retreat of 373 ± 33.5 m and 579 ± 33.5 m for Batal and Sutri Dhaka glaciers for the period 1962–2013, respectively.     

1980-2010年西藏波密地区典型冰川变化特征及其对气候变化的响应

运用遥感(RS)与地理信息系统(GIS)技术, 结合波密县1960-2010年气象数据, 分析了西藏波密地区冰川的主要分布特征和典型大冰川1980-2010年的时空变化. 结果显示: 波密县共有冰川数量2 040条, 总面积为4 382.5 km², 其中, 分布在海拔4 000~6 000 m的高山冰川总面积达4 086 km², 占冰川总面积的93.2%; 南坡分布冰川1 504条, 面积3 180.04 km², 分别占波密冰川总量的73.73%和72.56%, 而北坡占还不到三分之一. 提取1980、 1990、 2000和2010年4期面积大于20 km²的24条大冰川面积进行对比分析, 1980-2010年间波密县大冰川面积总体呈减小趋势, 由1980年的1 592.78 km²退缩至2010年1 567.04 km², 共退缩了25.74 km²; 其中, 1980-1990年冰川变化贡献最大, 冰川面积退缩了16.62 km², 占冰川总面积退缩量的64.6%. 波密县气象站数据显示, 50 a来冰川退缩主要受温度持续上升的影响, 降水量变化对冰川变化影响不大.     

Glacier changes and its effect on water resources in Urumqi River Basin,Tianshan Mountains,China, from 1964 to 2014

This work investigated changes in glaciers over the Urumqi River Basin from 1964 to 2014, and its role in the local water resource. Based on the glacier outlines on 1964, 2005 and 2014 derived from topographical maps and satellite images, the glaciers shrank 32.51% of the surface area between 1964 and 2005, and 12.12% between 2005 and 2014, respectively. The corresponding area reduction rate increased from 0.77%/a in 1964–2005 to 1.21%/a in 2005–2014, suggesting accelerated glacier retreat in recent decades. Our results showed that hydrological regime variability in both glacierized and non-glacierized catchments of the Urumqi River Basin was dependent on the current glacier conditions. Furthermore, glaciers with the area of 1–2 km² contributed most to the water resources in this region, but their regulation effects to river runoff were weakening. Accordingly, the accelerated glacier retreat was a dangerous signal for local water resource, and the continuous future glacier monitoring under the global warming were desperately needed.     

利用ASTER影像对慕士塔格-公格尔山冰川解译与目录编制

以帕米尔东缘的慕士塔格公格尔山为试验区,利用2001年ASTER遥感数据,综合空间锐化增强处理、比值图像取阀值和目视判读等提取冰川边界;利用ASTER的同轨立体像对提取DEM,区分表碛覆盖的冰川范围;自动、半自动和人工量算冰川的有关参数,进行冰川解译和新的冰川目录编制.与中国冰川编目数据对比分析,1962/1966-2001年间研究区冰川面积退缩了67.89km²,占总面积的(6.2±1.0)%.结果表明,运用高分辨率的ASTER遥感资料可快速、直观地实现基于GIS的冰川编目,方便地观测冰川的动态变化,从而节约冰川编目和观测冰川变化的时间和经费,在实践上具有很大的优势.     

Topography as a fundamental element of glacial systems

The equilibrium line of glaciers as a climate-sensitive parameter is indispensable for the assessment of changes in climate through time. The methods previously developed for calculating the equilibrium line do not obtain, however, satisfactory accuracy. Using the statistical evaluation of data collected from 223 glaciers it is shown here that the inaccuracy of the prevailing methods results from the negligence of the specific glacier geometry.In calculating realistic ELAs glaciers must be understood as dynamic systems whose variables, climatic environment and topography, are linked through feedback. The accompanying transformation in this dynamic system, which is expressed by the difference between a mathematical index and the ELA, can be exactly determined with a regression line. The climatically induced change in glacier geometry is the controlling factor, i.e. operator. The behaviour of glacial systems in view of long-term climatic variations can first be understood when the details of the interdependency between topographical and climatic parameters are fully known, as will be demonstrated here.ELA = Equilibrium Line Altitude     

Exploring the potential of tree-ring chronologies from the Trafoi Valley (Central Italian Alps) to reconstruct glacier mass balance

