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

Jacek Jania,Małgorzata Błaszczyk,Barbara Barzycka,Michał Laska,Etienne Berthier,Mateusz Czapla,Mariusz Grabiec,Leo Decaux,Leszek Kolondra,Bartłomiej Luks,Dariusz Ignatiuk

doi:10.3390/rs11091121

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.

Highlights

Recent elevation changes of glaciers worldwide have been successfully studied with digital elevation models (DEM) differencing
The most recent sources of elevation data over Svalbard used for estimation of volume change and geodetic mass balance are DEMs derived from aerial photographs acquired in 1990 [1,2,3] and 2009–2012 [4], repeat-track ICESat altimetry for 2003–2008 [2,5], airborne lidar profiles in 2003–2005 [6,7,8] and 2007/2008 SPOT DEMs from the IPY SPIRIT project [9,10]
The DEMs derived from Very High Resolution (VHR) satellites and aerial photographs are frequently used for studies on volume change in the Arctic

Summary

Introduction

Recent elevation changes of glaciers worldwide have been successfully studied with DEM (digital elevation model) differencing. In light of recent climate change, there is a need for more frequent and accurate data on elevation changes This is crucial, because Svalbard is one of the highest-potential areas for surge-type glaciers [11]. DEMs generated from Very High Resolution (VHR) sub-meter images have the potential to replace aerial photo DEMs to update more frequently glacier geodetic mass balances. Such DEMs have been used to measure elevation changes of glaciers worldwide in recent years [12,13,14]. The freely available and continuously updated ArcticDEM [15], (https://www.pgc.umn.edu/data/arcticdem/) provides a potent new source of glacier volume change (e.g., [16,17,18,19,20])

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