Annual mass balance is an important factor that reflects glacier change and glacier meltwater resources.In this study,we analyzed the changes in glacier area,snow line altitude(SLA)and surface elevation in theány...Annual mass balance is an important factor that reflects glacier change and glacier meltwater resources.In this study,we analyzed the changes in glacier area,snow line altitude(SLA)and surface elevation in theányêmaqên Mountain region using multisource remote sensing data.Then,the annual mass balance of two glaciers was reconstructed by using SLA-mass-balance gradient method.The results showed that the glacier area in theányêmaqên Mountains decreased by 29.4 km2from 1985 to 2017.The average SLAs of the Halong Glacier and Yehelong Glacier were approximately 5290 m and 5188 m,respectively.The glacier mass balance for the two glaciers from 1990 to 2020 was-0.71 m w.e.a^(-1) and-0.63 m w.e.a^(-1),respectively.Our results indicate that SLA is an important indicator of glacier changes,and a long sequence of SLAs can more accurately reconstruct the glacier mass balance of the glacier.The mean annual glacial meltwater-fed streamflow is 1.45×10^(7)m^(3) and 1.12×10^(7)m^(3),respectively.Sensitivity analysis indicates that summer air temperature plays a leading role in regard to the influential climatic factors of glacial retreat in theányêmaqên Mountains.This highlights the potential of the methodology for application on reconstructing annual glacier surface mass balance at larger scales without direct measurements.展开更多
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
One of the issues that geomorphology researchers have focused on is to trace the geomorphic effects and the snow lines in the Quaternary glaciers in Iran. This research has been carried out in the valleys of the south...One of the issues that geomorphology researchers have focused on is to trace the geomorphic effects and the snow lines in the Quaternary glaciers in Iran. This research has been carried out in the valleys of the southern slopes of Alvand Kuh Mountains, namely the Serkan and Mobarakabad valleys. The equilibrium line altitude between current and ancient glaciers is one of the parameters that is used as a variation indicator of climate. There are several ways to rebuild this parameter (Ancient ELA). Equilibrium Line altitude requires the accurate knowledge of glacial geomorphic landforms and evidence. According to Kuhle, Hofer and Luis methods, providing and estimating the ancient and permanent snow lines were carried out in this research during field operations within several intervals and the glacial geomorphic evidences were identified such as circuses, sidebar moraines and terminal moraines. The six glacier subwatersheds were developed in a study area based on Kuhle, Hofer and Luis methods in which only two valleys of Serkan 3 and Mubarak Abad 3 had a high degree of accuracy in their ELA drop rate and old snow lines. It should be noted that the current snowlines of the current study area are 4400 m and 1400 m (based on the Schweitzer map). The results of the estimated snow lines for each of the six valleys are shown in Table 4. At the present study, the main of the Mobarak Abad valley area was divided to six glacial valleys which are called Serkan 1, 2, 3 and Mobarak Abad 1, 2, 3 and then several layers were provided, including cirque layers, moraine layers, primary and secondary crest layers, high crest layers, 10-meter DEM layer, highlight, different contour line layers and valleys profiles and finally, the ultimate map of glacial geomorphology of Serkan and Mobarak Abad valleys was prepared.展开更多
The Palongzangbu River Basin contains the highest number of maritime province glaciers in China. There are 130 glacial lakes, 64 snow avalanche sites and 28 glacial debris flow gullies distributed within the basin. Sn...The Palongzangbu River Basin contains the highest number of maritime province glaciers in China. There are 130 glacial lakes, 64 snow avalanche sites and 28 glacial debris flow gullies distributed within the basin. Snow disasters play a controlling role in the Sichuan-Tibet Highway construction, due to the terrain’s special characteristics of high altitude and large height differential. Segmentation mitigation countermeasures for the Sichuan-Tibet Highway are presented based on snow disaster severity level and damage mode of the road. In the Ranwu to Midui section, snow avalanches are regional disasters, so the line should be placed in sunny slopes. In the Midui Gully to Yupu section, the line should be placed in shady slopes and at higher elevations to reduce the risk of glacial lake outburst. In the Yupu to Guxiang section, all three snow disasters are minimal. In the Guxiang to Tongmai section, glacier debris flows are the major threat, thus the road should be placed in shady slopes.展开更多
