Glacier area change and its impact on runoff in the Manas River Basin,Northwest China from 2000 to 2020

Understanding the distribution and dynamics of glaciers is of great significance to the management and allocation of regional water resources and socio-economic development in arid regions of Northwest China.In this study,based on 36 Landsat images,we extracted the glacier boundaries in the Manas River Basin,Northwest China from 2000 to 2020 using eCognition combined with band operation,GIS(geographic information system)spatial overlay techniques,and manual visual interpretation.We further analyzed the distribution and variation characteristics of glacier area,and simulated glacial runoff using a distributed degree-day model to explore the regulation of runoff recharge.The results showed that glacier area in the Manas River Basin as a whole showed a downward trend over the past 21 a,with a decrease of 10.86%and an average change rate of–0.54%/a.With the increase in glacier scale,the number of smaller glaciers decreased exponentially,and the number and area of larger glaciers were relatively stable.Glacier area showed a normal distribution trend of increasing first and then decreasing with elevation.About 97.92%of glaciers were distributed at 3700–4800 m,and 48.11%of glaciers were observed on the northern and northeastern slopes.The retreat rate of glaciers was the fastest(68.82%)at elevations below 3800 m.There was a clear rise in elevation at the end of glaciers.Glaciers at different slope directions showed a rapid melting trend from the western slope to the southern slope then to the northern slope.Glacial runoff in the basin showed a fluctuating upward trend in the past 21 a,with an increase rate of 0.03×10^(8) m^(3)/a.The average annual glacial runoff was 4.80×10^(8) m^(3),of which 33.31%was distributed in the ablation season(June–September).The average annual contribution rate of glacial meltwater to river runoff was 35.40%,and glacial runoff accounted for 45.37%of the total runoff during the ablation season.In addition,precipitation and glacial runoff had complementary regulation patterns for river runoff.The findings can provide a scientific basis for water resource management in the Manas River Basin and other similar arid inland river basins.

Climate change and glacier area variations in China during the past half century

Glacier variations in the Tibetan Plateau and surrounding mountain ranges in China affect the livelihood of over one billion people who depend on water from the Yellow, Yangtze, Brahmaputra, Ganges and Indus rivers originating in these areas. Based on the results of the present study and published literature, we found that the glaciers shrank ：5.7% in area from 1963 to 20：0 with an annual area change of -0.33%. The shrinkage generally decreased from peripheral mountain ranges to the interior of Tibet. The linear trends of annual air temperature and precipitation at 147 stations were 0.36℃（10a）^-1 and 8.96 mm （10a）^-1 respectively from 1961 to 2010. The shrinkage of glaciers was well correlated with the rising temperature and the spatial patterns of the shrinkage were influenced by other factors superimposed on the rising temperature such as glacier size, type, elevation, debris cover and precipitation.

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 km^(2)in 2020.The glaciers retreated by about 1.17 km^(2)/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℃/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.

Methods for calculating glacier area and length in a mountainous area based on remote-sensing data and a digital elevation model

In a mountainous region, the glacier area and length extracted form the satellite imagery data is the projected area and length of the land surface, which can’t be representative of the reality; there are always some errors. In this paper, the methods of calculating glacier area and length calculation were put forward based on satellite imagery data and a digital elevation model (DEM). The pure pixels and the mixed pixels were extracted based on the linear spectral un-mixing approach, the slop of the pixels was calculated based on the DEM, then the area calculation method was presented. The projection length was obtained from the satellite imagery data, and the elevation differences was calculated from the DEM. The length calculation method was presented based on the Pythagorean theorem. For a glacier in the study area of western Qilian Mountain, northwestern China, the projected area and length were 140.93 km2 and 30.82 km, respectively. This compares with the results calculated by the methods in this paper, which were 155.16 km2 and 32.11 km respectively, a relative error of the projected area and length extracted from the LandSat Thematic Mapper (TM) image directly reach to -9.2 percent and -4.0 percent, respectively. The calculation method is more in accord with the practicality and can provide reference for some other object’s area and length monitoring in a mountainous region.

