Glacier Surface Change Research Articles

Relationship between the variations in glacier features classified on a large scale with climate variables: a case study of Gangotri Glacier.

Changes in glacier area, glacial lakes, debris cover, and geomorphological features such as debris fans have a significant impact on glacial dynamics. Therefore, precise and timely observation and tracking of glacier surface changes is a necessity. The availability of high spatial resolution remote sensing images has made it viable to analyse the glacier surface changes at a local level. However, with an increase in spatial resolution, the spectral variability increases, giving rise to additional challenges (such as false changes and misregistration) in the change detection process. These challenges can preferably be dealt with using an object-based change detection (OBCD) approach rather than the conventional pixel-based change detection approach. Therefore, this study has proposed an OBCD methodology using high-spatial-resolution remote sensing images to detect changes in glacier features. Variability in glacier features has been further analysed by associating it with important climate variables, that is, air temperature and precipitation. As a case study, the changes in Gangotri Glacier (Uttarakhand Himalayas in India) features have been studied using high-spatial-resolution WorldView-2 and Linear Imaging Self-Scanning System (LISS)-4 images for a 3-year period 2011-2014. The spectral correspondences between glacier surface and non-glacier surface have been handled by considering brightness temperature and slope as ancillary data to improvise their distinction. A change detection accuracy of ~ 84% has been obtained using the OBCD approach. Results further show that the variations in glacier features are in congruence with the climatic observations.

Simulating surface height and terminus position for marine outlet glaciers using a level set method with data assimilation

We implement a data assimilation framework for integrating ice surface and terminus position observations into a numerical ice-flow model. The model uses the well-known shallow shelf approximation (SSA) coupled to a level set method to capture ice motion and changes in the glacier geometry. The level set method explicitly tracks the evolving ice–atmosphere and ice–ocean boundaries for a marine outlet glacier. We use an Ensemble Transform Kalman Filter to assimilate observations of ice surface elevation and lateral ice extent by updating the level set function that describes the ice interface. Numerical experiments on an idealized marine-terminating glacier demonstrate the effectiveness of our data assimilation approach for tracking seasonal and multi-year glacier advance and retreat cycles. The model is also applied to simulate Helheim Glacier, a major tidewater-terminating glacier of the Greenland Ice Sheet that has experienced a recent history of rapid retreat. By assimilating observations from remotely-sensed surface elevation profiles we are able to more accurately track the migrating glacier terminus and glacier surface changes. These results support the use of data assimilation methodologies for obtaining more accurate predictions of short-term ice sheet dynamics.

An analysis of the spatial and temporal changes on the Jakobshavn Glacier (Greenland) using remote sensing data

This article presents the problem of climate warming and the effect of melting ice caps. The problem of climate warming is discussed in two stages. In the first stage, the factors affecting global warming are discussed in detail and the effects and risks of ablation extensively described. Analyses were conducted on data available online from NASA and Carbon Dioxide Information Analysis Center. The Greenland area (Jakobshavn Glacier) was selected to visualize glacier calving front changes. The analysis of changes was performed on the selected satellite images covering the summer period (June to September) provided by the Landsat program. Then, the changes in the position of the calving front of the Jakobshavn Glacier were visualized for the period 1985–2020,with a repeatability of every 5 years. Thus, our results addressed the challenges of environmental changes to remote sensing data processing. In addition to the visualization, a surface summary of these changes was presented in the study. The results were discussed in the context of climate change data processed by means of the GIS method. Furthermore, an analysis of the effects of greenhouse gases on glacier surface changes was performed.In summary, the results reveal that satellite imagery is an excellent source of data on which to visualize glacier calving rates, comparing individual layers showing the position of the glacier calving front and calculating the area of calved ice.

Seasonal Surface Change of Urumqi Glacier No. 1, Eastern Tien Shan, China, Revealed by Repeated High-Resolution UAV Photogrammetry