Two tree-ring chronologies of stone pine ( Pinus cembra L.) and two of Norway spruce ( Picea abies Karst.) were constructed on the basis of data from three high-altitude sites in the Trafoi Valley (Central Alps, Italy) to test tree species sensitivity to climate at different sites and to explore the potential of the two species for reconstructing the mass balance of two glaciers in the same region (the Careser and Hintereis glaciers). Influence of climate on tree-ring growth and on glacier mass variations was tested by means of Pearson's correlation and response functions. At highest altitude sites, both species appeared to be sensitive to July temperatures, while stone pine also showed higher sensitivity than Norway spruce to previous winter precipitation. Comparing the dendrochronological and glaciological series, stone pine showed higher negative correlations with glacier mass balance series than Norway spruce. These different relationships reflect different species responses to climate, and stone pine is potentially useful in reconstructing past glacier mass balance in the Central Alps. Extreme climatic events induce different and even contrasting responses of tree-ring growth and glacier mass variations and may therefore bias tree-ring-based glacier mass balance reconstructions.     

高亚洲冰川系统物质平衡特征及其对全球变化响应研究进展与展望

分布在高亚洲的大量现代冰川,是亚洲中部干旱半干旱地区最重要的淡水资源.高亚洲各区因环境差异,各区冰川系统物质平衡及其对全球气候变化的响应就表现出不同特点,需进一步应用冰川系统理论和方法对高亚洲冰川系统进行合理分区,研究各分区冰川系统的结构特征、物质平衡特征及其对气候变化的响应过程.通过总结国内外高亚洲冰川系统研究的现状,找出了国内外研究的优势及不足;在此基础上,从高亚洲冰川系统的等级划分、气候地形背景、结构特征、物质平衡特征、对全球变化的响应以及冰川系统径流变化对冰川灾害及环境影响的评估等方面进行了研究展望.并认为需要根据各区气候、地理条件划分不同的次级冰川系统,然后分别对不同冰川系统的冰川变化进行预测,根据冰川变化趋势,制定最优利用冰川水资源方案和冰川灾害防范措施.     

Multivariate models for predicting glacier termini

Concerns over the rapid retreat rates of mountain glaciers have been rising as global temperatures have continued to increase. The extent of variation in the retreat of mountain glaciers can provide information about changes to different climatic conditions. Assessing the retreat rates of glaciers is crucial to assess the continuing existence of mountain glaciers and the ramifications of those retreats on water security for human societies. Therefore, mathematical and statistical models for the quantification of glacier dynamics in response to climate change are in high demand. In this research, we propose a multivariate regression model that estimates glacier change and predicts the location of glacier terminus over time, based on observed climate factors. The proposed method is applied to temporal sequences of ground observations for a number of glaciers around the globe. This model can potentially be used for monitoring glacier systems using climatic factors.     

念青唐古拉山西段冰川1977-2010年时空变化

青藏高原现代冰川变化是对气候变化的响应, 对区域水资源评估有着重要的理论意义和现实意义.采用GIS分析方法, 利用三期卫星遥感数据研究青藏高原中部念青唐古拉山西段冰川在2个时间段(1977-2001和2001-2010)的时空分布和变化, 并对比分析其在南坡和北坡变化速率趋势以及在不同海拔高度的变化特征.研究发现: (1)2010年念青唐古拉山西段冰川面积为571.81±16.01 km2, 主要分布在5 500~6 200 m的高山区; (2)1977-2010年念青唐古拉山西段冰川退缩明显, 总面积减少22.42%±2.90%;(3)相比于1977-2001年时间段, 近十年来该区冰川退缩速率呈明显加剧趋势; (4)与前一个时段相比, 低于5 700 m海拔区域, 各海拔段的冰川年均面积退缩速率呈减缓趋势; 而在5 700~7 000 m海拔区域, 则呈加剧趋势; (5)北坡冰川退缩率(23.6%±2.88%)高于南坡(21.97%±2.90%), 且南北坡2001-2010年年均冰川面积减少最大的海拔段比1977-2001年都升高了200 m, 研究区冰川的持续退缩有向高海拔转移的趋势; (6)南坡拉萨河流域内的冰川年均减少面积最大的海拔段比北坡高100 m左右.气温升高是影响近十年以来研究区的冰川退缩加剧的根本原因, 将对区域水文和生态环境产生重大的影响.      

