Barometer Calibration? Offset?

[Terranigmus]

Hi.
I'm having trouble with the Sense-Hat.

It seems like the barometric pressure is not quite correct.

I haven't been able to determine if it's just an offset or something more complicated but currently the Pi logs pressure at approx. 1023 hPa, however local Weatherstations(really close) show that the pressure is at 1029 hPa.
I haven't been able to get my hands on other recordings for the few days I've been logging, I found a graph and it looks somewhat similar in qualitative changes but not in absolute numbers.
I thought I'd ask you guys.

Does anyone have any experience with this?

[DougieLawson]

How high above mean sealevel (MSL) are you?

Code: Select all

def msl(pressure,altitude=112.2):
    msl = pressure/pow(1-(altitude/44330.0),5.255)
    return "%4.2f"  % (msl)

update that with your altitude and call it with your local reading.

At a rough estimate you're about 50 metres above MSL.

[Zorac]

here is the formula i use to get from absolute pressure to sealevel pressure:

http://keisan.casio.com/exec/system/1224575267

[Terranigmus]

Thanks!

That's it!
I've been using the Pi at 0 since I live at a coast but i moved to a different location over the holidays.
Didn't know that I had to do this.