The impact of ice mélange dynamics on the calving of two major Greenland tidewater glaciers, Helheim and Nunatakassaap Sermia

Ice mélange, a mixture of icebergs and sea ice located in front of tidewater glaciers usually terminating in relatively narrow fjords, is believed to impact the calving dynamics of said glaciers through buttressing force and to alter the fjord circulation through freshwater fluxes. Still, given its potential impact on sea level rise, research concerned with the influence of the mélange is scarce. This study seeks to clarify its’ effect on calving dynamics based on remote sensing data for the two fast flowing Greenland outlets Helheim Gletsjer (East Greenland) and Nunatakassaap Sermia (Alison Glacier, West Greenland).

To achieve this Sentinel-1 radar and Sentinel-2 optical images are combined to retrieve an intra-seasonal timeseries of ice mélange dynamics before the relationship between a shrinking/growing ice mélange and calving dynamics is analyzed. To further aid the interpretation of ice mélange composition, the radar images with mélange matrix are studied based on their statistical variations in pixel intensity. The detection of calving events’ and upper bounds for their respective size is based on the dataset of outlet glacier terminus position traces AutoTerm (Zhang et al., 2023) as well as near-terminus velocity mosaics from the ITS_LIVE dataset (Gardner et al., 2018). Finally, to investigate the impact of the mélange and of related driving mechanisms on calving dynamics for Helheim Gletsjer and Nunatakassaap Sermia, the resulting timeseries of mélange dynamics and calving event characterization are combined with datasets of sea surface temperature, surface temperature, glacier ice velocity, etc.