Spatiotemporal variations in glacier area and surface velocity of the northern Antarctic Peninsula during 2018-2022

Ice sheet serves as a crucial indicator for assessing climate change.Mass loss in recent remote sensing-based studies indicated that the Antarctic Peninsula has rapid rates of glacier retreat and speed up of surface velocity.However,observations of seasonal variability of ice speed are limited,and glacier-area changes require multi-temporal monitoring.This study investigated the changes in area and surface velocities of∼375 glaciers on the northern Antarctic Peninsula(NAP)utilizing satellite images acquired by the Sentinel 1&2 satellites during 2018-2022.The results indicate that the glacier area reduced by approximately 166.1±44.2 km^(2)(-0.2%±0.1%per year)during the study period,with an acceleration after 2020(-0.4%±0.3%per year),and the most dramatic reduction happened on the eastern NAP.The maximum annual ice speeds on the NAP generally exceeded 3500 m per year,while the ice speeds in 2021 were the highest(exceeded 4210 m per year).The ice speed variability in austral autumn was higher than in other seasons,meanwhile the summer ice speeds showed an increasing trend.The glacier G012158E47018N,McNeile Glacier,glacier G299637E64094S and Drygalski Glacier showed the most remarkable ice speed variations represented by high daily velocities and strong fluctuations on their termini.Our results demonstrated that the variations in glacier area and seasonal ice speed on the NAP were responsive to the ice-ocean-atmosphere processes.Therefore,seasonal velocity and area variations should be considered when conducting accurate mass balance calculations,model validations and change mechanism analyses under climate warming scenarios.

Glacier area variation and climate change in the Chinese Tianshan Mountains since 1960

Based on the statistics of glacier area variation measured in the Chinese Tianshan Mountains since 1960, the response of glacier area variation to climate change is discussed systematically. As a result, the total area of the glaciers has been reduced by 11.5% in the past 50 years, which is a weighted percentage according to the glacier area variations of 10 drainage basins separated by the Glacier Inventory of China （GIC）. The annual percentage of area changes （APAC） of glaciers in the Chinese Tianshan Mountains is 0.31% after the standardization of the study period. The APAC varies widely for different drainage basins, but the glaciers are in a state of rapid retreat, generally. According to the 14 meteorological sta- tions in the Chinese Tianshan Mountains, both the temperature and precipitation display a marked increasing tendency from 1960 to 2009 at a rate of 0.34℃·（10a）^-1 and 11 mm·（10a）^-1, respectively. The temperature in the dry seasons （from November to March） increases rapidly at a rate of 0.46℃·（10a）^-1, but the precipitation grows slowly at 2.3 mm·（10a）^-1. While the temperature in the wet seasons （from April to October） grows at a rate of 0.25℃·（10a）^-1, but the precipitation increases at 8.7 mm·（10a）^-1, The annual and seasonal climatic trends accelerate the retreat of glaciers.

Glacier area shrinkage in China and its climatic background during the past half century

Based on the glacier area variation records in the typical regions of China moni-tored by remote sensing, as well as the meteorological data of air temperature and precipitation from 139 stations and the 0℃ isotherm height from 28 stations, the glacier area shrinkage in China and its climatic background in the past half century was discussed. The initial glacier area calculated in this study was 23,982 km2 in the 1960s/1970s, but the present area was only 21,893 km2 in the 2000s. The area-weighted shrinking rate of glacier was 10.1%, and the interpolated annual percentage of area changes （APAC） of glacier was 0.3% a–1 since 1960. The high APAC was found at the Ili River Basin and the Junggar Interior Basin around the Tianshan Mountains, the Ob River Basin around the Altay Mountains, the Hexi Interior Basin around the Qilian Mountains, etc. The retreat of glacier was affected by the climatic background, and the influence on glacier of the slight-increased precipitation was counteracted by the significant warming in summer.

Using Landsat images to monitor changes in the snow-covered area of selected glaciers in northern Pakistan

Landsat satellite images were used to map and monitor the snow-covered areas of four glaciers with different aspects(Passu: 36.473°N, 74.766°E;Momhil: 36.394°N, 75.085°E; Trivor: 36.249°N,74.968°E; and Kunyang: 36.083°N, 75.288°E) in the upper Indus basin, northern Pakistan, from 1990-2014. The snow-covered areas of the selected glaciers were identified and classified using supervised and rule-based image analysis techniques in three different seasons. Accuracy assessment of the classified images indicated that the supervised classification technique performed slightly better than the rule-based technique. Snow-covered areas on the selected glaciers were generally reduced during the study period but at different rates. Glaciers reached maximum areal snow coverage in winter and premonsoon seasons and minimum areal snow coverage in monsoon seasons, with the lowest snow-covered area occurring in August and September. The snowcovered area on Passu glacier decreased by 24.50%,3.15% and 11.25% in the pre-monsoon, monsoon and post-monsoon seasons, respectively. Similarly, the other three glaciers showed notable decreases in snow-covered area during the pre-and post-monsoon seasons; however, no clear changes were observed during monsoon seasons. During pre-monsoon seasons, the eastward-facing glacier lost comparatively more snow-covered area than the westward-facing glacier. The average seasonal glacier surface temperature calculated from the Landsat thermal band showed negative correlations of-0.67,-0.89,-0.75 and-0.77 with the average seasonal snowcovered areas of the Passu, Momhil, Trivor and Kunyang glaciers, respectively, during pre-monsoon seasons. Similarly, the air temperature collected from a nearby meteorological station showed an increasing trend, indicating that the snow-covered area reduction in the region was largely due to climate warming.

