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IMPROVING RELIABILITY AND SENSITIVITY OF A LASER SNOW DEPTH GAUGE

IMPROVING RELIABILITY AND SENSITIVITY OF A LASER SNOW DEPTH GAUGE. Eckhard Lanzinger and Manfred Theel, Deutscher Wetterdienst (DWD). Comparison of ultrasonic and laser snow depth gauges.

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IMPROVING RELIABILITY AND SENSITIVITY OF A LASER SNOW DEPTH GAUGE

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  1. IMPROVING RELIABILITY AND SENSITIVITY OF A LASER SNOW DEPTH GAUGE Eckhard Lanzinger and Manfred Theel, Deutscher Wetterdienst (DWD)

  2. Comparison of ultrasonic and laser snow depth gauges • Campbell SR50G (ultrasonic)■ sonic cone with angle of aperture: 12° ■vertical measurement■measurement uncertainty: 1% of distance■ needs temperature compensation■ sensitive to snowfall and wind • Jenoptik SHM30 (laser)■ small red laser beam■ slanted measurement at an angle of 30° ■ measurement uncertainty: < 0.5 cm■ no temperature compensation needed■ insensitive to snowfall and wind Experimental setup Laser gauge provides backscatter signal

  3. Snowfall event on 23. January 2009 (Hamburg) 12:07 Onset of light / moderate snowfall wawa (Tab. 4680) 13:05 SHM 30 signal strength > 3.5 14:15 SHM 30 – snow depth > 0.5 cm SHM30 backscatter signal SHM30 snow depth 17:14 SR50 - snow depth ≥ 1cm SR50 (corrected 5 minute mean) Backscatter signal allows early detection of snow cover

  4. Operational Experience • Backscatter signal varies from gauge to gauge. Signal level should be calibrated and adjusted at the factory • Grey snow plate improves snow cover detection • Heating of housing has to be improved for icing conditions • Visible laser point can attract birds Comparison of two Laser snow depth gauges JENOPTIK SHM30. Icing problem of JENOPTIK SHM30.

  5. Operational Experience Both laser points were about 10 cm apart Very good correlation of two laser gauges and no zero drift

  6. Multipoint Measurement • Manufacturers should think about a scanning laser snow depth gauge to cover larger areas

  7. Conclusions • Positive features of Laser snow depth gauges■Slanted measurement with high accuracy■Practically independent of air temperature and wind■No drop outs even during heavy snowfall • Detection of snow cover by backscatter signal■Sensitivity increased■Reliability of snow depth measurement increased • Possible improvements■ Backscatter signal strength has to be calibrated■ Multipoint measurements Thank you for your attention!

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