Snow cover characteristics of the Alps derived from medium resolution remote sensing data

Kurzfassung

Snow cover is an important variable for water availability, it influences the radiation budget of the Earth surface, and may cause natural disasters such as avalanches or floods after the melting process. Within Europe especially in Norway, Sweden, and Switzerland, snow is an important source of freshwater for reservoirs and the subsequent production of electricity. Climate change affects parameters such as snow cover duration (SCD), generally leading to its decrease, a delayed snow cover onset and earlier snow melt. Further effects also include fewer frost days, reduced snow depth, reduced snow water equivalent, changes in soil frost and snow-fed river systems. Medium resolution remote sensing data originating from AVHRR and MODIS (and Sentinel 3) have been analyzed to understand both the current situation as well as possible long term tendencies of snow cover in the European Alps. The data is available on a daily basis which is essential as the snow cover extent can change rapidly during snow fall or snow melt events induced by sudden temperature increase. Data gaps caused by cloud cover can cause uncertainties, which make a post-processing of the time series necessary in order to estimate the snow cover status during cloud covered periods. The presentation will outline the current status of snow cover conditions in the Alps (mean SCD, mean early and late season SCD, stability) and it will demonstrate which processes can be observed within specific elevation or aspect zones.