Data For: Grounding zone of Helheim Glacier, Greenland, from terrestrial radar interferometry

Helheim Glacier, in East Greenland, is a major outlet glacier that
discharges about 33 Gigatons of ice per year into the ocean. Helheim has
been undergoing a retreat since 2003. Using a portable terrestrial radar
interferometer that scans the glacier every 2 minutes, we characterize its
regime of tidal flexure at the ice front margin in relation to oceanic
tide, bed slope, and iceberg calving events. The data reveals the presence
of a central bed ridge that acts as a fulcrum, with one side of the
glacier moving in phase with the tide, while the other is moving out of
phase with a reduced amplitude. We detect seawater intrusions of one full
thickness beneath the glacier front at high tide. Following tabular
calving events, most ice flexing ceases, indicating that the ice front
becomes grounded and that calving events involve ice blocks that are
already afloat.