scholarly journals Geodetic glacier mass balance (1975–1999) in the central Pamir using the SRTM DEM and KH-9 imagery

2019 ◽  
Vol 65 (250) ◽  
pp. 309-320 ◽  
Author(s):  
YUSHAN ZHOU ◽  
ZHIWEI LI ◽  
JIA LI ◽  
RONG ZHAO ◽  
XIAOLI DING
Keyword(s):  
Mass Balance ◽  
Snow Cover ◽  
Penetration Depth ◽  
Glacier Mass Balance ◽  
Mass Balances ◽  
Srtm Dem ◽  
Elevation Change ◽  
Mass Budget ◽  
Pamir Mountains ◽  
The Mean

ABSTRACTMultiple studies on regional glacier mass balance in the Pamir Mountains have been conducted using the geodetic method, but they were rarely extended to the period before 2000. In this study, we used KH-9 imagery acquired in 1975 to generate the historical DEM for the central Pamir, and then obtained the glacier elevation change by comparing this with the SRTM C-band DEM. The penetration depth of the C-band radar was corrected for different glacier surfaces, i.e. 2.96, 1.68 and 0 m for firn/snow cover, bare ice and debris-covered areas, respectively. The final results suggest that the central Pamir glaciers, overall, experienced a near-zero mass balance of −0.03 ± 0.24 m w.e. a−1 for 1975–99. Due to glacier surge activity, the elevation change patterns of individual glaciers were highly variable, and their mass balances varied from −0.12 ± 0.26 to 0.63 ± 0.20 m w.e. a−1. The mean mass budgets of the surge-type glaciers and non-surge-type glaciers were 0.03 ± 0.14 and −0.05 ± 0.28 m w.e. a−1, respectively. Concurring with previous studies, we conclude that the central Pamir glaciers may have been in a state of approximately balanced mass budget or slight mass deficit from the mid-1970s to the mid-2010s.

scholarly journals Comparison of direct and geodetic mass balances on a multi-annual time scale

2010 ◽  
Vol 4 (3) ◽  
pp. 1151-1194
Author(s):  
A. Fischer
Keyword(s):  
Mass Balance ◽  
Direct Method ◽  
Mean Difference ◽  
Published Data ◽  
Glacier Mass Balance ◽  
Mass Balances ◽  
Direct Data ◽  
The Mean ◽  
The Difference ◽  
Geodetic Mass Balance

Abstract. Glacier mass balance is measured with the direct or the geodetic method. In this study, the geodetic mass balances of six Austrian glaciers in 19 periods between 1953 and 2006 are compared to the direct mass balances in the same periods. The mean annual geodetic mass balance for all periods is −0.5 m w.e./year. The mean difference between the geodetic and the direct data is −0.7 m w.e., the minimum −7.3 m w.e. and the maximum 5.6 m w.e. The accuracy of geodetic mass balance resulting from the accuracy of the DEMs ranges from 2 m w.e. for photogrammetric data to 0.002 m w.e. for LIDAR data. Basal melt, seasonal snow cover and density changes of the surface layer contribute up to 0.7 m w.e. for the period of 10 years to the difference to the direct method. The characteristics of published data of Griesgletscher, Gulkana Glacier, Lemon Creek glacier, South Cascade, Storbreen, Storglaciären, and Zongo Glacier is similar to these Austrian glaciers. For 26 analyzed periods with an average length of 18 years the mean difference between the geodetic and the direct data is −0.4 m w.e., the minimum −7.2 m w.e. and the maximum 3.6 m w.e. Longer periods between the acquisition of the DEMs do not necessarily result in a higher accuracy of the geodetic mass balance. Specific glaciers show specific trends of the difference between the direct and the geodetic data according to their type and state. In conclusion, geodetic and direct mass balance data are complementary, but differ systematically.

scholarly journals Reduced melt on debris-covered glaciers: investigations from Changri Nup Glacier, Nepal

