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Thies Laser Precipitation Monitor for precipitation type detection

Thies Laser Precipitation Monitor for precipitation type detection. H. Bloemink, E. Lanzinger KNMI/DWD 06/05/05. Contents. Principle Experiment Results Conclusions Recommendation. Principle. Disdrometer ( Dis tribution Dro plets). IR light beam with 45 cm² measuring area

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Thies Laser Precipitation Monitor for precipitation type detection

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  1. Thies Laser Precipitation Monitor for precipitation type detection H. Bloemink, E. Lanzinger KNMI/DWD 06/05/05

  2. Contents • Principle • Experiment • Results • Conclusions • Recommendation

  3. Principle • Disdrometer (Distribution Droplets) • IR light beam with 45 cm² measuring area • Extinction measurement • amplitude: diameter • duration: fall speed

  4. Comparison to known statistics of diameter and velocity of various precipitation types • Example: • Temperature constraints: • > 9 °C: liquid (exception: hail) • < - 4 °C: solid • Output: spectra, precip type, precip intensity

  5. Experiment • Data from DWD test site at Wasserkuppe (Hessen)

  6. Available data: 12-10-2003 – 31-11-2003 • Observer: 1 minute interval • Reference: includes T, RH, PI, wind speed, precip detector • Disdrometer • FD12P present weather sensor (current KNMI sensor) • Some processing: • Precip detector used for precip/no precip distinction • Time synchronisation • Averaging

  7. Results • 10-minute comparison

  8. In terms of verification scores:

  9. Optimisation • Find best possible performance using • Averaging PW for rain & snow mixtures • Use wet-bulb temperature to distinguish freezing liquid precipitation • Use wet-bulb temperature to distinguish rain and snow mixtures vs. Rain • Results: no improvement compared to the observer • Possible causes: • Disdrometer tuned to Wasserkuppe conditions? • Changes tuned to Dutch conditions & FD12P

  10. Conclusions • Thies disdrometer and Vaisala FD12P show similar results for precipitation type • Thies slightly better for liquid, FD12P for solid precipitation • Test of the Thies disdrometer in Dutch weather conditions • Possible use: precipitation type for smaller weather stations, or improved precipitation type by combination with FD12P Future

  11. Acknowledgements Wiel Wauben Eckhard Lanzinger Manfred Theel

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