Bedrock topography and ice thickness distribution of three major Patagonian outlet glaciers unveiled by helicopter-borne ground penetrating radar

Abstract. We present the first helicopter-borne ground-penetrating radar dataset over Glaciar Viedma, Upsala, and Perito Moreno, three of the largest outlet glaciers of the Southern Patagonian Icefield in South America. The dataset comprises 116.021 individual ice-thickness measurements along 232 km of flight tracks. Data were acquired during two campaigns in March and April 2022 as well as in October 2024 using a 25 MHz shielded broadband antenna deployed as a helicopter sling load. For the first time, we reveal the complex subglacial topography of these glaciers in their lower regions and measured bed reflections at Glaciar Upsala in depths of up to 800 m. The newly obtained measurements were incorporated into an ice-thickness reconstruction method to derive glacier-wide ice-thickness distribution maps and the corresponding bedrock topography. The latter exerts primary control on the response of water-terminating glaciers to a changing climate. Our 100-m gridded ice-thickness maps indicate that the three glaciers had a combined ice volume of 831.14 km³ in the year 2000. The dataset and the well-constrained glacier-wide grids provide a valuable basis for future studies aiming to better understand the mechanisms driving glacier retreat and the susceptibility of these large outlet glaciers to climate change. All data are publicly available at Zenodo (https://doi.org/10.5281/zenodo.17464164; Koch et al., 2025a).