2016 ◽  
Author(s):  
C. Vincent ◽  
P. Wagnon ◽  
J. M. Shea ◽  
W. W. Immerzel ◽  
P. D. A. Kraaijenbrink ◽  
...  
Keyword(s):  
Mass Balance ◽  
Surface Mass Balance ◽  
Mass Balances ◽  
Elevation Change ◽  
Surface Mass ◽  
Future Evolution ◽  
Debris Cover ◽  
Aerial Vehicle ◽  
The Mean ◽  
Terrestrial Photogrammetry

Abstract. Debris-covered glaciers occupy more than 1/4 of the total glacierized area in the Everest region of Nepal, yet the surface mass balance of these glaciers has not been measured directly. In this study, ground-based measurements of surface elevation and ice depth are combined with terrestrial photogrammetry and unmanned aerial vehicle (UAV) elevation models to derive the surface mass balance of the debris-covered Changri Nup Glacier, located in the Everest region. Over the debris-covered tongue, the mean elevation change between 2011 and 2015 is −0.93 m ice/year or −0.84 m water equivalent per year (w.e. a−1). The mean emergence velocity over this region, estimated from the total ice flux through a cross-section immediately above the debris-covered zone, is +0.37 m w.e. a−1. The debris-covered portion of the glacier thus has an area-averaged mass balance of −1.21 ± 0.2 m w.e. a−1 between 5240 and 5525 m above sea level (m a.s.l.). The surface mass balances observed on nearby debris-free glaciers suggest that the ablation is strongly reduced (by ca. 1.8 m w.e. a−1) by the debris cover. The insulating effect of the debris cover largely dominates the enhanced ice ablation due to the supra-glacial ponds and exposed ice cliffs. This finding has major implications for modeling the future evolution of debris-covered glaciers.

scholarly journals ICESat laser altimetry over small mountain glaciers

2016 ◽  
Author(s):  
D. Treichler ◽  
A. Kääb
Keyword(s):  
Mass Balance ◽  
Glacier Mass Balance ◽  
Srtm Dem ◽  
Elevation Change ◽  
Laser Altimetry ◽  
Glacier Surface ◽  
Mountain Glaciers ◽  
Southern Norway ◽  
Spatially Varying

Abstract. Using sparsely glaciated southern Norway as a case study, we assess the potential and limitations of ICESat laser altimetry for analysing regional glacier elevation change in rough mountain terrain. Differences between ICESat GLAS elevations and reference elevation data are plotted over time to derive a glacier surface elevation trend for the ICESat acquisition period 2003–2008. We find spatially varying biases between ICESat and three tested digital elevation models (DEMs): the Norwegian national DEM, SRTM DEM and a high resolution LiDAR DEM. For regional glacier elevation change, the spatial inconsistency of reference DEMs – a result of spatio-temporal merging – has the potential to significantly affect or dilute trends. Elevation uncertainties of all three tested DEMs exceed ICESat elevation uncertainty by an order of magnitude, and are thus limiting the accuracy of the method, rather than ICESat uncertainty. After correction of reference elevation bias, we find that ICESat provides a robust and realistic estimate of a moderately negative glacier mass balance of around −0.30 m ± 0.06 ice per year. This regional estimate agrees well with the heterogeneous but overall negative in-situ glacier mass balance observed in the area. ICESat matches glacier size distribution of the study area well and measures also small ice patches not commonly monitored in-situ. The sample is large enough for spatial and thematic subsetting. Vertical offsets to ICESat elevations vary for different glaciers in southern Norway due to spatially inconsistent reference DEM age. We introduce a per-glacier correction that removes these spatially varying offsets, and considerably increases trend significance. Only after application of this correction do individual campaigns also fit to observed in-situ glacier mass balance. Our correction has the potential to improve glacier trend significance also for other causes of spatially varying vertical offsets, for instance due to radar penetration into ice and snow for the SRTM DEM, or as a consequence from mosaicking and merging that is common for national or global DEMs.

scholarly journals Mass balances of Yala and Rikha Samba glaciers, Nepal, from 2000 to 2017

2021 ◽  
Vol 13 (8) ◽  
pp. 3791-3818
Author(s):  
Dorothea Stumm ◽  
Sharad Prasad Joshi ◽  
Tika Ram Gurung ◽  
Gunjan Silwal
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Water Resource Management ◽  
Important Variable ◽  
Glacier Mass Balance ◽  
Mass Balances ◽  
Monitoring Strategies ◽  
Length Changes ◽  
The Mean ◽  
Geodetic Mass Balance

