All Messed Up

[LTCSZ]

I really need some assistance...I am using a Fine Offset AW-1090 station...My readings are totally out of line with close-by stations...My humidity is always at least 10 points lower than any other station...My temperature readings seem ok, but things like Dew Point and Barometric Pressure are extremely inaccurate...I have my sensor unit in one of the SRS100LX shields sold by Ambient Weather, and I think I have it located properly...Can't figure out what is wrong...Any advice would be appreciated!

Steve in Kansas

[steve]

Fine Offset stations aren't particularly good at humidity. Mine is currently showing 87%, and my Davis is showing 94%, so your 10% isn't far from the same difference. This will also of course affect your Dew Point, as that's calculated from the humidity.

As for the pressure, have you set your relative pressure (i.e. calibrated the barometer)? You need to set it to show the same as a nearby reliable station, and it should then track that station's reading, within the limits of its accuracy.

[RayProudfoot]

Hi Steve,

I don't have Fine-Offset equipment but adjusting pressure for your station's altitude is common to all stations. I've had a read of the manual here http://site.ambientweatherstore.com/Manuals/ws1080.pdf and for correct display of pressure you need to adjust the relative pressure on the console until it matches that of an official station close to you. It's best to do this when conditions are relatively calm so the pressure differences are small.

Read section 5.8 on page 19 and it explains what you need to do.

Humidity and Dew Point are linked and don't usually require the user to adjust anything. Someone with a Fine-Offset may be able to offer some help.

[MickinMoulden]

I've got a Fine Offset and found mine about 5% under. There is a guy (and I've just posted this in another thread - sorry), his is 33% lower than mine and he has a WMR928NX. What's that?
Anyway, both Steve's are right. I know you'll be wanting to calibrate the pressure ASAP, but it's all in the timing. Our BOM site in Aus only update every 30min (or there abouts), and in the tropics in goes up and down 4 times a day. For me I had do do it iether at 11am/pm or 4am/pm when the pressure change slows to 0 and it is steady enough to make the proper calibration.
Also, could it (humidity) be reading lower because you have it situated near concrete or something similar that radiates alot of heat or is in an area prone to convection updrafts causing it to read dry heat. Perhaps also height. Don't place to high. Right guys?
Don't follow my example, I've broken all the rules above (Oh oh Michael)

[serowe]

Our BOM site in Aus only update every 30min (or there abouts), and in the tropics in goes up and down 4 times a day. For me I had do do it iether at 11am/pm or 4am/pm when the pressure change slows to 0 and it is steady enough to make the proper calibration.

Or, of course, you could ring the BOM's local met number and they will give you the corrected pressure, for oyur location, over the phone. They have been offering/doing this service for at least the last 35 years. All the numbers are on the BOM web site.