[gradsusr] GrADS v2.0.a7.oga.3: modifying time axis units
Charles Seman
Charles.Seman at noaa.gov
Tue Mar 30 12:28:39 EDT 2010
Thanks, Jennifer,
I didn't think of using a descriptor file to open the source netCDF file!
"open" file: was able to get the "open" file descriptor file to work as
desired...
"xdfopen" file: gave these errors in GrADS v1.9b4:
...
Alleged time dimension (from TDEF) is not an SDF dimension. Cannot
continue.
Time dimension name is:
time
.
Alleged level dimension (from ZDEF) is not an SDF dimension. Cannot
continue.
Level dimension name is:
level
.
...
and this in GrADS v2.0.a7.oga.3:
...
gadsdf: Lev dimension level is not an SDF dimension.
...
the xdf file contains (dset path omitted):
dset ...
zdef level 1 levels 0
tdef time 1 linear 00Z01JAN1998 3hr
Is the xdfopen file set up correctly?
Thanks for your help!
Chuck
Jennifer Adams wrote:
> Hi, Charles --
> Good question! The units of the time axis cannot be changed with the
> 'set sdfattr' command. The units attribute will always be written out
> as 'minutes since' and the base time will always be the time value of
> the first time step in your defined variable. The way to fix this
> problem is to assign a time value of 1jan1998 to netcdf variable in
> the first place instead of allowing it to default to 1jan0001. Use a
> descriptor file (for xdfopen or open) that has a tdef statement with
> the time you wish to assign. Then when you define your variable and
> write it out with sdfwrite, it will have the correct time value.
> --Jennifer
>
> On Mar 29, 2010, at 7:58 PM, Charles Seman wrote:
>>
>> I'm unable to modify the time axis units for an sdfwrite netCDF file
>> using the following command:
>> 'set sdfattr time String units "minutes since 1998-01-01 00:00:00"'
>> the units remain at "minutes since 0001-01-01 00:00"
>>
>> Here are the commands used to generate "nc_file" (the original file had
>> only lat/lon axes; no "z" or "t" axes...)
>>
>> 'set sdfwrite -4d 'nc_file
>> 'set sdfattr level String long_name height'
>> 'set sdfattr level String units m'
>> 'set sdfattr time String units "minutes since 1998-01-01 00:00:00"'
>> 'set sdfattr rprecip String long_name regridded precipitation'
>> 'set sdfattr rprecip String units mm/h'
>> 'set undef 'undef_value ;* change from default -9.99e8 to use source
>> netCDF file undef
>> say
>> 'q sdfwrite'
>> say result
>> 'sdfwrite rprecip'
>> 'c sdfwrite'
>>
>> Here's the "q sdfwrite" output (except for the SDFwrite file name):
>>
>> SDFwrite format is NetCDF
>> SDFwrite output undef value is set to -9999.900000
>> SDFwrite file will have at least 4 dimensions
>> SDFwrite attribute metadata:
>> level String long_name height
>> level String units m
>> time String units "minutes since 1998-01-01 00:00:00"
>> rprecip String long_name regridded precipitation
>> rprecip String units mm/h
>>
>> Here's output from the "\ncdump -c" on the output "nc_file"... the
>> "level" and "rprecip" attributes were modified as desired, but not the
>> time units:
>>
>> dimensions:
>> longitude = 144 ;
>> latitude = 50 ;
>> level = 1 ;
>> time = 1 ;
>> variables:
>> double longitude(longitude) ;
>> longitude:units = "degrees_east" ;
>> longitude:long_name = "Longitude" ;
>> double latitude(latitude) ;
>> latitude:units = "degrees_north" ;
>> latitude:long_name = "Latitude" ;
>> double level(level) ;
>> level:units = "m" ;
>> level:long_name = "height" ;
>> double time(time) ;
>> time:long_name = "Time" ;
>> time:units = "minutes since 0001-01-01 00:00" ;
