Specifying Z levels

[Saji Hameed]

You could do this using NCL (NCAR Command Language)..It is easier to use
than NCAR...check the following page for a demonstration of this capability.

http://www.cgd.ucar.edu/csm/support/CSM_Graphics/2Dvertcoord.shtml

saji

Saji N. Hameed, Assistant Researcher,
IPRC-SOEST, 2525 Correa Road, Univ. of Hawaii,
Honolulu, HI 96822, U.S.A
http://iprc.soest.hawaii.edu/~saji
tel.: (808) 956 9534 , fax.: (808) 956 9425

----- Original Message -----
From: Ricardo Hallak <hallak at MODEL.IAG.USP.BR>
Date: Saturday, February 26, 2005 12:02 pm
Subject: Re: Specifying Z levels

> Dear Andrea,
>
> if I understood your problem correctly, you can try this:
>
> if your vertical coordinate z is dependent on (x,y), there is no
> way to plot
> exactily your data in GrADS. You can do it only by approximation on
> GrADS or
> try use NCAR Graphics. On the other hand, if your vertical
> coordinate depends
> only on z, you can write a .ctl file where de ZDEF VALUES are
> explicit, as the
> example bellow:
>
> ZDEF   40  LEVELS 50.00    100.00   250.00   450.00   750.00   1250.00
> 2000.00   3750.00   4250.00   4750.00   5250.00   5750.00   6250.00
>  6750.00
>  7250.00   7750.00   8250.00   8750.00   9250.00   9750.00  10250.00
> 10750.00  11250.00  11750.00  12250.00  12750.00  13250.00
> 13750.00  14250.00
> 14750.00  15250.00  15750.00  16250.00  16750.00  17250.00  17750.00
> 18250.00  18750.00  19250.00  19500.00
>
> Here, the zlevs are in meters from the ground. There is no
> necessity to have a
> logical interval of values. GrADS doesn't care.
>
> Remember that if your vertical coordinate is dependent on (x,y),
> this solution
> will work, but with same (I don know how many) variable error by
> approximation.
> Another cumbersome solution is to do an interpolation to constant z
> levels,before writting the data to bin. Thus, GrADS will "become
> happy" to see all
> your data on perfect cartesian coordinates.
>
> Regards,
>
> Ricardo
>
> On Fri, 25 Feb 2005 18:47:36 +0100, Andrea Storto wrote
> > I'll try to be clearer:
> >
> > In my model I've no grib output but binary files (not standard
> > format), so I convert in ascci format and then re-convert in binary
> > for GrADS. My output is in altimetric vertical coordinate and I'm
> > interested in high resolution visualization near surface (so to
> > interpolate to pressure levels or to get pressure variable and then
> > write is not the best!), since my model is a Limited Area model with
> > a very high resolution (subchilometric horizontal).
> >
> > So I can't use specified pressure levels for real vertical scale
> > visualization.
> > Moreover, I can fix the initial vertical spacing, and the
> > stretching ratio of my grid:
> >
> > DZ(i+1)/DZ(i)=K (constant, for example 1.2)
> >
> > where DZ(i+1)=Z(i+1)-Z(i);
> >
> > if you develope you have something like
> >
> > z(n)=(K^n)*DZ0+SUM(i varying from 0 to n-1)(over Zi)
> >
> > where DZ0 is the initial vertical spacing (fixed)
> >
> > and this is not a loghartimic function since it depends on
> > specific vertical level (SUM term).
> > So I can't use set logz.
> >
> > I surely can find some solutions (using pressure levels or logz),
> > but it could not be precise, and I'm also curious to understand
> > wheter a way to have specifed vertical
> > altimetric levels exists in GrADS.
> >
> > Thank you
> >
> > Andrea Storto
> >
> > ----- Original Message -----
> > From: "Rodrigo Sanchez" <rodrigo at dgf.uchile.cl>
> > To: <andrea.storto at TISCALI.IT>
> > Sent: Wednesday, February 23, 2005 10:22 PM
> > Subject: Re: Specifying Z levels
> >
> > > I'm a little bit confused ...
> > > Do you have a working ctl file ?
> > > or, Do you want to have one ?
> > >
> > > see, "set zlog"
> > > ---
> > > set zlog on|off
> > > Sets log scaling of the Z dimension on or off. Sticks until reset.
> > > ---
> > >
> > >
> > > > Hi,
> > > > I'll try your suggestion to know what I can get,
> > > > even if I don't understand how it could help me,
> > > > if I've only U,V,W variables (Components of wind)
> > > > and I want to plot, for instance, a W contour in vertical plane
> > > > (x-z) keeping real proportions of z levels?!
> > > > Think of a stretched grid: the first vertical spacing (at
> ground level)
> > is
> > > > about 30 m, while the last one (a little above tropopause) is
> > > > about 300 meters.
> > > >
> > > > Thanks
> > > >
> > > > Andrea
> > > >
> > >
> > >
>
>
> Hallak
>
> Laborat?rio de Estudos de Tempestades Severas (LETS)
> Departamento de Ci?ncias Atmosf?ricas (DCA)
> Instituto de Astronomia, Geof?sica e Ci?ncias Atmosf?ricas (IAG)
> Universidade de S?o Paulo (USP)
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>