Joint Geophysical Observations of Ice Stream Dynamics

Abstract

Ice streams play a major role in the ice mass balance and in the reckoning of the global sea level; they have km2 around the David Glacier. We have carried out several analyses using the combined data sets. These included the examination of the temporal evolution in earthquake magnitude and location and also the contemporaneous observation of both seismic activity and surface kinematics of the ice stream to possibly correlate the recorded microseismicity with the movement of the glacier, affected by the Ross Sea tides.Unfortunately, a clear correlation between the occurrence of seismic events and the movement of the glacier is not evident. Here we present some details of the two temporary networks and preliminary results and implications.3

Sea Tide Influence on Ice Flow of David Drygalski’s Ice Tongue Inferred from Geodetic GNSS Observations and SAR Offset Tracking Analysis

“…To understand some characteristics of the dynamics of the southern ice flow and the effect of the ocean tide on the movements of the floating and grounded parts of David Glacier, two dual-frequency GNSS geodetic receivers were installed on its surface at the end of 2006. These stations have become part of an observation network of seismic stations already operating in the study area [21].…”

“…Unfortunately, when the experiment was set up, the GNSS master station, installed on a rocky outcrop near the ice tongue, for some unidentified reason, stopped acquiring after a few days of operation. To overcome the problem, some satisfactory results have been achieved in post-processing, adopting the double difference technique, using data from a permanent GNSS station (TNB1), about 100 km away from the study area, at the Mario Zucchelli station (MZS) [21].…”

“…Unfortunately, when the experiment was set up, the GNSS master station, installed on a rocky outcrop near the ice tongue, for some unidentified reason, stopped acquiring after a few days of operation. To overcome the problem, some satisfactory results have been achieved in post-processing, adopting the double difference technique, using data from a permanent GNSS station (TNB1), about 100 km away from the study area, at the Mario Zucchelli station (MZS) [21]. Nowadays, the undifferenced GNSS post-processing analysis technique (Precise Point Positioning), together with the recent improvements available for the kinematic reconstruction of the position of a single GNSS instrument, with a sampling rate of even less than one minute, allow a detailed reanalysis of such data, highlighting signals that were not detectable with the analysis techniques used at the time of the experiment.…”

Overestimation and adjustment of Antarctic ice flow velocity fields reconstructed from historical satellite imagery

“…Velocities in this region from 1988 to 1992 were mapped by using GPS and image-featuretracking techniques (Frezzotti et al, 1998(Frezzotti et al, , 2000. A new GPS campaign was carried out in the region during 2005-2006(Danesi et al, 2008. Velocity changes from 2016 to 2020 were detected using Sentinel-1A SAR images (Moon et al, 2021).…”