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1. Glacier Image Velocimetry: an open-source toolbox for easy and rapid calculation of high-resolution glacier velocity fields

   https://doi.org/10.5194/tc-15-2115-2021  

   Van Wyk de Vries, Maximillian; Wickert, Andrew D. (January 2021, The Cryosphere)

   null (Ed.)

   Abstract. We present Glacier Image Velocimetry (GIV), an open-source and easy-to-use software toolkit for rapidly calculating high-spatial-resolutionglacier velocity fields. Glacier ice velocity fields reveal flow dynamics, ice-flux changes, and (with additional data and modelling) icethickness. Obtaining glacier velocity measurements over wide areas with field techniques is labour intensive and often associated with safetyrisks. The recent increased availability of high-resolution, short-repeat-time optical imagery allows us to obtain ice displacement fields using“feature tracking” based on matching persistent irregularities on the ice surface between images and hence, surface velocity over time. GIV isfully parallelized and automatically detects, filters, and extracts velocities from large datasets of images. Through this coupled toolchain and aneasy-to-use GUI, GIV can rapidly analyse hundreds to thousands of image pairs on a laptop or desktop computer. We present four example applicationsof the GIV toolkit in which we complement a glaciology field campaign (Glaciar Perito Moreno, Argentina) and calculate the velocity fields of smallmid-latitude (Glacier d'Argentière, France) and tropical glaciers (Volcán Chimborazo, Ecuador), as well as very large glaciers (Vavilov Ice Cap,Russia). Fully commented MATLAB code and a stand-alone app for GIV are available from GitHub and Zenodo (see https://doi.org/10.5281/zenodo.4624831, Van Wyk de Vries, 2021a). 

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2. GLAcier Feature Tracking testkit (GLAFT): a statistically and physically based framework for evaluating glacier velocity products derived from optical satellite image feature tracking

   https://doi.org/10.5194/tc-17-4063-2023  

   Zheng, Whyjay; Bhushan, Shashank; Van Wyk De Vries, Maximillian; Kochtitzky, William; Shean, David; Copland, Luke; Dow, Christine; Jones-Ivey, Renette; Pérez, Fernando (January 2023, The Cryosphere)

   Abstract. Glacier velocity measurements are essential to understand ice flow mechanics, monitor natural hazards, and make accurate projections of future sea-level rise. Despite these important applications, the method most commonly used to derive glacier velocity maps, feature tracking, relies on empirical parameter choices that rarely account for glacier physics or uncertainty. Here we test two statistics- and physics-based metrics to evaluate velocity maps derived from optical satellite images of Kaskawulsh Glacier, Yukon, Canada, using a range of existing feature-tracking workflows. Based on inter-comparisons with ground truth data, velocity maps with metrics falling within our recommended ranges contain fewer erroneous measurements and more spatially correlated noise than velocity maps with metrics that deviate from those ranges. Thus, these metric ranges are suitable for refining feature-tracking workflows and evaluating the resulting velocity products. We have released an open-source software package for computing and visualizing these metrics, the GLAcier Feature Tracking testkit (GLAFT). 

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3. InSAR-based characterization of rock glacier movement in the Uinta Mountains, Utah, USA

   https://doi.org/10.5194/tc-15-4823-2021  

   Brencher, George; Handwerger, Alexander L.; Munroe, Jeffrey S. (January 2021, The Cryosphere)

   Abstract. Rock glaciers are a prominent component of many alpine landscapes andconstitute a significant water resource in some arid mountainenvironments. Here, we employ satellite-based interferometric syntheticaperture radar (InSAR) between 2016 and 2019 to identify and monitor activeand transitional rock glaciers in the Uinta Mountains (Utah, USA), an area of∼3000 km2. We used mean velocity maps to generate aninventory for the Uinta Mountains containing 205 active and transitional rockglaciers. These rock glaciers are 11.9 ha in area on average andlocated at a mean elevation of 3308 m, where mean annual airtemperature is −0.25 ∘C. The mean downslope velocity for theinventory is 1.94 cm yr−1, but individual rock glaciers have velocities ranging from0.35 to 6.04 cm yr−1. To search for relationships with climaticdrivers, we investigated the time-dependent motion of three rock glaciers. Wefound that rock glacier motion has a significant seasonal component, withrates that are more than 5 times faster during the late summer compared to therest of the year. Rock glacier velocities also appear to be correlated withthe snow water equivalent of the previous winter's snowpack. Our resultsdemonstrate the ability to use satellite InSAR to monitor rock glaciers overlarge areas and provide insight into the environmental factors that controltheir kinematics. 

