Snow Cover Measurement
Instrumentation
Ultrasonic Snow Depth Sensor
The Ultrasonic Snow Depth Sensor is an inexpensive
solution for remotely measuring snow depth or water
levels. The sensor works by measuring the time required
for an ultrasonic pulse to travel to and from a target
surface. An integrated temperature probe with solar
radiation shield, provides an air temperature measurement
for properly compensating the distance measured. An
embedded microcontroller calculates a temperature
compensated distance and performs an error checking
routine.
Both
distance and air temperature are output as an analog
signal between 0 to 2.5 volts or 0 to 5 volts.
Measurements are also output digitally.
When coupled with a data logger, snow level data can be
recorded at regular time intervals providing good data at
a minimum expense. The data can then be transmitted via
telephone or radio link. The sensor is easily installed
using the 1 inch NPT nipple on the back of the sensor. It
should be located in an area where snow will not be
disturbed and drifting is not likely to occur.
1004-075 Ultrasonic Snow
Depth Sensor 4 lbs.
Rain/Snow Station Standpipe - Model 3655
The Model 3655 Rain/Snow Station incorporates a 12" dia.
standpipe with the upper portion having a PGE or glycometh
solution reservoir. The lower portion of standpipe has a
tipping bucket rain gage and transmitter. The upper
standpipe has a temperature compensating overflow
mechanism that adjusts to thermally generated changes in
PGE solution level and routes melted precipitation to the
tipping bucket rain gage.
This is a self-contained system which is powered by
battery and solar panel charging. Two different standpipes
are available both with access door and four drain holes.
Transmitter options can be UHF or VHF and are detailed
with the gaging station equipment.
1004-120 12 ft. Rain/Snow
Station Standpipe
92 lbs.
1004-122 16 ft. Rain/Snow
Station Standpipe 115 lbs.
1001-044 Wind Screen -
48" dia.
92 lbs.
Snotel-Snow Pillow Stations
Snow surveyors and water managers need timely data for
forecasting and water management decisions. They also need
a way to survey particularly remote and hazardous
snowpacks. Snow survey courses provide valuable
information, but the typical schedule for manual survey
results in weeks with no specific insight into the
condition of the snowpack. In that time, intense storms
may be adding an abnormally large amount of snow or rain;
perhaps an unreasonable warm spell at high elevation is
resulting in a rapid melt with ensuing flood hazards.
The Snotel Remote Site Snow Pillow Station features
automatic sensing and data transmission for real-time
data. Snow pillows are used to measure the water content
in snow by weight displacement. The snow pillow is filled
with a PGE or a glycometh solution mixed to a density of 1
which is displaced from the pillow as the weight of the
snow accumulates on the pillow. The pressure of this
displacement is measured by a pressure transducer. Since
the PGE or glycometh solution has the same density as
water, the pressure is directly proportional to the water
content of the snow.
The
pillows are made of stainless steel, welded construction
and are airtight. These tanks are animal and rodent proof,
use one fourth the amount of solution as alternate types,
and require much less time to install. Four pillows should
be used in parallel for reliable operation and to minimize
the possibility of ice bridging. The snow pillows are 4
ft. wide x 5 ft. long x 1/2" thick and hold 12 gallons
each. Two pressure transducers options are offered both
with a ±1% full scale accuracy but different sensitivity
and range.
The basic Snotel system consists of a standpipe
assembly with precipitation gage, temperature sensor, omni
antenna, transmitter, battery with solar panel charger,
pressure transducer, connecting cables and four snow
pillows. Additional sensors can be incorporated into a
particular site for measuring wind speed and direction,
soil temperature or snow depth.
1004-100 Basic Snotel
System
298 lbs.
1004-102 Pressure
Transducer 0.1" x 2' H2O
1 lb.
1004-103 Pressure
Transducer 0.5" x 10' H2O
1 lb.
1004-110 Replacement Snow
Pillow
53 lbs.
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