Fractional snow cover time series (1981 – 2021) (GCOS Swiss)

Contact: Helga Weber, Christoph Neuhaus, Kathrin Naegeli, Stefan Wunderle
Consortium:  Sven Kotlarksi (MeteoSwiss)
Funding source: MeteoSwiss in the framework of GCOS Switzerland
Duration: Summer 2020 – Winter 2021

Switzerland's snow cover is highly relevant to its climate, vegetation, hydrology, and tourism. Information on snow coverage in Switzerland is currently provided by a dense measurement network of stationary in-situ instruments, maintained by MeteoSwiss and SLF-WSL. With this project, missing spatial information will be overcome by generating a 40-year fractional snow cover time series for Switzerland based on Advanced Very High Resolution Radiometer (AVHRR) satellite data. Data source, is the University of Bern, which holds one of the largest European archives for AVHRR data.

For the time period 1981 until 2021, fractional snow cover will be calculated including its uncertainty and quality information (1km2). In addition, snow on ground will be estimated in forested areas to obtain better knowledge on the snow cover below trees. A temporal filtering approach will be applied to minimize the influence of clouds overcoming corresponding gaps. The spatial and temporal analysis of e.g. the derived 40-year monthly anomalies of snow cover will improve our understanding on the variability of Alpine snow cover. Further analysis of the new data set will be in close cooperation with Climate Evolution, MeteoSwiss. By that, the data set will serve as an improved basis for the Swiss climate services to enhance our process understanding in the field of snow cover dynamics and its impact on local society. The novel snow cover time series will be public available and supports climate studies as an independent data source on snow cover dynamics.