>> Has anyone used NCL to convert the NCEP-DOE Reanalysis (R2) monthly
>> atmospheric analyses in GRIB format to netCDF?
>> The R2 fields are on a global long-lat grid (144 x 73) with a 2.5 deg of
>> longitude resolution.
>>
>> John Kelley
>> NOAA/National Ocean Service
>> Durham, NH
>
>One of our data experts answered this question internally, and
>he said I could share it with ncl-talk, so here it is:
>
> The NCEP/DOE Reanalysis (R2) data files are in GRIB format. You
> should be able to convert the GRIB files into netcdf files using
> NCL.
>
> Before you start the conversion, please check the following
> site. CDC of NOAA may have what you need in netcdf files
> already. The definitions used in the CDC's netcdf files may be
> different from what NCL generates.
> http://www.cdc.noaa.gov/cdc/data.ncep.reanalysis2.html
>
>
>--Mary
Please note that CDC often stores the variables
as type short [ie: 16 bit integers]. These must be
scaled and have an offset added before use. In NCL,
the following is the best approach. It uses the
"short2flt" function located in contributed.ncl.
http://www.ncl.ucar.edu/Document/Functions/Contributed/short2flt.shtml
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
begin
f = addfile ("air.2m.gauss.1979.nc" , "r")
t2m = short2flt( f->air )
end
The short2flt example illustrates a few other things
that you might find useful.
Regards
D
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