[gradsusr] SDF file does not have any non-coordinate variables

[Ghan, Steven J]

I am using Grads version 2.0.a7.1 to open a netcdf file with xdfopen:

ga-> xdfopen t.ddf
Scanning Descriptor File:  t.ddf
gadsdf: SDF file does not have any non-coordinate variables.
SDF Descriptor file t.ddf was not successfully opened & parsed.

Where
t.ddf =
dset ^mam3_aerocom2.cam2.h0.0001-0005.avg.nc
TITLE AeroCom Present Day
UNDEF 1.e36
OPTIONS 365_day_calendar
tdef time 1 linear jan2000 1mo
VARS 1
t=>t 30 99
ENDVARS

According to ncdump,

netcdf mam3_aerocom2.cam2.h0.0001-0005.avg {
dimensions:
    lat = 96 ;
    lon = 144 ;
    lev = 30 ;
    time = UNLIMITED ; // (1 currently)
    double lat(lat) ;
        lat:long_name = "latitude" ;
        lat:units = "degrees_north" ;
    double lon(lon) ;
        lon:long_name = "longitude" ;
        lon:units = "degrees_east" ;
    double lev(lev) ;
        lev:long_name = "hybrid level at midpoints (1000*(A+B))" ;
        lev:units = "level" ;
        lev:positive = "down" ;
        lev:standard_name = "atmosphere_hybrid_sigma_pressure_coordinate" ;
        lev:formula_terms = "a: hyam b: hybm p0: P0 ps: PS" ;
    double time(time) ;
        time:long_name = "time" ;
        time:units = "days since 0000-01-01 00:00:00" ;
        time:calendar = "noleap" ;
        time:bounds = "time_bnds" ;
    float T(time, lev, lat, lon) ;
        T:units = "K" ;
        T:long_name = "Temperature" ;
        T:cell_methods = "time: mean" ;
// global attributes:
        :Conventions = "CF-1.0" ;
        :source = "CAM" ;
        :case = "mam3_aerocom2" ;
}
Interestingly, if I remove the
VARS 1
t=>t 30 99
ENDVARS
from t.ddf, I can open the netcdf file, but query tells me
ga-> q file
File 1 : AeroCom Present Day
  Descriptor: t.ddf
  Binary: mam3_aerocom2.cam2.h0.0001-0005.avg.nc
  Type = Gridded
  Xsize = 144  Ysize = 96  Zsize = 30  Tsize = 1  Esize = 1
  Number of Variables = 1
       30  t,z,y,x  Temperature

The variable name is missing! So grads is unable to get the variable name. And of course I have no way of identifying the variable.

The curious thing is that I was not having any such trouble until I produced a new batch of model history.  I compared the ncdumps from the history that I could read with history that I could not, and found only trivial differences unrelated to variable names.

Any suggestions out there regarding this puzzler?

-Steve Ghan

_________________________________
Steven Ghan, PhD.
FUNDAMENTAL & COMPUTATIONAL SCIENCES DIRECTORATE
Atmospheric Sciences and Global Change Division
Pacific Northwest National Laboratory
902 Battelle Boulevard
P.O. Box 999, MSIN K9-24
Richland, WA 99352 USA
Tel: 509-372-6169
Fax: 509-372-6168
steve.ghan at pnl.gov
http://www.pnl.gov/atmospheric/staff/staff_info.asp?staff_num=5663