Topic: How to Test Temperature Sensor?

[pertman]

Hi All: I have a Davis VP2 wireless station with an additional temperature sensor located in my citrus area. The station is mounted on a Davis tripod on our flat roof here in Tucson. What I am concerned about is the significant temperature difference between the sensor on the station and in the citrus area. The additional sensor ranges from 7-9 degrees F lower than the one on the roof. I have the additional sensor mounted on a wood post about 5' from the ground. The elevation difference between the two sensors can't be more than 18-20 feet. I don't have another thermometer to test the second sensor. I have had it about 4 years now. The original sensor seems to be working fine since it is within a degree or two of the airport's reported temp here in Tucson (as well as being consistent with surrounding reports on a Mesonet. 

Any suggestions about how to see if the second sensor is working correctly? Is there a built in test function?

Many thanks (from a longtime lurker)!

P.

[bigharps]

Just a couple of thoughts:

• Is the extra sensor surrounded by the citrus trees? If it is there could well be a fair temperature difference between it and the one on a roof. I'm assuming you are quoting Fahrenheit degrees, so it is only about 4 or 5 Celsius degrees. I suspect you would expect a cooler temperature between or near the trees.
• If you have no other thermometer, how difficult would it be to temporarily put the extra one on the roof, next to the station, even for an half hour or maybe less? There is a big difference between the amount of heat reflected by soil and from that reflected by roofing materials. Both sensors in the same place would be a good test.

As far as I know, there is no built in testing function.

[ValentineWeather]

That's the simple solution move the sensors together.
Trust the nearby Mesonet station they have accurate temperatures. 

[ocala]

Just a couple of thoughts:

• Is the extra sensor surrounded by the citrus trees? If it is there could well be a fair temperature difference between it and the one on a roof. I'm assuming you are quoting Fahrenheit degrees, so it is only about 4 or 5 Celsius degrees. I suspect you would expect a cooler temperature between or near the trees.
• If you have no other thermometer, how difficult would it be to temporarily put the extra one on the roof, next to the station, even for an half hour or maybe less? There is a big difference between the amount of heat reflected by soil and from that reflected by roofing materials. Both sensors in the same place would be a good test.

[/b]
As far as I know, there is no built in testing function.

This is the problem. A temperature sensor shouldn't be placed over any type of roof.

[bigharps]

This is the problem. A temperature sensor shouldn't be placed over any type of roof.

Agreed. Unfortunately, the station is where it is. His easiest solution is to move the extra sensor to the roof for long enough for the temperature to stabilise and then compare.
I find it difficult to worry over other people's station positioning, because mine is about 6'6" above the ground. Ideal positioning was easy when we had acres, now we have only about 1000 square metres, and there are houses and trees all around. I got the anemometer up about 7 metres, so it is pretty well in the clear. Unfortunately suburbia makes for problematic siting.

[pertman]

Thanks for the suggestion. That didn't even occur to me. I will need to do some disassembly but a great idea. Will do after this recent cold snap here in Tucson.

Have a great week!

P.

[azchrisf]

Here in Arizona putting a station on a roof that gets 150+ in the summer is just asking for a bad reading.I tried it as a experiment.

Have you read the CWOP station siting guide by any chance ? Has some good tips.

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