Grounding Line Retreat Observed in the Eastern Totten Glacier Grounding Zone with DInSAR

Abstract:

Totten Glacier discharges more ice than any other in East Antarctica (Rignot, 2006) and its catchment contains enough ice and snow grounded below sea level to raise global eustatic sea level by at least 3.5 meters (Greenbaum et al., 2015). Further, the coastal part of Totten Glacier has had the fastest thinning rate in all of East Antarctica since orbital altimetry observations began in the 1990’s (Zwally et al., 2015). For these reasons, there has been increased interest in monitoring Totten Glacier. One way to probe the possible retreat of Totten Glacier is to monitor the location of the grounding line, the boundary between grounded and floating ice, through differential SAR interferometry (DInSAR). Here we present an analysis of the position of the Totten Glacier grounding line with ERS-1/ERS-2 data collected in 1996 as well as newly acquired multiyear SAR data collected by Sentinel 1A/B mission from 2017 to 2020. We used GMTSAR to process the data and found an indication of trough connecting the eastern Totten Glacier Grounding Zone with the ocean in 1996. We also found a 2.0 km retreat of the grounding line between 1996 and 2017 on a retrograde slope right next to the trough. The trough itself also widened from 1.8 km to 3.4 km. A variation of the grounding line position ranging from 0.2 km to 2.5 km has been identified through hand-tracing 14 differential SAR interferograms produced with Sentinel 1A/B data. This variation limits our ability to monitor sub-decadal grounding line retreat. Our finding of the trough and grounding line migration demonstrates a rapid basal melt in the eastern Totten Glacier Grounding Zone.

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