Abstract. The glacier mass balance is an important variable to describe the climate system and is used for various applications like water resource management or runoff modelling. The direct or glaciological method and the geodetic method are the standard methods to quantify glacier mass changes, and both methods are an integral part of international glacier monitoring strategies. In 2011, we established two glacier mass-balance programmes on Yala and Rikha Samba glaciers in the Nepal Himalaya. Here we present the methods and data of the directly measured annual mass balances for the first six mass-balance years for both glaciers from 2011/2012 to 2016/2017. For Yala Glacier we additionally present the directly measured seasonal mass balance from 2011 to 2017, as well as the mass balance from 2000 to 2012 obtained with the geodetic method. In addition, we analysed glacier length changes for both glaciers. The directly measured average annual mass-balance rates of Yala and Rikha Samba glaciers are −0.80 ± 0.28 and −0.39 ± 0.32 m w.e. a−1, respectively, from 2011 to 2017. The geodetically measured annual mass-balance rate of Yala Glacier based on digital elevation models from 2000 and 2012 is −0.74 ± 0.53 m w.e. The cumulative mass loss for the period 2011 to 2017 for Yala and Rikha Samba glaciers is −4.80 ± 0.69 and −2.34 ± 0.79 m w.e., respectively. The mass loss on Yala Glacier from 2000 to 2012 is −8.92 ± 6.33 m w.e. The winter balance of Yala Glacier is positive, and the summer balance is negative in every investigated year. The summer balance determines the annual balance. Compared to regional mean geodetic mass-balance rates in the Nepalese Himalaya, the mean mass-balance rate of Rikha Samba Glacier is in a similar range, and the mean mass-balance rate of Yala Glacier is more negative because of the small and low-lying accumulation area. During the study period, a change of Yala Glacier's surface topography has been observed with glacier thinning and downwasting. The retreat rates of Rikha Samba Glacier are higher than for Yala Glacier. From 1989 to 2013, Rikha Samba Glacier retreated 431 m (−18.0 m a−1), and from 1974 to 2016 Yala Glacier retreated 346 m (−8.2 m a−1). The data of the annual and seasonal mass balances, point mass balance, geodetic mass balance, and length changes are accessible from the World Glacier Monitoring Service (WGMS, 2021), https://doi.org/10.5904/wgms-fog-2021-05.

scholarly journals The impact of Saharan dust and black carbon on albedo and long-term mass balance of an Alpine glacier

2015 ◽  
Vol 9 (4) ◽  
pp. 1385-1400 ◽  
Author(s):  
J. Gabbi ◽  
M. Huss ◽  
A. Bauder ◽  
F. Cao ◽  
M. Schwikowski
Keyword(s):  
Mass Balance ◽  
Black Carbon ◽  
Mineral Dust ◽  
Swiss Alps ◽  
Saharan Dust ◽  
Glacier Mass Balance ◽  
Mass Balances ◽  
The Mean ◽  
The Impact

Abstract. Light-absorbing impurities in snow and ice control glacier melt as shortwave radiation represents the main component of the surface energy balance. Here, we investigate the long-term effect of snow impurities, i.e., mineral dust and black carbon (BC), on albedo and glacier mass balance. The analysis was performed over the period 1914–2014 for two sites on Claridenfirn, Swiss Alps, where an outstanding 100-year record of seasonal mass balance measurements is available. Information on atmospheric deposition of mineral dust and BC over the last century was retrieved from two firn/ice cores of high-alpine sites. A combined mass balance and snow/firn layer model was employed to assess the effects of melt and accumulation processes on the impurity concentration at the surface and thus on albedo and glacier mass balance. Compared to pure snow conditions, the presence of Saharan dust and BC lowered the mean annual albedo by 0.04–0.06 depending on the location on the glacier. Consequently, annual melt was increased by 15–19 %, and the mean annual mass balance was reduced by about 280–490 mm w.e. BC clearly dominated absorption which is about 3 times higher than that of mineral dust. The upper site has experienced mainly positive mass balances and impurity layers were continuously buried whereas at the lower site, surface albedo was more strongly influenced by re-exposure of dust and BC-enriched layers due to frequent years with negative mass balances.

