scholarly journals Sensitivity of geodetic glacier mass balance estimation to DEM void interpolation

2018 ◽  
Author(s):  
Robert McNabb ◽  
Christopher Nuth ◽  
Andreas Kääb ◽  
Luc Girod
Keyword(s):  
Mass Balance ◽  
Terrestrial Ecosystems ◽  
Glacier Mass Balance ◽  
Direct Impact ◽  
Glacier Surface ◽  
Southeast Alaska ◽  
Digital Elevation ◽  
Regional Basis ◽  
The Impact

Abstract. Glacier mass balance is a direct expression of climate change, with implications for sea level, ocean chemistry, oceanic and terrestrial ecosystems, and water resources. Traditionally, glacier mass balance has been estimated using in-situ measurements of changes in surface height and density at select locations on the glacier surface, or by comparing changes in surface height using repeat, full-coverage digital elevation models (DEMs), also called the geodetic method. DEMs often have gaps in coverage (voids) based on the nature of the sensor used and the surface being measured. The way that these voids are accounted for has a direct impact on the estimate of geodetic glacier mass balance, though a systematic comparison of different proposed methods has been heretofore lacking. In this study, we determine the impact and sensitivity of void-filling methods on estimates of volume change. Using two spatially complete, high-resolution DEMs over Southeast Alaska, USA, we compare 11 different void-filling methods on a glacier-by-glacier and regional basis. We find that a few methods introduce biases of up to 20 % in the regional results, while other methods give results very close (

scholarly journals Sensitivity of glacier volume change estimation to DEM void interpolation

2019 ◽  
Vol 13 (3) ◽  
pp. 895-910 ◽  
Author(s):  
Robert McNabb ◽  
Christopher Nuth ◽  
Andreas Kääb ◽  
Luc Girod
Keyword(s):  
Mass Balance ◽  
Volume Change ◽  
Thermal Emission ◽  
Glacier Mass Balance ◽  
Southeast Alaska ◽  
Interpolation Methods ◽  
Digital Elevation ◽  
Regional Basis ◽  
The Impact ◽  
Voided Volume

Abstract. Glacier mass balance has been estimated on individual glacier and regional scales using repeat digital elevation models (DEMs). DEMs often have gaps in coverage (“voids”), the properties of which depend on the nature of the sensor used and the surface being measured. The way that these voids are accounted for has a direct impact on the estimate of geodetic glacier mass balance, though a systematic comparison of different proposed methods has been heretofore lacking. In this study, we determine the impact and sensitivity of void interpolation methods on estimates of volume change. Using two spatially complete, high-resolution DEMs over southeast Alaska, USA, we artificially generate voids in one of the DEMs using correlation values derived from photogrammetric processing of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) scenes. We then compare 11 different void interpolation methods on a glacier-by-glacier and regional basis. We find that a few methods introduce biases of up to 20 % in the regional results, while other methods give results very close (<1 % difference) to the true, non-voided volume change estimates. By comparing results from a few of the best-performing methods, an estimate of the uncertainty introduced by interpolating voids can be obtained. Finally, by increasing the number of voids, we show that with these best-performing methods, reliable estimates of glacier-wide volume change can be obtained, even with sparse DEM coverage.

scholarly journals 10 year mass balance by glaciological and geodetic methods of Glaciar Bahía del Diablo, Vega Island, Antarctic Peninsula

2015 ◽  
Vol 56 (70) ◽  
pp. 141-146 ◽  
Author(s):  
Sebastián Marinsek ◽  
Evgeniy Ermolin
Keyword(s):  
Mass Balance ◽  
Antarctic Peninsula ◽  
Field Survey ◽  
Field Measurements ◽  
Mass Change ◽  
Glacier Mass Balance ◽  
Glacier Surface ◽  
Field Surveys ◽  
Digital Elevation

