[RegCNET] How to get the output data of RegCM in pressure cordinates ?

[Alexander Bryan]

Hi Christian,

Run "sigma2p" (found in the PostProc directory) on one ATM file at a time
like so:

./sigma2p [output_path]/[sim_name]_ATM.[yyyymmddhh].nc

This creates a new file (same file name, but with "_pressure" appended) in
pressure coordinates at standard pressure levels. Note that anywhere the
surface pressure is less than 1000 hPa, the surface value is used.

If you are just looking for the values at the standard pressure levels,
sigma2p works. If, however, you want to calculate a vertical gradient with
pressure (i.e. d/dp) of a variable, do not use sigma2p, otherwise dp will
give you missing values at the surface where surface pressure is less than
1000 hPa. Instead, compute pressure yourself using the surface pressure
(ps) and top of atmosphere pressure (ptop) variables, where:

p = sigma * (ps - ptop) + ptop

Alex


On Sun, Apr 13, 2014 at 2:31 PM, CHOUMBOU Paul Christian <
paulchoumbou at gmail.com> wrote:

>    Hi!
>  I RegCM4 model simulations, however files ATM outputs allow me to use
> pressure coordinates as the data are sigma coordinates.
> I would have to know the outputs of the RegCM model in pressure
> coordinates (1000hPa, 975hPa, 950hPa, ect ...) whereas the latter is
> in sigma coordinates.
>    Thank you in advance to have a look for my problem.
> Regard
>                               Christian
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