scholarly journals ICESat laser altimetry over small mountain glaciers

2016 ◽  
Vol 10 (5) ◽  
pp. 2129-2146 ◽  
Author(s):  
Désirée Treichler ◽  
Andreas Kääb
Keyword(s):  
Mass Balance ◽  
Glacier Mass Balance ◽  
Srtm Dem ◽  
Elevation Change ◽  
Laser Altimetry ◽  
Glacier Surface ◽  
Mountain Glaciers ◽  
Southern Norway ◽  
Spatially Varying

Abstract. Using sparsely glaciated southern Norway as a case study, we assess the potential and limitations of ICESat laser altimetry for analysing regional glacier elevation change in rough mountain terrain. Differences between ICESat GLAS elevations and reference elevation data are plotted over time to derive a glacier surface elevation trend for the ICESat acquisition period 2003–2008. We find spatially varying biases between ICESat and three tested digital elevation models (DEMs): the Norwegian national DEM, SRTM DEM, and a high-resolution lidar DEM. For regional glacier elevation change, the spatial inconsistency of reference DEMs – a result of spatio-temporal merging – has the potential to significantly affect or dilute trends. Elevation uncertainties of all three tested DEMs exceed ICESat elevation uncertainty by an order of magnitude, and are thus limiting the accuracy of the method, rather than ICESat uncertainty. ICESat matches glacier size distribution of the study area well and measures small ice patches not commonly monitored in situ. The sample is large enough for spatial and thematic subsetting. Vertical offsets to ICESat elevations vary for different glaciers in southern Norway due to spatially inconsistent reference DEM age. We introduce a per-glacier correction that removes these spatially varying offsets, and considerably increases trend significance. Only after application of this correction do individual campaigns fit observed in situ glacier mass balance. Our correction also has the potential to improve glacier trend significance for other causes of spatially varying vertical offsets, for instance due to radar penetration into ice and snow for the SRTM DEM or as a consequence of mosaicking and merging that is common for national or global DEMs. After correction of reference elevation bias, we find that ICESat provides a robust and realistic estimate of a moderately negative glacier mass balance of around −0.36 ± 0.07 m ice per year. This regional estimate agrees well with the heterogeneous but overall negative in situ glacier mass balance observed in the area.

scholarly journals Reduced melt on debris-covered glaciers: investigations from Changri Nup Glacier, Nepal

2016 ◽  
Vol 10 (4) ◽  
pp. 1845-1858 ◽  
Author(s):  
Christian Vincent ◽  
Patrick Wagnon ◽  
Joseph M. Shea ◽  
Walter W. Immerzeel ◽  
Philip Kraaijenbrink ◽  
...  
Keyword(s):  
Mass Balance ◽  
Surface Mass Balance ◽  
Mass Balances ◽  
Elevation Change ◽  
Surface Mass ◽  
Future Evolution ◽  
Total Mass Loss ◽  
Debris Cover ◽  
Aerial Vehicle ◽  
The Mean

Abstract. Approximately 25 % of the glacierized area in the Everest region is covered by debris, yet the surface mass balance of debris-covered portions of these glaciers has not been measured directly. In this study, ground-based measurements of surface elevation and ice depth are combined with terrestrial photogrammetry, unmanned aerial vehicle (UAV) and satellite elevation models to derive the surface mass balance of the debris-covered tongue of Changri Nup Glacier, located in the Everest region. Over the debris-covered tongue, the mean elevation change between 2011 and 2015 is −0.93 m year−1 or −0.84 m water equivalent per year (w.e. a−1). The mean emergence velocity over this region, estimated from the total ice flux through a cross section immediately above the debris-covered zone, is +0.37 m w.e. a−1. The debris-covered portion of the glacier thus has an area-averaged mass balance of −1.21 ± 0.2 m w.e. a−1 between 5240 and 5525 m above sea level (m a.s.l.). Surface mass balances observed on nearby debris-free glaciers suggest that the ablation is strongly reduced (by ca. 1.8 m w.e. a−1) by the debris cover. The insulating effect of the debris cover has a larger effect on total mass loss than the enhanced ice ablation due to supraglacial ponds and exposed ice cliffs. This finding contradicts earlier geodetic studies and should be considered for modelling the future evolution of debris-covered glaciers.

