REMA reveals spatial variability within the Dotson Melt Channel

Abstract

Abstract. The intrusion of warm circumpolar deep water causes ice shelves in the Amundsen and Bellinghausen Sea Embayments of Antarctica to melt from below, thereby potentially putting their stability at risk. Earlier studies have shown how digital elevation models can be used to obtain high-resolution ice shelf basal melt rates. However, there has been limited availability of high-resolution elevation data, a gap the Reference Elevation Model of Antarctica (REMA) has filled. In this study we use a novel combination of REMA and CryoSat-2 elevation data to obtain high-resolution basal melt rates of the Dotson Ice Shelf in a Lagrangian framework, at a 50 m spatial resolution on a 3-yearly temporal resolution. We present a novel Basal melt rates Using REMA and Google Earth Engine (BURGEE) method, which high resolution is supported through a sensitivity study assuming that the quality of the Lagrangian displacement is the main error source. The high-resolution basal melt rates show a good agreement with an earlier 500-m resolution basal melt product based on CryoSat-2, with a wide melt channel extending from the grounding line to the ice shelf front. Our high-resolution product indicates that the pathway and spatial variability of the main channel is influenced by a pinning point on the ice shelf. Additionally, it reveals a narrower coastal channel running along the western margin, which was not identified in the lower-resolution melt product, but does show up in a recent ocean modeling study. This emphasizes the importance of high-resolution basal melt rates to expand our understanding of channel formation and melt patterns. BURGEE can be expanded to a Pan-Antarctic study of high-resolution basal melt rates. This will provide a better picture of the (in)stability of Antarctic ice shelves.

Basal channels, ice thinning and grounding zone retreat at Thwaites Glacier, West Antarctica

“…While relatively frequent and accurate, observations from spaceborne altimetry, such as ICESat and ICESat-2, are limited to ground tracks. Recently, high-resolution digital surface models (DSMs) produced from stereoscopic satellite imagery, combined with altimetry, have been used to map changes in basal channels and other iceshelf structures (Chartrand and Howat, 2020;Shean et al, 2019;Zinck et al, 2023). Using the extensive collection of repeat DSMs provided by the Reference Elevation Model of Antarctica (REMA) project (Howat et al, 2019), we map the positions of surface depressions overlying basal channels on the TGIS and subglacial channels within grounded ice as well as the landward extent of the transition to flotation as a proxy for the grounding line, termed the hydrostatic boundary (HB).…”