Thermometers v AWS sensors

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Richard Griffith
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Location: Horsham West Sussex
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Thermometers v AWS sensors

Post by Richard Griffith » Sun Jul 31, 2016 8:15 am

I recently had the misfortune to break a minimum thermometer, I checked various suppliers and was amazed at the prices. For the supply of a sheathed maximum and sheathed minimum thermometer I have been quoted anything between £216 - £450. Thank goodness for my AWS system. Due to these high costs I am seriously considering buying another TingTag data logger (I already have one which logs air temperature every 2min) but this time, one with an external probe - cost of this would be around £150 and the battery lasts for around 3yrs. I am not sure how many climate stations still use glass thermometers but with the regulations around the use of mercury and costs of glass thermometers it will be interesting to see how AWS sensors continue to develop.

Regards
Richard Griffith
Amateur Meteorologist
Horsham, West Sussex
follow me on twitter @Metman062

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Nicholas Gardner
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Location: Rural riverside valley location near the village of Newton Poppleford and 2 km from the sea.
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Re: Thermometers v AWS sensors

Post by Nicholas Gardner » Fri Aug 05, 2016 7:32 pm

Richard, I have minimum and maximum thermometers in a Stevenson Screen alongside the AWS thermo/humidity probe within the screen. Over the years I have come to rely on the daily task of reading the sheathed thermometers less and less. The Davis AWS actually reads pretty much the same as the normal sheathed thermometers so makes that daily task less relevant. Even so, I generally still do my daily manual readings but I now rely on the AWS for my temperature records.

Interestingly, just for no reason other than slight interest, I have an old Oregon Scientific WMR200A thermo-humidity probe in the Stevenson Screen as well and this reads astonishingly similar to the Davis AWS for temperature, nearly always within 0.2°C but generally slightly less for humidity.

Using the AWS TBR for accurate rainfall measurement is a definite no-go area as the differences between it and my standard 5" rain gauge can be out by as much as 10% to 20%.
Otter Valley Weather
Near Newton Poppleford, Sidmouth - Devon
50:41N 3:17 W; 20 metres AMSL; Station Grade B-BAAA37
http://www.ottervalleyweather.me.uk

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Michael Brown
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Re: Thermometers v AWS sensors

Post by Michael Brown » Sun Aug 07, 2016 12:00 pm

I too have both types in my screen. Standard Met Office sheather thermometers and my own design sensors connected to a Labjack unit. I have also found the same as Nicholas that the results are generally no more than 0.2 C degrees different, mostly 0.1 or nil difference. The only problem I ave found is that they do not compare well to the maximum thermeomter which is always 0.6 ˚C out. This I believe to be a fault of the sheathed thermometer, not the elctronic sensor. When I bought them they were around £5 each, and required a small circuit to conenct to the long hard wiring connection.

Mike

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