Meltwater drainage and iceberg calving observed in high-spatiotemporal resolution at Helheim Glacier, Greenland

• Published in: Journal of Glaciology
• Main Authors: Sierra M. Melton, Richard B. Alley, Sridhar Anandakrishnan, Byron R. Parizek, Michael G. Shahin, Leigh A. Stearns, Adam L. LeWinter, David C. Finnegan
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2022
• Subjects: Arctic glaciology; glacier hydrology; iceberg calving; melt-surface; remote sensing; Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; Arctic; Greenland; East Greenland; glacier; Iceberg*; Journal of Glaciology; Tidewater
• Online Access: https://doi.org/10.1017/jog.2021.141; https://doaj.org/article/65f79e3e50184fefa7f84ccf950914f8

Marine-terminating glaciers lose mass through melting and iceberg calving, and we find that meltwater drainage systems influence calving timing at Helheim Glacier, a tidewater glacier in East Greenland. Meltwater feeds a buoyant subglacial discharge plume at the terminus of Helheim Glacier, which rises along the glacial front and surfaces through the mélange. Here, we use high-resolution satellite and time-lapse imagery to observe the surface expression of this meltwater plume and how plume timing and location compare with that of calving and supraglacial meltwater pooling from 2011 to 2019. The plume consistently appeared at the central terminus even as the glacier advanced and retreated, fed by a well-established channelized drainage system with connections to supraglacial water. All full-thickness calving episodes, both tabular and non-tabular, were separated from the surfacing plume by either time or by space. We hypothesize that variability in subglacial hydrology and basal coupling drive this inverse relationship between subglacial discharge plumes and full-thickness calving. Surfacing plumes likely indicate a low-pressure subglacial drainage system and grounded terminus, while full-thickness calving occurrence reflects a terminus at or close to flotation. Our records of plume appearance and full-thickness calving therefore represent proxies for the grounding state of Helheim Glacier through time.