Topic: How much is the ultrasonic anemometer affected by pole sway?

[beruk]

Hello!

Today, I mounted my HP2553's ultrasonic anemometer on a 4-foot PVC pipe, thinking "this is only temporary" as I was mounting it. The pole does sway a bit. It hasn't been windy at all today so I don't know how much of a sway there will be in windy conditions, but I am pretty sure it will.

Before spending on a metal pole to make this installation more solid and less prone to sway, I was wondering: how much does swaying affect wind readings with the ultrasonic anemometer?

Thanks,

Pascal

[DaleReid]

A rough way to look at it is the movement of the device is no more than one or two miles per hour at the most.  Sound in air depending on temperature and altitude is under standard conditons 767 mph, so the fraction added or taken away by sway will be small.

In addition,I'm not sure how that one works, but a Met One 50.5 only measures when commanded to do so, so depending upon the timing you may or may not hit a slack period at the end of the oscillation.  Other devices may trigger differently.

Just back of the envelop guesses as to factors that will make measurement vary from true.

[Mandrake]

Clearly there will be some minor impact but I would guess no more than a Mph or two.
Probably within the margin of error.
At the end of the day the location and method of measuring is your local climate measure and so some degree of error is acceptable.
Its not going to be a met office site so rather than stressing about making it perfect concentrate on whether the location is suitable for you.
If its in a reasonably unobstructed location and one that will allow maintenance then all is good.

[beruk]

Thanks for your replies, gentlemen! I’ll leave it as-is for now.