Topic: Anyone currently using the new Davis Sonic Anemometer?

[TraderGary]

https://www.davisinstruments.com/product/sonic-anemometer/

I'm curious if anyone has made comparisons for accuracy?

[johnd]

It wouldn't be commonplace for Davis owners to run comparisons - a VP2 station obviously only accepts a single anemometer input and a lot of VP2 compatible software also only expects to handle data from a single anemometer.

That said, it would be possible to look at 2 anemometer if using Weatherlink Live as the upload device to weatherlink.com and it's possible some users are doing this. We've actually had both running side by side with an EM station alongside a VP2/Connect IIRC and the readings are broadly the same, though they won't be exactly identical because the sample times for the two won't be synchronised. (ie other than a dead calm, wind speed is constantly changing, especially inland. so unless 2 anemometer start their measurement window at the same precise instant then the results will tend to be at least eg 1-2mph different. The same applies to capturing maximum gust speed during a gale.)

IIRC these LCJ anemometers (ie what Davis are selling as 6415) are individually calibrated/checked at the factory in France during manufacture.

[TraderGary]

It wouldn't be commonplace for Davis owners to run comparisons - a VP2 station obviously only accepts a single anemometer input and a lot of VP2 compatible software also only expects to handle data from a single anemometer.

That said, it would be possible to look at 2 anemometer if using Weatherlink Live as the upload device to weatherlink.com and it's possible some users are doing this. We've actually had both running side by side with an EM station alongside a VP2/Connect IIRC and the readings are broadly the same, though they won't be exactly identical because the sample times for the two won't be synchronised. (ie other than a dead calm, wind speed is constantly changing, especially inland. so unless 2 anemometer start their measurement window at the same precise instant then the results will tend to be at least eg 1-2mph different. The same applies to capturing maximum gust speed during a gale.)

IIRC these LCJ anemometers (ie what Davis are selling as 6415) are individually calibrated/checked at the factory in France during manufacture.

Very informative as usual, John!
I'm using the Davis WeatherLink Live 6100, so that would allow me to make comparisons. Although I hadn't considered where in a 2.5 second interval a wind speed reading would actually be made. So I suppose the only really valid comparison would be averages over time?

[johnd]

I'm using the Davis WeatherLink Live 6100, so that would allow me to make comparisons. Although I hadn't considered where in a 2.5 second interval a wind speed reading would actually be made. So I suppose the only really valid comparison would be averages over time?

It's not really where in the window the reading is taken (actually I think the VP2 window is 2.25 secs long, ie it's slightly shorter than the channel #1 transmitter interval). My picture is that the number of revolutions of the cups is counted for the full 2.25 secs. But it's the precise time that the window starts, which I suspect won't be identical across transmitters. And then of course there's the factor that even given near-identical exposure, a conventional and ultrasonic anemometer are obviously using different sensing mechanisms and so are unlikely to record identical mph figures. So the cups clearly have spindle friction and cups inertia plus there's the aspect of how accurate the secondary correction for wind blowing across the arm from different directions might be, while the U/S will doubtless have other factors to consider.

All that said, yes I agree that  eg 10 minute mean wind speed values might be expected to agree within perhaps 2-3% or 2mph say for two anemometers with near-identical exposure.

[TraderGary]

Thanks John, I've learned a lot from this post!

[FurryOne]

https://www.davisinstruments.com/product/sonic-anemometer/

I'm curious if anyone has made comparisons for accuracy?

I've been running the sonic anemometer for a few months now on my VP2, but it replaced my old cups/vane setup that was sticking on both functions.  All I can say is that it works as advertised, though I miss the visual indication when I'm outside.   

[CW2274]

https://www.davisinstruments.com/product/sonic-anemometer/

I'm curious if anyone has made comparisons for accuracy?

though I miss the visual indication when I'm outside.   

  Ya know, I never though about that..

[doubleohwhatever]

Does rain and snow not cause issues with this sonic anemometer? Excellent if not but the design has me concerned.

[FurryOne]

Does rain and snow not cause issues with this sonic anemometer? Excellent if not but the design has me concerned.

I haven't noticed any problems with rain.  Heavy, sticky snow and freezing rain might be another story, but that would affect the regular anemometer too.

[Mattk]

A "proper" Ultra Sonic anemometer designed with heating will handle very harsh freezing/ice/snow conditions (down to -40C) with inbuilt heating but require considerable power (typically from 24 volt) with heating which is something the #6415 is not capable of. These Ultra Sonic are way better than any conventional anemometer in extreme cold conditions.

[doubleohwhatever]

My concern was primarily with rain puddling but also snow collecting under the transducers and skewing the readings.

[Otis]

I just installed one to replace the original cups/vane of my VP2.
I am anxious to see how it does through the winter.  I too already miss the visual indication and also liking not having to get up on the roof; I have had problems with the cups/vane either sticking as a result of dust of freezing in the winter.

Anyway, it is up and running - easy install too.

