Tom Keffer <[email protected]> writes: > I don't know what they mean by "If your site specifies a unit for Air > Pressure." In any case, we send "barometer", which is pressure corrected > for altitude and temperature. Reading this very confusing passage, I think > we should send "altimeter" and remind users to mark MSLP as "Captured." > > Any other opinions?
I see later you can specify hPa or mb. That's funny because they are the same unit, vs mmHg or inHg. So the question ends up being "what is MSLP". This is such a good question, there is a huge document about it: https://library.wmo.int/records/item/59469-methods-in-use-for-the-reduction-of-atmospheric-pressure Basically, different countries use various various formulas for reduction of station pressure to SLP. From memory, there are broad groups about use of water content vs not. So 1) It seems really off that the Met Office isn't more precise. 2) In an international data set, it's a really interesting question whether each station should use the nationally-appropriate reduction instead of all using the same (UK?) reduction. I am unclear on what's changed since 1966. But I bet that there isn't a single standard for SLP. (Yes, I realize ICAO/airplanes use a common definition of altimeter pressure. But that is not really concerned with weather; it's about having your pressure altimeter be right when you arrive someplace else.) -- 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 visit https://groups.google.com/d/msgid/weewx-user/rmi348amzrr.fsf%40s1.lexort.com.