The seasonal surface changes of glaciers in Tien Shan have seen little prior investigation despite the increase in geodetic studies of multi-year changes. In this study, we analyzed the potential of an Unmanned Aerial Vehicle (UAV) to analyze seasonal surface change processes of the Urumqi Glacier No. 1 in eastern Tien Shan. We carried out UAV surveys at the beginning and the end of the ablation period in 2018. The high-precision evolution of surface elevation, geodetic mass changes, surface velocity, and terminus change in the surveyed ablation area were correspondingly derived in combination with ground measurements, including stake/snow-pit observation and GPS measurement. The derived mean elevation change in the surveyed ablation area was −1.64 m, corresponding to the geodetic mass balance of approximately −1.39 m w.e. during the ablation period in 2018. The mean surface velocity was 3.3 m/yr and characterized by the spatial change of the velocity, which was less in the East Branch than in the West Branch. The UAV survey results were a little less than those from the ground measurements, and the correlation coefficient was 0.88 for the surface elevation change and 0.87 for surface displacement. The relative error of the glacier terminus change was 4.5% for the East Branch and 6.2% for the West Branch. These results show that UAV photogrammetry is ideal for assessing seasonal glacier surface changes and has a potential application in the monitoring of detailed glacier changes.

Long‐term shifts in feedbacks among glacier surface change, melt generation and runoff, McMurdo Dry Valleys, Antarctica

AbstractGlaciers of the McMurdo dry valleys (MDVs) Antarctica are the main source of streamflow in this polar desert. Because summer air temperatures hover near 0°C small changes in the energy balance strongly affect meltwater generation. Here we demonstrate that increased surface roughness, which alters the turbulent transfer of energy between the ice surface and atmosphere, yields a detectable increase in meltwater runoff. At low elevations on the glaciers, basin‐like topography became significantly rougher over 13 years between repeat lidar surveys, yielding greater melt. In contrast, the smoother ice at higher elevation exhibited no detectable change in roughness. We pose a conceptual model of the cycle of glacier surface change as a result of climate forcing whereby glacier surfaces transition from being dominated by sublimation to becoming increasingly melt‐dominated, which is reversible under prolonged cool periods. This research advances our understanding of warm season effects on polar glaciers.

Measurement of rock glacier surface change over different timescales using terrestrial laser scanning point clouds

Abstract. Topographic change at a given location usually results from multiple processes operating over different timescales. However, interpretations of surface change are often based upon single values of movement, measured over a specified time period or in a single direction. This work presents a method to help separate surface change types that occur at different timescales related to the deformation of an active rock glacier, drawing on terrestrial lidar monitoring at sub-monthly intervals. To this end, we derive 3D topographic changes across the Äußeres Hochebenkar rock glacier in the Ötztal Alps. These changes are presented as the relative contribution of surface change during a 3-week period (2018) to the annual surface change (2017–2018). They are also separated according to the spatially variable direction perpendicular to the local rock glacier surface (using point cloud distance computation) and a single main direction of rock glacier flow, indicated by movement of individual boulders. In a 1500 m2 sample area in the lower tongue section of the rock glacier, the contribution of the 3-week period to the annual change perpendicular to the surface is 20 %, compared with 6 % in the direction of rock glacier flow. Viewing change in this way, our approach provides estimates of surface change in different directions that are dominant at different times of the year. Our results demonstrate the benefit of more frequent lidar monitoring and, critically, the requirement for novel approaches to quantifying and disaggregating surface change, as a step towards rock glacier observation networks focusing on the analysis of 3D surface change over time.

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

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.

Paraglacial Rock Slope Adjustment Beneath a High Mountain Infrastructure—The Pilatte Hut Case Study (Écrins Mountain Range, France)

Landslides triggered by shrinking glaciers are an expected outcome of global climate change and they pose a significant threat to inhabitants and infrastructure in mountain valleys. In this study we document the rock slope movement that has affected the Pilatte hut (2572 m a.s.l.) in the Ecrins range (French alps) since the 1980s. We reconstructed the geometry of the unstable rock mass using Terrestrial Laser Scanning and quantified the unstable volume (~ 400,000 m3). Field observations and annual crack surveys have been used to identify the dynamics of past movements. These movements initiated in the late 1980s and have accelerated since 2000. The current trend seems to be towards a relative stabilization. Reconstruction of the glacier surface using past images taken since 1960 and ‘Structure from Motion’ photogrammetry showed that the glacier probably applied stresses to the rock slope during its short-lived advance during the 1980s, followed by debuttressing caused by rapid surface lowering until the present day. The relationship between observed crack propagation and glacier surface change suggests that the rock slope instability is a paraglacial response to glacier surface changes, and highlights that such responses can occur within a decade of glacier change.