scholarly journals Glacier Mass Balance in the Nyainqentanglha Mountains between 2000 and 2017 Retrieved from ZiYuan-3 Stereo Images and the SRTM DEM

2020 ◽  
Vol 12 (5) ◽  
pp. 864 ◽  
Author(s):  
Shaoting Ren ◽  
Massimo Menenti ◽  
Li Jia ◽  
Jing Zhang ◽  
Jingxiao Zhang ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Glacier Mass Balance ◽  
The Tibetan Plateau ◽  
Ablation Zone ◽  
Mass Balances ◽  
Srtm Dem ◽  
Stereo Images ◽  
Glacier Surface ◽  
Accumulation Zone

Mountain glaciers are excellent indicators of climate change and have an important role in the terrestrial water cycle and food security in many parts of the world. Glaciers are the major water source of rivers and lakes in the Nyainqentanglha Mountains (NM) region, where the glacier area has the second largest extent on the Tibetan Plateau. The potential of the high spatial resolution ZiYuan-3 (ZY-3) Three-Line-Array (TLA) stereo images to retrieve glacier mass balance has not been sufficiently explored. In this study, we optimized the procedure to extract a Digital Elevation Model (DEM) from ZY-3 TLA stereo images and estimated the geodetic mass balance of representative glaciers in the two typical areas of the NM using ZY-3 DEMs and the C-band Shuttle Radar Topography Mission (SRTM) DEM in three periods, i.e., 2000–2013, 2013–2017 and 2000–2017. The results provide detailed information towards better understanding of glacier change and specifically show that: (1) with our new stereo procedure, ZY-3 TLA data can significantly increase point cloud density and decrease invalid data on the glacier surface map to generate a high resolution (5 m) glacier mass balance map; (2) the glacier mass balance in both the Western Nyainqentanglha Mountains (WNM) and Eastern Nyainqentanglha Mountains (ENM) was negative in 2000–2017, and experienced faster mass loss in recent years (2013–2017) in the WNM. Overall, the glaciers in the western and eastern NM show different change patterns since they are influenced by different climate regimes; the glacier mass balances in WNM was –0.22 ± 0.23 m w.e. a−1 and –0.43 ± 0.06 m w.e. a−1 in 2000–2013 and 2013–2017, respectively, while in 2000–2017, it was –0.30 ± 0.19 m w.e. a−1 in the WNM and –0.56 ± 0.20 m w.e. a−1 in the ENM; (3) in the WNM, the glaciers experienced mass loss in 2000–2013 and 2013–2017 in the ablation zone, while in the accumulation zone mass increased in 2000–2013 and a large mass loss occurred in 2013–2017; as regards the ENM, the glacier mass balance was negative in 2000–2017 in both zones; (4) glacier mass balance can be affected by the fractional abundance of debris and glacier slope; (5) the glacier mass balances retrieved by ZY-3 and TanDEM-X data agreed well in the ablation zone, while a large difference occurred in the accumulation zone because of the snow/firn penetration of the X-band SAR signal.

scholarly journals Long-range terrestrial laser scanning measurements of annual and intra-annual mass balances for Urumqi Glacier No. 1, eastern Tien Shan, China

2019 ◽  
Vol 13 (9) ◽  
pp. 2361-2383 ◽  
Author(s):  
Chunhai Xu ◽  
Zhongqin Li ◽  
Huilin Li ◽  
Feiteng Wang ◽  
Ping Zhou
Keyword(s):  
Mass Balance ◽  
Long Range ◽  
Tien Shan ◽  
Glacier Mass Balance ◽  
Surface Mass Balance ◽  
Mass Balances ◽  
Surface Mass ◽  
Mass Conversion ◽  
Geodetic Mass Balance

