Topic: WMR 968 anemometer

[Meteorologica]

It was me on the old forum that started off the discussion about adjusting the calibration for the WMR968 anemometer.

We did a load of testing here between assorted anemometer makes and came to the conclusion that while the OS device measures very accurately in a constant flow (checked by attaching it to a pole sticking out of the car roof and then driving it at a constant speed on a still day and using a GPS speedo to check it) the problem occurs on dynamically varying days due to the difference in sampling rate between the OS device and a Davis for example. The longer sampling period naturally smooths out the short gusts so the anemometer appears to record lower than the much faster sampling Davis. The 1.25 correction factor simply brings its apparent measurement back into line with the Davis. Its only advisable to use this in a domestic environment where the surrounding houses tend to make the wind speed very lumpy and turbulent. If you were installing it on a cliff top, for example, I would not recommend using the correction factor.

The factor needs to be applied to both average speed and gust to be consistent.

[killwilly]

The factor needs to be applied to both average speed and gust to be consistent.

Thank you for the clarification.

[mackbig]

I just assumed (and still think) mine was off by that factor all the time.   Otherwise in a contant wind storm (like many of our winter events) I would have been 25% over rather than bang on with the the official station after the change.

If OS qc on anemometers is anything like their humidity sesnors, then I am sure results may very. Some owners may have bang on wind, and some may need a 1.40 offset.

Andrew

[sam2004gp]

I just assumed (and still think) mine was off by that factor all the time.   Otherwise in a contant wind storm (like many of our winter events) I would have been 25% over rather than bang on with the the official station after the change.

If OS qc on anemometers is anything like their humidity sesnors, then I am sure results may very. Some owners may have bang on wind, and some may need a 1.40 offset.

Andrew

I had those thoughts as well.  When ever I would question my wind speed reading.

[port1]

  My annemometer has been accurate...I suppose I'm very fortunate to have received an accurate one with my OS purchase.  But I definitely improved my accuracy with the 1.2 offset (plenty of huge oak trees to my south).  The only downside is that I never have a "dead calm" reading, ever.  Life is full of compromises.

Henry

[Bashy]

As far as im aware mine has been pretty good too as far as accuracy goes, had the odd issue of a sticking reed switch and the darn thing freezing in winter (hopefully resolved the latter)