Primary investigation of statistical correlation between changes in ice volume and area of glaciers

This study makes an attempt to investigate through statistical analysis the correlation between changes in ice volume and area of glaciers. Using data from nine sample glaciers in the Tian Shan, the results show that a linear relation exists between changes in ice volume and area, with a correlation coefficient of 0.700. However, the accuracy estimation is difficult due to the limited number of samples. The correlation was not improved after adding eleven glacier samples in other mountains. Two reference glaciers are then analyzed in more detail. The linear correlation coefficient is higher than 0.800 when using the observed changes in ice volume and area during different periods on Urumqi Glacier No. 1, which suggests that the linear relation is valid for one glacier for different periods if its shape does not change noticeably and also for other glaciers of the same shape during the same period. The relation between changes in ice volume and area of Qingbingtan Glacier No. 72 is different during different periods due to change in the shape of the glacier tongue and the influence of the debris cover. Moreover, errors in glacier-change monitoring and-volume estimation have an important influence on the correlation results. Therefore, further study needs to focus not only on the distinction between glacier types and between different periods but also on the accuracy of volume estimation.

1976-2016年普若岗日冰川和流域湖泊变化及其对气候变化的响应

基于藏北地区普若岗日冰川1976-2016年多时相Landsat系列卫星影像数据,以及气温、降水量数据,采用ARCGIS空间分析、线性趋势分析、相关分析等方法,研究了普若岗日冰川和流域湖泊面积变化及其对气候变化的响应。结果表明:近41年普若岗日冰川面积呈显著退缩趋势,41年内冰川面积减少了52.32 km^(2),减小率为12.01%;冰川西北部退缩最为严重,冰川面积减少了12.29 km^(2),减小率为15.77%;且冰川西北部、北部、东部和东南部末端消融显著;其他区域也有不同程度的退缩。流域湖泊面积呈显著增长趋势,共增长了27.17 km^(2),增长率为22.22%;流域气温总体上呈显著增加趋势,平均每10年增加0.48℃;降水量呈不显著上升趋势,平均每10年增加15 mm。降水对冰川和流域湖泊面积影响较小,温度的持续升高是冰川和流域湖泊变化的主要因素。

海洋型冰川表碛与退缩区土壤微生物群落特征——以阿扎冰川和米堆冰川为例

以藏东南阿扎冰川和米堆冰川为研究区,采用细菌16S rRNA基因扩增子测序和真菌ITS测序技术,研究了冰川表碛与退缩区不同植被演替阶段土壤中微生物群落特征及土壤化学性质影响.结果表明,两条冰川表碛与退缩区土壤中共发现细菌门38个,其中Proteobacteria(40%)、Actinobacteriota(23%)、Bacteroidota(14%)为优势群,共发现真菌门7个,Basidiomycota(47%)和Ascomycota(45%)为优势群.阿扎和米堆冰川表碛中Patescibacteria、RCP2-54、Bacteroidota、Gemmatimonadota和Acidobacteriota的菌群丰度存在显著差异,米堆冰川表碛和退缩区土壤中微生物群落结构和丰度存在显著差异(P<0.05),而退缩区三个演替阶段之间的群落结构差异不显著.适应极端环境的微生物群落在表碛中丰度最高,而随着演替进程参与植物定殖或与植物共生的微生物群落丰度与多样性显著增加,微生物群落的α多样性上升,NMDS模型也逐渐接近重叠,群落结构在植被演替后期逐渐趋于稳定,.除全钾外,养分含量在两条冰川表碛中均较低,随着植被演替土壤pH值逐渐降低而养分逐渐增加,演替后期显著高于前两阶段.表碛中的微生物群落与pH值和全钾显著正相关(P<0.05),而退缩区土壤中则与速效钾、硝酸盐氮、全磷、可溶性有机碳显著正相关(P<0.05),并以磷限制为主.

