[aprssig] Barometric pressure compensation
scott at opentrac.org
Mon Oct 19 16:38:20 CDT 2009
I'm making good progress on my APRS weather station kit, but I've run
into a minor snag.
To be useful, the station barometric pressure reading has to be reduced
to sea level. This means making an estimate based on a fictitious layer
of air between the station and sea level, and that estimate makes
assumptions about the temperature and lapse rate in that layer.
The NWS has an official algorithm for this, but it'd be rather tricky to
implement in a low-cost station. The other amateur stations I can find
information on (uWeather, Hobby Boards) seem to have simple offsets with
no temperature compensation, which seems a little too simplistic.
Among professional stations like those by Davis and Peet Bros, is there
any standard for how the sea level reduction is calculated? Or do we
just assume that we're not going to get any meaningful data about
horizontal pressure gradients from home stations and only look at one
station at a time?
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