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.
Highlights
Remote sensing is becoming an increasingly important tool in climate research [1], with SyntheticAperture Radar (SAR) being one of the techniques that has experienced a faster growth
The aim of the paper is to show the performance of the Sentinel-1 SyntheticAperture Radar (SAR) Single Look Complex (SLC) Interferometric Wide-swath level-1 product for retrieving glacier surface velocities using offset tracking and differential interferometry (D-InSAR) techniques
We can broadly group our studied glacier into three groups: (1) fast flowing with winter velocities greater than 600 m year−1 ; (2) medium flowing with winter velocities within 50–200 m year−1 ; and (3) slow flowing with speeds less than 50 m year−1
Summary
Remote sensing is becoming an increasingly important tool in climate research [1], with SyntheticAperture Radar (SAR) being one of the techniques that has experienced a faster growth. Space Agency (ESA) has long supported various satellite Earth Observation missions with SAR sensors onboard such as the European Remote Sensing (ERS-1 and ERS-2) and ESA Environmental. Continuing this long-term policy of providing continuous and consistent observational data, Sentinel-1A was launched in 2014, with its twin satellite, Sentinel-1b, launched in 2016. The Sentinel mission is part of the Copernicus program (formerly known as Global Monitoring for Environment and Security, GMES), which comprises three components: space, in situ and services. The latter component is in charge of defining the Sentinel-1 observation scenario [4].
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