AbstractWe present new glacier mass-balance field data from Glaciar Bahía del Diablo, Vega Island, northeastern Antarctic Peninsula. The results provided here represent glacier mass-balance data over a 10 year period (2001–11) obtained by the glaciological and geodetic methods relying on field measurements. Glacier surface digital elevation models (DEMs) were obtained in 2001 and 2011 from a kinematic GPS field survey with high horizontal and vertical accuracies. In situ mass-balance data were collected from yearly stake measurements. The results attained by the two methods agree, which may be considered a measure of their accuracy. A cumulative mass change of –1.90 ± 0.31 m w.e. over the 10 year period was obtained from the annual mass-balance field surveys. The total mass change derived from DEM differencing was –2.16 ± 0.23 m w.e.

scholarly journals Sensitivity of mountain glacier mass balance to changes in bare-ice albedo

2017 ◽  
Vol 58 (75pt2) ◽  
pp. 119-129 ◽  
Author(s):  
Kathrin Naegeli ◽  
Matthias Huss
Keyword(s):  
Mass Balance ◽  
Balance Model ◽  
Glacier Mass Balance ◽  
Landsat 8 ◽  
Glacier Surface ◽  
Mountain Glacier ◽  
Albedo Feedback ◽  
In Situ Data ◽  
The Impact ◽  
Near Future

ABSTRACT Albedo is an important parameter in the energy balance of bare-ice surfaces and modulates glacier melt rates. The prolongation of the ablation period enforces the albedo feedback and highlights the need for profound knowledge on impacts of bare-ice albedo on glacier mass balance. In this study, we assess the mass balance sensitivity of 12 Swiss glaciers with abundant long-term in-situ data on changes in bare-ice albedo. We use pixel-based bare-ice albedo derived from Landsat 8. A distributed mass-balance model is applied to the period 1997–2016 and experiments are performed to assess the impact of albedo changes on glacier mass balance. Our results indicate that glacier-wide mass-balance sensitivities to changes in bare-ice albedo correlate strongly with mean annual mass balances (r 2 = 0.81). Large alpine glaciers react more sensitively to bare-ice albedo changes due to their ablation areas being situated at lower elevations. We find average sensitivities of glacier-wide mass balance of −0.14 m w.e. a−1 per 0.1 albedo decrease. Although this value is considerably smaller than sensitivity to air temperature change, we stress the importance of the enhanced albedo feedback that will be amplified due to atmospheric warming and a suspected darkening of glacier surface in the near future.

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 Examining geodetic glacier mass balance in the eastern Pamir transition zone

2020 ◽  
Vol 66 (260) ◽  
pp. 927-937
Author(s):  
Mingyang Lv ◽  
Duncan J. Quincey ◽  
Huadong Guo ◽  
Owen King ◽  
Guang Liu ◽  
...  
Keyword(s):  
Mass Balance ◽  
Statistical Difference ◽  
Mass Gain ◽  
High Mountain ◽  
Glacier Mass Balance ◽  
Negative Mass ◽  
Glacier Surface ◽  
Digital Elevation ◽  
Elevation Changes ◽  
Individual Scale

AbstractGlaciers in the eastern Pamir have reportedly been gaining mass during recent decades, even though glaciers in most other regions in High Mountain Asia have been in recession. Questions still remain about whether the trend is strengthening or weakening, and how far the positive balances extend into the eastern Pamir. To address these gaps, we use three different digital elevation models to reconstruct glacier surface elevation changes over two periods (2000–09 and 2000–15/16). We characterize the eastern Pamir as a zone of transition from positive to negative mass balance with the boundary lying at the northern end of Kongur Tagh, and find that glaciers situated at higher elevations are those with the most positive balances. Most (67% of 55) glaciers displayed a net mass gain since the 21st century. This led to an increasing regional geodetic glacier mass balance from −0.06 ± 0.16 m w.e. a−1 in 2000–09 to 0.06 ± 0.04 m w.e. a−1 in 2000–15/16. Surge-type glaciers, which are prevalent in the eastern Pamir, showed fluctuations in mass balance on an individual scale during and after surges, but no statistical difference compared to non-surge-type glaciers when aggregated across the region.

