On Wed, Jul 5, 2023 at 4:31 PM [email protected] <[email protected]> wrote:
> Very interesting. For US-centric SLP/MSLP calculaions I would have thought > that 12 hour temp averages would always be used; > Again, from Dr. Burch: *T (avg) = [ T(0h) + T(-12h) ] ÷ 2. *He did a > study on this comparing QFF results using T(0h) and another data set using > T(avg) and remarks*: * "..[our] study is remarkable evidence that we must > use the average temperature over the past 12h when correcting QNH to get > QFF". > > Why would one want to convert QFF/SLP back down to station pressure? > > I don't have a Davis weather station but could it be that Davis VP2 > consoles send SLP to WeeWX and then WeeWX converts it back to station > pressure so that WeeWX can calculate both Altimeter and SLP??. If a Davis > console is set to zero elevation what is sent to WeeWX?. I am guessing raw > station pressure and then again, WeeWX calculates Altimeter and SLP. from > station pressure. Did I get that right? > Pretty much. CWOP demands altimeter, which, until Davis introduced "LOOP2" packets, the Vantage series did not emit. So, it had to be backcalculated from the types at hand, which was barometer. This was about 10 years ago, and I don't remember the provenance of the formula. It could be from wview. I would be very surprised if the formulas are the inverse of each other. If someone wants to work on that, it would be appreciated. -tk -- 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/CAPq0zEBOe9bQ04%3DsrbcBQLzSY%3DJDF1amj3%3DZeEjpjd%3DTtyzjAw%40mail.gmail.com.
