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 Larson5/25/2011

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)

Marshall

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)

• Location is critical• Ground surface is

critical• Signal is cleaner• hourly totals...

UltrasonicLaser

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

• Sonic

• Laser

• Scanning

• GPS

• Lidar

Accuracy

1cm

1mm

<1cm

~1-2cm

>5-10cm

Area

1m2

1mm2

<7km2

3000m2

100km2

Comments

Location / Cheap

Location / Cheapish

Stability / Cost

Location / (Free)

Accuracy / Cost / Time