scholarly journals An optimized method to calculate the geodetic mass balance of mountain glaciers

2018 ◽  
Vol 64 (248) ◽  
pp. 917-931 ◽  
Author(s):  
RUBÉN BASANTES-SERRANO ◽  
ANTOINE RABATEL ◽  
CHRISTIAN VINCENT ◽  
PASCAL SIRGUEY
Keyword(s):  
Spatial Variability ◽  
Mass Balance ◽  
Mean Difference ◽  
Full Density ◽  
Elevation Change ◽  
Low Contrast ◽  
Mountain Glaciers ◽  
Elevation Changes ◽  
Geodetic Mass Balance ◽  
Similar Accuracy

ABSTRACTUnderstanding the effects of climate on glaciers requires precise estimates of ice volume change over several decades. This is achieved by the geodetic mass balance computed by two means: (1) the digital elevation model (DEM) comparison (SeqDEM) allows measurements over the entire glacier, however the low contrast over glacierized areas is an issue for the DEM generation through the photogrammetric techniques and (2) the profiling method (SePM) is a faster alternative but fails to capture the spatial variability of elevation changes. We present a new framework (SSD) that relies upon the spatial variability of the elevation change to densify a sampling network to optimize the surface-elevation change quantification. Our method was tested in two small glaciers over different periods. We conclude that the SePM overestimates the elevation change by ~20% with a mean difference of ~1.00 m (root mean square error (RMSE) = ~3.00 m) compared with results from the SeqDEM method. A variogram analysis of the elevation changes showed a mean difference of <0.10 m (RMSE = ~2.40 m) with SSD approach. A final assessment on the largest glacier in the French Alps confirms the high potential of our method to compute the geodetic mass balance, without going through the generation of a full-density DEM, but with a similar accuracy than the SeqDEM approach.

scholarly journals Surface elevation changes during 2007–13 on Bowdoin and Tugto Glaciers, northwestern Greenland

2016 ◽  
Vol 62 (236) ◽  
pp. 1083-1092 ◽  
Author(s):  
SHUN TSUTAKI ◽  
SHIN SUGIYAMA ◽  
DAIKI SAKAKIBARA ◽  
TAKANOBU SAWAGAKI
Keyword(s):  
Mass Balance ◽  
Satellite Observations ◽  
Surface Elevation ◽  
Surface Mass Balance ◽  
Elevation Change ◽  
Predominant Role ◽  
Ice Dynamics ◽  
Surface Mass ◽  
Elevation Changes ◽  
Negative Surface

ABSTRACTTo quantify recent thinning of marine-terminating outlet glaciers in northwestern Greenland, we carried out field and satellite observations near the terminus of Bowdoin Glacier. These data were used to compute the change in surface elevation from 2007 to 2013 and this rate of thinning was then compared with that of the adjacent land-terminating Tugto Glacier. Comparing DEMs of 2007 and 2010 shows that Bowdoin Glacier is thinning more rapidly (4.1 ± 0.3 m a−1) than Tugto Glacier (2.8 ± 0.3 m a−1). The observed negative surface mass-balance accounts for <40% of the elevation change of Bowdoin Glacier, meaning that the thinning of Bowdoin Glacier cannot be attributable to surface melting alone. The ice speed of Bowdoin Glacier increases down-glacier, reaching 457 m a−1 near the calving front. This flow regime causes longitudinal stretching and vertical compression at a rate of −0.04 a−1. It is likely that this dynamically-controlled thinning has been enhanced by the acceleration of the glacier since 2000. Our measurements indicate that ice dynamics indeed play a predominant role in the rapid thinning of Bowdoin Glacier.

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 Geodetic Mass Balance of Haxilegen Glacier No. 51, Eastern Tien Shan, from 1964 to 2018

2022 ◽  
Vol 14 (2) ◽  
pp. 272
Author(s):  
Chunhai Xu ◽  
Zhongqin Li ◽  
Feiteng Wang ◽  
Jianxin Mu ◽  
Xin Zhang
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Laser Scanning ◽  
Mean Value ◽  
Tien Shan ◽  
Glacier Mass Balance ◽  
Topographic Map ◽  
Glacier Surface ◽  
Elevation Changes ◽  
Geodetic Mass Balance

