Text S5: PROMICE KAN_M Automated Weather Station data and processing
Hourly weather station data were downloaded for the PROMICE KAN_M automated weather station (AWS; Fausto and van As, 2019 , available at https://www.promice.org/PromiceDataPortal/). The KAN_M AWS is located just outside the 2016 Rio Behar catchment (Figure 1 ). This station, operated by the Geological Survey of Denmark and Greenland, records a range of surface atmospheric variables and ice conditions. Here we use hourly mean energy balance components, surface air temperature and surface ablation measurements to examine the relationship between atmospheric forcing and ice sheet motion. The hourly melt energy (Figure 2a ) is calculated by summing the net longwave radiation, net shortwave radiation, sensible heat flux and latent heat flux. The shortwave radiation is corrected for any sensor tilt recorded. Sensible heat flux is calculated from the wind speed and temperature gradients between the surface and the sensor height, with an assumed aerodynamic surface roughness of 0.001m. Latent heat flux is calculated from the wind speed and humidity gradients between the surface and sensor height using the same aerodynamic roughness prescribed for sensible heat flux. Air temperature is presented as recorded by the AWS. Ice surface ablation is calculated by differencing the hourly observations of the pressure transducer (drilled into the underlying ice) every 6 hours. During the observation period, the pressure transducer remained fully embedded within the underlying ice and did not need to be reinstalled.