Getting a bit confused by all the terms.... For personal weather statons station (non-airports) station elevation is the ASL height of the barometric sensor and sea level pressure (Altimeter and MSLP) is calculated from that elevation.
For airports, station elevation and pressure are calculated valuse derived from the sensor elevation that is corrected ( removal correction) to field elevation.. The datum (station elevation) is usually the highest point of the runway (station elevation). This would be QFE. The obscure and elusive "removal correction" has been difficult to track down. Steve Hatchett gives a formula in the WeeWX code but I could not find out where Steve obtained it or verify the source.I don't think a removal correction is utilized for any personal weather stations - only airports. The term "barometric pressure" is somewhat confusing. U.S weather equipment manufacturers tend to call this sea level pressure however the NOAA/NWS definition is very different. So is Canada's definition. Barometric pressure is a reading from a barometer which could be anything.. In Europe, the term "air pressure" is commonly used although it can also have more than one meaning. Bottom line - at airports, station elevation, station pressure and QFE are calculated values. So is QNH and QFF. Sounds like the Tower of Babel doesn't it? In deference to Tom's use of altitude versus elevation and gauge pressure, my preference for "universal" barometer terms for personal weather stations are restricted to station elevation, station presure, Altimeter and SLP (MSLP). I try to avoid "sea level pressure" because it can refer to either Altimeter or METAR's SLP depending on the context.Both are reduced sea level pressures. We could also have a long discussion about absolute pressure and relative pressure but I think I hear "enough already!". On Friday, June 30, 2023 at 9:17:28 AM UTC-4 Karen K wrote: > Regarding the station altitude the user's guide of WeeWX > <https://weewx.com/docs/latest/usersguide.htm#%5BStation%5D> simly says > "station altitude". > > The WMO distinguishes between the station altitude and the pressure gauge > altitude. > > - The station altitude is defined as the elevation of the ground below > the air temperature sensor. > - The pressure gauge altitude is the real altitude of the pressure > gauge, used to calculate sea level pressure (barometer value). > > The altitude in the [Station] section of weewx.conf is directly used to > calculate the sea level pressure (barometer value) in the > weewx.wxxtypes.PressureCooker class. So strictly spoken it is not the > station altitude but the pressure gauge altitude, what the user has to put > there. > > Would it make sense to clarify that in the user's guide? > -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/weewx-user/4bf726db-758a-44ea-9177-c7d566cd7695n%40googlegroups.com.
