Just got off the phone with Davis Technical Support, Round 2.
Summary:Davis has its own formula for correcting barometric pressure for altitude. It is not the same formula used by NOAA, but it is much less complicated and provides
almost the same result (within .03%). The Davis formula uses temperature as a variable whilst NOAA does not. The Davis formula does not produce an official "altimeter reading" due to the differences in its formula from the official NOAA formula. More information is available here, scroll down to the Barometric Pressure section:
http://www.davisnet.com/product_documents/weather/app_notes/AN_28-derived-weather-variables.pdfTwo methods to adjust:Davis says there are two ways to adjust pressure for altitude.
- Enter your altitude in the console setup screen; the Davis formula will be used to calculate pressure adjusted for your altitude
- Leave the console altitude setting blank, then manually calibrate your pressure to match the closest airport or other pressure reading you trust
If you do not want your pressure adjusted for altitude, leave the elevation setting blank and do not calibrate the console pressure.
WeatherCatI still don't know if WeatherCat does anything with barometric pressure other than capture it straight off the console. Altitude is a setting we enter in WC, but I don't know that it used in any calculation. If you want to use Method 2 above as your altitude correction method, you can, of course, calibrate the barometric pressure either in the Davis console or in WeatherCat.
AWEKASAWEKAS apparently wants the raw pressure reading, not adjusted for altitude. Since no other weather service wants the pressure reported this way, unless WeatherCat has some way to do an unadjusted pressure calculation, it appears my best option is to stop reporting data to AWEKAS, so I am considering taking my toys and going home.