Glacial Runoff Likely Reached Peak in the Mountainous Areas of the Shiyang River Basin,China

Glacier runoff in mountain areas of the Shiyang River Basin(SRB), Qilian Mountain, western China is important for the river and water supply downstream. Small glaciers with area of less than 1km2 are dominant(87%) in the SRB. A modified monthly degree-day model was applied to quantify the glacier mass balance, area, and changes in glacier runoff in the SRB during 1961–2050. The comparison between the simulated and observed snow line altitude, annual glacier runoff, and mass balance from1961 to 2008 suggests that the degree-day model may be used to analyze the long-term change of glacier mass balance and runoff in the SRB. The glacier accumulation shows a significant(p<0.01) decreasing trend of-0.830 mm a-1. The mass balance also shows a significant(p<0.01) decreasing trend of-5.521 mm a-1. The glacier total runoff has significantly(p<0.05)increased by 0.079 × 105 m3 from 1961 to 2008. The monthly precipitation and air temperature are projected to significant(p<0.005) increase during2015 to 2050 under three different scenarios. The ablation is projected to significant(p<0.001) increase,while the accumulation has no significant(p=0.05)trend. The mass balance is projected to decrease, theglacier area is projected to decrease, and the glacier runoff depth is projected to increase. However, the glacier total runoff is projected to decrease. These results indicate that the glacier total runoff over glacier areas observed in 1970 reached its peak in the 2000 s. This will exacerbate the contradiction between water supply and downstream water demands in the SRB.

开都河流域冰川面积变化及其消融季冰川融水对径流的贡献

全球变暖背景下冰川及冰川水资源的可能变化对径流的影响,是水文领域持续关注的重点内容。通过分析开都河流域冰川面积及其融水变化趋势,量化评估冰川融水对径流的贡献情况,探究冰川-径流-气候之间的响应关系。结果表明:开都河流域冰川面积占比小,平均覆盖度约为1.55%,小规模冰川条数较多,约有78.17%分布在小于0.5 km2的规模上,整体呈现衰退趋势;2009—2018年冰川面积减少了3.69%,冰川条数减少了1.33%;2014—2021年流域径流、冰川融水、降水均呈先增加后减少的变化趋势,其中夏季流量高达15.48×10~8 m^(3),约为其他季节径流量的2倍以上,消融季(6—9月)冰川融水约为9.96×10~8 m^(3),其对径流的平均贡献率达54.3%,是径流的重要组成部分;流域降水与河川径流的相关性高于温度与其的相关性,而温度是影响流域冰川融水变化的主导因子。研究结果对深化流域河川径流过程变化的认识和水资源利用具有重要意义。

青藏高原海螺沟冰川退缩区原生演替序列优势乔木氮磷化学计量及重吸收特征研究

以海螺沟冰川退缩区原生演替序列为对象,研究各演替阶段优势乔木氮(N)、磷(P)化学计量及重吸收效率特征。结果表明:优势乔木鲜叶及凋落叶N、P浓度随演替下降,且鲜叶的N∶P在整个演替序列中总体小于14,表明该演替序列优势乔木的生长主要受N元素限制;优势乔木N、P的重吸收效率在演替中期最高,表明植物较高的生长速率会增加其对养分的吸收利用效率;优势乔木N、P的重吸收效率与其生长速率呈正相关关系,而与土壤的N、P储量呈负相关关系,说明树木生长速率(需求)和土壤养分状况(供给)共同调节植物对养分的吸收模式;优势乔木N重吸收效率与其鲜叶N∶P呈正相关关系,表明植物对N的重吸收过程对维持其体内N∶P的平衡有着重要意义。研究结果有助于深入认识原生演替过程中植被对养分的利用机制,可为植被恢复提供理论依据。

植物多样性与物种组成随原生演替进程的变化规律——以贡嘎山冰川退缩区为例

研究原生演替过程中植物多样性与物种组成的演变规律有助于解析植物群落的演替动态与构建机制。以冰川退缩区原生演替序列上7个演替阶段(S1~S7)的植物群落为研究对象,于2022年开展群落调查工作,结合α、β多样性两方面,分析其乔木层、灌木层、草本层植物多样性和物种组成的变化规律。结果显示:(1)本次调查在海螺沟冰川退缩区原生演替序列中记录到植物共41科66属100种,其中单(寡)种属居多,初步反映了本研究区植物物种组成的复杂性和多样性;(2)原生演替序列上,各层植物的优势种组成在不同演替阶段差异明显,出现明显的更替;(3)随着演替的进行,乔木层和灌木层的多项α多样性指数均呈“单峰型”响应格局,演替初期上升,达到峰值后缓慢下降;(4)不同生活型植物在演替序列上的β多样性差异明显,物种周转在物种组成变化中起主要作用,其中草本层的周转程度最高,为92.16%,而灌木层的周转程度最低,为58.01%;(5)冰川退缩区植物群落的主林层(乔木层)主要经历了先锋群落、落叶阔叶林、针阔混交林、顶级针叶林4个演替阶段。研究结果可为原生演替过程中植物群落的构建机制提供参考。

