Investigating Glacier Mass Loss in the South Shetland Islands Using Open-source Data Loggers and Off-the-shelf Sensors

The South Shetland Islands (SSI) are located 160 km north of the Antarctic Peninsula. These islands are subjected to maritime climate and are strongly influenced by the Southern Westerly Winds (SWW), which increasingly deliver warm air and rain to the ice caps, leading to rapid recession and surface lowering (Osmanoğlu et al., 2013). Although extensive temperature records from Antarctic research bases and satellite imagery permit observation of such changes, information collected directly from the ice is scarce, thereby preventing a comprehensive understanding of the local dynamics governing these glaciers. Therefore, we conducted a field survey during the 2020/2021 austral summer at Fourcade Glacier, located on King George Island. We prepared three automated ablation stakes, each outfitted with a temperature and relative-humidity sensor, an ultrasonic rangefinder, and an open-source Margay data logger (Schulz, 2021). We deployed two atop the glacier to quantify ice-surface-elevation change across an altitudinal gradient, and attached one to a large boulder in a proglacial river to gauge its stage during the melt season. We converted the frequently measured river stage to discharge through a rating curve built using a salt-dilution approach, which we constructed during one 24-hour period to sample the full diurnal melt cycle as well as through the entirety of the field season in order to track any changes in the stage-discharge relationship; such changes could result from evolving channel geometry. Moreover, we measured discharge at 2 additional meltwater channels to account for the total catchment area of the glacier that drains into these proglacial rivers. Results indicate that Fourcade Glacier ablated ~2.5 m and evacuated an average of ~5 m3/s of freshwater through the meltwater channels (i.e., the terrestrially terminating portion of its margin) during the entire melt season. These inexpensive, automated, and open-source data loggers and their smooth interface with cost-effective off-the-shelf sensors proved effective for monitoring this highly-dynamic sub-polar environment.