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 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 Mass balance of Pizolgletscher

2010 ◽  
Vol 65 (2) ◽  
pp. 80-91 ◽  
Author(s):  
M. Huss
Keyword(s):  
Mass Balance ◽  
Swiss Alps ◽  
Aerial Photographs ◽  
Balance Model ◽  
New Approach ◽  
Ice Volume ◽  
North Eastern ◽  
First Results ◽  
Data Points

Abstract. Half of the glaciers in the Swiss Alps are smaller than 0.1 km2. Despite this, the mass budget of small glaciers and their response to ongoing climate change is rarely studied. A new mass balance monitoring programme on Pizolgletscher (0.08 km2) in north-eastern Switzerland was started in 2006. This paper presents first results and describes a new approach to determining the mass balance of glaciers. Seasonal field observations are interpreted using a distributed mass balance model in daily resolution that allows spatial inter- and extrapolation of sparse data points and the calculation of mass balance over arbitrary time periods. Evaluation of aerial photographs acquired in subdecadal intervals since 1968 allows inclusion of data on changes in glacier area and ice volume, contributing towards a long-term reconstruction of Pizolgletscher's mass balance. The analysis revealed fast mass loss over the last three years with annual balances of -1.61 m w.e. in 2006/2007, -0.71 m w.e. in 2007/2008, and -1.46 m w.e. in 2008/2009 and high spatial variability of mass balance on Pizolgletscher.

scholarly journals Glaciological and geodetic mass balance of ten long-term glaciers in Norway

2015 ◽  
Vol 9 (6) ◽  
pp. 6581-6626 ◽  
Author(s):  
L. M. Andreassen ◽  
H. Elvehøy ◽  
B. Kjøllmoen ◽  
R. V. Engeset
Keyword(s):  
Mass Balance ◽  
Uncertainty Assessment ◽  
Glacier Mass Balance ◽  
Surface Mass ◽  
Independent Observations ◽  
Observation Series ◽  
Field Notes ◽  
Geodetic Mass Balance ◽  
Year 2000

Abstract. The glaciological and geodetic methods provide independent observations of glacier mass balance. The glaciological method measures the surface mass balance, on a seasonal or annual basis, whereas the geodetic method measures surface, internal and basal mass balances, over a period of years or decades. In this paper, we reanalyse the 10 glaciers with long-term mass balance series in Norway. The reanalysis includes (i) homogenisation of both glaciological and geodetic observation series, (ii) uncertainty assessment, (iii) estimates of generic differences including estimates of internal and basal melt, (iv) validation, and (v) partly calibration of mass balance series. This study comprises an extensive set of data (454 mass balance years, 34 geodetic surveys and large volumes of supporting data, such as metadata and field notes). In total, 21 periods of data were compared and the results show discrepancies between the glaciological and geodetic methods for some glaciers, which in part are attributed to internal and basal ablation and in part to inhomogeneity in the data processing. Deviations were smaller than 0.2 m w.e. a−1 for 12 out of 21 periods. Calibration was applied to seven out of 21 periods, as the deviations were larger than the uncertainty. The reanalysed glaciological series shows a more consistent signal of glacier change over the period of observations than previously reported: six glaciers had a significant mass loss (14–22 m w.e.) and four glaciers were nearly in balance. All glaciers have lost mass after year 2000. More research is needed on the sources of uncertainty, to reduce uncertainties and adjust the observation programmes accordingly. The study confirms the value of carrying out independent high-quality geodetic surveys to check and correct field observations.

scholarly journals Geodetic mass balance of Abramov Glacier from 1975 to 2015

2021 ◽  
pp. 1-12
Author(s):  
Florian Denzinger ◽  
Horst Machguth ◽  
Martina Barandun ◽  
Etienne Berthier ◽  
Luc Girod ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Central Asia ◽  
Aerial Imagery ◽  
Time Intervals ◽  
Thickness Change ◽  
Time Period ◽  
Stereo Imagery ◽  
Geodetic Mass Balance

