The Sentinel-1 Mission: New Opportunities for Ice Sheet Observations

Abstract

Abstract:The Sentinel satellite constellation series, developed by the European Space Agency, represents the dedicated space component of the European Copernicus program, committed to long-term operational services in a wide range of application domains. Here, we address the potential of the Sentinel-1 mission for mapping and monitoring the surface velocity of glaciers and ice sheets. We present an ice velocity map of Greenland, derived from synthetic aperture radar (SAR) data acquired in winter 2015 by Sentinel-1A, the first satellite of the Copernicus program in orbit. The map is assembled from about 900 SAR scenes acquired in Interferometric Wide swath (IW) mode, applying the offset tracking technique. We discuss special features of IW mode data, describe the procedures for producing ice velocity maps, and assess the uncertainty of the ice motion product. We compare the Sentinel-1 ice motion product with velocity maps derived from high resolution SAR data of the TerraSAR-X mission and from PALSAR data. Beyond supporting operational services, the Sentinel-1 mission offers enhanced capabilities for comprehensive and long-term observation of key climate variables, such as the motion of ice masses.

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

“…The speckle tracking technique has its own peculiarities when it is applied to TOPS products, in particular when applied to non-stationary areas such as glaciers or ice caps [20] (e.g., TOPS azimuth antenna scan entails phase deramping and azimuth common band filtering [9]). Orbital accurate ephemerides are becoming a common resource in new space missions, as is the case for the Sentinel-1 [21,51] mission, which allows for a seamless generation of wide regional surface displacement products.…”

“…This was a critical factor for choosing Ellesmere Island as a suitable area to apply a full co-registration procedure using the matching and the spectral diversity methods. When no interferometry is required and the only derived product is to be offset tracking displacements, the Sentinel-1 ephemerides are sufficient for comprehensive, region-wide results [21].…”

“…However, there is also a limit on the amount of movement that the feature tracking algorithms are able to resolve. Nagler et al [21], using an in-house developed algorithm, were able to resolve velocities up to 12 m d −1 when using Sentinel-1 IW data (the same sensor that we are using). With increasing image resolution (smaller pixel size), larger velocities could be resolved.…”

“…The application of interferometry to ascending and descending passes is also well documented for glacier surface velocity estimations [12][13][14]. There are plenty of articles dealing with glacier velocity retrieval using the offset tracking technique [15][16][17][18][19], including the particular case of Sentinel-1 TOPS acquisitions [20,21], the latter reference providing a comprehensive velocity field for the entire Greenland Ice Sheet. Furthermore, the combination of both techniques has also been covered with different approaches (e.g., merging of results or using least squares [22][23][24][25]) and also for entire ice sheets, such as the study by Mouginot et al [26] for the Antarctic Ice Sheet.…”

Dynamic changes in outlet glaciers in northern Greenland from 1948 to 2015

“…Winter velocities for 2013/14 were derived from intensity tracking of RADARSAT-2 satellite data, and from offset tracking of Sentinel-1 radar data for 2014/15 and 2015/16, as part of the ESA CCI project (Nagler et al, 2016). The mean error of these data from a central section of northern Greenland is 7.3 m a -1 (Nagler et al, 2015). Using the earliest full regional velocity map (1995/96) and the most recent record (2015/16), the rate of annual velocity change was calculated over this 20-year period.…”