unable to display a variable : CDO operator gradsdes
Added by Syed Ali over 7 years ago
I have a netcdf file which has a variable Band1 (see attached). I have thousands of such files which cannot be merged using CDO due to memory issue. Therefore, I made a grads control file using CDO operator gradsdes, as shown below. But when I open this control file in grads I get an error: Data Request Error: Error for variable 'band1' DISPLAY error: Invalid expression
- Generated by CDO operator gradsdes
*
DSET ^Indus_maxt_19600102.flt.nc
DTYPE netCDF
XDEF 878 LINEAR 60.712500 0.025000
YDEF 557 LINEAR 23.362500 0.025000
ZDEF 1 LEVELS 0
TDEF 1 LINEAR 00:00Z00jan0000 1mn
TITLE Indus_maxt_19600102.flt.nc 878x557 grid
UNDEF -999
VARS 1
Band1 0 y,x GDAL Band Number 1
ENDVARS
Replies (1)
RE: unable to display a variable : CDO operator gradsdes - Added by Karin Meier-Fleischer about 7 years ago
Hi Syed,
this is more a question of how to open a netCDF file in GrADS. If you would have taken a look into your netCDF file you would have seen
ncdump -h Indus_maxt_19620316.flt.nc
netcdf Indus_maxt_19620316.flt { dimensions: lon = 878 ; lat = 557 ; variables: char crs ; crs:grid_mapping_name = "latitude_longitude" ; crs:long_name = "CRS definition" ; crs:longitude_of_prime_meridian = 0. ; crs:semi_major_axis = 6378137. ; crs:inverse_flattening = 298.257223563 ; crs:spatial_ref = "GEOGCS[\"WGS 84\",DATUM[\"WGS_1984\",SPHEROID[\"WGS 84\",6378137,298.257223563,AUTHORITY[\"EPSG\",\"7030\"]],AUTHORITY[\"EPSG\",\"6326\"]],PRIMEM[\"Greenwich\",0,AUTHORITY[\"EPSG\",\"8901\"]],UNIT[\"degree\",0.0174532925199433,AUTHORITY[\"EPSG\",\"9122\"]],AUTHORITY[\"EPSG\",\"4326\"]]" ; crs:GeoTransform = "60.7 0.025 0 37.27500000000001 0 -0.025 " ; double lat(lat) ; lat:standard_name = "latitude" ; lat:long_name = "latitude" ; lat:units = "degrees_north" ; double lon(lon) ; lon:standard_name = "longitude" ; lon:long_name = "longitude" ; lon:units = "degrees_east" ; float Band1(lat, lon) ; Band1:long_name = "GDAL Band Number 1" ; Band1:_FillValue = -999.f ; Band1:grid_mapping = "crs" ; // global attributes: :Conventions = "CF-1.5" ; :GDAL = "GDAL 2.2.2, released 2017/09/15" ; :history = "Thu Nov 09 10:11:18 2017: GDAL CreateCopy( Indus_maxt_19620316.flt.nc, ... )" ; }
This tells you that you can directly load the file within grads:
grads -lc "sdfopen Indus_maxt_19620316.flt.nc"
You don't need a descriptor file because it is netcdf with dimension names lat and lon.
-Karin