Sub-seasonal thaw slump mass wasting is not consistently energy limited at the landscape scale Simon Zwieback1,2, Steven V. Kokelj3, Frank Günther4, Julia Boike4, Guido Grosse4, and Irena Hajnsek2,5 1Department of Geography, University of Guelph, Guelph, Canada 2Department of Environmental Engineering, ETH Zurich, Zurich, Switzerland 3Northwest Territories Geological Survey, Government of Northwest Territories, Yellowknife, Canada 4Periglacial Research, Alfred Wegener Institute, Potsdam, Germany 5Microwaves and Radar Institute, German Aerospace Center (DLR), Wessling, Germany Correspondence to: Simon Zwieback (
[email protected]), Irena Hajnsek (
[email protected]) Abstract. Predicting future thaw slump activity requires a sound understanding of the atmospheric drivers and geomorphic controls on mass wasting across a range of time scales. On sub-seasonal time scales, sparse measurements indicate that mass wasting at active slumps is often limited by the energy available for melting ground ice, but other factors such as rainfall or the formation of an insulating veneer may also be relevant. To study the sub-seasonal drivers, we derive topographic changes from 5 single-pass radar interferometric data acquired by the TanDEM-X satellites. The estimated elevation changes at 12 m resolution complement the commonly observed planimetric retreat rates by providing information on volume losses. Their high vertical precision (around 30 cm), frequent observations (11 days) and large coverage (5000 km2) allow us to track mass wasting as drivers such as the available energy change during the summer of 2015 in two study regions. We find that thaw slumps in the Tuktoyaktuk coastlands, Canada, are not energy limited in June, as they undergo limited mass wasting (height loss of around 0 10 cm/day) despite the ample available energy, suggesting the widespread presence of an early-season insulating snow or debris veneer.