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uk.sci.weather (UK Weather) (uk.sci.weather) For the discussion of daily weather events, chiefly affecting the UK and adjacent parts of Europe, both past and predicted. The discussion is open to all, but contributions on a practical scientific level are encouraged. |
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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. |
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"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 |
#3
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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. |
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"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 |
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