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4. Supervised Methods for Modeling Spatiotemporal Glacier Variations by Quantification of the Area and Terminus of Mountain Glaciers Using Remote Sensing

   https://doi.org/10.3390/a16100486  

   Robbins, Edmund; Hlaing, Thu Thu; Webb, Jonathan; Kachouie, Nezamoddin N (October 2023, Algorithms)

   Glaciers are important indictors of climate change as changes in glaciers physical features such as their area is in response to measurable evidence of fluctuating climate factors such as temperature, precipitation, and CO2. Although a general retreat of mountain glacier systems has been identified in relation to centennial trends toward warmer temperatures, there is the potential to extract a great deal more information regarding regional variations in climate from the mapping of the time history of the terminus position or surface area of the glaciers. The remote nature of glaciers renders direct measurement impractical on anything other than a local scale. Considering the sheer number of mountain glaciers around the globe, ground measurements of terminus position are only available for a small percentage of glaciers and ground measurements of glacier area are rare. In this project, changes in the terminal point and area of Franz Josef and Gorner glaciers were quantified in response to climate factors using satellite imagery taken by Landsat at regular intervals. Two supervised learning methods including a parametric method (multiple regression) and a nonparametric method (generalized additive model) were implemented to identify climate factors that impact glacier changes. Local temperature, CO2, and precipitation were identified as significant factors for predicting changes in both Franz Josef and Gorner glaciers. Spatiotemporal quantification of glacier change is an essential task to model glacier variations in response to global and local climate factors. This work provided valuable insights on quantification of surface area of glaciers using satellite imagery with potential implementation of a generic approach. 

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5. Monitoring tropical debris-covered glacier dynamics from high-resolution unmanned aerial vehicle photogrammetry, Cordillera Blanca, Peru

   https://doi.org/10.5194/tc-11-2463-2017  

   Wigmore, Oliver; Mark, Bryan (January 2017, The Cryosphere)

   The glaciers of the Cordillera Blanca, Peru, are rapidly retreating and thinning as a result of climate change, altering the timing, quantity and quality of water available to downstream users. Furthermore, increases in the number and size of proglacial lakes associated with these melting glaciers is increasing potential exposure to glacier lake outburst floods (GLOFs). Understanding how these glaciers are changing and their connection to proglacial lake systems is thus of critical importance. Most satellite data are too coarse for studying small mountain glaciers and are often affected by cloud cover, while traditional airborne photogrammetry and lidar are costly. Recent developments have made unmanned aerial vehicles (UAVs) a viable and potentially transformative method for studying glacier change at high spatial resolution, on demand and at relatively low cost.Using a custom designed hexacopter built for high-altitude (4000–6000 m a. s. l. ) operation, we completed repeat aerial surveys (2014 and 2015) of the debris-covered Llaca Glacier tongue and proglacial lake system. High-resolution orthomosaics (5 cm) and digital elevation models (DEMs) (10 cm) were produced and their accuracy assessed. Analysis of these datasets reveals highly heterogeneous patterns of glacier change. The most rapid areas of ice loss were associated with exposed ice cliffs and meltwater ponds on the glacier surface. Considerable subsidence and low surface velocities were also measured on the sediments within the pro-glacial lake, indicating the presence of extensive regions of buried ice and continued connection to the glacier tongue. Only limited horizontal retreat of the glacier tongue was observed, indicating that measurements of changes in aerial extent alone are inadequate for monitoring changes in glacier ice quantity. 

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