scholarly journals Detecting Short-Term Surface Melt on an Arctic Glacier Using UAV Surveys

2018 ◽  
Vol 10 (10) ◽  
pp. 1547 ◽  
Author(s):  
Eleanor Bash ◽  
Brian Moorman ◽  
Allison Gunther
Keyword(s):  
Mass Balance ◽  
Point Clouds ◽  
Glacier Mass Balance ◽  
Short Term ◽  
Glacier Surface ◽  
Surface Change ◽  
Glacier Ice ◽  
Arctic Glacier ◽  
Surface Changes

Current understanding of glacier mass balance changes under changing climate is limited by scarcity of in situ measurements in both time and space, as well as resolution of remote sensing products. Recent innovations in unmanned aerial vehicles (UAVs), as well as structure-from-motion photogrammetry (SfM), have led to increased use of digital imagery to derive topographic data in great detail in many fields, including glaciology. This study tested the capability of UAV surveys to detect surface changes over glacier ice during a three-day period in July 2016. Three UAV imaging missions were conducted during this time over 0.185 km 2 of the ablation area of Fountain Glacier, NU. These were processed with the SfM algorithms in Agisoft Photoscan Professional and overall accuracies of the resulting point clouds ranged from 0.030 to 0.043 m. The high accuracy of point clouds achieved here is primarily a result of a small ground sampling distance (0.018 m), and is also influenced by GPS precision. Glacier surface change was measured through differencing of point clouds and change was compared to ablation stake measurements. Surface change measured with the UAV-SfM method agreed with the coincident ablation stake measurements in most instances, with RMSE values of 0.033, 0.028, and 0.042 m for one-, two-, and three-day periods, respectively. Total specific melt over the study area measured with the UAV was 0.170 m water equivalent (w.e.), while interpolation of ablation measurements resulted in 0.144 m w.e. Using UAVs to measure small changes in glacier surfaces will allow for new investigations of distribution of mass balance measurements.

scholarly journals Multi-decadal mass balance series of three Kyrgyz glaciers inferred from transient snowline observations

2017 ◽  
Author(s):  
Martina Barandun ◽  
Matthias Huss ◽  
Etienne Berthier ◽  
Andreas Kääb ◽  
Erlan Azisov ◽  
...  
Keyword(s):  
Mass Balance ◽  
Tien Shan ◽  
High Mountain ◽  
Glacier Mass Balance ◽  
The Past ◽  
Digital Elevation ◽  
Direct Measurements ◽  
Pamir Mountains ◽  
Continuous Mass

Abstract. Glacier mass balance observations in the Tien Shan and Pamir mountains are sparse and often discontinuous. Nevertheless, glaciers are one of the most important components of the high-mountain cryosphere in the region; they strongly influence water availability in the arid, continental and intensely populated downstream areas. This study provides reliable and continuous mass balance series for selected glaciers located in the Tien Shan and Pamir-Alay. A combination of three independent methods was used to reconstruct for the past two decades the mass balance of the three benchmark glaciers, Abramov, Golubin and No. 354. By applying different approaches, it was possible to compensate for the limitations and shortcomings of each individual method. This study proposes the use of transient snowline observations throughout the melting season obtained from satellite imagery and terrestrial automatic cameras. By combining modelling with remotely acquired information on summer snow depletion, it was possible to infer glacier mass changes for unmeasured years. Multi-annual mass changes based on high accuracy digital elevation models and in situ glaciological surveys were used to validate the results for the investigated glaciers. Substantial mass loss was confirmed for the three studied glaciers by all three methods, ranging from −0.30 ± 0.19 m w. e. a−1 to −0.41 ± 0.33 m w. e. a−1 over the 2004–2016 period. Our results indicate that integration of snowline observations into mass balance modelling significantly narrows the uncertainty ranges of the estimates, and hence highlights the potential of the methodology for application to inaccessible glaciers at larger scales for which no direct measurements are available.