Glacier variations and their response to climate change in an arid inland river basin of Northwest China

Glaciers are a critical freshwater resource of river recharge in arid areas around the world.In recent decades,glaciers have shown evidence of retreat due to climate change,and the accelerated ablation of glaciers and associated impacts on water resources have received widespread attention.Glacier variations result from climate change,so they can serve as an indicator of climate change.Considering the climatic differences in different elevation ranges,it is worthwhile to explore whether different responses exist between glacier area and air temperature in each elevation zone.In this study,we selected a typical arid inland river basin(Sugan Lake Basin)in the western Qilian Mountains of Northwest China to analyze the glacier variations and their response to climate change.The glacier area data from 1989 to 2016 were delineated using Landsat Thematic Mapper(TM),Enhanced TM+(ETM+)and Operational Land Imager(OLI)images.We compared the relationships between glacier area and air temperature at seven meteorological stations in the glacier-covered areas and in the Sugan Lake Basin,and further analyzed the relationship between glacier area and mean air temperature of the glacier surfaces in July–August in the elevation range of 4700–5500 m a.s.l.by the linear regression method and correlation analysis.In addition,based on the linear regression relationship established between glacier area and air temperature in each elevation zone,we predicted glacier areas under future climate scenarios during the periods of 2046–2065 and 2081–2100.The results indicate that the glaciers experienced a remarkable shrinkage from 1989 to 2016 with a shrinkage rate of–1.61 km^2/a(–0.5%/a),and the rising temperature is the decisive factor dominating glacial retreat;there is a significant negative linear correlation between glacier area and mean air temperature of the glacier surfaces in July–August in each elevation zone from 1989 to 2016.The variations in glaciers are far less sensitive to changes in precipitation than to changes in air temperature.Due to the influence of climate and topographic conditions,the distribution of glacier area and the rate of glacier ablation first increased and then decreased in different elevation zones.The trend in glacier shrinkage will continue because air temperature will continue to increase in the future,and the result of glacier retreat in each elevation zone will be slightly slower than that in the entire study area.Quantitative glacier research can more accurately reflect the response of glacier variations to climate change,and the regression relationship can be used to predict the areas of glaciers under future climate scenarios.These conclusions can offer effective references for assessing glacier variations and their response to climate change in arid inland river basins in Northwest China as well as other similar regions in the world.

天山冰川退缩区土壤汞分布特征及累积

本文以新疆天山乌鲁木齐河源一号冰川退缩区为研究区域,通过^(210)Pbex、^(137)Cs放射性同位素测年和侵蚀性堆积地貌判定退缩区的年代演替序列,并据此设置了系列采样点,对土壤进行分层采样,测定样品总汞浓度等指标,计算各年代退缩区的汞累积速率,探究乌鲁木齐河源一号冰川退缩区土壤中汞的分布特征及其累积过程.结果表明:冰川退缩区土壤汞含量和汞储量随着退缩时间增长呈现出增加的趋势,各层土壤汞的平均含量由大到小依次为:0~5cm[(13.28±6.60)μg/kg]>5~10cm[(11.47±7.34)μg/kg]>10~15cm[(10.19±6.57)μg/kg]>基岩[(0.23±0.09)μg/kg];冰川退缩区植被生长促进了土壤汞的富集,退缩区内土壤汞浓度与土壤有机碳、氮含量呈显著正相关,而且由于植被生物量很小,退缩区土壤中汞的累积速率也较低(0.09~33.43μg/(m^(2)·a),平均值为16.92μg/(m^(2)·a));近250a来(1777年以来),天山一号冰川退缩区土壤汞累积速率呈加速增加趋势,由1777年的0.09μg/(m^(2)·a)增加至2017年的33.43μg/(m^(2)·a),这意味着自工业革命以来大气汞含量及沉积量在不断增加.

