Transcript Deutscher Wetterdienst Titelfoto auf dem Titelmaster einfügen IMPROVING RELIABILITY AND SENSITIVITY OF A LASER SNOW DEPTH GAUGE Eckhard Lanzinger and Manfred Theel, Deutscher Wetterdienst.

Deutscher Wetterdienst
Titelfoto auf dem Titelmaster einfügen
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
 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
Laser gauge provides backscatter signal
DWD / E. Lanzinger
Experimental setup
TECO-2010, 30. August – 1. September 2010, Helsinki, Finland
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
SHM30 backscatter signal
SHM30 snow depth
14:15 SHM 30 – snow depth > 0.5 cm
SR50 (corrected 5 minute mean)
17:14 SR50 - snow depth ≥ 1cm
Backscatter signal allows early detection of snow cover
DWD / E. Lanzinger
TECO-2010, 30. August – 1. September 2010, Helsinki, Finland
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.
DWD / E. Lanzinger
TECO-2010, 30. August – 1. September 2010, Helsinki, Finland
Operational Experience
Both laser points were
about 10 cm apart
Very good correlation of two laser gauges and no zero drift
DWD / E. Lanzinger
TECO-2010, 30. August – 1. September 2010, Helsinki, Finland
Multipoint Measurement
 Manufacturers should think about
a scanning laser snow depth
gauge to cover larger areas
DWD / E. Lanzinger
TECO-2010, 30. August – 1. September 2010, Helsinki, Finland
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!
DWD / E. Lanzinger
TECO-2010, 30. August – 1. September 2010, Helsinki, Finland