Ws2350 Wind Speed Problems

[paul_n]

Hi,

I've just purchased and set up my first weather station - a LaCrosse WS2350 and have a "newbie" question about wind speed readings please.

Generally the equipment all seems to be working fine : the sensors are wirelessly connected to the base station and seem to be giving very reliable signals with no '---' readings for the month or so I've had it installed. Temperature, rainfall and wind direction readings all seem good and match the local met office station quite well. However, the wind speed readings seem to be much lower than what I'd expect. Even when there is a good strong steady breeze blowing, which the local met office station reckons to be some 25+ MPH my weather station only shows about 5-10MPH. Even when the winds have been very strong (around gale force), my max reading has been 20MPH. The anemometer is mounted above the roof in free air and I can see the cups revolving freely so...why the low readings ?

To help me understand this, perhaps someone could explain how does the WS2350 work out its wind speed reading ? I know the readings are transmitted to the base station every couple of minutes (I doubt I've seen wind speed readings high enough to invoke the faster sample rate) so does that mean the reading I'm getting is the average wind speed for that whole two minute period ? Or is it just a reading taken over the second or two while the sample is being generated ?

I'm aware that the unit can not be expected to give accurate readings for wind gusts but I would have expected to see something more approaching reality for average wind speeds. Or maybe this is just how the WS2350 works...?

Comments and suggestions gratefully received....

Thanks, Paul (PS: I did try a search for this question before posting but didn't find anything directly related)

[Greyowl]

I can suggest a couple of things that will have a bearing on your windspeed. The roof angles will give updraughts maybe causing the annanometer to slow. The met probably get their windspeed from the top of a tall building so the height variance will make a difference. One thing you could try is using the cable to connect to base station and see if that changes the readings.

Can't think of anything else but hope that helps you.

[paul_n]

Thanks Greyowl. I'll certainly try moving the anemometer to see if that helps but even where it is located now my puzzle is that I can see the cups rotating quickly in a brisk breeze, but still only get these low readings. If anyone could explain how the WS2300/2350 measures wind speed relative to the sample interval I'd still be very interested to learn.

Regards, Paul

[Coast]

Yep the sample rate for the wireless enabled anemometer is something like 180 seconds so if you don't catch a full gust or constant high windspeed the moment it downloads, it could look lower than it actually is. Hard wire is the most efficient way and getting it up on the roof or as high as possible helps.

[Supercell]

I have upgraded my weather station to record the higher wind speeds. My old Oregon Scientific WMR928 updated the wind speed every 14 or so seconds which missed most of the stronger gusts. Maximum gust I recorded in my two years of recordings was 37mph, significantly lower than the 50-70mph speeds at local sites during Atlantic storms.

The Davis Vantage Pro 2 records the wind speed every 2.5 seconds. I am far more likely to achieve greater gusts with a more regular interval update. So I can't wait for a good strong low to batter us a bit

http://www.davisnet.com/news/VP2vsCompSpecs.pdf - This specification table compares the DVP2 to other stations.

Even with average wind speeds, the longer the interval update the more the recordings suffer in speed also. The DVP2 produces a 10 minute average wind speed which is very accurate. I am afraid, unless you go for the DVP2, your measurements for all the variables will differ from local stations. I still run my Oregon scientific WMR928 station and it isn't in the same league as the DVP2.

Edited February 13, 2009 by Supercell

[paul_n]

Thanks for all the advice...sounds like a combination of factors may be producing my lower-than-expected wind speed readings : a long averaging period (128 secs) plus perhaps some turbulence causing the speed to vary (drop) more than expected during that period.

Regards, Paul