Glacier dynamics in the Canadian High Arctic from RADARSAT-1 speckle tracking

Short, N; Gray, Alistair

doi:10.5589/m05-010

Cited by 45 publications

(88 citation statements)

References 26 publications

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“…Independent of this surge behaviour, glacier ice velocities during the summer are typically an order of magnitude larger than the mean annual velocities, and summer calving rates are 2-8 times larger than the annual average [41,43]. Other studies point to a high interannual variability of the velocities of the large outlet glaciers [44]. van Wychen et al [39] showed that velocity changes associated with the termination or initiation of surges can rapidly change the rate of ice discharge to the oceans.…”

Section: Study Area and Data Sourcesmentioning

confidence: 99%

Glacier Surface Velocity Retrieval Using D-InSAR and Offset Tracking Techniques Applied to Ascending and Descending Passes of Sentinel-1 Data for Southern Ellesmere Ice Caps, Canadian Arctic

Sánchez-Gámez

Navarro

2017

Remote Sensing

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Abstract:The Terrain Observation by Progressive Scans (TOPS) acquisition mode of the Sentinel-1 mission provides a wide coverage per acquisition with resolutions of 5 m in range and 20 m in azimuth, which makes this acquisition mode attractive for glacier velocity monitoring. Here, we retrieve surface velocities from the southern Ellesmere Island ice caps (Canadian Arctic) using both offset tracking and Differential Interferometric Synthetic Aperture Radar (D-InSAR) techniques and combining ascending and descending passes. We optimise the offset tracking technique by omitting the azimuth offsets. By doing so, we are able to improve the final resolution of the velocity product, as Sentinel-1 shows a lower resolution in the azimuth direction. Simultaneously, we avoid the undesired ionospheric effect manifested in the data as azimuth streaks. The D-InSAR technique shows its merits when applied to slow-moving areas, while offset tracking is more suitable for fast-moving areas. This research shows that the methods used here are complementary and the use of both to determine glacier velocities is better than only using one or the other. We observe glacier surface velocities of up to 1200 m year −1 for the fastest tidewater glaciers. The land-terminating glaciers show typical velocities between 12 and 33 m year −1 , though with peaks up to 150 m year −1 in narrowing zones of the confining valleys.

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Section: Study Area and Data Sourcesmentioning

confidence: 99%

Glacier Surface Velocity Retrieval Using D-InSAR and Offset Tracking Techniques Applied to Ascending and Descending Passes of Sentinel-1 Data for Southern Ellesmere Ice Caps, Canadian Arctic

Sánchez-Gámez

Navarro

2017

Remote Sensing

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“…If obvious features are present (e.g. crevasses), the program will track the displacement of those features instead (Short and Gray, 2005). Displacements were calculated for both azimuth and range directions using chip sizes of ∼453 m in azimuth and ∼688 m in range for the fine beam imagery, and ∼177 m in azimuth and ∼188 m in range for the ultrafine beam imagery.…”

Section: Speckle Tracking (Radar Imagery)mentioning

confidence: 99%

Ice velocity changes on Penny Ice Cap, Baffin Island, since the 1950s

2017

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ABSTRACT. Predicting the velocity response of glaciers to increased surface melt is a major topic of ongoing research with significant implications for accurate sea-level rise forecasting. In this study we use optical and radar satellite imagery as well as comparisons with historical ground measurements to produce a multi-decadal record of ice velocity variations on Penny Ice Cap, Baffin Island. Over the period 1985-2011, the six largest outlet glaciers on the ice cap decelerated by an average rate of 21 m a The recent slowdown of outlet glaciers has coincided with increases in mass loss, terminus retreat and an inferred reduction in basal sliding. Measured decelerations are greater than the total shortterm variability measured from both seasonal and interannual fluctuations, and support the hypothesis that glacier thinning and/or increased meltwater production promotes a long-term reduction in ice motion.

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“…In 2012, the study area was extended southward to include the terminus of Hubbard Glacier, with 23 image pairs from seven swaths used to cover an ice area of 15 103 km 2 . The speckle-tracking algorithm comprised a custom MATLAB ® script previously used in the Canadian High Arctic others, 2012, 2014; modified from Short and Gray, 2005). The script employs a spatial crosscorrelation approach to determine the two-dimensional (2-D) displacement of the pattern of 'speckle' in the phase returns between two time-separated single-look complex radar images.…”

Section: Speckle Trackingmentioning

confidence: 99%