Re: ncl_convert2nc and cdo

Hi David,

>From looking at your netCDF header, it is clear that your file
is not Climate Forecast (CF) compliant.

http://cf-pcmdi.llnl.gov/

In particular, your file does not have the "time" coordinate
defined according to the CF specifications.

http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.6/cf-conventions.htm
l#time-coordinate

CDO requires that your file conform to the CF convention,
and must include the time coordinate. You have a "time"
like coordinate, but these do not appear to conform to the CF
convention. Note that your time coordinate must be named
"time" as CDO will only recognize this. Coordinate (or
record dimensions) can easily be renamed using netCDF
Operators utility called ncrename.

http://nco.sourceforge.net/nco.html#ncrename-netCDF-Renamer

Syntax looks similar to this:

% ncrename -d old_coord_name,new_coord_name.

I do not recall whether NCL can be used to change the name of
a coordinate variable, so I'll have to defer to one of the
gurus for that.

I hope this helps.

Daran

Daran Rife
Head of Mesoscale Modeling
GL Garrad Hassan

9665 Chesapeake Drive, Suite 435, San Diego, CA 92123, USA
Tel: +1 303 271 1450 / Fax: +1 303 271 1450 / Mobile: +1 303 968 6821
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--
Message: 9
Date: Thu, 26 Apr 2012 16:04:07 -0600
From: "David B. Reusch" <dreusch@ees.nmt.edu>
Subject: ncl_convert2nc and cdo
To: ncl-talk@ucar.edu
Message-ID: <4F99C657.2000502@ees.nmt.edu>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hello,
I don't know if this is a NCL problem or a CDO problem, but since I can 
get it to work if I don't use the output of ncl_convert2nc, I thought 
I'd start with NCL.  The problem is that I get the following when trying
to use CDO on a netCDF file created by ncl_convert2nc:
> cdo sellonlatbox,-90,-55,0,360 input.nc output.nc
> cdf_get_vara_double : ncid = 65536 varid = 6
>
> Error (cdf_get_vara_double) : NetCDF: Index exceeds dimension bound
If I apply cdo to the original grb file, I do not get this error.
> cdo -f nc -t ecmwf sellonlatbox,-90,-55,0,360 input.grb output2.nc
> cdo sellonlatbox: Processed 191889408 values from 1 variable over 1464
> timesteps. ( 1.38s )
The ncl_convert2nc command works without obvious errors:
> ncl_convert2nc input.grb
> Processing file: input.grb...
>  Copyright (C) 1995-2011 - All Rights Reserved
>  University Corporation for Atmospheric Research
>  NCAR Command Language Version 6.0.0
>  The use of this software is governed by a License Agreement.
>  See http://www.ncl.ucar.edu/ for more details.
> Classic model NetCDF does not support string types, converting 
> initial_time0 to a character array
> Dimension 'ncl_strlen_0' will be added
The original file is a forecast file from ERA-Interim 
(ei.oper.fc.sfc.regn128sc.strd_175.1980).  I copied it to input.grb to 
save typing!
All of this is on bluefire.  Files can be found in 
/glade/user/dbr/fc/ncl_cdo_test.  See below for the ncdump output for 
the NCL-converted file.
I've found alternate methods to get my needed processing done so this 
isn't an urgent problem.  Mostly I'm just curious whether this is NCL or
CDO (v1.5.3), and what the underlying cause might be.
Thanks,
Dave
ncdump output:
netcdf input {
dimensions:
         initial_time0_hours = 732 ;
         forecast_time1 = 2 ;
         g4_lat_2 = 256 ;
         g4_lon_3 = 512 ;
         ncl_strlen_0 = 18 ;
variables:
         char initial_time0(initial_time0_hours, ncl_strlen_0) ;
                 initial_time0:NCL_converted_from_type = "string" ;
                 initial_time0:units = "mm/dd/yyyy (hh:mm)" ;
                 initial_time0:long_name = "Initial time of first
record" ;
         int forecast_time1(forecast_time1) ;
                 forecast_time1:units = "hours" ;
                 forecast_time1:long_name = "Forecast offset from 
initial time" ;
         float g4_lon_3(g4_lon_3) ;
                 g4_lon_3:La1 = 89.463f ;
                 g4_lon_3:Lo1 = 0.f ;
                 g4_lon_3:La2 = -89.463f ;
                 g4_lon_3:Lo2 = 359.297f ;
                 g4_lon_3:Di = 0.7031252f ;
                 g4_lon_3:N = 128.f ;
                 g4_lon_3:units = "degrees_east" ;
                 g4_lon_3:GridType = "Gaussian Latitude/Longitude Grid"
;
                 g4_lon_3:long_name = "longitude" ;
         float g4_lat_2(g4_lat_2) ;
                 g4_lat_2:La1 = 89.463f ;
                 g4_lat_2:Lo1 = 0.f ;
                 g4_lat_2:La2 = -89.463f ;
                 g4_lat_2:Lo2 = 359.297f ;
                 g4_lat_2:Di = 0.7031252f ;
                 g4_lat_2:N = 128.f ;
                 g4_lat_2:units = "degrees_north" ;
                 g4_lat_2:GridType = "Gaussian Latitude/Longitude Grid"
;
                 g4_lat_2:long_name = "latitude" ;
         double initial_time0_encoded(initial_time0_hours) ;
                 initial_time0_encoded:units = "yyyymmddhh.hh_frac" ;
                 initial_time0_encoded:long_name = "initial time encoded
as double" ;
         double initial_time0_hours(initial_time0_hours) ;
                 initial_time0_hours:units = "hours since 1800-01-01 
00:00" ;
                 initial_time0_hours:long_name = "initial time" ;
         float STRD_GDS4_SFC(initial_time0_hours, forecast_time1, 
g4_lat_2, g4_lon_3) ;
                 STRD_GDS4_SFC:parameter_number = 175 ;
                 STRD_GDS4_SFC:parameter_table_version = 128 ;
                 STRD_GDS4_SFC:gds_grid_type = 4 ;
                 STRD_GDS4_SFC:level_indicator = 1 ;
                 STRD_GDS4_SFC:_FillValue = 1.e+20f ;
                 STRD_GDS4_SFC:units = "W m**-2 s" ;
                 STRD_GDS4_SFC:long_name = "Surface thermal radiation 
downwards" ;
                 STRD_GDS4_SFC:center = "European Center for 
Medium-Range Weather Forecasts (RSMC)" ;
// global attributes:
                 :creation_date = "Thu Apr 26 15:49:03 MDT 2012" ;
                 :NCL_Version = "6.0.0" ;
                 :system = "AIX be1005en 3 5 00CBF2314C00 AIX" ;
                 :conventions = "None" ;
                 :grib_source = "input.grb" ;
                 :title = "NCL: convert-GRIB-to-netCDF" ;
}
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