Accuracy of instrumentation

[HansR]

In this world of amateur meteorology we pay little attention to the accuracy of measurements. However, that this can be really significant and that calibration may really be an issue, is shown by what laulau is doing ( ).

Because he has two installations of the CumulusUtils website ( ), we are able to see measurements - not the least pwsFWI - on the same spot by two different instruments: one self built Arduino (if I understand it well) and one Davis VP2.

Look for yourself and seek the differences

A man with a thermometer always knows the temperature. A man with two thermometers, not so sure.

[laulau]

It all started when my father was offered a weather station for his retirement in 1999!
A Davis Weather Monitor II not onlinr but still workink

[HansR]

You took over well, thanks to your father
It is a really interesting exercise two instruments side by side!
Thanks for using CumulusUtils for that.

[laulau]

My WeatherDuino use also Davis wind and rain sensor since a while. (had my old WM918 sensors befor)
I started with a WM918 then a WMR968. The WM918 sensors where attached to WeatherDuino at some point.
Then I bought the Davis rain and wind sensors as I went along. The WMR raingauge died two years ago and wasn't reparable, I abandoned the WMR968.
It was around this time that I got the VP2.
Ill post some photos od the installation later...

[laulau]

There was an air base just nearby (4km) their meteo station still works (no more metar ) the data can be viewed here:Colmar/Meyenheim
At some point i did have an excel spreadsheet to get same data from Infoclimat to create a dayfile but a lost it

[HansR]

OK, really nice.
And how are you going to deal with the differences in measurements?

[laulau]

I found why i had so much differrence in rain measurement, spider web:

IMG_20200516_160357_resize_91.jpg

lack of maintenance
But i decided to change to the new tipping bucketanyway
thats how i see that spiders where inside of my rain gauge, it never happens before and the new tipping bucket won't stop them from coming

[HansR]

Yes, that is a problem. I have to clean the buckets and the collector once a month at least of birdshit, insects and leaves and branches, in autumn even more often. Only during two to three summer months (let's say june-august) I can leave it.
The advantage of the silver tipping bucket is that you definitely see when it needs cleaning

Nice new bucket btw. Didn't know they had changed system. Is that usable on older systems too?
Don't know how it functions exactly, but it looks as if it has more small openings which can pollute or be occupied by spiders and other insects.
It will definitely need maintenance as well.

[laulau]

Totally compatible with old VP2 rain gauges;
Davis starts to use this type of buckets on their Vue rain gauges Vue spoon rain gauge
If adjustment is needed there is only one adjustment screw but it is not accessible without disassembly.

[HansR]

Looks good. And great: first taking everything apart before assembly .
You like motoring as well

[laulau]

Hope i don't nees to make adjustment its a 1/4" screw, not current here

[HansR]

@laulau: And while I'm at it: I thought there was also an exchange somewhere between you and Mark, about the wiring of the Temp/Hum sensor.
Can't find it any more though. Any idea?

[laulau]

@ Hans : viewtopic.php?f=36&t=18081&p=142564#p142564

[HansR]

Right! That's the one Thnx