Sub-seasonal thaw slump mass wasting is not consistently energy limited at the landscape scale

Abstract

Abstract. Predicting future thaw slump activity requires a sound understanding of the atmospheric drivers and geomorphic controls on mass wasting across a range of timescales. On sub-seasonal timescales, 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 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 km 2 ) 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 cm day −1 ) despite the ample available energy, suggesting the widespread presence of early season insulating snow or debris veneer. Later in summer, height losses generally increase (around 3 cm day −1 ), but they do so in distinct ways. For many slumps, mass wasting tracks the available energy, a temporal pattern that is also observed at coastal yedoma cliffs on the Bykovsky Peninsula, Russia. However, the other two common temporal trajectories are asynchronous with the available energy, as they track strong precipitation events or show a sudden speed-up in late August respectively. The observed temporal patterns are poorly related to slump characteristics like the headwall height. The contrasting temporal behaviour of nearby thaw slumps highlights the importance of complex local and temporally varying controls on mass wasting.

Permafrost Terrain Dynamics and Infrastructure Impacts Revealed by UAV Photogrammetry and Thermal Imaging

“…The headwall of an active thaw slump is often characterized as near-vertical with an angled lower slope, but the morphology represents a time transient continuum that varies with exposure height, nature of materials, and rates of thaw. Quantifying these complexities enables the controls on headwall morphology to be explored and provides boundary conditions relevant to modeling processes of headwall ablation [3,80]. At a macroscale, the headwall of slump FM3 is relatively uniform by mid-summer, likely due to the homogeneity of surface topography and subsurface ground-ice conditions (Figures 5 and 6).…”

“…Circumpolar warming has heightened the need to develop and implement new tools to visualize and quantify permafrost terrain dynamics and related infrastructure impacts. The acceleration of climate-driven permafrost thaw is modifying landscapes [1][2][3] and placing infrastructure at increased risk [4,5]. Permafrost terrain processes are largely governed by freeze-thaw of the active-layer [6].…”

“…Advances in remote sensing technology and techniques to image landscapes and monitor surface changes are resolving landscapes at higher spatial and temporal resolutions [11], and providing new insights into cold climate geomorphic processes [3,[12][13][14]. Studies that track permafrost thaw and consequent ecosystem change have effectively utilized sequential aerial photographs [8,15,16], Light Detection and Ranging (LiDAR) [14,17], Landsat-derived change products [12,[18][19][20], and Interferometric Synthetic Aperture Radar (InSAR) [3,13,21]. These tools and techniques have their respective advantages, but satellite-and manned aircraft-based sensors inherently lack the flexibility to provide cloud-free high spatial resolution data (e.g., <10 cm) at frequent user-defined intervals, typically desirable in field-scale study of permafrost dynamics.…”

Investigation of a Small Landslide in the Qinghai-Tibet Plateau by InSAR and Absolute Deformation Model

“…After June, the rapid increase of precipitation and thaw depth led to the occurrence of landslides, becoming the main controlling factor of deformation ( Figure 8). The events were widespread in subarctic and Arctic areas [75,76], Siberia [77] and Qinghai-Tibet [78] and attributable to anomalously high air temperature and high precipitation during the thawing season in these years.…”

GPS Interferometric Reflectometry Reveals Cyclic Elevation Changes in Thaw and Freezing Seasons in a Permafrost Area (Barrow, Alaska)

“…But this method is time-consuming and labor intensive. Recently, new data and methods such as satellite stereo-photogrammetry (Günther et al, 2015;Zwieback et al, 2018), airborne light detection and ranging (Jones et al, 2013;Obu et al, 2017), interferometric synthetic aperture radar (Daout et al, 2017;Liu et al, 2010Liu et al, , 2012, and differential Global Positioning System (GPS; Little et al, 2003;Shiklomanov et al, 2013) have emerged for measuring vertical displacements of frozen ground. All the aforementioned techniques only provide measurements annually or monthly.…”