Identification and characterization of alpine subglacial lakes using interferometric synthetic aperture radar (InSAR): Brady Glacier, Alaska, USA

Capps, Denny M.; Rabus, Bernhard; Clague, John J.; Shugar, D. H.

doi:10.3189/002214310794457254

Cited by 20 publications

(22 citation statements)

References 31 publications

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“…InSAR provides avenues to study glaciers in terms of snout and glacial lake monitoring, as well as ground displacement and topographic variations, using interferograms (Luckman, Quincey, and Bevan 2007;Kumar et al 2008;Capps et al 2010). Glacier monitoring using InSAR is advancing towards new frontiers; in this study, we develop coherence maps using SAR image pairs to map the location of the snout of the Gangotri glacier.…”

Section: Coherence Detection For Glacier Retreatmentioning

confidence: 99%

Recent changes in the snout position and surface velocity of Gangotri glacier observed from space

Saraswat

Syed

Famiglietti

et al. 2013

International Journal of Remote Sensing

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Glacier mass variations have a direct impact on some of the key components of the global water cycle, including sea level rise and freshwater availability. Apart from being one of the largest Himalayan glaciers, Gangotri is one of the sources of water for the Ganges river, which has a considerable influence on the socioeconomic structure of a largely over-populated catchment area accounting for ∼26% of India's landmass. In this study, we present the most recent assessment of the Gangotri glacier dynamics, combining the use of interferometric techniques on synthetic aperture radar data and sub-pixel offset tracking on Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite imagery. Results show that on average, the Gangotri glacier snout has receded at a rate of 21.3 ± 3 m year −1 over a period of 6 years (2004-2010). While glacier surface velocity near the snout is estimated to be between 24.8 ± 2.3 and 28.9 ± 2.3 m year −1 , interior portions of the glacier recorded velocities in the range of 13.9 ± 2.3 to 70.2 ± 2.3 m year −1 . Further, the average glacier surface velocity in the northern (lower) portions (28.1 ± 2.3 m year −1 ) is observed to be significantly lower than in the southern (higher) portions (48.1 ± 2.3 m year −1 ) of the Gangotri glacier. These values are calculated with an uncertainty of less than 5 m year −1 . Results also highlight a consistent retreat and non-uniform dynamics of the Gangotri glacier.

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Section: Coherence Detection For Glacier Retreatmentioning

confidence: 99%

Recent changes in the snout position and surface velocity of Gangotri glacier observed from space

Saraswat

Syed

Famiglietti

et al. 2013

International Journal of Remote Sensing

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“…In the past decade, research has confirmed that glacier-dammed lakes and jökulhlaups can ice-dammed lakes (Larsen, et al, 2007;Capps et al, 2010). Six of the ten lakes are primarily subaerial (Fig.…”

Section: Introductionmentioning

confidence: 92%

“…Based on the results of this study and the conclusions reached by Capps et al (2010), these lakes will become increasingly subaerial if Brady Glacier continues to downwaste and retreat, especially as the calving fronts increase in width and depth, thereby creating a positive feedback cycle for more ice loss. Oscar Lake recently began a rapid subaerial expansion.…”

Section: Space As a Proxy For Timementioning

confidence: 99%

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Evolution of glacier-dammed lakes through space and time; Brady Glacier, Alaska, USA

