Topic: WS-2902A Rainfall Calibration

[lexmedic157]

Just put a new weather station on my tower (approx 45ft up).  I noticed the rainfall accuracy is way off, all the other stations in the area were getting near an inch and mine shows 2.5 inches.  I KNOW it hasn't rained that much.  Did I forget to do something on the install?  I twisted the cup in, and it's level on the mount.  I adjusted the calibration settings down to 50, but it's still a little high.  Suggestions?

[PaulMy]

Just put a new weather station on my tower (approx 45ft up). I KNOW it hasn't rained that much.

More rain up that high?
Maybe a bit of movement that high up??
https://www.ndsu.edu/fileadmin/ndsco/documents/Information_Packet.pdf

Enjoy,
Paul

[lexmedic157]

So you're thinking vibrations may be doing it?  Hasn't been that windy, and read zero rainfall the last couple of days, until it actually rained.  Hmm.  I guess it just seemed to be really over sensing, and I have no more calibration to on the lower end to play with. 

This is my station:
https://www.wunderground.com/weather/us/va/lexington/KVALEXIN21

And this is the next closest station to mine.  It seems to be fairly the same as the others in the area.
https://www.wunderground.com/weather/us/va/buena-vista/KVABUENA2

Wondering what else I can do to read a little better?

[PaulMy]

Sorry, I am not familiar with the WS-2902 and don't have any recommendation.  I know height can make a big differences as well as location, and also some stations and uploads send different rain measurement data.

Enjoy,
Paul

[CW2274]

So you're thinking vibrations may be doing it?  Hasn't been that windy, and read zero rainfall the last couple of days, until it actually rained.
Wondering what else I can do to read a little better?

Well, dropping it down from 45' certainly wouldn't hurt considering rain should be measured around 2' as a standard. Also, if your mast isn't all but perfectly still, wind will cause shimmy which will cause false tips to occur by dumping the rain filling spoon too quickly. It's probably all but impossible to dump an empty spoon from wind, it needs to start filling first to get to the critical point the shimmy prematurely dumps the spoon.
These are just two reasons of countless ones, but certainly pertinent.

[kbellis]

I haven't purchased one yet, but I'm thinking about getting this gauge as a check:
https://www.ambientweather.com/stprraga.html

CW2274's suggestion that you're getting additional tips from mast sway makes sense. Please post photos of your 45' tower.

Viewing the level bubble probably will require a drone in order to get a good look at; another aspect to be thinking about even if your tower is motionless.

In any event, I would not consider calibrating your new weather station until you gather more data at your own site.

[Sir_MAK]

The Osprey rain gauge is a little different then some of the other types.  It uses a spring loaded single dump bucket.  Though still sensitive to motion I don't think it is as sensitive as the two bucket rocker (see-saw) type gauge.  There is a way to adjust the physical gauge on the Osprey, but I could not locate instructions for it.  You might want to contact Ambient Customer support, they may want to just send a replacement sensor to you if its under warranty.  I have two Ospreys in different locations and they are always in close agreement to the stations near them.