Multi-sensor approach of monitoring ice-ocean interaction at high resolution at a major ocean-terminating glacier in South Greenland

About half of the current rapid mass loss of the Greenland ice sheet (GIS) is through dynamic processes driven by calving and frontal ablation. However, related insitu observations in such dynamic environments are challenging and our process understanding is therefore still limited. Within the wider context of the GreenFjord-project on Greenland Fjord ecosystem we introduce here a multi-sensor approach for observing process interactions at high spatial and temporal resolution at the ice-ocean boundary of the major ocean-terminating outlet glacier Eqalorutsit Kangillit Sermiat (EKaS) in South Greenland. Besides multiple all year-round time lapse cameras, broadband seismometers and tidegauges distributed around the glacier terminus and running since summer 2022, we deployed for the first time in summer 2023 a fibre optic cable at the fjord-bed along the calving front and performed continuous distributed acoustic and temperature sensing measurements (DAS and DTS) during more than two weeks. In parallel, we run a terrestrial radar interferometer (TRI) at 1min repeat intervals that recorded high resolution flow-fields as well as calving events (time, size and location). Our comprehensive observational approach is further complemented by local meteo-station data and more than 20 CTD profiles in the fjord near the calving front. In addition, two ocean bottom seismometers together with a simple CTD mooring have been deployed in summer 2023 and are planned to be recovered in the coming summer. Besides our observational approach, we present here a broad overview and preliminary analysis of this unique observational dataset. We are not only able to record and cross-validate the same processes or events (e. g. calving and ice flow) from multiple sensors, but also clearly extend our observational ability (e. g. detection sensitivity, calving type and size, fjord circulation, spatial and temporal resolution). We further get more insights into related subglacial and submarine processes such as fjord temperature variations, plume discharge and internal waves in the fjord. Our results thereby contribute to improve our understanding of ice-ocean interaction at a calving front and helps to develop sustainable observational systems of related processes.