170 likes | 279 Views
Automated Snow Measurement R&D at NCAR and NOAA: the Marshall testbed. Ethan Gutmann, Bruce Baker, Roy Rasmussen, John Kochendorfer , David Gochis , Scott Landolt , Tilden Meyers, Kristine Larson 5/25/2011. Snow measurement importance. Which size snowplow would you want? .
E N D
Automated Snow Measurement R&D at NCAR and NOAA: the Marshall testbed • Ethan Gutmann, Bruce Baker, Roy Rasmussen, John Kochendorfer, David Gochis, Scott Landolt, Tilden Meyers, Kristine Larson • 5/25/2011
Snow measurement importance • Which size snowplow would you want?
Snow Measurement is HARD • Spatial variation • Snow depth varies from 0-3m over the space of 50m! • harsh environments • ice on equipment • temperatures <<0C Map of
Existing and Emerging methods • Ultrasonic distance • Scanning (or not) laser rangefinder • GPS interference reflectometry • Precipitation: snow gauges • (COSMOS, Snow Pillows, Aircraft LIDAR,…) (*there is always the good old ruler)
Precipitation measurement • Wind shields affect precipitation measurement
Ultrasonic Snow Depth • Bounce a sound wave off the snow • footprint: ~1m2 • Affected by • air temperature • snow in air
Ultrasonic Snow Depth • Location is critical • Ground surface is critical • Replication is critical • Hourly totals? • 6hr?
Ultra Sonic Depth • Sensor can shift almost imperceptibly • with snow on them... ~30cm Snow Event
Laser Rangefinder (non-scanning) • Bounce light pulse off snow • footprint: 1mm2 • NOT affected by • air temperature • snow in air
Laser Rangefinder (non-scanning) Ultrasonic • Location is critical • Ground surface is critical • Signal is cleaner • hourly totals... Laser
Scanning Laser Rangefinder • Bounce a light pulse off the snow • footprint: <7km2 • affected by: • snow on lens and in air
Laser Rangefinder (non-scanning) • Produces a map! • Location is NOT (too) critical • Ground surface is NOT (too) critical • Stability is critical
GPS Interference Reflectometry (GPS-IR) • Observe noise in GPS signal • footprint: 2000m2 • affected by: • topography • vegetation
GPS-IR • Location is important • Ground cover is important • Free existing networks! • ~1-2hr averages...
Sensor Review Comments Location / Cheap Location / Cheapish Stability / Cost Location / (Free) Accuracy / Cost / Time Accuracy 1cm 1mm <1cm ~1-2cm >5-10cm Area 1m2 1mm2 <7km2 3000m2 100km2 • Sonic • Laser • Scanning • GPS • Lidar