Glacier variations and rising temperature in the Mt.Kenya since the Last Glacial Maximum

High-resolution imagery can be used to reconstruct former glacier boundaries through the identification of glacial erosional and sedimentary geomorphology. We employed moraine mapping and the accumulation–area ratio method(AAR), in conjunction with Landsat, Google Earth, and SRTM imagery, to reconstruct glacier boundaries and equilibrium-line altitudes(ELAs) for Mt. Kenya in the Last Glacial Maximum(LGM), the Little Ice Age(LIA), and at present. Our results show that the areas of Lewis Glacier and the Tyndall-I glacier system were 0.678 km^2 and 0.390 km^2, respectively, during the maximum of LIA. Those mean that the both glaciers have shrunken by 87.0% and 88.7%, respectively since the LIA. Area change ratios for each glacier were significantly larger in the period of 2000 through 2015 than the former periods, indicating that glacier recession has accelerated. Continuous ice loss in this region has been driven by rising temperature and fluctuating precipitation. Linear regression data for Lewis glacier show that mass balance sensitivity to dry season temperature was –315 mm w.e./℃, whereas the sensitivity to dry season precipitation was 5.2 mm w.e./mm. Our data also show that the ELA on the western slope of Mt. Kenya rose by 716-816 m from the LGM to the modern era, corresponding to that temperature rose by 5.2℃-6.5℃.

Ice thickness distribution and volume estimation of Burqin Glacier No.18 in the Chinese Altay Mountains

Information on the thickness distribution and volume of glacier ice is highly important for glaciological applications;however,detailed measurements of the ice thickness of many glaciers in the Chinese Altay Mountains remain lacking.Burqin Glacier No.18 is a northeast-orientated cirque glacier located on the southern side of the Altay Mountains.This study used PulseEKKO®PRO 100A enhancement ground-penetrating radar(GPR)to survey the ice thickness and volume of Burqin Glacier No.18 in summer 2018.Together with GPR surveying,spatial distributed profiles of the GPR measurements were concurrently surveyed using the real-time kinematic(RTK)global navigation satellite system(GNSS,Unistrong E650).Besides,we used QuickBird,WorldView-2,and Landsat TM to delineate accurate boundary of the glacier for undertaking estimation of glacier ice volume.GPR measurements revealed that the basal topography of profile B1-B2 was flat,the basal topography of profile C1-C2 presented a V-type form,and the basal topography of profile D1-D2 had a typical U-type topographic feature because the bedrock near the central elevation of the glacier was relatively flat.The longitudinal profile A1-A2 showed a ladder-like distribution.Glacier ice was thin at the terminus and its thickness increased gradually from the elevation of approximately 2620 m a.s.l.along the main axis of the glacier tongue with an average value of 80(±1)m.The average ice thickness of the glacier was determined as 27(±2)m and its total ice volume was estimated at 0.031(±0.002)km3.Interpretation of remote sensing images indicated that during 1989–2016,the glacier area reduced from 1.30 to 1.17 km2(reduction of 0.37%/a)and the glacier terminus retreated at the rate of 8.48 m/a.The mean ice thickness of Burqin Glacier No.18 was less than that of the majority of other observed glaciers in China,especially those in the Qilian Mountains and Central Chinese Tianshan Mountains;this is probably attributable to differences in glacier type and climatic setting.

1990—2020年冬克玛底流域冰川变化遥感监测

冰川变化是气候变化的重要体现,对全球水资源和生态环境有着深远影响。本文基于Landsat系列遥感影像,运用目视解译法提取了近30年冬克玛底冰川边界,分析了1990—2020年冬克玛底河冰川面积变化特征;同时基于大气校正法反演了冰面温度,探究了冰川变化与气候变化的响应关系。结果表明:(1)1990—2020年冬克玛底冰川面积持续减退,总面积退缩1 km^(2),年均变化率为-0.21%。(2)冬克玛底冰川在海拔[5600,5800)m处分布较广泛,海拔[5300,5400)m处冰川退缩最强烈。近30年来大、小冬克玛底冰川分别后退382.89和141.39 m。(3)2017—2020年冬克玛底冰川表面形变速率介于-233.192~172.512 mm/a之间,高海拔区冰面整体呈积累状态,冰舌和部分区域呈减薄趋势。(4)冬克玛底冰川表面温度较高区域主要分布于大冬克玛底冰川西部到南部边缘和小冬克玛底冰川西部边缘与部分东部边缘,较低温度区域主要分布于整个冰川东部,气温上升可能是导致冬克玛底冰川消融的主要因素。