基于遥感技术的高山极高山区冰川冰湖变化动态监测

在全球变暖的大背景下,我国藏南地区冰川持续退缩,冰湖不断扩张,从而引发了一系列的地质灾害问题。文章利用Landsat系列影像,在面向对象分类方法的基础上采用波段比值法和NDWI指数提取了藏南希夏邦玛峰地区1994—2018年共9期冰川和冰湖的面积。研究表明,希夏邦玛峰地区净冰川持续退缩,总体速率为（1.28±0.32）%/a,冰湖的扩张速率约为（1.88±1.07）%/a。同时,面积小于1 km2的冰川退缩极为严重,高达33.25%。其次气象再分析数据表明夏季气温和降水的增加可能是该地区净冰川退缩加快的重要原因,并且共同促进了冰湖的加速扩张,大大提高了该地区冰湖溃决的风险。     

1993-2015年喀喇昆仑山努布拉流域冰川变化遥感监测

利用Landsat TM/ETM+及OLI遥感影像,通过比值阈值法和目视解译法提取冰川边界,分析了1993-2015年喀喇昆仑山努布拉流域的冰川变化特征。结果表明：（1）冰川面积萎缩103.24 km²,占冰川总面积的4.64%,年均萎缩率为0.20%。与青藏高原其他地区相比,研究区冰川萎缩幅度较小。气温升高是冰川面积萎缩的主要因素。（2）规模≤ 0.1 km²的冰川面积萎缩幅度最大,规模较大的冰川萎缩幅度相对较小。（3）不同朝向的冰川均处于萎缩状态,北朝向冰川萎缩率最大,因为北朝向多为小规模冰川,而东朝向冰川的萎缩率最小。（4）有9条冰川末端发生前进现象。     

On the sensitivity of Holocene talus-derived rock glaciers to climate change in the Ben Ohau Range,New Zealand

The morphology and surface ages of talus-derived rock glaciers are investigated to establish the timing of rock glacier formation in the central Southern Alps. Samples of rock weathering rinds show that all rock glaciers studied were formed during the Neoglacial period, but differences exist between sites in the number of new rock glacier lobes formed by Holocene climatic fluctuations. A qualitative conceptual model is proposed to explain rock glacier formation in terms of two thresholds. An external threshold relates to the presence of a cool climate capable of allowing internal ice to form within talus slopes. An internal threshold relates to the presence of sufficiently thick talus at a site to generate a shear stress capable of overcoming internal friction within the talus/ice mass. The model produces a non-steady-state response to explain why unmodified talus, single-lobed and double-lobed rock glaciers developed at adjacent sites under the same climatic regime. Individual landforms have different sensitivities to formation, which depend partly on the previous history of talus accumulation and rock glacier activity at a site. The model demonstrates how successive cool climate periods may be fully represented by rock glacier lobes at sensitive sites but under-represented at insensitive sites. Sensitivity (and therefore climatic representativeness) is favoured by high rates of debris supply. By implication, the timing of formation of rock glacier lobes in regions of prolonged cool climate and low debris production is less likely to correspond to the timing of climatic cooling and more likely to follow the ‘rules’ of deterministic chaos.     

Remote Sensing Monitoring of Glacier Changes in the Western Region of Tanggula Mountains in Recent 25 Years

