[RegCNET] A RegCM3 CRU processing problem

[Sara Rauscher]

Hi Simon,

I think you need to make a data descriptor file to view the netCDF data
with the proper projection in grads. Say you use the CRU processor to
make a netCDF file that has one month of precipitation data for August
2002, so that your netCDF file is named PRE2002.nc. Create a data
descriptor file called "cruppt" like this, where you substitute your
projection information (pdef, xdef, etc.):

DSET ^PRE2002.nc
dtype netcdf
undef -32767 
UNPACK scale_factor add_offset
pdef   49   32 lcc   45.39   13.48   24.50   16.00   30.00   60.00   13.48  60000.  60000.
xdef  175 linear   -9.61  0.2703
ydef   78 linear   34.70  0.2703
zdef 1 levels 1008.43
tdef  1 linear  00Z15AUG2002 1mo
vars  1 
PRE=>pre      0 t,y,x Precipitation 
endvars


Then open the file in grads: open cruppt

Note that descriptor files (for netcdf!) work with Grads version 1.9 and
above ONLY - you can see the documentation at
http://grads.iges.org/grads/gadoc/descriptorfile.html.

I sent a more detailed example to the RegCNET list back in February -
Simon, I will forward you that email. Let me know if you need more help.

cheers,
sara



Simon Krichak wrote:

>  
> Dear Xunqiang,
>
>  
>
>  
>
> We are running some of our RegCM3 runs  over a rather large domain
> using the Lamber projection.
>
> To compare the results with the CRU data from the ICTP RegCNET site,
> we use the RegCM3 CRU interpolation tool. Everything goes fine but a
> discrepancy  in positioning of the boundaries of sea areas in the CRU
> based patterns with the GrADS geography is evident  - since the CRU
> data are available over land only. No such problem is found in the
> case when the interpolation is made using normal Mercator  projection.
>
>  
>
> Any suggestion please.
>
>   Simon
>
> Krichak
>
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-- 

Sara A. Rauscher
Earth System Physics Section 
The Abdus Salam International Centre for Theoretical Physics
Strada Costiera 11 
34014 Trieste ITALY
ph: +39 040 2240 225 fax: +39 040 2240 449
email: srausche at ictp.it