The dataset consists of three shapefiles containing terminus positions of the Koge Bugt North, Koge Bugt Central, and Koge Bugt South glaciers respectively, between 2022-2023. The terminus positions were manually digitised using either Landsat-8 or Landsat-9 imagery, downloaded from the USGS Earth Explorer (https://earthexplorer.usgs.gov/). If suitable optical imagery was unavailable, MEaSUREs Sentinel-1A and Sentinel-1B synthetic aperture radar (SAR) mosaics were employed, downloaded from the National Snow and Ice Data Center (NSIDC; Joughin, 2021). The dataset comprises 71 terminus positions in total, each digitised from imagery collected between 2022-01-11 and 2023-12-08. Hannah Picton acknowledges funding from the E4 DTP (Edinburgh Earth, Ecology and Environment Doctoral Training Partnership), NE/S007407/1.

The dataset consists of a single shapefile containing terminus positions of Jakobshavn Isbrae, Ilulissat Icefjord, Greenland, between 2022-2023. Jakobshavn Isbrae is a fast-flowing outlet glacier situated in central west Greenland and terminates in Ilulissat Icefjord, a deep fjord basin renewed by water from Disko Bay (Gladish et al., 2015). Each polyline feature in this dataset reflects a terminus position manually digitised using synthetic aperture radar (SAR) mosaics downloaded from the National Snow and Ice Data Center (NSIDC; Joughin, 2021). The dataset comprises 31 terminus positions in total, each digitised from imagery collected between 02/01/2022 and 28/12/2022. Hannah Picton acknowledges funding from the E4 DTP (Edinburgh Earth, Ecology and Environment Doctoral Training Partnership), NE/S007407/1.

High-resolution basal topography and basal properties were calculated from two 3x3 km2 radar datasets acquired approximately 50 km upstream of the grounding line of Rutford Ice Stream in West Antarctica. The provided datasets contain several csv-files including the coordinates, bed elevation below the WGS84 ellipsoid and the reflectivity of the bed reflection. The X and Y coordinates are projected in EPSG:3031 - WGS 84 / Antarctic Polar Stereographic coordinate system. Radar data were acquired between December 2017 and late January 2018 using the British Antarctic Survey's ground-based DELORES system as part of the BEAMISH project. Data acquisition and processing was compliant with 3D processing and migration. Radar data were frequency filtered and 3D migrated (using a 3D Kirchhoff Time Migration approach in SeisSpace/ProMAX (LGCHalliburton Software) and migration velocity of 0.168 m ns-1), followed by the picking of the bed reflection using Petrel (Schlumberger Software). For the interpretation of variation of bed properties, basal reflectivity was calculated as described in Schlegel et al., 2022 and Schlegel et al., 2024. This work was funded by NERC AFI award numbers NE/G014159/1, NE/G013187/1 and NE/F015879/1, and NERC National Capability Science: Strategic Research and Innovation Short Projects. Geophysical equipment was provided by NERC's Geophysical Equipment Facility, loan number 887. We thank BAS Operations and N. Gillett for fieldwork support and B. Craven for software support. University of Leeds acknowledges support of this work by Landmark Software and Services, a Landmark Company and use of SeisSpace/ProMAX via the Landmark University Grant Program, Agreements 2004-COM-024982, 2008-CON-010888 and subsequent renewals. The British Antarctic Survey acknowledges support of this work by Landmark Software and Services, a Landmark Company.

20 Ice Trackers were deployed at the MOSAiC drifting site. The deployment of the trackers was made from the helicopter onboard RV Polarstern during Leg 5 of the expedition. The data contain the GPS positioning of the trackers (and the motion of the ice on which the trackers were deployed). The data record starts from early September 2020 and lasted until July 2021 for the longest-surviving trackers. The trackers started their drift near the North Pole and move to the south through the Fram Strait. The deployment of the trackers was done in collaboration with the MOSAiC ice team. This work was funded by NERC MOSAiC program NE/S002545/1.