The ice cap Ulugh Muztagh in the central Kunlun Shan at the northern fringe of the Tibetan Plateau is a very isolated region with arid cold conditions. No observational, meteorological or glaciological ground truth da...The ice cap Ulugh Muztagh in the central Kunlun Shan at the northern fringe of the Tibetan Plateau is a very isolated region with arid cold conditions. No observational, meteorological or glaciological ground truth data is available. Using the Moderate-resolution Imaging Spectroradiometer(MODIS) Level 1 radiance Swath Data(MOD02QKM) with a spatial resolution of 250 m, transient snow lines during the months of July to September in 2001 to 2014 are derived. Results are used to calibrate the physical based Coupled Snowpack and Ice surface energy and Mass balance model(COSIMA). The model runs on a representative detail region of Ulugh Muztagh(UM) on a digital elevation model with the same spatial resolution as the MODIS bands. In the absence of field observations, the model is driven solely by dynamically downscaled global analysis data from the High Asia Refined analysis(HAR). We compare remote sensing derived and modelled mean regional transient snow line altitudes in the course of consecutive summer seasons in 2008 to 2010. The resulting snow line altitude(SLA) and annual equilibrium line altitude(ELA) proxy of both methods coincide very well in their interannual variability in accordance with interannual variability of climatic conditions. Since SLAs of both methods do notconsistently agree on a daily basis a usage of remote sensing derived SLAs for model calibration in the absence of field observation data is only limitedly feasible for daily analysis. ELA approximation using the highest SLA at the end of ablation period may not be applied to UM because the negative winter mass balance(MB) is not reflected in the summer SLA. The study reveals moderate negative MB for UM throughout the modelling period. The mean regional MB of UM accounts for-523±410 mm w.e. a-1 in the modelling period. Hence UM seems not to belong to the area of the ‘Karakorum anomaly' comprising a region of positive mass balances in recent years which has its centre presumably in the Western Kunlun Shan.展开更多
冰湖接触型冰川的“湖-冰”相互作用显著,且共同作用于高山区水循环过程,在山区涵养水源、调节径流、维护生态多样性等方面发挥重要作用。本文基于Landsat遥感影像和ERA5-Land再分析资料,对东昆仑木孜塔格峰冰川区冰湖演变、冰川物质平...冰湖接触型冰川的“湖-冰”相互作用显著,且共同作用于高山区水循环过程,在山区涵养水源、调节径流、维护生态多样性等方面发挥重要作用。本文基于Landsat遥感影像和ERA5-Land再分析资料,对东昆仑木孜塔格峰冰川区冰湖演变、冰川物质平衡进行了探讨。结果表明,木孜塔格峰冰川区冰湖主要分布于海拔5275~5400 m,多为冰川阻塞湖。1990—2020年分布有冰湖16个,其中,冰川5Y624E0022和5Y624F0020阻塞形成的两个冰湖分别发生3次和2次冰湖溃决事件。两湖均为周期性溃决冰湖,前者于1999年和2001年发生较大规模冰湖溃决,溃决前面积分别为(0.250±0.044)km^(2)、(0.500±0.097)km^(2),溃决水量分别为(0.014±0.003)km^(3)、(0.026±0.006)km3;后者为2000年形成的冰川阻塞湖,溃决前面积为(0.110±0.030)km^(2),同年溃决,水量为(0.006±0.002)km^(3)。期间,冰湖数量有所增加,面积和储量均有减少趋势。然而,2000—2010年冰川累积物质平衡呈增加趋势,2010—2020年呈减少趋势,且有冰湖接触型冰川年均物质平衡呈显著的减小趋势(-0.024 m w.e.·a^(-1)),略大于无冰湖接触型冰川的减小趋势(-0.022 m w.e.·a^(-1))。此外,冰川热融侵蚀和冰崩作用使得冰鳞川和木孜塔格冰湖与冰川相连位置分别加速退缩了0.65 km、0.28 km。总之,该地区冰湖正处于数量增加、冰湖空间扩张阶段,其加速了母冰川的物质亏损。展开更多
基金supported by the German Research Foundation(DFG)Priority Programme 1372,‘Tibetan Plateau:Formation Climate Ecosystems’through the DynRG-TiP(‘Dynamic Response of Glaciers on the Tibetan Plateau to Climate Change’)project under codes SCHN 680/3-3 and SCHE 750/4-3the German Federal Ministry of Education and Research(BMBF)Central Asia Monsoon Dynamics and GeoEcosystems(CAME)program,through the WET project(‘Variability and Trends in Water Balance Components of Benchmark Drainage Basins on the Tibetan Plateau’)under code 03G0804A