Abstract. The direct glaciological method provides in situ observations of annual or seasonal surface mass balance, but can only be implemented through a succession of intensive in situ measurements of field networks of stakes and snow pits. This has contributed to glacier surface mass-balance measurements being sparse and often discontinuous in the Tien Shan. Nevertheless, long-term glacier mass-balance measurements are the basis for understanding climate–glacier interactions and projecting future water availability for glacierized catchments in the Tien Shan. Riegl VZ®-6000 long-range terrestrial laser scanner (TLS), typically using class 3B laser beams, is exceptionally well suited for repeated glacier mapping, and thus determination of annual and seasonal geodetic mass balance. This paper introduces the applied TLS for monitoring summer and annual surface elevation and geodetic mass changes of Urumqi Glacier No. 1 as well as delineating accurate glacier boundaries for 2 consecutive mass-balance years (2015–2017), and discusses the potential of such technology in glaciological applications. Three-dimensional changes of ice and firn–snow bodies and the corresponding densities were considered for the volume-to-mass conversion. The glacier showed pronounced thinning and mass loss for the four investigated periods; glacier-wide geodetic mass balance in the mass-balance year 2015–2016 was slightly more negative than in 2016–2017. Statistical comparison shows that agreement between the glaciological and geodetic mass balances can be considered satisfactory, indicating that the TLS system yields accurate results and has the potential to monitor remote and inaccessible glacier areas where no glaciological measurements are available as the vertical velocity component of the glacier is negligible. For wide applications of the TLS in glaciology, we should use stable scan positions and in-situ-measured densities of snow–firn to establish volume-to-mass conversion.

scholarly journals Seasonal and annual mass balances of Mera and Pokalde glaciers (Nepal Himalaya) since 2007

2013 ◽  
Vol 7 (4) ◽  
pp. 3337-3378 ◽  
Author(s):  
P. Wagnon ◽  
C. Vincent ◽  
Y. Arnaud ◽  
E. Berthier ◽  
E. Vuillermoz ◽  
...  
Keyword(s):  
Mass Balance ◽  
Cross Sections ◽  
Mass Balances ◽  
Equilibrium Line Altitude ◽  
Nepal Himalaya ◽  
Limited Mass ◽  
In Situ Observations ◽  
The Mean ◽  
Southern Flank

Abstract. In the Everest region, Nepal, ground-based monitoring programs were started on the debris-free Mera Glacier (27.7° N, 86.9° E; 5.1 km2, 6420 to 4940 m a.s.l.) in 2007 and on the small Pokalde Glacier (27.9° N, 86.8° E; 0.1 km2, 5690 to 5430 m a.s.l., ∼ 25 km North of Mera Glacier) in 2009. These glaciers lie on the southern flank of the central Himalaya under the direct influence of the Indian monsoon and receive more than 80% of their annual precipitation in summer (June to September). Despite a large inter-annual variability with glacier-wide mass balances ranging from −0.77± 0.40 m w.e. in 2011–2012 (Equilibrium-line altitude (ELA) at ∼ 6055 m a.s.l.) to + 0.46 ± 0.40 m w.e. in 2010–2011 (ELA at ∼ 5340 m a.s.l.), Mera Glacier has been shrinking at a moderate mass balance rate of −0.10± 0.40 m w.e. yr−1 since 2007. Ice fluxes measured at two distinct transverse cross sections at ∼ 5350 m a.s.l. and ∼ 5520 m a.s.l. confirm that the mean state of this glacier over the last one or two decades corresponds to a limited mass loss, in agreement with remotely-sensed region-wide mass balances of the Everest area. Seasonal mass balance measurements show that ablation and accumulation are concomitant in summer which in turn is the key season controlling the annual glacier-wide mass balance. Unexpectedly, ablation occurs at all elevations in winter due to wind erosion and sublimation, with remobilized snow likely being sublimated in the atmosphere. Between 2009 and 2012, the small Pokalde Glacier lost mass more rapidly than Mera Glacier with respective mean glacier-wide mass balances of −0.72 and −0.26 ± 0.40 m w.e. yr−1. Low-elevation glaciers, such as Pokalde Glacier, have been usually preferred for in-situ observations in Nepal and more generally in the Himalayas, which may explain why compilations of ground-based mass balances are biased toward negative values compared with the regional mean under the present-day climate.

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