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.