Statistical inference of the ice velocity response to meltwater runoff,
terminus position, and bed topography at Helheim Glacier, Greenland
Abstract
The Greenland Ice Sheet discharges ice to the ocean through hundreds of
outlet glaciers.
Recent acceleration of Greenland outlet glaciers has been linked to both
oceanic and atmospheric drivers.
Here, we leverage temporally dense observations, regional climate model
output, and newly developed time series analysis tools to assess the
most important forcings causing ice flow variability at one of the
largest Greenland outlet glaciers, Helheim Glacier, from 2009 to 2017.
We find that ice speed correlates most strongly with
catchment-integrated runoff at seasonal to interannual scales, while
multi-annual flow variability correlates most strongly with multi-annual
terminus variability. The multiple relevant time scales and the
influence of subglacial topography on Helheim Glacier’s dynamics
highlight different regimes that can inform modeling and forecasting of
its future. Notably, our results suggest that the recent terminus
history observed at Helheim is a response to, rather than the cause of,
upstream changes.