This paper focuses on revealing the status quo and variation of glaciers in the western region of Tanggula Mountains. The ratio threshold, NIR water identification and visual interpretation were used to extract the boundary of glaciers based on Landsat data (TM/ETM+/OLI) from 1990 to 2015. In particular, the NIR water identification is a new method to extract glaciers from water, which is suitable to improve the traditional method of ratio threshold. This study used spatial interpolation method to evaluate temperature and precipitation changes. The kriging interpolation method was adapted to manipulate and to extract the appropriate data based on ten weather stations. Comparing to the variations and characteristics of glaciers and climate change from 1990 to 2015, we concluded that glacial retreat in the western region of Tanggula Mountains was serious. The glacier area reduced from 1 693.65 km² to 1 490.81 km², respectively, in 1990 and 2015, in general, approximately 202.84 km² (11.98%) of glacier area has been retreated in the last 25 years. Moreover, the rate of glacier decline after 2000 was much faster than the last decade of the 20th century. In addition, the decreased area of glaciers in the lower altitude basins below 5 000 meters occupied 94.84% of the total change area while the glacier above 5 000 meters almost had no change. The kriging interpolation of the meteorological data indicated that the southeast of the study area was damp and hot while the northwest was cold and dry. The characteristic of temperature distribution from the northwest to the southeast presented from low to high, and precipitation increased in the first of the study period and then decreased but both of them were not very significant. In short, the temperature of study area was increased more prominently since 2000, while the precipitation change was very weak. The mean annual temperature and precipitation of 1980-1989a, 1990-1999a, and 2000-2013a were -3.53 ℃, -3.20 ℃, -2.22 ℃, and 384.49 mm, 354.27 mm, 428.13 mm, respectively. The study found that the glacier change was consistent with temperature variation in spite of the adverse effects of increased precipitation. Therefore, the research concluded that the precipitation change was not more significant comparing to temperature change. In other words, the main reason of the rapid decrease of glaciers in study area was likely due to the rise of temperature.     

Recent glacier variations on active ice capped volcanoes in the Southern Volcanic Zone (37°–46°S), Chilean Andes

Glaciers in the southern province of the Southern Volcanic Zone (SVZ) of Chile (37–46°S) have experienced significant frontal retreats and area losses in recent decades which have been primarily triggered by tropospheric warming and precipitation decrease. The resulting altitudinal increase of the Equilibrium Line Altitude or ELA of glaciers has lead to varied responses to climate, although the predominant volcanic stratocone morphologies prevent drastic changes in their Accumulation Area Ratios or AAR. Superimposed on climate changes however, glacier variations have been influenced by frequent eruptive activity. Explosive eruptions of ice capped volcanoes have the strongest potential to destroy glaciers, with the most intense activity in historical times being recorded at Nevados de Chillán, Villarrica and Hudson. The total glacier area located on top of the 26 active volcanoes in the study area is ca. 500 km². Glacier areal reductions ranged from a minimum of −0.07 km² a ⁻¹ at Mentolat, a volcano with one of the smallest ice caps, up to a maximum of −1.16 km² a ⁻¹ at Volcán Hudson. Extreme and contrasting glacier–volcano interactions are summarised with the cases ranging from the abnormal ice frontal advances at Michinmahuida, following the Chaitén eruption in 2008, to the rapid melting of the Hudson intracaldera ice following its plinian eruption of 1991. The net effect of climate changes and volcanic activity are negative mass balances, ice thinning and glacier area shrinkage. This paper summarizes the glacier changes on selected volcanoes within the region, and discusses climatic versus volcanic induced changes. This is crucial in a volcanic country like Chile due to the hazards imposed by lahars and other volcanic processes.     

Response of glacier area variation to climate change in the Kaidu-Kongque river basin,Southern Tianshan Mountains during the last 20 years

Glaciers are crucial water resources for arid inland rivers in Northwest China. In recent decades, glaciers are largely experiencing shrinkage under the climate-warming scenario, thereby exerting tremendous influences on regional water resources. The primary role of understudying watershed scale glacier changes under changing climatic conditions is to ensure sustainable utilization of regional water resources, to prevent and mitigate glacier-related disasters. This study maps the current (2020) distribution of glacier boundaries across the Kaidu-Kongque river basin, south slope of Tianshan Mountains, and monitors the spatial evolution of glaciers over five time periods from 2000–2020 through thresholded band ratios approach, using 25 Landsat images at 30 m resolution. In addition, this study attempts to understand the role of climate characteristics for variable response of glacier area. The results show that the total area of glaciers was 398.21 km² in 2020. The glaciers retreated by about 1.17 km²/a (0.26%/a) from 2000 to 2020. The glaciers were reducing at a significantly rapid rate between 2000 and 2005, a slow rate from 2005 to 2015, and an accelerated rate during 2015–2020. The meteorological data shows slight increasing trends of mean annual temperature (0.02°C/a) and annual precipitation (2.07 mm/a). The correlation analysis demonstrates that the role of temperature presents more significant correlation with glacier recession than precipitation. There is a temporal hysteresis in the response of glacier change to climate change. Increasing trend of temperature in summer proves to be the driving force behind the Kaidu-Kongque basin glacier recession during the recent 20 years.© 2021 China Geology Editorial Office.