Quality Assessment and Glaciological Applications of Digital Elevation Models Derived from Space-Borne and Aerial Images over Two Tidewater Glaciers of Southern Spitsbergen

Abstract

In this study, we assess the accuracy and precision of digital elevation models (DEM) retrieved from aerial photographs taken in 2011 and from Very High Resolution satellite images (WorldView-2 and Pléiades) from the period 2012–2017. Additionally, the accuracy of the freely available Strip product of ArcticDEM was verified. We use the DEMs to characterize geometry changes over Hansbreen and Hornbreen, two tidewater glaciers in southern Spitsbergen, Svalbard. The satellite-based DEMs from WorldView-2 and Pléiades stereo pairs were processed using the Rational Function Model (RFM) without and with one ground control point. The elevation quality of the DEMs over glacierized areas was validated with in situ data: static differential GPS survey of mass balance stakes and GPS kinematic data acquired during ground penetrating radar survey. Results demonstrate the usefulness of the analyzed sources of DEMs for estimation of the total geodetic mass balance of the Svalbard glaciers. DEM accuracy is sufficient to investigate glacier surface elevation changes above 1 m. Strips from the ArcticDEM are generally precise, but some of them showed gross errors and need to be handled with caution. The surface of Hansbreen and Hornbreen has been lowering in recent years. The average annual elevation changes for Hansbreen were more negative in the period 2015–2017 (−2.4 m a−1) than in the period 2011–2015 (−1.7 m a−1). The average annual elevation changes over the studied area of Hornbreen for the period 2012–2017 amounted to −1.6 m a−1. The geodetic mass balance for Hansbreen was more negative than the climatic mass balance estimated using the mass budget method, probably due to underestimation of the ice discharge. From 2011 to 2017, Hansbreen lost on average over 1% of its volume each year. Such a high rate of relative loss illustrates how fast these glaciers are responding to climate change.

Factors Controlling Terminus Position of Hansbreen, a Tidewater Glacier in Svalbard

“…Moon et al., 2015; Motyka et al., 2017; Murray et al., 2015; Schild & Hamilton, 2013; Seale et al., 2011; Van Wychen et al., 2016), although glaciers with similar fluctuations to Hansbreen can be found in other places in the Arctic as well (e.g., Carr et al., 2017; Catania et al., 2018; Howat & Eddy, 2011; McNabb et al., 2015; Ritchie et al., 2008). Regardless of these differences, Hansbreen can be representative for other glaciers in Svalbard with regard to type, dynamics, and size (Błaszczyk et al., 2009; Nuth et al., 2013). Our studies support previous results identifying the crucial role of the surface and submarine melting (Bartholomaus et al., 2013; Jenkins, 2011; Luckman et al., 2015; Motyka et al., 2003, 2013; Rignot et al., 2010; Truffer & Motyka, 2016; Xu et al., 2012) and glacier basal and seabed topography (e.g., Brown et al 1982; Catania et al., 2018; Enderlin et al., 2013; Jania, 1988; Meier & Post, 1987; Oerlemans & Nick, 2005; Pfeffer, 2007) in driving the front positional changes.…”

“…The bathymetry data for Hansbukta include depth measurements from different sources: data from the Norwegian Hydrographic Service collected using a multibeam survey in 2007–2008 (The Norwegian Mapping Authority, Kartverk), data collected in 2014, 2016, and 2017 from a small boat using a Norbit Wideband Multibeam Sonar with a positioning system, and measurements collected in 2015 from a small boat using single beam echosounder Lowrance HDS5 with positioning. Accuracy of the bathymetry from these different sources is assessed as ±5 m. The longitudinal profile of the glacier surface is derived from continuous DEM generated from satellite data (Błaszczyk, Ignatiuk, Grabiec, et al., 2019), while the profile of the bed under the glacier is interpolated from ground‐penetrating radar data (Grabiec et al., 2012). The mean water depth at the front position was determined as the mean depth of the area enclosed by minimum and maximum glacier extent in the year.…”

“…This introduces significant uncertainty into analyses of tidewater glacier extents on the regional and global scale. Long‐term and interannual changes of glacier termini in Svalbard are usually reported based on data from summer and autumn (Błaszczyk et al., 2009; Jania, 1988; Nuth et al., 2013; Urbański, 2018; Ziaja & Ostafin, 2015) while, for the proper estimation of interannual changes in terminus position, it is crucial to report minimal glacier length in the season. In Hornsund, SW Spitsbergen, it occurs in late autumn or winter and the date of the minimal length varies from year‐to‐year (Błaszczyk, Ignatiuk, Grabiec, et al., 2019; Błaszczyk, Ignatiuk, Uszczyk, et al., 2019).…”

Reconciling Svalbard Glacier Mass Balance

“…(2011-2015 and 2015-2017), based on differencing elevations obtained by photogrammetry using high-resolution satellite images (Błaszczyk et al, 2019). The surge of Basin 3 of Austfonna led to significant mass loss that has been quantified by McMillan et al (2014) using repeat altimetry.…”

A Relief Dependent Evaluation of Digital Elevation Models on Different Scales for Northern Chile

“…Additionally, DEMs are crucial for ecological analysis, such as vegetation and plant distribution research [22][23][24]. Climatic issues, like the observation of glacier changes [25], sea-level rise [26] or climatic modelling [27] are also fields of application, where terrain information is needed.…”