Capps

Clague

2014

Geomorphology

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Glacier-dammed lakes and their associated jökulhlaups cause severe flooding in downstream areas and substantially influence glacier dynamics. The goal of this dissertation is to identify and characterize the evolution of glacier-dammed lakes in order to predict their future behaviour using ground-truthed remote sensing techniques and dendrochronology. Brady Glacier in southeast Alaska is particularly well suited for a study of these phenomena because it presently dams ten large (> 1 km 2 ) lakes and many smaller ones. This dissertation comprises three studies. First, I used interferometric synthetic aperture radar (InSAR) to identify and characterize three previously unknown subglacial lakes. InSAR allowed me to quantify the vertical displacement and volume of water discharged from the three lakes through time. From the fall of 1995 to the spring of 1996, subsidence ranged from 4 to 26 cm/day and the volume of water discharged ranged from 22,000 ± 2000 to 243,000 ± 14,000 m 3 /day. Subsidence and discharge rates declined significantly during the winter and continued at a lesser rate through March. Second, I used dendrochronology and precise elevation-constrained mapping to date glacially overridden and drowned trees at the glacier margin. Brady Glacier impounded Spur Lake to an elevation of 83 m a.s.l. around AD 1830 and 121 m a.s.l. around 1839. The glacier continued to advance, thickening by at least 77 m between ca. 1844 and 1859 at a site down-glacier of Spur Lake on the opposite glacier margin. Farther down-glacier, North Trick Lake began to form by 1861 and reached its highest elevation at approximately 130 m a.s.l. when Brady Glacier reached its maximum extent around 1880. Third, I georeferenced a variety of maps, airphotos, and optical satellite imagery to characterize the evolution of the glacier and lakes and also created five bathymetric maps. The main terminus of Brady Glacier has changed little since 1880. However, it downwasted at rates of 2-3 m/yr between 1948 and 2000, more than the regional average. The most dramatic retreat (2 km) and downwasting (123 m) occurred adjacent to glacierdammed lakes. These lakes will continue to evolve and play a pivotal role in the evolution of Brady Glacier. If downwasting and retreat continue at rates comparable to the past, the glacier may return to a tidewater regimen and retreat catastrophically until it stabilizes in shallow water.

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“…Glacial lakes are important indicators of the regional glacier dynamics in response to climate warming and changing precipitation [1][2][3]. With the continuous retreating and thinning of mountain glaciers in the Tibetan Plateau, a large number of glacial lakes have developed and experienced rapid expansion in recent decades, leading to the increased hazard risk of glacial lake outburst floods (GLOFs) [4].…”

Section: Introductionmentioning

confidence: 99%

High-Frequency Glacial Lake Mapping Using Time Series of Sentinel-1A/1B SAR Imagery: An Assessment for the Southeastern Tibetan Plateau

Zhang

Chen

Tian

et al. 2020

IJERPH

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Glacial lakes are an important component of the cryosphere in the Tibetan Plateau. In response to climate warming, they threaten the downstream lives, ecological environment, and public infrastructures through outburst floods within a short time. Although most of the efforts have been made toward extracting glacial lake outlines and detect their changes with remotely sensed images, the temporal frequency and spatial resolution of glacial lake datasets are generally not fine enough to reflect the detailed processes of glacial lake dynamics, especially for potentially dangerous glacial lakes with high-frequency variability. By using full time-series Sentinel-1A/1B imagery over a year, this study presents a new systematic method to extract the glacial lake outlines that have a fast variability in the southeastern Tibetan Plateau with a time interval of six days. Our approach was based on a level-set segmentation, combined with a median pixel composition of synthetic aperture radar (SAR) backscattering coefficients stacked as a regularization term, to robustly estimate the lake extent across the observed time range. The mapping results were validated against manually digitized lake outlines derived from Gaofen-2 panchromatic multi-spectral (GF-2 PMS) imagery, with an overall accuracy and kappa coefficient of 96.54% and 0.95, respectively. In comparison with results from classical supervised support vector machine (SVM) and unsupervised Iterative Self-Organizing Data Analysis Technique Algorithm (ISODATA) methods, the proposed method proved to be much more robust and effective at detecting glacial lakes with irregular boundaries that have similar backscattering as the surroundings. This study also demonstrated the feasibility of time-series Sentinel-1A/1B SAR data in the continuous monitoring of glacial lake outline dynamics.

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Identification and characterization of alpine subglacial lakes using interferometric synthetic aperture radar (InSAR): Brady Glacier, Alaska, USA

Cited by 20 publications

References 31 publications

Recent changes in the snout position and surface velocity of Gangotri glacier observed from space

Recent changes in the snout position and surface velocity of Gangotri glacier observed from space

Evolution of glacier-dammed lakes through space and time; Brady Glacier, Alaska, USA

High-Frequency Glacial Lake Mapping Using Time Series of Sentinel-1A/1B SAR Imagery: An Assessment for the Southeastern Tibetan Plateau

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