TanDEM-X and Sentinel-2: Opportunities for Investigating Retrogressive Thaw Slumps

Among the most rapid and dramatic changes related to Arctic permafrost thaw are retrogressive thaw slumps. These slumps evolve by a retreat of the slump headwall during the summer months, making their change visible by comparing digital elevation models over time or by identifying the induced vegetation changes in time-series of optical satellite images. In this study we use digital elevation models generated from TanDEM-X observations to detect and derive volume and area change rates for RTSs on the Taymyr Peninsula. The available data takes allows to compare two time periods: from 2010/11/12 to 2016/17 and from 2017/18 to 2020/21. From 2016 onwards optical Sentinel-2 observations are available for which we manually map thaw slumps for each year in a small sub-area and compare the results to the TanDEM-X mapped RTSs. We found a strong, non-linear increase in the second time-period of the TanDEM-X period and by using the optical mapped RTSs we could attribute this increase to the Siberian heatwave in 2020.