Decadal changes of Campbell Glacier Tongue in East Antarctica from 2010 to 2020 and implications of ice pinning conditions analyzed by optical and SAR datasets

Abstract

Changes in ice shelf dynamics significantly impact the discharge rate of grounded ice, sea ice formation, and marine environments. In particular, changes of a sub-shelf pinning point induce complex dynamics of an ice shelf. In this study, we investigated decadal changes (2010？2020) in the area, ice velocity, and grounding line position of Campbell Glacier Tongue (CGT) in East Antarctica, which has an ice pinning point at the southwestern end, and analyzed the effect of the pinning conditions on the dynamics of CGT. Panchromatic band images of Landsat-7 Enhanced Thematic Mapper Plus and Landsat-8 Operational Land Imager, COSMO-SkyMed X-band synthetic aperture radar (SAR), and Sentinel-1 C-band SAR datasets were employed. The surface area of CGT digitized from the optical and SAR imagery decreased by 8% in the last decade, during which four ice calving events that caused icebergs with an area range of 3.8？5.4 km2. The largest calving at the ice pinning point occurred in March 2014, which created an iceberg with 4 km2. The ice velocity of CGT was measured via the normalized cross correlation-based image matching of the Landsat panchromatic images. The ice velocity along the flow direction and its anomaly of CGT hardly changed in the hinge zone from 2011 to 2020. The ice velocity increased by ~7% and the flow direction steered abruptly ~7° to the east in the freely floating zone after the 2014 calving at the ice pinning point. Considering the retreat of the local grounding line at the pinning point analyzed by COSMO-SkyMed double-differential interferometric SAR, the advancing glacier tongue came in contact with the sloping eastern flank of the locally elevated seabed at the pinning point after the calving, and the ice-bed contact area decreased, causing a sudden acceleration and eastward rotation of ice flow. It is expected that continuous calving at the ice pinning point of CGT may lead to an abrupt changes in glacier tongue dynamics again, and continuous monitoring is necessary.