scholarly journals Reconstructing the annual mass balance of the Echaurren Norte glacier (Central Andes, 33.5° S) using local and regional hydroclimatic data

2016 ◽  
Vol 10 (2) ◽  
pp. 927-940 ◽  
Author(s):  
Mariano H. Masiokas ◽  
Duncan A. Christie ◽  
Carlos Le Quesne ◽  
Pierre Pitte ◽  
Lucas Ruiz ◽  
...  
Keyword(s):  
Mass Balance ◽  
Balance Model ◽  
Glacier Mass Balance ◽  
Monthly Precipitation ◽  
Mass Balances ◽  
Positive Mass ◽  
Glacier Surface ◽  
Surface Mass ◽  
The Andes

Abstract. Despite the great number and variety of glaciers in southern South America, in situ glacier mass-balance records are extremely scarce and glacier–climate relationships are still poorly understood in this region. Here we use the longest (>  35 years) and most complete in situ mass-balance record, available for the Echaurren Norte glacier (ECH) in the Andes at  ∼  33.5° S, to develop a minimal glacier surface mass-balance model that relies on nearby monthly precipitation and air temperature data as forcing. This basic model is able to explain 78 % of the variance in the annual glacier mass-balance record over the 1978–2013 calibration period. An attribution assessment identified precipitation variability as the dominant forcing modulating annual mass balances at ECH, with temperature variations likely playing a secondary role. A regionally averaged series of mean annual streamflow records from both sides of the Andes between  ∼  30 and 37° S is then used to estimate, through simple linear regression, this glacier's annual mass-balance variations since 1909. The reconstruction model captures 68 % of the observed glacier mass-balance variability and shows three periods of sustained positive mass balances embedded in an overall negative trend over the past 105 years. The three periods of sustained positive mass balances (centered in the 1920s–1930s, in the 1980s and in the first decade of the 21st century) coincide with several documented glacier advances in this region. Similar trends observed in other shorter glacier mass-balance series suggest that the Echaurren Norte glacier reconstruction is representative of larger-scale conditions and could be useful for more detailed glaciological, hydrological and climatological assessments in this portion of the Andes.

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 Investigating the bias of TanDEM-X digital elevation models of glaciers on the Tibetan Plateau: impacting factors and potential effects on geodetic mass-balance measurements

2021 ◽  
pp. 1-14
Author(s):  
Jia Li ◽  
Zhi-Wei Li ◽  
Jun Hu ◽  
Li-Xin Wu ◽  
Xin Li ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Mass Balance ◽  
Glacier Mass Balance ◽  
The Tibetan Plateau ◽  
Digital Elevation ◽  
Impacting Factors ◽  
Geodetic Mass Balance ◽  
Study Sites ◽  
West Kunlun ◽  
The Impact

Abstract The TanDEM-X DEM is a valuable data source for estimating glacier mass balance. However, the accuracy of TanDEM-X elevation over glaciers can be affected by microwave penetration and phase decorrelation. To investigate the bias of TanDEM-X DEMs of glaciers on the Tibetan Plateau, these DEMs were subtracted from SPOT-6 DEMs obtained around the same time at two study sites. The average bias over the studied glacier areas in West Kunlun (175.0 km2) was 2.106 ± 0.012 m in April 2014, and it was 1.523 ± 0.011 m in Geladandong (228.8 km2) in October 2013. By combining backscatter coefficients and interferometric coherence maps, we found surface decorrelation and baseline decorrelation can cause obvious bias in addition to microwave penetration. If the optical/laser data and winter TanDEM-X data were used as new and historic elevation sources for mass-balance measurements over an arbitrary observation period of 10 years, the glacier mass loss rates in West Kunlun and Geladandong would be potentially underestimated by 0.218 ± 0.016 and 0.158 ± 0.011 m w.e. a−1, respectively. The impact is therefore significant, and users should carefully treat the bias of TanDEM-X DEMs when retrieving a geodetic glacier mass balance.

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