Abstract Multi-decadal mass loss estimates are available for few glaciers of Central Asia. On Abramov Glacier (Pamir-Alay, Kyrgyzstan), comprehensive long-term glaciological measurements have been carried out from 1968 to 1999 and re-initiated in 2011. A climatological interpretation of this benchmark glacier in Central Asia requires bridging the gap between historical and renewed measurements. This is achieved here by computing the geodetic mass balance from 1975 to 2015 using previously unreleased Soviet aerial imagery and Pléaides stereo-imagery. During 1975–2015, Abramov Glacier lost 2.2 km2 (8.2%) of its area. The mean annual thickness change was − 0.43 ± 0.14 m a−1 for the period 1975–2015, corresponding to a volume change of − 0.45 ± 0.15 km3. The average specific geodetic mass balance amounts to − 0.38 ± 0.12 m w.e. a−1. The 1975–2015 glacier mass loss lies within the range of glaciological and geodetic mass-balance estimates that were previously published for disparate and shorter time intervals since 1968. This study covers a much longer time period than earlier geodetic estimates and demonstrates the capacity to geodetically constrain glacier change at high spatial resolution in Central Asia using historic aerial imagery and Structure from Motion techniques. Therefore, it could serve as a benchmark for future studies of regional mass change.

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.

scholarly journals Evolution of Ossoue Glacier (French Pyrenees) since the end of the Little Ice Age

2015 ◽  
Vol 9 (2) ◽  
pp. 2431-2494 ◽  
Author(s):  
R. Marti ◽  
S. Gascoin ◽  
T. Houet ◽  
O. Ribière ◽  
D. Laffly ◽  
...  
Keyword(s):  
Mass Balance ◽  
Little Ice Age ◽  
Atlantic Multidecadal Oscillation ◽  
Ablation Rate ◽  
Ice Age ◽  
Glacier Length ◽  
Geodetic Mass Balance ◽  
High Elevations ◽  
Topographic Surveys

Abstract. Long-term climate records are rare at high elevations in Southern Europe. Here, we reconstructed the evolution of Ossoue Glacier (42°46' N, 0.45 km2), located in the Pyrenees (3404 m a.s.l.), since the Little Ice Age (LIA). Glacier length, area, thickness and mass changes indicators were generated from historical datasets, topographic surveys, glaciological measurements (2001–2013), a GPR survey (2006) and stereoscopic satellite images (2013). The glacier has receded considerably since the end of the LIA, losing 40 % of its length and 60% of its area. Three periods of marked ice depletion can be identified: 1850–1890, 1928–1950 and 1983–2013, as well as two periods of stabilization or slightly growth: 1905–1928 and 1950–1983; these agree with climatic datasets (air temperature, precipitation, North Atlantic Oscillation, Atlantic Multidecadal Oscillation). In the early 2000s, the area of the glacier dropped below 50% of its area at the end of the LIA. Geodetic mass balance measurements over 1983–2013 indicated −30.1 ± 1.7 m w.e. (−1 m w.e. yr−1) whereas glaciological mass balance measurements show −17.36 ± 2.9 m w.e. (−1.45 m w.e. yr−1) over 2001–2013, resulting in a doubling of the ablation rate in the last decade. In 2013 the maximum ice thickness was 59 ± 10.3 m. Assuming that the current ablation rate stays constant, Ossoue Glacier will disappear midway through the 21st century.

scholarly journals Reanalysis of long-term series of glaciological and geodetic mass balance for 10 Norwegian glaciers

2016 ◽  
Vol 10 (2) ◽  
pp. 535-552 ◽  
Author(s):  
Liss M. Andreassen ◽  
Hallgeir Elvehøy ◽  
Bjarne Kjøllmoen ◽  
Rune V. Engeset
Keyword(s):  
Mass Balance ◽  
Uncertainty Assessment ◽  
Glacier Mass Balance ◽  
Surface Mass ◽  
Independent Observations ◽  
Observation Series ◽  
Field Notes ◽  
Geodetic Mass Balance ◽  
Year 2000