文摘The ice cap Ulugh Muztagh in the central Kunlun Shan at the northern fringe of the Tibetan Plateau is a very isolated region with arid cold conditions. No observational, meteorological or glaciological ground truth data is available. Using the Moderate-resolution Imaging Spectroradiometer(MODIS) Level 1 radiance Swath Data(MOD02QKM) with a spatial resolution of 250 m, transient snow lines during the months of July to September in 2001 to 2014 are derived. Results are used to calibrate the physical based Coupled Snowpack and Ice surface energy and Mass balance model(COSIMA). The model runs on a representative detail region of Ulugh Muztagh(UM) on a digital elevation model with the same spatial resolution as the MODIS bands. In the absence of field observations, the model is driven solely by dynamically downscaled global analysis data from the High Asia Refined analysis(HAR). We compare remote sensing derived and modelled mean regional transient snow line altitudes in the course of consecutive summer seasons in 2008 to 2010. The resulting snow line altitude(SLA) and annual equilibrium line altitude(ELA) proxy of both methods coincide very well in their interannual variability in accordance with interannual variability of climatic conditions. Since SLAs of both methods do notconsistently agree on a daily basis a usage of remote sensing derived SLAs for model calibration in the absence of field observation data is only limitedly feasible for daily analysis. ELA approximation using the highest SLA at the end of ablation period may not be applied to UM because the negative winter mass balance(MB) is not reflected in the summer SLA. The study reveals moderate negative MB for UM throughout the modelling period. The mean regional MB of UM accounts for-523±410 mm w.e. a-1 in the modelling period. Hence UM seems not to belong to the area of the ‘Karakorum anomaly' comprising a region of positive mass balances in recent years which has its centre presumably in the Western Kunlun Shan.
文摘冰湖接触型冰川的“湖-冰”相互作用显著,且共同作用于高山区水循环过程,在山区涵养水源、调节径流、维护生态多样性等方面发挥重要作用。本文基于Landsat遥感影像和ERA5-Land再分析资料,对东昆仑木孜塔格峰冰川区冰湖演变、冰川物质平衡进行了探讨。结果表明,木孜塔格峰冰川区冰湖主要分布于海拔5275~5400 m,多为冰川阻塞湖。1990—2020年分布有冰湖16个,其中,冰川5Y624E0022和5Y624F0020阻塞形成的两个冰湖分别发生3次和2次冰湖溃决事件。两湖均为周期性溃决冰湖,前者于1999年和2001年发生较大规模冰湖溃决,溃决前面积分别为(0.250±0.044)km^(2)、(0.500±0.097)km^(2),溃决水量分别为(0.014±0.003)km^(3)、(0.026±0.006)km3;后者为2000年形成的冰川阻塞湖,溃决前面积为(0.110±0.030)km^(2),同年溃决,水量为(0.006±0.002)km^(3)。期间,冰湖数量有所增加,面积和储量均有减少趋势。然而,2000—2010年冰川累积物质平衡呈增加趋势,2010—2020年呈减少趋势,且有冰湖接触型冰川年均物质平衡呈显著的减小趋势(-0.024 m w.e.·a^(-1)),略大于无冰湖接触型冰川的减小趋势(-0.022 m w.e.·a^(-1))。此外,冰川热融侵蚀和冰崩作用使得冰鳞川和木孜塔格冰湖与冰川相连位置分别加速退缩了0.65 km、0.28 km。总之,该地区冰湖正处于数量增加、冰湖空间扩张阶段,其加速了母冰川的物质亏损。
文摘为了评估木孜塔格峰冰川在全球气候变暖背景下的变化,利用历史地形图数据、Landsat遥感影像、数字高程模型(digital elevation model,DEM)数据及TerraSAR-X/TanDEM-X数据,基于合成孔径雷达干涉测量(interferometry synthetic aperture Radar,InSAR)和大地测量法对木孜塔格峰地区1972—2011年间的冰川面积变化和物质平衡进行了详细研究。结果表明:1972—2011年间木孜塔格峰地区冰川面积年均缩减率为0.02±0.06%,其中47条冰川表现为退缩,2条冰川表现为前进;木孜塔格峰地区冰川物质呈现微弱的负平衡(-0.06±0.01 m w.e./a)趋势,其中1999年以前为-0.11±0.02 m w.e./a,主要受气温升高所影响,1999年后几乎接近于平衡状态(0.02±0.04 m w.e./a),降水的增加弥补了气温升高造成的物质亏损;木孜塔格峰地区冰川前进不同于正常前进冰川,其前进原因可能是冰川内部消融引起的液态水润滑作用导致上游物质向下转移;在当前气候背景下,该区域大部分冰川表现为退缩,2条冰川有前进现象,1条冰川有过跃动(崩塌)现象,总体上该区域冰川呈现微弱的物质负平衡。
