Aufeis (naleds) from 1958 historical maps and 2013-2017/2019 Landsat-8 OLI images in North-Eastern Eurasia

Historical data collection is created based on the Cadastre of aufeis (naled) of the North-East of the USSR (1958). Each aufeis was digitized as point feature by the inventory map (scale 1:2 000 000), or by topographic maps. Attributive data was obtained from the Cadastre of aufeis. Present-day aufeis dataset was created by Landsat-8 OLI images for the period 2013-2017/2019. Each aufeis was delineated by satellite images as polygon. Cloud-free Landsat images are obtained immediately after snowmelt season (e.g. between May, 17 and June, 16), to detect the highest possible number of aufeis. Critical values of Normalized Difference Snow Index (NDSI) were used for semi-automated aufeis detection. However, a detailed expert-based verification was performed after automated procedure, to distinguish snow-covered areas from aufeis and cross-reference historical and satellite-based data collections.