Abstract. Glaciological and geodetic methods provide independent observations of glacier mass balance. The glaciological method measures the surface mass balance, on a seasonal or annual basis, whereas the geodetic method measures surface, internal, and basal mass balances, over a period of years or decades. In this paper, we reanalyse the 10 glaciers with long-term mass-balance series in Norway. The reanalysis includes (i) homogenisation of both glaciological and geodetic observation series, (ii) uncertainty assessment, (iii) estimates of generic differences including estimates of internal and basal melt, (iv) validation, and, if needed, (v) calibration of mass-balance series. This study comprises an extensive set of data (484 mass-balance years, 34 geodetic surveys, and large volumes of supporting data, such as metadata and field notes). In total, 21 periods of data were compared and the results show discrepancies between the glaciological and geodetic methods for some glaciers, which are attributed in part to internal and basal ablation and in part to inhomogeneity in the data processing. Deviations were smaller than 0.2 m w.e. a−1 for 12 out of 21 periods. Calibration was applied to 7 out of 21 periods, as the deviations were larger than the uncertainty. The reanalysed glaciological series shows a more consistent signal of glacier change over the period of observations than previously reported: six glaciers had a significant mass loss (14–22 m w.e.) and four glaciers were nearly in balance. All glaciers have lost mass after the year 2000. More research is needed on the sources of uncertainty to reduce uncertainties and adjust the observation programmes accordingly. The study confirms the value of carrying out independent high-quality geodetic surveys to check and correct field observations.

scholarly journals Geodetic mass balance record with rigorous uncertainty estimates deduced from aerial photographs and lidar data – Case study from Drangajökull ice cap, NW Iceland

2016 ◽  
Vol 10 (1) ◽  
pp. 159-177 ◽  
Author(s):  
E. Magnússon ◽  
J. Muñoz-Cobo Belart ◽  
F. Pálsson ◽  
H. Ágústsson ◽  
P. Crochet
Keyword(s):  
High Resolution ◽  
Mass Balance ◽  
Bias Correction ◽  
Aerial Photographs ◽  
Glacier Surface ◽  
Ice Cap ◽  
Uncertainty Estimates ◽  
Lidar Dem ◽  
Geodetic Mass Balance

Abstract. In this paper we describe how recent high-resolution digital elevation models (DEMs) can be used to extract glacier surface DEMs from old aerial photographs and to evaluate the uncertainty of the mass balance record derived from the DEMs. We present a case study for Drangajökull ice cap, NW Iceland. This ice cap covered an area of 144 km2 when it was surveyed with airborne lidar in 2011. Aerial photographs spanning all or most of the ice cap are available from survey flights in 1946, 1960, 1975, 1985, 1994 and 2005. All ground control points used to constrain the orientation of the aerial photographs were obtained from the high-resolution lidar DEM. The lidar DEM was also used to estimate errors of the extracted photogrammetric DEMs in ice- and snow-free areas, at nunataks and outside the glacier margin. The derived errors of each DEM were used to constrain a spherical semivariogram model, which along with the derived errors in ice- and snow-free areas were used as inputs into 1000 sequential Gaussian simulations (SGSims). The simulations were used to estimate the possible bias in the entire glaciated part of the DEM and the 95 % confidence level of this bias. This results in bias correction varying in magnitude between 0.03 m (in 1975) and 1.66 m (in 1946) and uncertainty values between ±0.21 m (in 2005) and ±1.58 m (in 1946). Error estimation methods based on more simple proxies would typically yield 2–4 times larger error estimates. The aerial photographs used were acquired between late June and early October. An additional seasonal bias correction was therefore estimated using a degree-day model to obtain the volume change between the start of 2 glaciological years (1 October). This correction was largest for the 1960 DEM, corresponding to an average elevation change of −3.5 m or approx. three-quarters of the volume change between the 1960 and the 1975 DEMs. The total uncertainty of the derived mass balance record is dominated by uncertainty in the volume changes caused by uncertainties of the SGSim bias correction, the seasonal bias correction and the interpolation of glacier surface where data are lacking. The record shows a glacier-wide mass balance rate of Ḃ  = −0.26 ± 0.04 m w.e. a−1 for the entire study period (1946–2011). We observe significant decadal variability including periods of mass gain, peaking in 1985–1994 with Ḃ  = 0.27 ± 0.11 m w.e. a−1. There is a striking difference when Ḃ  is calculated separately for the western and eastern halves of Drangajökull, with a reduction of eastern part on average  ∼  3 times faster than the western part. Our study emphasizes the need for applying rigorous geostatistical methods for obtaining uncertainty estimates of geodetic mass balance, the importance of seasonal corrections of DEMs from glaciers with high mass turnover and the risk of extrapolating mass balance record from one glacier to another even over short distances.

scholarly journals Quality Assessment and Glaciological Applications of Digital Elevation Models Derived from Space-Borne and Aerial Images over Two Tidewater Glaciers of Southern Spitsbergen

