Assessment of the Topographic Wetness Index in Permafrost landscapes

Arctic permafrost regions are subject to rapid changes due to climate warming affecting hydrology, topography and ecology. Soil wetness is of great importance in these regions facilitating for example upscaling of carbon fluxes. In this study we therefore investigate the Topographic Wetness Index (TWI) as often used in land surface modelling, focusing on study regions in the Siberian and Canadian Arctic. We analyse the influence of the used Digital Elevation Model (DEM) by comparing results of the openly available ArcticDEM (2m resolution) and Copernicus DEM (30m resolution). Results are being validated against near-surface soil moisture in-situ measurements. Further comparisons are being made to other wetness indices such as the Tasselled Cap Wetness index or the Normalized Differential Moisture Index derived from Landsat 8. The relationship to InSAR derived surface displacements as an indicator of soil wetness is explored, as well as additional parameters such as the Topographic Position Index and correlations to other moisture indicators including land cover products.