Temporal Variations in Ice Thickness of the Shirase Glacier Derived from Cryosat-2/SIRAL Data

Abstract

This study presents the feasibility of estimating the ice thickness of the Shirase Glacier using the synthetic aperture interferometric radar altimeter (SIRAL) on board the CryoSat-2 and the interannual variation of the ice thickness of the Shirase Glacier in 2011–2020. The SIRAL data were converted to ice thickness by assuming hydrostatic equilibrium, and the results showed that the ice thickness decreased from the grounding line to the terminus of the glacier. Furthermore, the ice thickness decreased 30 km downstream from the grounding line of the glacier in 2012 and 2017, and decreased 55 km and 60 km downstream from the grounding line of the glacier at other times, which was attributed to the discharge of landfast ice and the retreat of the glacier terminus. When the flow of glacial ice can be reasonably approximated as an incompressible fluid, and the law of conservation of mass can be applied to the ice stream, the multiple of the velocity and the underlying ice thickness under a constant ice density can be shown to correspond to the equation of continuity. Consequently, this study revealed that the ice thickness decreases with accelerating flow velocity, which is coincident with past outflow events.