Jul 28, 2021
The unusual behaviour of Harald Moltke Bræ, a glacier in northwest Greenland
Flow velocity of the glacier during its quiescent phase in March 2012. The main branch of flows from East to West to the glacier front in the top left corner of the image. Flow speeds in this quiescent phase range from 0 m/day (blue) to 0.35m/day (orange).
About 1 % of glaciers worldwide are surge-type glaciers. Their glacier flow alternates between long-time quiescent phases with very slow movement and shorter surge phases with fast flow. Seasonal variations in glacier speed are a very different type of glacier flow variation, frequently observed in Greenland.
Harald Moltke Bræ is a surge-type glacier in northwest Greenland. While its previously observed surges lasted 2 to 4 years, its latest surge lasted 6 years from 2013 to 2019. During this surge phase, glacier speed varied extremely during each year, peaking in the early melt season and decreasing rapidly later when meltwater runoff was maximum.
On 21 July 2021, the journal The Cryosphere published our detailed analysis of this peculiar combination of surging and seasonal velocity variation, along with a discussion of possible causal mechanisms.
The study benefitted from a wealth of new data on glacier flow velocities. They include flow velocities calculated at TU Dresden from satellite images of the Landsat missions as well as results based on the Sentinel-1 and TerraSAR-X missions.
First author Lukas Müller (now at ETH Zurich) shaped results of his TU Dresden Master's thesis into this publication. The study builds on extensive previous work of colleagues at TU Dresden as well as on collaborations with partners at the Bavarian Academy of Sciences and Humanities, the German Aerospace Center (DLR) and the Technical University of Denmark.
Link to the paper: https://doi.org/10.5194/tc-15-3355-2021
Geodetic Data Portal including the portal for flow velocity fields of Greenland outlet glaciers: https://data1.geo.tu-dresden.de/