DESCRIPTION: SN-OBS-4
Snow water equivalent by MW radiometry

Maps of snow water equivalent derived by MW measurements sensitive to snow thickness and density. The product may be processed in different ways and have different quality depending on the surface being flat, forested or mountainous. This product is scheduled to be released in a late phase of the Project.

  • Coverage: The H-SAF area [25-75°N lat, 25°W-45°E long]
  • Cycle: Daily/weekly
  • Resolution: 10-30 km (0.25 degrees), depending on the location (best for northern parts, worst for southern parts of the H-SAF area)
  • Accuracy: To be assessed - Tentative: 20 mm - Depending on geographical situation (flat/forested, mountainous)
  • Timeliness: Fixed time of the day, product updated to account for data available until 1 h before delivery
  • Dissemination: By dedicated lines to centres connected by GTS - By EUMETCast to most other users, especially scientific
  • Formats: Values in fixed latitude/longitude grid, each representing the area covered by the nominal resolution of the used instrument. - Also JPEG or similar for quick-look.

Short description of the basic principles for product generation

Microwaves are sensitive to snow thickness and density, i.e. to the snow water equivalent. Depending on the snow being dry or wet, the penetration changes (dry snow is more transparent). High frequencies are required for dry snow, which is an advantage from the resolution viewpoint. However, with increasing snow depth, lower frequencies are necessary for better penetration, thus a multifrequency approach is required. It is an all-weather, night-and-day measurement, whose processing requires considerable support from ancillary information. Method and performance may be different for flat/forested areas and mountainous regions. The potential capability of radar scatterometry also will be assessed. Method and performance may be different for flat/forested areas and mountainous regions. The variation of snow density and snow characteristics in terms of grain size with respect to elevation and time scale are considered in the method for mountainous regions.