DESCRIPTION: SN-OBS-2
Snow status (dry/wet) by MW radiometry

This product indicates the status of the snow mantle, whether it is wet or dry and, in time series, thawing or freezing, by multi-channel MW observation (middle frequencies).

  • Coverage: The H-SAF area [25-75°N lat, 25°W-45°E long]
  • Cycle: Daily
  • Resolution: 10-30 km (0.25 deg grid), depending on the location (best for northern parts, worst for southern parts of the H-SAF area)
  • Accuracy: HR 80 %, FAR 10 % - Depending on snow thickness (it must not be too shallow)
  • 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 grid points in latitude/longitude grid - Also JPEG or similar for quick-look.

Short description of the basic principles for product generation

In the microwave range, snow emissivity is substantially different for dry and wet snow, therefore snow status observation is a relatively straightforward application, also facilitated by the all-weather capability. The emissivity substantially increases when snow is wet, enabling detection of snow status. Middle frequencies are used (19 and 37 GHz). The recognition of dry snow for snow pack shallower than 80 mm is unreliable due to high penetration depth of microwaves in dry snow. The algorithm as stand-alone is unable to discriminate wet snow from bare ground (a problematic solution for mountainous regions), thus wet snow status is recorded only for those locations where Snow detection (product SN-OBS-1) has revealed snow or there has been dry snow in the preceding product.