If I turn off seapressure sensor, how do you get altimeter?

[doncurtis]

Pretty much as the title says, WS-1090, if I leave absolute pressure sensor on, but turn off seapressure sensor, does meteobridge calculate relative pressure and/or altimeter values based on station elevation and send those values to my weather networks?

Thanks,
Don

[admin]

Yes, Meteobridge calculates sea level and altimeter (needed to report to CWOP) based on station pressure given by the station and altitude given inside Meteobridge.

[doncurtis]

Yes, Meteobridge calculates sea level and altimeter (needed to report to CWOP) based on station pressure given by the station and altitude given inside Meteobridge.

Here is current live data:

Indoor 4 sec 23.4°C 23% 1018.8hPa (839.5hPa) 74.1°F 23% 30.09inHg (24.79inHg)

Yet CWOP is getting
FW0503>APRS,TCPXX*,qAX,CWOP3:@050255z4024.25N/10505.78W
_305/002g004t053r000p000P015b10080h18eMB31

which show pressure at 1008.0 hPa instead of 1018 from live data

while WU and others are getting the 30.09inHg as noted in live data.

I understand CWOP uses altimeter setting which live data shows as 24.79, but adding 5" to that (I am at 5 000 feet almost exactly) would be 29.79 inHg or 1008.8 hPa which matches what CWOP is getting, why don't WU and the others get 29.79 inHg? Where does the 30.09 come from?

And... All official weather service stations within 20 miles of me are reporting pressure 29.78 to 29.84 nothing even close to 30.09

[admin]

Sea level and altimeter readings do vary widely, when you are on higher altitudes.
CWOP and airports works with altimeter, WU and most other services with sea level.
It is as it is.

[doncurtis]

Stations in the US work off attiltude NOT MSLP. See my new thread with supporting evidence.

[admin]

I don't know what stations in the US work with and I don't care. I care about feeding data to weather networks in the way they demand it. I will check your "evidence" in the case of AWEKAS. over and out.

[doncurtis]

Well then, let me show you how to get that note from AWEKAS

Presuming you have a station, or know someone who does, go to this URL after logging in

http://www.awekas.at/en/benutzer.php

Go down to Air Pressure Adjustment and click on the question mark. You will get this:

Air pressure adjustment:

In AWEKAS altimeter pressure (relative air pressure) is displayed. As some software give the absolute pressure, it is also possible to enter a correction value. This value can be positive or negative. In most case a correction value is NOT necessary. This value can be amended at any time in the user settings.

FYI, I subtract 0.4 inHg from what meteobridge sends and magic, I am now +/- 0.02 inHg from comparison stations.

And... data I am sending CWOP and the adjusted data on AWEKAS are the same.

I can't adjust WU so what I send them is high by about 0.4 inHg from what WU reports for my town.

Over

[admin]

I asked Othmar Gattriger, who is running AWEKAS, and he confirmed that AWEKAS is working with SLP, not altimeter.

[doncurtis]

I asked Othmar Gattriger, who is running AWEKAS, and he confirmed that AWEKAS is working with SLP, not altimeter.

Ok... Thanks for checking.
They need to change the text on their help page, I will send thrm a note.

[doncurtis]

Please read this thread.... AWEKAS want's absolute pressure reduced to sea level. Taking into account elevation only.

http://www.awekas.at/for2/index.php?pag ... highlight=

Only the sea level pressure, which allows to compare the various pressure by equivalence correctly. That also allows to draw isobaric curves.

The air pressure sensor of your weather station measures the absolute pressure at the level of this one. You shall indicate the elevation of your station into your console, in meter or feet. Roughly, it is about 0,118 hPa per meter high for normal pressure (1013,25 hPa) at 15°C. By example, you have to add 11.8 hPa more for an 100m-elevation. The sea level pressure will be 1025,8 hPa for an absolute pressure of of 1014,0 hPa.

[admin]

I checked with AWEKAS, they expect SLP, not altimeter.