Volume change of tropical Peruvian glaciers from multi-temporal digital elevation models and volume–surface area scaling

ABSTRACTTo estimate hydrological storage and better understand the climatic implications of glacier retreat, the volume of glacial ice is a critical but problematic variable. High-accuracy mapping of glacier surface changes over time can directly estimate volume changes, allowing for explicit testing and refining of scaling relationships between changes in glacier volume and surface area that are necessary for making an inventory of remaining glacier mass with remote imagery. A combination of airborne LiDAR, spaceborne remote sensing imagery, digital photogrammetry, and geospatial techniques is used to assess the changes in volume and surface area of six glaciers in the Cordillera Blanca, Peru, between 1962 and 2008. The loss of glacier surface area ranges from 30.79% to 72.62%, corresponding to individual glacier volume changes ranging from 0.019 to 0.150 km3. The volume–surface area scaling is deduced from the change in volume related to the change in surface area by a power relationship quantified from 13 different epoch series. The result shows that there is about 36% more volume loss relative to the loss expected from surface area alone of these individual glaciers in the study area than other glaciers in mid- and high-latitudes from the previous study. Since the error of volume estimation shows a much larger impact on the increase with the size of glaciers, volume–surface area scaling analysis needs to include larger ice masses with regional inventories for a more accurate estimation.

The future sea-level rise contribution of Greenland’s glaciers and ice caps

We calculate the future sea-level rise contribution from the surface mass balance of all of Greenland’s glaciers and ice caps (GICs, ∼90 000 km2) using a simplified energy balance model which is driven by three future climate scenarios from the regional climate models HIRHAM5, RACMO2 and MAR. Glacier extent and surface elevation are modified during the mass balance model runs according to a glacier retreat parameterization. Mass balance and glacier surface change are both calculated on a 250 m resolution digital elevation model yielding a high level of detail and ensuring that important feedback mechanisms are considered. The mass loss of all GICs by 2098 is calculated to be 2016 ± 129 Gt (HIRHAM5 forcing), 2584 ± 109 Gt (RACMO2) and 3907 ± 108 Gt (MAR). This corresponds to a total contribution to sea-level rise of 5.8 ± 0.4, 7.4 ± 0.3 and 11.2 ± 0.3 mm, respectively. Sensitivity experiments suggest that mass loss could be higher by 20–30% if a strong lowering of the surface albedo were to take place in the future. It is shown that the sea-level rise contribution from the north-easterly regions of Greenland is reduced by increasing precipitation while mass loss in the southern half of Greenland is dominated by steadily decreasing summer mass balances. In addition we observe glaciers in the north-eastern part of Greenland changing their characteristics towards greater activity and mass turnover.

DEM quality assessment for quantification of glacier surface change

AbstractPhotogrammetric digital elevation models (DEMs) are often used to derive and monitor surfaces in inaccessible areas. They have been used to monitor the spatial and temporal change of glacier surfaces in order to assess glacier response to climate change. However, deriving photogrammetric DEMs of steep mountainous topography where the surface is often obscured by regions of deep shadow and snow is particularly difficult. Assessing the quality of the derived surface can also be problematic, as high-accuracy ground-control points may be limited and poorly distributed throughout the modelled area. We present a method of assessing the quality of a derived surface through a detailed sensitivity analysis of the DEM collection parameters through a multiple input failure warning model (MIFWM). The variance of a DEM cell elevation is taken as an indicator of surface reliability allowing potentially unreliable areas to be excluded from further analysis. This analysis allows the user to place greater confidence in the remaining DEM. An example of this method is presented for a small mountain glacier in Svalbard, and the MIFWM is shown to label as unreliable more DEM cells over the entire DEM area, but fewer over the glacier surface, than other methods of data quality assessment. The MIFWM is shown to be an effective and easily used method for assessing DEM surface quality.

Estimating volume change of mountain glaciers using SRTM and map-based topographic data

