subsetting single variable from CFSR reanalysis data
Added by Joseph S over 5 years ago
Greetings CDO support community:
I've encountered an error (shown below) while attempting to subset a single variable from a netcdf file that contains CFSR reanalysis data. I routinely subset variables without any issues, but I think this type of nc file is creating an issue because time is also defined as a variable. I'm unsure how to proceed.
So far, I have tried multiple variations of the command shown below:
$ cdo selname,ICEC_L1 icecon.cdas1.201908.grb2.nc ICEC_L1_201908.nc
Warning (cdfCheckVars): Unsupported data type (char/string), skipped variable valid_date_time!
Warning (cdfCheckVars): Unsupported data type (char/string), skipped variable ref_date_time!
cdf_put_vara_float: name=ICEC_L1 type=NC_FLOAT minval=0.000000 maxval=0.639000
Error (cdf_put_vara_float): Operation not supported
Error (cdf_close): Operation not supported
Additional details about the file (icecon.cdas1.201908.grb2.nc) are attached to the post.
I suspect that the issue may require a defined time axis, but I tried that and it also produced an error (shown below):
$ cdo -settaxis,2019-08-01,00:00:00,1hour -selname,ICEC_L1 icecon.cdas1.201908.grb2.nc ICEC_L1_201908.nc
cdo(1) selname: Process started
Warning (cdfCheckVars): Unsupported data type (char/string), skipped variable valid_date_time!
Warning (cdfCheckVars): Unsupported data type (char/string), skipped variable ref_date_time!
cdf_put_vara_double: name=ICEC_L1 type=NC_FLOAT minval=0.000000 maxval=0.639000
Error (cdf_put_vara_double): Operation not supported
Error (cdf_close): Operation not supported
I would appreciate any suggestions regarding how to subset the ICEC_L1 variable from the file. I am using CDO version
Thanks kindly,
Joseph
| icecon.cdas1.201908.grb2.nc (7.38 MB) icecon.cdas1.201908.grb2.nc | icecon.cdas1.201908.grb2.nc | ||
| filedes.txt (16 Bytes) filedes.txt | filedes | ||
| showtimestamp.txt (15.3 KB) showtimestamp.txt | showtimestamp | ||
| showname.txt (23 Bytes) showname.txt | showname | ||
| info.txt (159 KB) info.txt | info | ||
| showatts.txt (396 Bytes) showatts.txt | showatts | ||
| sinfo.txt (3.44 KB) sinfo.txt | sinfo | ||
| ncdump.txt (6 MB) ncdump.txt | ncdump | ||
| cdo_version.txt (2.17 KB) cdo_version.txt | cdo_version |
Replies (2)
RE: subsetting single variable from CFSR reanalysis data - Added by Karin Meier-Fleischer over 5 years ago
Hi Joseph,
the problem is the type of the variables valid_date_time and ref_date_time which is char.
ncdump -h icecon.cdas1.201908.grb2.nc
netcdf icecon.cdas1.201908.grb2 {
dimensions:
time = UNLIMITED ; // (744 currently)
lat = 24 ;
lon = 108 ;
tstrlen = 10 ;
variables:
float time(time) ;
time:name = "time" ;
time:long_name = "time" ;
time:units = "hours since 2019-08-01 00:00:00.0 +0:00" ;
time:calendar = "standard" ;
char valid_date_time(time, tstrlen) ;
valid_date_time:name = "valid_date_time" ;
valid_date_time:long_name = "valid date and time as YYYYMMDDHH" ;
char ref_date_time(time, tstrlen) ;
ref_date_time:name = "ref_date_time" ;
ref_date_time:long_name = "reference date and time as YYYYMMDDHH" ;
int forecast_hour(time) ;
forecast_hour:long_name = "forecast hour" ;
forecast_hour:units = "hours" ;
float lat(lat) ;
lat:name = "lat" ;
lat:long_name = "latitude" ;
lat:units = "degree_north" ;
lat:valid_range = 69.1993f, 73.90116f ;
float lon(lon) ;
lon:name = "lon" ;
lon:long_name = "longitude" ;
lon:units = "degree_east" ;
lon:valid_range = 199.0227f, 220.9091f ;
float ICEC_L1(time, lat, lon) ;
ICEC_L1:long_name = "Ice cover" ;
ICEC_L1:product_description = "Forecast over hours" ;
ICEC_L1:units = "fraction" ;
ICEC_L1:level = "Ground or water surface" ;
ICEC_L1:_FillValue = 3.4e+38f ;