The eastern Tien Shan hosts substantial mid-latitude glaciers, but in situ glacier mass balance records are extremely sparse. Haxilegen Glacier No. 51 (eastern Tien Shan, China) is one of the very few well-measured glaciers, and comprehensive glaciological measurements were implemented from 1999 to 2011 and re-established in 2017. Mass balance of Haxilegen Glacier No. 51 (1999–2015) has recently been reported, but the mass balance record has not extended to the period before 1999. Here, we used a 1:50,000-scale topographic map and long-range terrestrial laser scanning (TLS) data to calculate the area, volume, and mass changes for Haxilegen Glacier No. 51 from 1964 to 2018. Haxilegen Glacier No. 51 lost 0.34 km2 (at a rate of 0.006 km2 a−1 or 0.42% a−1) of its area during the period 1964–2018. The glacier experienced clearly negative surface elevation changes and geodetic mass balance. Thinning occurred almost across the entire glacier surface, with a mean value of −0.43 ± 0.12 m a−1. The calculated average geodetic mass balance was −0.36 ± 0.12 m w.e. a−1. Without considering the error bounds of mass balance estimates, glacier mass loss over the past 50 years was in line with the observed and modeled mass balance (−0.37 ± 0.22 m w.e. a−1) that was published for short time intervals since 1999 but was slightly less negative than glacier mass loss in the entire eastern Tien Shan. Our results indicate that Riegl VZ®-6000 TLS can be widely used for mass balance measurements of unmonitored individual glaciers.

scholarly journals Terminus advance, kinematics and mass redistribution during eight surges of Donjek Glacier, St. Elias Range, Canada, 1935 to 2016

2019 ◽  
Vol 65 (252) ◽  
pp. 565-579 ◽  
Author(s):  
WILLIAM KOCHTITZKY ◽  
HESTER JISKOOT ◽  
LUKE COPLAND ◽  
ELLYN ENDERLIN ◽  
ROBERT MCNABB ◽  
...  
Keyword(s):  
Mass Balance ◽  
Dynamic Balance ◽  
Active Phase ◽  
Aerial Photographs ◽  
Ablation Zone ◽  
Elevation Change ◽  
Glacier Terminus ◽  
Mass Redistribution ◽  
Geodetic Mass Balance

ABSTRACTDonjek Glacier has an unusually short and regular surge cycle, with eight surges identified since 1935 from aerial photographs and satellite imagery with a ~12 year repeat interval and ~2 year active phase. Recent surges occurred during a period of long-term negative mass balance and cumulative terminus retreat of 2.5 km since 1874. In contrast to previous work, we find that the constriction where the valley narrows and bedrock lithology changes, 21 km from the terminus, represents the upper limit of surging, with negligible surface speed or elevation change up-glacier from this location. This positions the entire surge-type portion of the glacier in the ablation zone. The constriction geometry does not act as the dynamic balance line, which we consistently find at 8 km from the glacier terminus. During the 2012–2014 surge event, the average lowering rate in the lowest 21 km of the glacier was 9.6 m a−1, while during quiescence it was 1.0 m a−1. Due to reservoir zone refilling, the ablation zone has a positive geodetic balance in years immediately following a surge event. An active surge phase can result in a strongly negative geodetic mass balance over the surge-type portion of the glacier.

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 &amp;pm; 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 Latest Geodetic Changes of Austre Lovénbreen and Pedersenbreen, Svalbard

2019 ◽  
Vol 11 (24) ◽  
pp. 2890 ◽  
Author(s):  
Songtao Ai ◽  
Xi Ding ◽  
Florian Tolle ◽  
Zemin Wang ◽  
Xi Zhao
Keyword(s):  
Mass Balance ◽  
Snow Depth ◽  
Spline Interpolation ◽  
Time Interval ◽  
Short Time Interval ◽  
Mass Balances ◽  
Glacier Surface ◽  
Elevation Changes ◽  
Rtk Gps ◽  
Geodetic Mass Balance