2019 ◽  
Vol 11 (9) ◽  
pp. 1121 ◽  
Author(s):  
Małgorzata Błaszczyk ◽  
Dariusz Ignatiuk ◽  
Mariusz Grabiec ◽  
Leszek Kolondra ◽  
Michał Laska ◽  
...  
Keyword(s):  
Mass Balance ◽  
Digital Elevation Models ◽  
Control Point ◽  
Aerial Photographs ◽  
Differential Gps ◽  
Tidewater Glaciers ◽  
Digital Elevation ◽  
High Resolution Satellite Images ◽  
Elevation Changes ◽  
Geodetic Mass Balance

In this study, we assess the accuracy and precision of digital elevation models (DEM) retrieved from aerial photographs taken in 2011 and from Very High Resolution satellite images (WorldView-2 and Pléiades) from the period 2012–2017. Additionally, the accuracy of the freely available Strip product of ArcticDEM was verified. We use the DEMs to characterize geometry changes over Hansbreen and Hornbreen, two tidewater glaciers in southern Spitsbergen, Svalbard. The satellite-based DEMs from WorldView-2 and Pléiades stereo pairs were processed using the Rational Function Model (RFM) without and with one ground control point. The elevation quality of the DEMs over glacierized areas was validated with in situ data: static differential GPS survey of mass balance stakes and GPS kinematic data acquired during ground penetrating radar survey. Results demonstrate the usefulness of the analyzed sources of DEMs for estimation of the total geodetic mass balance of the Svalbard glaciers. DEM accuracy is sufficient to investigate glacier surface elevation changes above 1 m. Strips from the ArcticDEM are generally precise, but some of them showed gross errors and need to be handled with caution. The surface of Hansbreen and Hornbreen has been lowering in recent years. The average annual elevation changes for Hansbreen were more negative in the period 2015–2017 (−2.4 m a−1) than in the period 2011–2015 (−1.7 m a−1). The average annual elevation changes over the studied area of Hornbreen for the period 2012–2017 amounted to −1.6 m a−1. The geodetic mass balance for Hansbreen was more negative than the climatic mass balance estimated using the mass budget method, probably due to underestimation of the ice discharge. From 2011 to 2017, Hansbreen lost on average over 1% of its volume each year. Such a high rate of relative loss illustrates how fast these glaciers are responding to climate change.

scholarly journals Satellite Remote Sensing of the Greenland Ice Sheet Ablation Zone: A Review

2019 ◽  
Vol 11 (20) ◽  
pp. 2405
Author(s):  
Matthew Cooper ◽  
Laurence Smith
Keyword(s):  
Remote Sensing ◽  
Mass Balance ◽  
Satellite Remote Sensing ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ablation Zone ◽  
Elevation Change ◽  
Laser Altimetry ◽  
Surface Elevation Change ◽  
Optical Imagery

The Greenland Ice Sheet is now the largest land ice contributor to global sea level rise, largely driven by increased surface meltwater runoff from the ablation zone, i.e., areas of the ice sheet where annual mass losses exceed gains. This small but critically important area of the ice sheet has expanded in size by ~50% since the early 1960s, and satellite remote sensing is a powerful tool for monitoring the physical processes that influence its surface mass balance. This review synthesizes key remote sensing methods and scientific findings from satellite remote sensing of the Greenland Ice Sheet ablation zone, covering progress in (1) radar altimetry, (2) laser (lidar) altimetry, (3) gravimetry, (4) multispectral optical imagery, and (5) microwave and thermal imagery. Physical characteristics and quantities examined include surface elevation change, gravimetric mass balance, reflectance, albedo, and mapping of surface melt extent and glaciological facies and zones. The review concludes that future progress will benefit most from methods that combine multi-sensor, multi-wavelength, and cross-platform datasets designed to discriminate the widely varying surface processes in the ablation zone. Specific examples include fusing laser altimetry, radar altimetry, and optical stereophotogrammetry to enhance spatial measurement density, cross-validate surface elevation change, and diagnose radar elevation bias; employing dual-frequency radar, microwave scatterometry, or combining radar and laser altimetry to map seasonal snow depth; fusing optical imagery, radar imagery, and microwave scatterometry to discriminate between snow, liquid water, refrozen meltwater, and bare ice near the equilibrium line altitude; combining optical reflectance with laser altimetry to map supraglacial lake, stream, and crevasse bathymetry; and monitoring the inland migration of snowlines, surface melt extent, and supraglacial hydrologic features.

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