// global attributes:
:Creation\ date\ and\ time = "2019-09-14 11:36:09 -0600" ;
:Conventions = "CF-1.5" ;
:Creator = "NCAR - CISL RDA (dattore)" ;
}
You can delete these variables and forecast_hour if not needed with NCO's ncks
ncks -O -x -v valid_date_time,ref_date_time,forecast_hour icecon.cdas1.201908.grb2.nc ICEC_L1_201908.ncNow, CDO can handle the file correctly
cdo sinfo ICEC_L1_201908.nc
File format : NetCDF
-1 : Institut Source T Steptype Levels Num Points Num Dtype : Parameter ID
1 : unknown unknown v instant 1 1 2592 1 F32 : -1
Grid coordinates :
1 : lonlat : points=2592 (108x24)
lon : 199.0227 to 220.9091 by 0.2045455 degree_east
lat : 73.90116 to 69.1993 by -0.204429 degree_north
Vertical coordinates :
1 : surface : levels=1
Time coordinate : 744 steps
RefTime = 2019-08-01 00:00:00 Units = hours Calendar = standard
YYYY-MM-DD hh:mm:ss YYYY-MM-DD hh:mm:ss YYYY-MM-DD hh:mm:ss YYYY-MM-DD hh:mm:ss
2019-08-01 01:00:00 2019-08-01 02:00:00 2019-08-01 03:00:00 2019-08-01 04:00:00
2019-08-01 05:00:00 2019-08-01 06:00:00 2019-08-01 07:00:00 2019-08-01 08:00:00
2019-08-01 09:00:00 2019-08-01 10:00:00 2019-08-01 11:00:00 2019-08-01 12:00:00
2019-08-01 13:00:00 2019-08-01 14:00:00 2019-08-01 15:00:00 2019-08-01 16:00:00
2019-08-01 17:00:00 2019-08-01 18:00:00 2019-08-01 19:00:00 2019-08-01 20:00:00
2019-08-01 21:00:00 2019-08-01 22:00:00 2019-08-01 23:00:00 2019-08-02 00:00:00
2019-08-02 01:00:00 2019-08-02 02:00:00 2019-08-02 03:00:00 2019-08-02 04:00:00
2019-08-02 05:00:00 2019-08-02 06:00:00 2019-08-02 07:00:00 2019-08-02 08:00:00
2019-08-02 09:00:00 2019-08-02 10:00:00 2019-08-02 11:00:00 2019-08-02 12:00:00
2019-08-02 13:00:00 2019-08-02 14:00:00 2019-08-02 15:00:00 2019-08-02 16:00:00
2019-08-02 17:00:00 2019-08-02 18:00:00 2019-08-02 19:00:00 2019-08-02 20:00:00
2019-08-02 21:00:00 2019-08-02 22:00:00 2019-08-02 23:00:00 2019-08-03 00:00:00
2019-08-03 01:00:00 2019-08-03 02:00:00 2019-08-03 03:00:00 2019-08-03 04:00:00
2019-08-03 05:00:00 2019-08-03 06:00:00 2019-08-03 07:00:00 2019-08-03 08:00:00
2019-08-03 09:00:00 2019-08-03 10:00:00 2019-08-03 11:00:00 2019-08-03 12:00:00
................................................................................
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2019-08-29 13:00:00 2019-08-29 14:00:00 2019-08-29 15:00:00 2019-08-29 16:00:00
2019-08-29 17:00:00 2019-08-29 18:00:00 2019-08-29 19:00:00 2019-08-29 20:00:00
2019-08-29 21:00:00 2019-08-29 22:00:00 2019-08-29 23:00:00 2019-08-30 00:00:00
2019-08-30 01:00:00 2019-08-30 02:00:00 2019-08-30 03:00:00 2019-08-30 04:00:00
2019-08-30 05:00:00 2019-08-30 06:00:00 2019-08-30 07:00:00 2019-08-30 08:00:00
2019-08-30 09:00:00 2019-08-30 10:00:00 2019-08-30 11:00:00 2019-08-30 12:00:00
2019-08-30 13:00:00 2019-08-30 14:00:00 2019-08-30 15:00:00 2019-08-30 16:00:00
2019-08-30 17:00:00 2019-08-30 18:00:00 2019-08-30 19:00:00 2019-08-30 20:00:00
2019-08-30 21:00:00 2019-08-30 22:00:00 2019-08-30 23:00:00 2019-08-31 00:00:00
2019-08-31 01:00:00 2019-08-31 02:00:00 2019-08-31 03:00:00 2019-08-31 04:00:00
2019-08-31 05:00:00 2019-08-31 06:00:00 2019-08-31 07:00:00 2019-08-31 08:00:00
2019-08-31 09:00:00 2019-08-31 10:00:00 2019-08-31 11:00:00 2019-08-31 12:00:00
2019-08-31 13:00:00 2019-08-31 14:00:00 2019-08-31 15:00:00 2019-08-31 16:00:00
2019-08-31 17:00:00 2019-08-31 18:00:00 2019-08-31 19:00:00 2019-08-31 20:00:00
2019-08-31 21:00:00 2019-08-31 22:00:00 2019-08-31 23:00:00 2019-09-01 00:00:00
cdo sinfo: Processed 1 variable over 744 timesteps [0.01s 22MB]
-Karin
RE: subsetting single variable from CFSR reanalysis data - Added by Joseph S over 5 years ago
Thank you very much for the solution, Karin. It works perfectly now. 
Kind regards,
Joseph