20 Jan 2023
 | 20 Jan 2023
Status: this preprint is currently under review for the journal TC.

Atmospheric drivers of melt-related ice speed-up events on the Russell Glacier in Southwest Greenland

Timo Schmid, Valentina Radić, Andrew Tedstone, James M. Lea, Stephen Brough, and Mauro Hermann

Abstract. The Greenland ice sheet is a major contributor to current and projected sea level rise in the warming climate. However, uncertainties in Greenland’s contribution to future sea level rise remain, partly due to challenges in constraining the role of ice dynamics. One process that has the potential to indirectly affect the mass budget of the ice sheet are transient ice accelerations, or ice speed-up events, lasting from one day to a week and triggered by overloading the subglacial drainage system with an increase in water supply. In this study, we identify melt-induced ice speed-up events at the Russell Glacier, Southwest Greenland, in order to analyse synoptic patterns driving these events. The short-term speed-up events are identified from daily ice velocity time series collected from six GPS stations along the glacier, for each summer (May–September) from 2009 to 2012. In total, 45 ice speed-up events are identified, of which 36 are considered melt-induced events where melt is derived from two in-situ observational datasets and one regional climate model forced by ERA5 reanalysis. 16 out of the 45 speed-up events co-occur with lake drainage events, and only four are linked with extreme rainfall events. The 36 melt-induced speed-up events occur during synoptic patterns that can be grouped into three main clusters: (1) patterns that resemble atmospheric rivers with a landfall in Southwest Greenland, (2) patterns with anticyclonic blockings centred over Southwest Greenland, and (3) patterns that show low pressure systems centred either south or southeast of Greenland. Out of these clusters, the one resembling atmospheric river patterns is linked to the strongest speed-up events induced by a 2–3 day continuously increasing surface melt driven by anomalously high sensible heat flux and incoming longwave radiation. In the other two clusters, the net shortwave radiation dominates the contribution to the melt energy. As the frequency and intensity of these weather patterns may change in the warming climate, so may the frequency and intensity of ice speed-up events, ultimately altering the mass loss of the ice sheet.

Timo Schmid et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2023-1', Anonymous Referee #1, 14 Feb 2023
  • RC2: 'Comment on tc-2023-1', Anonymous Referee #2, 11 May 2023

Timo Schmid et al.

Timo Schmid et al.


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Short summary
The Greenland ice sheet contributes strongly to sea level rise in the warming climate. One process that can affect the ice sheet's mass balance are short-term ice speed-up events. These can be caused by high melting or rainfall as the water flows underneath the glacier and allows for faster sliding. In this study we found three main weather patterns that cause such ice speed-up events on the Russell Glacier in Southwest Greenland and analyse how they induce local melting and ice accelerations.