Processing Converted GRIB2 Data

[Eric Konieczny]

Dear GrADS users,
 I am trying to process an NDFD GRIB2 dataset with GrADS.  The
dataset is packed with only one variable and has multiple time steps.
First, I converted the GRIB2 file to GRIB1, using NCEP's cnvgrib v. 1.1.1
converter.  Next I created the .ctl file using grib2ctl and the
corresponding .idx file with gribmap.  Grib2ctl produced the following
control file:

dset ^newGRIB1.grb
index ^newGRIB1.grb.idx
undef 9.999E+20
title newGRIB1.grb
*  produced by grib2ctl v0.9.12.5p33f
dtype grib 255
pdef 1073 689 lcc 20.191000 238.445000 1 1 25.000000 25.000000 265.000000
5079 5079
xdef 1073 linear 238.445000 0.0491959539055032
ydef 689 linear 20.191000 0.0461727272727273
tdef 1 linear 14Z08aug2005 1mo
zdef 1 linear 1 1
vars 1
TCDCsfc  0 71,1,0  ** surface Total cloud cover [%]
ENDVARS

The tdef line is produced for whatever reason incorrectly, so I tried
changing it to what it should be:
tdef 36 linear 14Z08aug2005 3hr

I can open the .ctl file in GrADS and display the variable at the first
time instance (t=1), but when I switch to another time step, an error
occurs


ga-> open data/newGRIB1.ctl
Scanning description file:  data/newGRIB1.ctl
Data file data/newGRIB1.grb is open as file 1
LON set to 238.445 291.183
LAT set to 20.191 51.9578
LEV set to 1 1
Time values set: 2005:8:8:14 2005:8:8:14
Notice: Implied interpolation for file data/newGRIB1.ctl
 Interpolation will be performed on any data displayed from this file

ga-> set t 2
Time values set: 2005:8:8:17 2005:8:8:17
ga-> d tcdcsfc
Notice:  Automatic Grid Interpolation Taking Place
GRIB I/O Error: Bit Map I/O
Data Request Error:  Error for variable 'tcdcsfc'
  Error ocurred at column 1
DISPLAY error:  Invalid expression
  Expression = tcdcsfc

Obviously there are some issues with accessing the multiple time steps.
To further investigate this I ran an inventory on the GRIB1 file with both
wgrib and degrib (from the MDL).  While degrib seemed to recognize the
different time steps, wgrib did not.

Has anyone else had success reading a GRIB2 dataset (converted to GRIB1)
in GrADS?  Is there some other change that I need to make in the .ctl
file?  Any ideas/suggestions would be greatly appreciated.

Thanks in advance,
Eric Konieczny