Integrating DInSAR and Ice-Penetrating Radar for Assessing Grounding Line Consistency and Variations in Contrasting Antarctic Ice Shelves

Abstract

The Antarctic grounding line is a subsurface feature, making its detection challenging. Differential Interferometric Synthetic Aperture Radar (DInSAR) enables large-scale and continuous inversion of grounding lines from surface deformation, while Ice-Penetrating Radar (IPR) allows direct observation of basal features. However, the accuracy of these methods for grounding line detection has not been fully assessed, and the correspondence between surface and basal observations remains unclear. In this study, we integrated satellite synthetic aperture radar (SAR), airborne IPR, and existing datasets to analyze grounding lines in three contrasting sectors of Antarctic ice shelves: Abbot and Cosgrove, Larsen D and Larsen E, and Dotson and Crosson. Considering radar reflection intensity, subsurface topography and surrounding signal features, we detected 335 basal grounding points over 300 km of IPR survey lines. Multidimensional metrics were applied to quantify the spatial consistency between different datasets. The results show the highest spatial consistency between surface grounding lines from DInSAR inversions and basal grounding points detected by IPR, with an average absolute distance of 0.37 km. In particular, the IPR-detected basal grounding points are highly consistent with the landward boundary of the grounding zone inverted by DInSAR. Between 1994 and 2020, grounding lines in Abbot and Larsen remained stable, while Dotson exhibited a persistent and rapid retreat. Smith West and Pope Glaciers show significant fluctuations in retreat rates, with a maximum retreat rate of 5.7 km/yr and a minimum of 1.0 km/yr at Smith West. During 1996–2014, the retreat rate of Pope Glacier was ∼60% higher than previous reports.