This paper describes a method for estimating the volume change of mountain glaciers using the Shuttle Radar Topography Mission (SRTM) C-band data (2000) and a digital elevation model (DEM) generated from topographic maps. This approach was developed with SRTM data and topographic maps of 1 : 25 000 scale (1977) from the Akshiirak glaciers (Tien Shan, Central Asia). The DEM for 1977 was generated using 10-m contour lines from 18 map sheets covering the Akshiirak massif and surrounding area. The nominal vertical accuracy of the maps is 3.3 m. The standard deviation of the differences between the map-derived DEM and the SRTM data on glacier-free areas of less than 25deg is 6.3 m. A single localized region in the western periphery of the study area with systematic error in the SRTM data from -20 to 12 m on a 30-km spatial scale was found and excluded from the error analysis. Assuming a 10-m map error on the upper snow-covered glacier areas, the estimated root-mean-square error of the glacier surface change is 8.2 m. From 1977 to 1999, the average glacier surface thinning is 15.1 m, and the estimated volume loss is 6.15 km3. The rate of the Akshiirak glacier volume loss has increased by 2.7 times, compared with historical data from 1943 to 1977. The SRTM data show an opportunity for quantifying climatic and dynamic surface elevation changes in mountain glaciers. Ice, Cloud, and land Elevation Satellite (ICESat) laser altimetry and SRTM data could also be used for the estimation of short-term surface changes of mountain glaciers

Using airborne lidar to assess the influence of glacier downwasting on water resources in the Canadian Rocky Mountains

Knowledge of the changing dimensions of alpine glacier surfaces is critical from both a water resources and climate change indication perspective. With the development of airborne light detection and ranging (lidar) technologies with the capability to rapidly map large areas of topography at high resolutions, there is a need to assess the utility of this technology for glacier surface change detection and water resources assessment. The study presented here compares two lidar digital elevation models (DEMs) collected 23 months apart in 2000 and 2002 over Peyto Glacier, Canadian Rocky Mountains, for the purposes of intensity image feature recognition and surface downwasting assessment. The 2002 DEM was subtracted from the 2000 DEM to quantify the total and spatial variability in surface downwasting (or growth) within the glacial and periglacial environments. It was found that there was a reduction in volume totaling 33 × 106 m3 over the Peyto Glacier surface and surrounding ice-cored moraines. This downwasting was estimated to be equivalent to approximately 22 × 106 m3 of water volume and, after extrapolation, 16% of total basin runoff. The water-equivalent contribution from ice-cored moraines was estimated to be 6% of the total glacier runoff contribution, highlighting the importance of monitoring this component of glacial melt.

Glacier geomorphometry — an approach for analyzing long-term glacier surface changes using grid-based digital elevation models

This paper presents an approach to long-term glacier monitoring. Mathematical surface descriptors, such as altitude, slope and curvature (surface form) are used to classify and quantify glacier surface developments. The analysis is based on photogrammetically derived grid-based digital elevation models over a period of decades. This paper outlines the concept and applies it to five valley glaciers in Spitsbergen, Svalbard, which differ with respect to size, thermal regime and dynamics. The results reflect differences between the glaciers investigated which are attributable to glacier dynamics, in particular concerning the glacier’s possible surge behaviour during a period with retreat and mass losses.

Glacier geomorphometry — an approach for analyzing long-term glacier surface changes using grid-based digital elevation models

This paper presents an approach to long-term glacier monitoring. Mathematical surface descriptors, such as altitude, slope and curvature (surface form) are used to classify and quantify glacier surface developments. The analysis is based on photogrammetically derived grid-based digital elevation models over a period of decades. This paper outlines the concept and applies it to five valley glaciers in Spitsbergen, Svalbard, which differ with respect to size, thermal regime and dynamics. The results reflect differences between the glaciers investigated which are attributable to glacier dynamics, in particular concerning the glacier’s possible surge behaviour during a period with retreat and mass losses.

Glacier monitoring by satellite

A multitemporal analysis on the Mount Disgrazia glaciers was performed by using the 1975, 1978 and 1980 MSS Landsat images. On these images the glaciers were completely described in their boundaries and surface features. Fixed structures were used along their boundaries as fiducial points of the ground control table for the multitemporal comparison of the glaciers. This makes it possible to estimate the glacier surface changes due to frontal displacements as well as the changes, in the snow-covered area due to the displacements of the snow transient line. The procedure is possible since the recordings of Landsat satellites are continuous in space and time. It gives completeness to the individual data on the glaciers as provided by the field measurements and it makes the management of the water resources possible.

Near-Surface Temperatures in the Superimposed Ice Zone and Lower Part of the Soaked Zone of Polar Ice Sheets

Near-Surface Temperatures in the Superimposed Ice Zone and Lower Part of the Soaked Zone of Polar Ice Sheets

Near-Surface Temperatures in the Superimposed Ice Zone and Lower Part of the Soaked Zone of Polar Ice Sheets

Near-Surface Temperatures in the Superimposed Ice Zone and Lower Part of the Soaked Zone of Polar Ice Sheets