Application of the DInSAR Technique for the Grounding Line Location - Round Robin Contribution to the Ice_Sheets_CCI
Pierdicca, Nazzareno¹; Pulvirenti, Luca²; Ticconi, Francesca³; Scharrer, Killian⁴; Nagler, Thomas^4
1University Saoienza of Rome, ITALY; ²University Sapienza of Rome, ITALY; ³University of Leeds, UNITED KINGDOM; ⁴Enveo, AUSTRIA

Calving glaciers play an essential role in the dynamics and mass balance of the Greenland ice sheet. The location of the grounding line, where the ice separates from the grounded part and becomes afloat, is of particular interest for monitoring the stability of these glaciers. Processes at the grounding lines are important for understanding the response of the ice masses to changing boundary conditions and to establish realistic scenarios for the response to climate change. A substantial collection of literature can be found on detecting grounding line location in Antarctica; however, there are only few studies on grounding lines in Greenland on a very limited number of glaciers. For this reason, ESA has launched the Ice Sheets Climate Change Initiative (CCI). The CCI programme focuses on those Essential Climate Variables where the biggest impact on advancing understanding of the climate system is expected, maximising the use of data from the ESA and other European archives. The ice sheets have been identified as one of these variables because of their importance in understanding and contributing to the interpretation of changes in the long term record of sea level. Within the projects four parameters have been selected as key parameters for describing the state and changes of the ice sheets: surface elevation changes, surface velocities, calving front locations, and Grounding Line Locations (GLL). This work represents the GLL results obtained following the invitation received for contributing to the Round Robin experiment of the project. This experiment has as main goal the comparison of various algorithms and the identification of the best performing algorithm, in terms of accuracy, coverage and processing effort, for the generation of GLL products.
In this work, the Differential InSAR (DInSAR) technique has been applied using ERS-1 data acquired over the Peterman Glacier and made available from the Enveo team, which is part of the consortium leading the project. It utilises two sets of three consecutive passes acquired on 4, 7 and 10 of February 1992 and on 25 and 28 February and 2 March 1992, respectively. This technique allows separating the tidal motion, and hence locating the grounding line, by differencing the two topography-corrected interferograms obtained coupling the ERS-1 images over the same time interval.