Geodetic mass changes in the Svalbard glaciers Austre Lovénbreen and Pedersenbreen were studied via high-precision real-time kinematic (RTK)-global positioning system (GPS) measurements from 2013 to 2015. To evaluate the elevation changes of the two Svalbard glaciers, more than 10,000 GPS records for each glacier surface were collected every year from 2013 to 2015. The results of several widely used interpolation methods (i.e., inverse distance weighting (IDW), ordinary kriging (OK), universal kriging (UK), natural neighbor (NN), spline interpolation, and Topo to Raster (TTR) interpolation) were compared. Considering the smoothness and accuracy of the glacier surface, NN interpolation was selected as the most suitable interpolation method to generate a surface digital elevation model (DEM). In addition, we compared two procedures for calculating elevation changes: using DEMs generated from the direct interpolation of the RTK-GPS points and using the elevation bias of crossover points from the RTK-GPS tracks in different years. Then, the geodetic mass balances were calculated by converting the elevation changes to their water equivalents. Comparing the geodetic mass balances calculated with and without considering snow depth revealed that ignoring the effect of snow depth, which differs greatly over a short time interval, might lead to bias in mass balance investigation. In summary, there was a positive correlation between the geodetic mass balance and the corresponding elevation. The mass loss increased with decreasing elevation, and the mean annual gradients of the geodetic mass balance along the elevation of Austre Lovénbreen and Pedersenbreen in 2013–2015 were approximately 2.60‰ and 2.35‰, respectively. The gradients at the glacier snouts were three times larger than those over the whole glaciers. Additionally, some mass gain occurred in certain high-elevation regions. Compared with a 2019 DEM generated from unmanned aerial vehicle measurement, the glacier snout areas presented an accelerating thinning situation in 2015–2019.

scholarly journals Reanalysing the 2007–19 glaciological mass-balance series of Mera Glacier, Nepal, Central Himalaya, using geodetic mass balance

2020 ◽  
pp. 1-9
Author(s):  
Patrick Wagnon ◽  
Fanny Brun ◽  
Arbindra Khadka ◽  
Etienne Berthier ◽  
Dibas Shrestha ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Mass Balance ◽  
Central Himalaya ◽  
Positive Bias ◽  
Stereo Images ◽  
Negative Mass ◽  
Geodetic Mass Balance

Abstract The 2007–19 glaciological mass-balance series of Mera Glacier in the Everest Region, East Nepal, is reanalysed using the geodetic mass balance assessed by differencing two DEMs obtained from Pléiades stereo-images acquired in November 2012 and in October 2018. The glaciological glacier-wide annual mass balance of Mera Glacier has to be systematically decreased by 0.11 m w.e. a−1 to match the geodetic mass balance. We attribute part of the positive bias of the glaciological mass balance to an over-estimation of the accumulation above 5520 m a.s.l., likely due to a measurement network unable to capture its spatial variability. Over the period 2007–19, Mera Glacier has lost mass at a rate of −0.41 ± 0.20 m w.e. a−1, in general agreement with regional averages for the central Himalaya. We observe a succession of negative mass-balance years since 2013.

scholarly journals Elevation changes measured on Svalbard glaciers and ice caps from airborne laser data

2005 ◽  
Vol 42 ◽  
pp. 202-208 ◽  
Author(s):  
Jonathan L. Bamber ◽  
William Krabill ◽  
Vivienne Raper ◽  
Julian A. Dowdeswell ◽  
J. Oerlemans
Keyword(s):  
Mass Balance ◽  
Elevation Change ◽  
Svalbard Archipelago ◽  
Ice Caps ◽  
Airborne Laser ◽  
Air Temperatures ◽  
Lower Elevation ◽  
Elevation Changes ◽  
The Mean ◽  
Negative Balance

AbstractPrecise airborne laser surveys were conducted during spring in 1996 and 2002 on 17 ice caps and glaciers in the Svalbard archipelago covering the islands of Spitsbergen and Nordaustlandet. We present the derived elevation changes. Lower-elevation glaciers in south Spitsbergen show the largest thinning rates of ∼ 0.5 m a-1, while some of the higher, more northerly ice caps appear to be close to balance. The pattern of elevation change is complex, however, due to several factors including glacier aspect, microclimatological influences and the high natural annual variability in local accumulation and ablation rates. Anomalous changes were observed on Fridtjovbreen, which started surging in 1996, at the start of the measurement period. On this glacier, thinning (of > 0.6 m a-1) was observed in the accumulation area, coincident with thickening at lower elevations. Asymmetric thinning was found on two ice caps on Nordaustlandet, with the largest values on the eastern side of Vestfonna but the western slopes of Vegafonna. The mean elevation change for all ice masses was -0.19 m a-1 w.e., which is 1.6 times the net mass-balance value determined for the last 30 years. Using mass-balance sensitivity estimates for Svalbard suggests that the implied increase in negative balance is linked to warmer air temperatures in the late 1990s. Multiple linear regression suggests that mass balance is most closely correlated with latitude, rather than mean altitude or longitude.

