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How accurate is the WH1081 anemometer?

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hungerdunger
Posts: 74
Joined: Fri 26 Dec 2008 8:03 pm
Weather Station: Maplin N96GY (WH-1081)
Operating System: Windows 10 Pro
Location: Carmarthen, West Wales

How accurate is the WH1081 anemometer?

Post by hungerdunger »

Over the last few days it has been pretty windy here, and the BBC weather forecast has predicted winds well in excess of 20mph.

Yesterday the highest gust was 13mph and today 21 mph, while the highest wind was 8 and 13 mph respectively.

At times when it felt really windy, it was recording winds of around 7 to 10 mph.

I suspect that it is not recording the wind speed accurately, and I'm wondering if other people have similar observations.

BTW, the pole it's mounted on is exactly vertical and the anemometer spins freely.
Capel Dewi (Carmarthen) Weather Station:
https://twitter.com/CapelDewiWeathr
skyewright
Posts: 34
Joined: Wed 03 Dec 2008 3:45 pm
Weather Station: WMR200+928>RFXCOM>Meteohub
Location: Elgol, Isle of Skye
Contact:

Re: How accurate is the WH1081 anemometer?

Post by skyewright »

hungerdunger wrote:BTW, the pole it's mounted on is exactly vertical and the anemometer spins freely.
How high?
Any obstructions anywhere near?

Official anemometers are usually mounted on 10m masts and well clear of any obstructions (and probably sample over a shorter period -I'm not sure what period the WH1081 uses?).
Regards
David

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hungerdunger
Posts: 74
Joined: Fri 26 Dec 2008 8:03 pm
Weather Station: Maplin N96GY (WH-1081)
Operating System: Windows 10 Pro
Location: Carmarthen, West Wales

Re: How accurate is the WH1081 anemometer?

Post by hungerdunger »

skyewright wrote:
hungerdunger wrote:BTW, the pole it's mounted on is exactly vertical and the anemometer spins freely.
How high?
Any obstructions anywhere near?

Official anemometers are usually mounted on 10m masts and well clear of any obstructions (and probably sample over a shorter period -I'm not sure what period the WH1081 uses?).
It's only about 4 metres above ground level, but there are no obstructions. I live on a smallholding and it's situated above a hedge between two fields well away from the house.
Capel Dewi (Carmarthen) Weather Station:
https://twitter.com/CapelDewiWeathr
skyewright
Posts: 34
Joined: Wed 03 Dec 2008 3:45 pm
Weather Station: WMR200+928>RFXCOM>Meteohub
Location: Elgol, Isle of Skye
Contact:

Re: How accurate is the WH1081 anemometer?

Post by skyewright »

hungerdunger wrote:It's only about 4 metres above ground level, but there are no obstructions. I live on a smallholding and it's situated above a hedge between two fields well away from the house.
I use a WMR200, but with that, when I raised my anemometer from ~2.5m to ~5.5m I estimate that it increased gust measurements by up to 20%.

The spec. I found doesn't mention the sampling period. That can be very significant for gust measurement. A VP2 sampling over 2.5 seconds is bound to 'catch' better gust speeds than (say) a WMR200 sampling over 15 seconds. I remember seeing, but can't currently find, an interesting topic on another Forum that included some analysis of the impact of different sampling periods.

It seems a little odd that the spec. doesn't mention claimed accuracy either, just range, but overall it's not unlikely that the WH1081 is simply reporting what it finds, within its capabilities and that is unlikley to be the same as what an ideally situated much more expensive anemometer would manage. :(
Regards
David

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skyewright
Posts: 34
Joined: Wed 03 Dec 2008 3:45 pm
Weather Station: WMR200+928>RFXCOM>Meteohub
Location: Elgol, Isle of Skye
Contact:

Re: How accurate is the WH1081 anemometer?

Post by skyewright »

skyewright wrote:I remember seeing, but can't currently find, an interesting topic on another Forum that included some analysis of the impact of different sampling periods.
Here's the topic I was thinking of.
The message with the analysis of sampling periods is about halfway down the second page.
Regards
David

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