[BigOkie]

I just installed one to replace the original cups/vane of my VP2.
I am anxious to see how it does through the winter.  I too already miss the visual indication and also liking not having to get up on the roof; I have had problems with the cups/vane either sticking as a result of dust of freezing in the winter.

Anyway, it is up and running - easy install too.

the freezing affects official (airport) stations as well. I've seen notations on ATIS/METARs that will indicate when the anemometers are frozen.

[Bashy]

What about spiders/webs etc, could these cause issues? they bloody cause enough with the standard anemometer during the Spring, Summer and early Autumn months, for me anyway, saying that it's lot of wonga just to resolve a spider issue lol

[Randall Kayfes]

I am currently using the Sonic for about two months and have had no problems in comparing my sensor to nearby cup and vanes. I do miss the visual indications, but I do not miss the always reading north error 

Have had zero problems in the rain so far but have not had a true monsoon rainstorm so I will keep you all updated when that happens.

[CW2274]

Have had zero problems in the rain so far but have not had a true monsoon rainstorm so I will keep you all updated when that happens.

Well considering that's six months away, I guess we all should get a snack. 

[boggydew]

So, how is the 6415 working out for everyone?  I am concerned about it being solar charged / battery powered.  If the panel gets dirty the battery will go flat.  Because anemometers are generally put in inaccessible places, i.e. on the end of long poles, it is difficult to clean them regularly.  I need my application to be reliable ... and want to modify the unit by removing the battery and disconnecting the solar panel. Replace the cable for a 6 core, with 6p6c connector and put a 5V supply on the extra wires.  I want to find out what the part number for the switching regulator is that regulates the panels output. It is a QFN-20 3x3 package with markings "1050 B006"......?

[Randall Kayfes]

We have had rain again but nothing like an inch in 15 minutes so still no update there (big rain is what we are trying to get to the bottom of). We are in southern Arizona, so I imagine the battery will perform flawlessly as does my ISS battery. So, I could tell you the battery has been zero problems but that is Arizona. Interesting though is heat kills off a lot batteries here in Arizona including car batteries. However, my ISS batteries have gone on for five years with zero problems...

[Otis]

Funny, I was getting ready to give an update on my sonic anemometer and just this morning had an anomaly.

First; around November 9, 2021, I replaced my existing anemometer (cups) with the Davis sonic.  It is mounted on a tri-pod on the roof of house, about 350 feet from shore of Lake Huron.  So far, the winter has been typical with wind and snow.  Had some freezing drizzle a couple weeks ago and figured the previous anemometer would have frozen, sonic has performed very well – until this last night through this morning.

Present; Winter storm came in last night; high winds, snow, and blowing snow.  The sonic anemometer reporting “froze” at 3.2 mph and a direction of 180 degrees.  This started approximately 9pm last night and lasted through just after 9am this morning.  At which time everything appears to have returned to normal – speed and direction.



I blew approximately 6 inches of fresh snow off the drive this morning around 7am and can report that there was a stiff wind out of the NNW while the sonic reported a S wind at 3.2 mph.  No way, just sayin. 

Anyway, again seems to be reporting fine and had been until this anomaly.  Will keep an eye on it.

[Mattk]

Ultrasonic anemometers expected to work in freezing snow/ice conditions would typically have some fairly powerfull heating arrangements, something that a couple of low power batteries is not going to be able to provide.

There would become a point much like a standard cup type anemometer where things are simply going to freeze over under the right conditions. Based on the spec, the Sonic (6415) operating range is +5°F to +131°F, compared to -40°F to +149°F for the 6410 which should be factored into which version might be best for individual circumstances

[thomas]

My sonic pretty much acted like Otis's did last night.  Very high winds with a intense snow squall and it pretty much flat lined till the sun came out this AM and I assume melted the snow.  Other than  this situation I have been pretty happy with the ultrasonic.  I also have a Davis unit with cups and they will stop working in heavy wet snow or freezing rain.  I have a super soaker with deicer in it when that happens.  Not going up on my roof in the winter.

[Randall Kayfes]

Well, here is my Sonic update after experiencing a very wind and wet Monsoon season. The Davis Sonic has performed flawlessly with absolutely no anomalies even during our incredible monsoon t-Storms. I am absolutely satisfied with the purchase.

[Buick]

I just installed a 6415 today and according to the user manual the anemometer calculates wind speed and direction, calibrated by temperature measurements. I'm curious about the source of said temperature measurements. Does the anemometer include an integral temperature sensor? Do the temperature measurements used for calibration come from a temperature or temperature/humidity sensor which is connected to the same sensor transmitter as the 6415? If anyone can answer my question I would appreciate the input!

[Mattk]

Ultrasonic anemometers can derive a virtual air temperature, an approximate ambient temperature determined from the ultrasonic sensors relative to the velocity of propagation of sound 

[Buick]

So, the anemometer derives an estimated ambient temperature based on the speed of sound propagation between the transducers, which is a function of the wind speed, and uses this value as a means to calibrate the measurement of wind speed and direction?