scholarly journals Observations of enhanced thinning in the upper reaches of Svalbard glaciers

2012 ◽  
Vol 6 (6) ◽  
pp. 1369-1381 ◽  
Author(s):  
T. D. James ◽  
T. Murray ◽  
N. E. Barrand ◽  
H. J. Sykes ◽  
A. J. Fox ◽  
...  
Keyword(s):  
Mass Balance ◽  
Average Rate ◽  
Winter Precipitation ◽  
Svalbard Archipelago ◽  
Ice Surface ◽  
Considerable Research ◽  
Elevation Data ◽  
Elevation Changes ◽  
The Subject ◽  
Geodetic Mass Balance

Abstract. Changes in the volume and extent of land ice of the Svalbard archipelago have been the subject of considerable research since their sensitivity to changes in climate was first noted. However, the measurement of these changes is often necessarily based on point or profile measurements which may not be representative if extrapolated to a whole catchment or region. Combining high-resolution elevation data from contemporary laser-altimetry surveys and archived aerial photography makes it possible to measure historical changes across a glacier's surface without the need for extrapolation. Here we present a high spatial resolution time-series for six Arctic glaciers in the Svalbard archipelago spanning 1961 to 2005. We find high variability in thinning rates between sites with prevalent elevation changes at all sites averaging −0.59 ± 0.04 m a−1 between 1961–2005. Prior to 1990, ice surface elevation was changing at an average rate of −0.52 ± 0.09 m a−1 which decreased to −0.76 ± 0.10 m a−1 after 1990. Setting the elevation changes against the glaciers' altitude distribution reveals that significant increases in thinning rates are occurring most notably in the glaciers' upper reaches. We find that these changes are coincident with a decrease in winter precipitation at the Longyearbyen meteorological station and could reflect a decrease in albedo or dynamic response to lower accumulation. Further work is required to understand fully the causes of this increase in thinning rates in the glaciers' upper reaches. If on-going and occurring elsewhere in the archipelago, these changes will have a significant effect on the region's future mass balance. Our results highlight the importance of understanding the climatological context of geodetic mass balance measurements and demonstrate the difficulty of using index glaciers to represent regional changes in areas of strong climatological gradients.

scholarly journals Moderate mass loss of Kanchenjunga Glacier in the eastern Nepal Himalaya since 1975 revealed by Hexagon KH-9 and ALOS satellite Imageries

2016 ◽  
Author(s):  
Damodar Lamsal ◽  
Koji Fujita ◽  
Akiko Sakai
Keyword(s):  
Mass Balance ◽  
Flow Speed ◽  
Elevation Change ◽  
Nepal Himalaya ◽  
Covered Area ◽  
Digital Elevation ◽  
The Difference ◽  
Glacier Velocity ◽  
Geodetic Mass Balance ◽  
Moderate Mass

Abstract. This study presents the geodetic mass balance of Kanchenjunga Glacier, a heavily debris-covered glacier, in the easternmost Nepal Himalaya between 1975 and 2010 using high-resolution (5-m) digital elevation models (DEMs) generated from Hexagon KH-9 and ALOS PRISM stereo-images. Glacier velocities are also calculated using a feature tracking method with two ALOS ortho-images taken in 2010. The difference between the two DEMs shows the rate of elevation change of the glacier, considerable surface lowering across the debris-covered area, and slight thickening in the accumulation area between 1975 and 2010. The velocity throughout the debris-covered area is slow, which stands in contrast with the faster velocity in the lower accumulation area. The rates of elevation change positively correlate with the elevation along the debris-free part, while they negatively correlate with elevation over the debris-covered part, which may result from the distribution of debris thickness. The rate of elevation change also positively correlates with the glacier velocity, whereas no correlation is found with slope and gradient of flow speed. Significant surface lowering is observed at supraglacial ponds, though the ponds should have short life spans. The geodetic mass balance of Kanchenjunga Glacier for the period of 1975–2010 (–0.14 ± 0.12 m w.e. a–1) is considerably less negative than those estimated for Khumbu Glacier (–0.27 m w.e. a–1) in the neighbouring Khumbu region. Disparities in the density of supraglacial ponds and the area contributions of accumulation and debris-covered areas may be principal causes of the difference in geodetic mass balance between the two glaciers.

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