Snow Monitoring

Snow has a major influence on runoff patterns in many parts of Central Europe and especially in the Alps. Accurate knowledge of snow cover can help to better understand the water balance and to better predict extreme events in runoff (floods), but also stored water (energy production).

Due to the automatic and direct processing of optical data, maps with the following information are available within a short time after satellite overflight:

  • Snow covered areas

  • Snow boundaries

  • Snow free areas

  • Wet snow / melting snow

Snow maps are operationally provided within Polar View and other commercial services for different catchments and users. Adaptation of the outputs to the format desired by the users can be made.

The derivation of snow cover using optical data is hampered by clouds (dark gray). In the melting phase, the use of C-band microwave data (e.g., Sentinel-1, ENVISAT, and RADARSAT) allows detection of areas of melting snow with high liquid water content (dark blue).

Operational analysis of satellite data determines the extent of snow cover ideally on a daily basis and within a short time (near-real-time); left: NOAA-AVHRR, Rhine catchment (25.1.2009); right: automatic snow-cloud classification.

Observation of the decrease of snow cover in the catchment of the upper Danube in the period 25.2. – 1.3.2009; left: derived from NOAA-AVHRR (optical); right: derived from ENVISAT ASAR (C-band SAR)

The availability of Sentinel-1 data (since 2014) and operational access pathways such as those being established under Copernicus, among others, provide new opportunities for continuous observation of snow cover.

A significant added value for the user is provided by the modeling of the snow cover. In combination with the assimilation of satellite observations, the snow-water equivalent, i.e. the water stored in the snow, can be recorded and predicted for each point and each time step.

Snow cover (right) and snow water equivalent derived by modeling (left).

Thus, not only spatial distribution, but also the volume of stored water in the study area can be retrieved at any time step.

A movie of the snow cover progression between November 2011 and April 2012 can be found in the external link:

Synopsis of the Snow in Europe During the 2011/2012 Winter