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Interesting conversation with ECC re: barometer calibration


I think we all agree that calibrating our baros are complex enough but then there is the unexpected.

For pws owners that compare readings with METAR and Mesowest, sometimes things go askew.

In my case, Environment Canada/NAVcan data readings for my local METAR did not match Mesowest.

Say whaat?

Nope. Station pressure and Altimeter were different between ECC and Mesowest.

Emails to ECC confirmed that the elevation was wrong at Mesowest. Not by a huge amount but it was out by 3 meters (approx. 10 feet). Significant enough if you are calibrating.

I also found out that  airport station pressure is calculated to the highest point  of the runway(s). I had assumed elevation was based on aerodrome elevation but that was not correct. I knew that in aviation, station pressure is a calculated amount as sensor height is corrected down to field elevation.

For our personal weather stations we normally assume station pressure = sensor pressure at whatever the sensor height is so it is a measured pressure.

Kudos to Mesowest responding instantly and they will be correcting my airport's elevation forthwith.

I could sleep soundly tonight except for one nagging did Mesowest get the right SLP with the wrong elevation?

Not quite there yet.

Elevation for CYZEhas been corrected from 193 meters to 190. No decimal meters in Mesowest? At least we are closer to true elevation. However, station pressures do not match with the source data nor does Mesowest match NOAA/NWS CYZE Altimeter(setting).

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