R: Meaning of descriptor file (*.ctl) variable names

[Wesley Ebisuzaki]

Diego,

The rule that generates the variable suffix has changed over
time and will change if I think it needs updating. Here is what happens

(1) look for vertical coordinate (not layer) that has the most levels
(grib2ctl >= 2,
g2ctl >= 3) and make that the vertical coordinate. The vertical coordinate
could be pressure levels, vertical height, sigma, potential temperature,
etc.
(There are options that affect the selection of the vertical coordinate)

(2) variables that use a different vertical coordinate or only 1 level
will have suffixes with their
level information.

(3) variables with > 1 level and using the selected vertical coordinate
use prs for pressure level,
something else for sigma, etc.

Wesley

Diego Morelli wrote:
> Hello Wesley,
>
> Can I say that the rule is:
>
> If, about a certain variable relative to an isobaric level, it's available
> only one level, then the variable get the suffix <level>+<mb>, otherwise it
> get the suffix "prs" ??
>
> In the attachment there is a file in which there is 2 variables available on
> 2 levels, and they are declared of the kind "prs". Here bottom is its ctl
> file.
>
> dset /home/cyprus/grads/compiled_env/grads-2.0.a7.1/bin/cyprus.b
> index /home/cyprus/grads/compiled_env/grads-2.0.a7.1/bin/cyprus.b.idx
> undef 9.999E+20
> title /home/cyprus/grads/compiled_env/grads-2.0.a7.1/bin/cyprus.b
> *  produced by grib2ctl v0.9.12.5p45
> dtype grib 11
> options yrev
> ydef 37 linear -90.000000 2.5
> xdef 37 linear 90.000000 2.500000
> tdef 1 linear 00Z28apr2005 1mo
> *  z has 2 levels, for prs
> zdef 2 levels
> 850 500
> vars 4
> HGT500mb  0 7,100,500 ** 500 mb Geopotential height [gpm]
> PRMSLsfc  0 2,1,0  ** surface Pressure reduced to MSL [Pa]
> UGRDprs 2 33,100,0 ** (profile) u wind [m/s]
> VGRDprs 2 34,100,0 ** (profile) v wind [m/s]
> ENDVARS
>
> -----Messaggio originale-----
> Da: GRADSUSR at LIST.CINECA.IT [mailto:GRADSUSR at LIST.CINECA.IT] Per conto di
> Wesley Ebisuzaki
> Inviato: giovedì 12 novembre 2009 16.02
> A: GRADSUSR at LIST.CINECA.IT
> Oggetto: Re: Meaning of descriptor file (*.ctl) variable names
>
> Diego,
>
> Sometimes a variable may be available as a vertical profile. Sometimes a
> variable may only be available on
> one or two levels. When a variable is available as a vertical profile on
> pressure surfaces, the suffix "prs" is
> used. If the variable is not available on a vertical profile, the suffix
> is the level descriptor.
>
> Wesley Ebisuzaki
>
>
> Diego Morelli wrote:
>
>> When I use grib2ctl (v0.9.12.5p45) it issues a ctl file with some
>> variables having the suffix “mb”. These variables are relative to an
>> isobaric level type (value 100 in the PDS grib section, octet number
>> 10), with a value expressed in hPa.
>>
>> I see that the variables with suffix prs are relative also to an
>> isobaric level type.
>>
>> My questions is to know what is the difference between the variable
>> with suffix mb and those with suffix prs.
>>
>> Here there is an example of a descriptor file:
>>
>>
>>
> ----------------------------------------------------------------------------
> ----------------------------------------------
>
>> dset ^LFPW00190127.20090718144212_P4320PT76BE_BPMG12.86093.b
>>
>> index ^LFPW00190127.20090718144212_P4320PT76BE_BPMG12.86093.b.idx
>>
>> undef 9.999E+20
>>
>> title LFPW00190127.20090718144212_P4320PT76BE_BPMG12.86093.b
>>
>> * produced by grib2ctl v0.9.12.5p45
>>
>> dtype grib 255
>>
>> options yrev
>>
>> ydef 66 linear 10.000000 1
>>
>> xdef 126 linear -60.000000 1.000000
>>
>> tdef 1 linear 12Z18jul2009 1mo
>>
>> * z has 6 levels, for prs
>>
>> zdef 6 levels
>>
>> 925 850 700 500 400 300
>>
>> vars 2
>>
>> * GPprs * 6 6,*100*,0 ** (profile) Geopotential [m^2/s^2]
>>
>> * VGRD925mb * 0 34,*100*,925 ** 925 mb v wind [m/s]
>>
>> ENDVARS
>>
>>
>>
> ----------------------------------------------------------------------------
> ----------------------------------------------
>
>> Regards,
>>
>> Diego
>>
> >