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19990416: reducing station pressure to level other than sea level

Robert,
as you mention, the operators for gridded data are present and straight
forward. The SF/SN parm operators are only rudimentary.

Since you need the 700mb temperatures, you would need upperiar files.
The upperair reports should have the station pressure as a mandatory level.
Similarly, you can get station pressure and 700mb temp from the hourly ruc2.
A function can be created and added to the $GEMTBL/parm/pcconv.tbl for
surface/upperair data, and a new calculation routine added to the gempak
library. After that, plotting with snmap would be no trouble.

However, from your question, it sounds like you want to be using the
surface files for the standard hourly altimeter reports. If thats the case,
then you need to get 700mb temp from somewhere. Do you use the last available
sounding 700mb temp and hope it hasn't changed too much?

If you want to outline the data sources, I can try to come up with a best
way around your problem.

Steve CHiswell
Unidata User Support 


>From: weather <address@hidden>
>Organization: .
>Keywords: 199904162012.OAA18354

>We have a routine that runs on a Vax that backs out station pressure
>from altimeter setting and then reduces that pressure to 850 mb
>using the 700mb temperature reduced to the station pressure level.
>
>I need to be able to do this on our Unix machine quickly and 
>I believe I see how this could be done for gridded data,
>but it involves two exponents(not integers), I do not see where that operator
>is available for sfparm, only multpily, divide, add subtract.  
>
>I would like to be able to plot the newly calculated pressures for
>each station.  Is there a way to do it with sfmap?
>
>Thanks,
>Robert Mullenax
>
>