Topic: VP2 temperature bouncy after DFARS added

[vinceskahan]

I recently added a DFARS to my jan-09 VP2 and notice that the temperature readings are much bouncier than the pretty smooth readings that I historically see.  Very smooth when the fan isn't running, a bit choppy when it's running. Is that something to be expected ?

The ISS is at about 7 feet height attached to a E/W fence, so the sensor itself is about a foot above the top of the fence the pole is mounted to.   Photo attached (the trees are at least 100 feet away).

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Here are a couple grafana plots of temperature and wind for a couple 2-day periods.  Readings are coming from weewx via MQTT so they're once per 5-minutes averages rather than simply captures of the LOOP data.

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[ashland weather]

Move your station off the fence. Out in your yard far as possible from the fence, house and other buildings. elevate the station 5 to 7 feet above the ground. wind eddys caused by the fence is reason for the bouncy tempature readings. experiment with different locations until you find a suitable location.

[vinceskahan]

I thought so, but it's not really possible to do the preferred grassy middle of the yard thing with such a small property.  I did notice that the bounciness is only when the wind is from the SSW (the grey fence runs N/S) and the readings have been very smooth the last couple days with wind from the N.

So I'm thinking to go 'up' a foot or two if safety permits and try to get above ripples from the back fence.  Prevailing wind here is from the SW.  The pitch of the hill makes going much higher than that likely unreasonable.

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Thanks for the reply !

[CW7491]

In addition to the fence, you may be getting a little influence from 21st Ave SW as well on a SW wind, but generally you’ll find a “noisier” temperature signal with artificial aspiration.

I’m just across Commencement Bay from you and I tend to see more noise on a SW wind too during daytime heating (I’ve got an AC fan in mine). On a N wind it tends to be more dampened because of the breeze coming off the Sound.

Also, I noticed you’ve got your CWOP ID as C6681, but it looks like you’re actually C6881.

[vinceskahan]

Yup - I raised it a couple feet earlier this afternoon which helped a bit, but yes we can sure get some gusts blowing SW=>NE up the street in a little bit of a wind tunnel effect.   Fixed the typo re: my CWOP number (thanks!).