A recent Euro News TV report called - "Mapping Out The Future of
Alpine Glaciers" features a Campbell Scientific weather station in use
in Northern Italy. When you see the challenging environments the
station endures and the journey required to access it one can see why
reliability and low power are so important in these solar powered,
autonomous systems.

The camera shows a number of sensors including the SR50A sonic snow
depth sensor; all sensors are measured by the CR3000 datalogger in the
enclosure which also processes and stores the data onboard and
controls the telecommunications to transmit data back to the control
centre.

See the report here http://bit.ly/adCTnB - I hope you all find it of
interest.

"Iain Thornton" wrote ...
A recent Euro News TV report called - "Mapping Out The Future of
Alpine Glaciers" features a Campbell Scientific weather station in
use
in Northern Italy. When you see the challenging environments the
station endures and the journey required to access it one can see
why
reliability and low power are so important in these solar powered,
autonomous systems.
The camera shows a number of sensors including the SR50A sonic snow
depth sensor; all sensors are measured by the CR3000 datalogger in
the
enclosure which also processes and stores the data onboard and
controls the telecommunications to transmit data back to the control
centre.
See the report here http://bit.ly/adCTnB - I hope you all find it of
interest.

.... Thanks! indeed it was: I would have liked to see more of the
'innards' of the system, i.e., a demonstration of how the snow
depth/thickness is actually measured, some idea of how accurate these
particular sensors are & how they cope when high-altitude weather is
'extreme' and the snow levels are fluctuating dramatically - but I
realise this was for a general audience.

Martin.




--
Martin Rowley
West Moors, East Dorset (UK): 17m (56ft) amsl
Lat: 50.82N Long: 01.88W
NGR: SU 082 023

On 23 Mar, 13:30, "Martin Rowley"
wrote:
"Iain Thornton" wrote ...



A recent *Euro News TV report called - "Mapping Out The Future of
Alpine Glaciers" features a Campbell Scientific weather station in
use
in Northern Italy. When you see the challenging environments the
station endures and the journey required to access it one can see
why
reliability and low power are so important in these solar powered,
autonomous systems.
The camera shows a number of sensors including the SR50A sonic snow
depth sensor; all sensors are measured by the CR3000 datalogger in
the
enclosure which also processes and stores the data onboard and
controls the telecommunications to transmit data back to the control
centre.
See the report herehttp://bit.ly/adCTnB- I hope you all find it of
interest.

... Thanks! indeed it was: I would have liked to see more of the
'innards' of the system, i.e., a demonstration of how the snow
depth/thickness is actually measured, some idea of how accurate these
particular sensors are & how they cope when high-altitude weather is
'extreme' and the snow levels are fluctuating dramatically - but I
realise this was for a general audience.

Martin.

--
Martin Rowley
West Moors, East Dorset (UK): 17m (56ft) amsl
Lat: 50.82N * Long: 01.88W
NGR: SU 082 023

Hi Martin,

The SR50A snow depth sensor is manufactured by Campbell Scientifc
Canada and is designed specifically to withstand harsh Canadian
conditions. Mounted horizontally at a known height pointing at the
ground, the sensor emits ultrasonic pulses and measures the elapsed
time between the emission and return of the pulse to determine any
change in height. An air temperature measurement is also required to
correct for variance in the speed of sound, this can either be taken
from a seperate temperature sensor (usually available on the AWS) or
on variant SR50AT a built-in sensor provides the reading. Measurement
range is 0.5-10m with a resolution of 0.25mm and an accuracy of ±1.0cm
or ±0.4% of target distance whichever is greatest. The sensor will
operate within specification between -45°C and +50°. Some idea of the
likely snow height is useful before positioning the sensor so that it
doesn't end up buried. I am hoping to feature an application story on
this sensor in our next newsletter.

Interestingly there has been some discussion about the surface beneath
the sensor - clearly if it is grass then regular mowing is required to
prevent erroneous snow readings in summer so artificial surfaces are
sometimes used. I am positive that I once read a report that rabbits
and other small animals liked to sit beneath the sensors also causing
false readings but I can't for the life of me track it down - if
anything you would imagine the ultrasonic pulses to scare animals
away.

These sensors are used by many of the world's national met services
and quite extensively in mountainous regions such as the Alps - if
interested there is an independent paper entitled EVALUATION OF
ULTRASONIC SNOW DEPTH SENSORS FOR AUTOMATED SURFACE OBSERVING SYSTEMS
(ASOS) which can be found by Googling the title. A leaflet and manual
for the sensor is also available on our website at
http://www.campbellsci.co.uk/index.cfm?id=233.

Hope that helps.

"Iain Thornton" wrote ...

The SR50A snow depth sensor is manufactured by Campbell Scientifc
Canada and is designed specifically to withstand harsh Canadian
conditions. Mounted horizontally at a known height pointing at the
ground, the sensor emits ultrasonic pulses and measures the elapsed
time between the emission and return of the pulse to determine any
change in height.
snip

These sensors are used by many of the world's national met services
and quite extensively in mountainous regions such as the Alps - if
interested there is an independent paper entitled EVALUATION OF
ULTRASONIC SNOW DEPTH SENSORS FOR AUTOMATED SURFACE OBSERVING SYSTEMS
(ASOS) which can be found by Googling the title.
snip

Hope that helps.

.... Indeed it does! Many thanks for that very full answer, and also
for indicating the appropriate paper: I managed to locate it, and for
others, the abbreviated url is he-

http://tinyurl.com/ydl8fbm

It's a long read, but well worth it as it is an important subject. The
photographs of typical installations are worth looking at, and the
introduction & conclusions/recommendations would provide a useful
summary if you're not inclined to plough through the entire paper,
though looking at Section 3 would also be appropriate.

As a life-long member of the 'we used to do it better with a ruler'
brigade, I was *very* impressed, and, as long as some of the
limitations were taken into account (high winds/heavy snow/snow
character etc.), which seem to be detectable relatively easily, the
system, particularly the Campbell units, returned creditable
performances. I suppose that, as with rainfall measurement, there will
always be problems with power supply fluctuation/failure and data
transfer loss - but the rigs themselves seem to be very rugged and
give a decently low mean error and small s.d.

There's probably a continuing problem with *small* amounts of snow
(and patchy but 50% cover) given the fixed nature of the sensor, but
this was recognized by the recommendation that multiple sensors should
be employed.

I shall look at these data with much more understanding in the future.
Once again, a most useful post.

All the best,

Martin.


--
Martin Rowley
West Moors, East Dorset (UK): 17m (56ft) amsl
Lat: 50.82N Long: 01.88W
NGR: SU 082 023