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP,Grant No.2019QZKK0205)the National Natural Science Foundation of China(grant No.42071077,42171148)the Fundamental Research Funds for the Central Universities(lzujbky-2021-sp11)。
文摘Annual mass balance is an important factor that reflects glacier change and glacier meltwater resources.In this study,we analyzed the changes in glacier area,snow line altitude(SLA)and surface elevation in theányêmaqên Mountain region using multisource remote sensing data.Then,the annual mass balance of two glaciers was reconstructed by using SLA-mass-balance gradient method.The results showed that the glacier area in theányêmaqên Mountains decreased by 29.4 km2from 1985 to 2017.The average SLAs of the Halong Glacier and Yehelong Glacier were approximately 5290 m and 5188 m,respectively.The glacier mass balance for the two glaciers from 1990 to 2020 was-0.71 m w.e.a^(-1) and-0.63 m w.e.a^(-1),respectively.Our results indicate that SLA is an important indicator of glacier changes,and a long sequence of SLAs can more accurately reconstruct the glacier mass balance of the glacier.The mean annual glacial meltwater-fed streamflow is 1.45×10^(7)m^(3) and 1.12×10^(7)m^(3),respectively.Sensitivity analysis indicates that summer air temperature plays a leading role in regard to the influential climatic factors of glacial retreat in theányêmaqên Mountains.This highlights the potential of the methodology for application on reconstructing annual glacier surface mass balance at larger scales without direct measurements.
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One of the issues that geomorphology researchers have focused on is to trace the geomorphic effects and the snow lines in the Quaternary glaciers in Iran. This research has been carried out in the valleys of the southern slopes of Alvand Kuh Mountains, namely the Serkan and Mobarakabad valleys. The equilibrium line altitude between current and ancient glaciers is one of the parameters that is used as a variation indicator of climate. There are several ways to rebuild this parameter (Ancient ELA). Equilibrium Line altitude requires the accurate knowledge of glacial geomorphic landforms and evidence. According to Kuhle, Hofer and Luis methods, providing and estimating the ancient and permanent snow lines were carried out in this research during field operations within several intervals and the glacial geomorphic evidences were identified such as circuses, sidebar moraines and terminal moraines. The six glacier subwatersheds were developed in a study area based on Kuhle, Hofer and Luis methods in which only two valleys of Serkan 3 and Mubarak Abad 3 had a high degree of accuracy in their ELA drop rate and old snow lines. It should be noted that the current snowlines of the current study area are 4400 m and 1400 m (based on the Schweitzer map). The results of the estimated snow lines for each of the six valleys are shown in Table 4. At the present study, the main of the Mobarak Abad valley area was divided to six glacial valleys which are called Serkan 1, 2, 3 and Mobarak Abad 1, 2, 3 and then several layers were provided, including cirque layers, moraine layers, primary and secondary crest layers, high crest layers, 10-meter DEM layer, highlight, different contour line layers and valleys profiles and finally, the ultimate map of glacial geomorphology of Serkan and Mobarak Abad valleys was prepared.
基金financially supported by the general project of Natural Science Foundation of China (No. 41571004)Scientific and technological research and development plan of China Railway Corporation (No. 2015G002-N)General project of Natural Science Foundation of China (No. 41172321)
文摘The Palongzangbu River Basin contains the highest number of maritime province glaciers in China. There are 130 glacial lakes, 64 snow avalanche sites and 28 glacial debris flow gullies distributed within the basin. Snow disasters play a controlling role in the Sichuan-Tibet Highway construction, due to the terrain’s special characteristics of high altitude and large height differential. Segmentation mitigation countermeasures for the Sichuan-Tibet Highway are presented based on snow disaster severity level and damage mode of the road. In the Ranwu to Midui section, snow avalanches are regional disasters, so the line should be placed in sunny slopes. In the Midui Gully to Yupu section, the line should be placed in shady slopes and at higher elevations to reduce the risk of glacial lake outburst. In the Yupu to Guxiang section, all three snow disasters are minimal. In the Guxiang to Tongmai section, glacier debris flows are the major threat, thus the road should be placed in shady slopes.
