DESCRIPTION: PR-OBS-5
Accumulated precipitation at ground by blended MW and IR

Derived from precipitation maps generated by merging MW images from operational sun-synchronous satellites and IR images from geostationary satellites (i.e., products PR-OBS-3 and PR-OBS-4). Presented in polar stereographic projection.

  • Coverage: The rectangular area of the stereographic projection that includes the H-SAF area [25-75°N lat, 25°W-45°E long]
  • Cycle: Each 3 hours: MW+IR integrated over the previous 3, 6, 12 and 24
  • Resolution: Average over Europe: 8 km intended as sampling, ~ 30 km effective (controlled by the resolution of MW data)
  • Accuracy: From PR-OBS-3 or PR-OBS-4: 40 % (lower bias from PR-OBS-4). More accurate for 24-h than for 3-h integration
  • Timeliness: At fixed times of the day, within 15 min after synoptic hours (00, 03, 06, 09, 12, 15, 18 and 21 UTC)
  • Dissemination: By dedicated lines to centres connected by GTS - By EUMETCast to most other users, especially scientific
  • Formats: GRIB - Also JPEG or similar for quick-look

Short description of the basic principles for product generation

Product derived by time integration of product PR-OBS-3 and PR-OBS-4 (96 samples/day at 15-min intervals) over 3, 6, 12 and 24 hours. The product from PR-OBS-4 (i.e. by "Morphing") should be better (lower bias) than that one from PR-OBS-3, but the latter is more prompt since does not have to wait for a fresh MW determination. PR-OBS-4 is considered for use in Version-2. Computing accumulated precipitation is not only a simple integration of precipitation intensities but involves some information sources like rain gauges data and QPF coming from NWP in order to minimize bias and random errors and to take into account orography. The error structure of the precipitation rate measurements is accounted for. Rain gauge data are corrected for surface wind effect. Climatological thresholds are applied on the final products to avoid some outliers.