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to compute relative pressure (sea level equivalent). Correction tables
can be found on-line in many places. One example is the table found at
https://novalynx.com/manuals/bp-elevation-correction-
Locate your elevation in the first column and read the correction in the
third column. This table, however is rather coarse, making it hard to be
precise. An alternative is an on-line calculator such as the one found
here:
http://www.csgnetwork.com/barcorrecthcalc.html
For our example of 42 ft. above sea level we input 42 ft. of elevation
and a standard pressure of 1013.25 hPa/mb and press calculate. We find
an “absolute barometer value” that should be -1.5626061222588443
hPa lower than at sea level. The inverse (because relative pressure is
higher than absolute pressure) of this number will be our “REL PRESS
OFFSET” value. Use the settings procedure to increase REL by +1.6
(nearest rounded value we can input).
5.
Now we need a reliable reference for pressure at sea level. Locate the
official identifier for the nearest airport. Refer to “
” at
https://www.world-airport-codes.com
Enter your location or nearby airport name, and press “Search.” Select
the correct airport from your search results and click on it. For example,
search for “Mountain View” and click on “Moffet Field.”
6.
From the resulting page find the ICAO code, if listed. Otherwise use the
IATA code. For the example above, you would find IATA code
“NUQ.”
7.
Now go to a web site like
https://www.aviationweather.gov/metar?gis=off
the code you found in step 2, and click “Decoded” (to make the next
step easier) before requesting the METAR information. For the
example we would enter “KNUQ” and find a result output like: “30.09
inches Hg (1019.0 mb) [Sea level pressure: 1019.1 mb]”
8.
Go to the calibration settings page and observe the “REL Barometer
value (this is the value we just adjusted in step 4 above). Compare the
Summary of Contents for GW1003
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