>> double rprecip(time, level, latitude, longitude) ;
>> rprecip:missing_value = -9999.9 ;
>> rprecip:long_name = "regridded precipitation" ;
>> rprecip:units = "mm/h" ;
>> data:
>>
>> longitude = 1.25, 3.75, 6.25, 8.75, 11.25, 13.75, 16.25, 18.75, 21.25,
>> 23.75, 26.25, 28.75, 31.25, 33.75, 36.25, 38.75, 41.25, 43.75, 46.25,
>> 48.75, 51.25, 53.75, 56.25, 58.75, 61.25, 63.75, 66.25, 68.75, 71.25,
>> 73.75, 76.25, 78.75, 81.25, 83.75, 86.25, 88.75, 91.25, 93.75, 96.25,
>> 98.75, 101.25, 103.75, 106.25, 108.75, 111.25, 113.75, 116.25, 118.75,
>> 121.25, 123.75, 126.25, 128.75, 131.25, 133.75, 136.25, 138.75,
>> 141.25,
>> 143.75, 146.25, 148.75, 151.25, 153.75, 156.25, 158.75, 161.25,
>> 163.75,
>> 166.25, 168.75, 171.25, 173.75, 176.25, 178.75, 181.25, 183.75,
>> 186.25,
>> 188.75, 191.25, 193.75, 196.25, 198.75, 201.25, 203.75, 206.25,
>> 208.75,
>> 211.25, 213.75, 216.25, 218.75, 221.25, 223.75, 226.25, 228.75,
>> 231.25,
>> 233.75, 236.25, 238.75, 241.25, 243.75, 246.25, 248.75, 251.25,
>> 253.75,
>> 256.25, 258.75, 261.25, 263.75, 266.25, 268.75, 271.25, 273.75,
>> 276.25,
>> 278.75, 281.25, 283.75, 286.25, 288.75, 291.25, 293.75, 296.25,
>> 298.75,
>> 301.25, 303.75, 306.25, 308.75, 311.25, 313.75, 316.25, 318.75,
>> 321.25,
>> 323.75, 326.25, 328.75, 331.25, 333.75, 336.25, 338.75, 341.25,
>> 343.75,
>> 346.25, 348.75, 351.25, 353.75, 356.25, 358.75 ;
>>
>> latitude = -49, -47, -45, -43, -41, -39, -37, -35, -33, -31, -29, -27,
>> -25,
>> -23, -21, -19, -17, -15, -13, -11, -9, -7, -5, -3, -1, 1, 3, 5, 7,
>> 9, 11,
>> 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45,
>> 47, 49 ;
>>
>> level = 0 ;
>>
>> time = 0 ;
>>
>> Thanks for your help,
>> Chuck
>>
>> --
>>
>> Please note that Charles.Seman at noaa.gov
>> <mailto:Charles.Seman at noaa.gov> should be considered my NOAA
>> email address, not cjs at gfdl.noaa.gov <mailto:cjs at gfdl.noaa.gov>.
>>
>> ********************************************************************
>> Charles Seman Charles.Seman at noaa.gov
>> <mailto:Charles.Seman at noaa.gov>
>> U.S. Department of Commerce / NOAA / OAR
>> Geophysical Fluid Dynamics Laboratory voice: (609) 452-6547
>> 201 Forrestal Road fax: (609) 987-5063
>> Princeton, NJ 08540-6649 http://www.gfdl.noaa.gov/~cjs/
>> <http://www.gfdl.noaa.gov/%7Ecjs/>
>> ********************************************************************
>>
>> "The contents of this message are mine personally and do not necessarily
>> reflect any position of the Government or NOAA."
>>
>> _______________________________________________
>> gradsusr mailing list
>> gradsusr at gradsusr.org <mailto:gradsusr at gradsusr.org>
>> http://gradsusr.org/mailman/listinfo/gradsusr
>
> --
> Jennifer M. Adams
> IGES/COLA
> 4041 Powder Mill Road, Suite 302
> Calverton, MD 20705
> jma at cola.iges.org <mailto:jma at cola.iges.org>
>
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
>
--
Please note that Charles.Seman at noaa.gov should be considered my NOAA
email address, not cjs at gfdl.noaa.gov.
********************************************************************
Charles Seman Charles.Seman at noaa.gov
U.S. Department of Commerce / NOAA / OAR
Geophysical Fluid Dynamics Laboratory voice: (609) 452-6547
201 Forrestal Road fax: (609) 987-5063
Princeton, NJ 08540-6649 http://www.gfdl.noaa.gov/~cjs/
********************************************************************
"The contents of this message are mine personally and do not necessarily
reflect any position of the Government or NOAA."
More information about the gradsusr
mailing list