# Re: Pressure to height and Potential Temp calculation

From: Dennis Shea <shea_at_nyahnyahspammersnyahnyah>
Date: Wed Apr 27 2011 - 15:03:24 MDT

On 4/27/11 2:41 PM, sbasu@iarc.uaf.edu wrote:
> Hi,
>
> I have two questions. Is there any function to use which will convert the
> pressure levels like 900mb,850mb etc to height using Hypsometric equation?

http://www.ncl.ucar.edu/Document/Functions/Built-in/pslhyp.shtml
>
> I have standard CAM3.output. Its in hybrid sigma levels.What is the best
> way to calculate potential temperature at different pressure levels ? I
> interpolated my temperatures in hybrid sigma levels to pressure levels
> like 900mb, 850mb etc using vinth2p.

You do not have to interpolate to constant pressure levels.
You can calculate potential temperature at each hybrid level
directly.

Use:

hyam = f->hyam ; read from a file the mid-layer coef
hybm = f->hybm ; read from a file
ps = f->PS ; surface pressure [Pa]
p0 = 100000. ; since ps is in Pa or [ f->P0]

p = pres_hybrid_ccm(ps,p0,hyam,hybm) ; (ntim,klev,nlat,mlon)

t = f->T ; (ntim,klev,nlat,mlon)

Then use

theta = t*(1000/p)^0.286

>
> Thanks,
> Soumik
>
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Received on Wed Apr 27 15:03:34 2011

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