[ferret_users] Problem with description files and short type

[Erwan Monier <emonier@xxxxxxxxxxx>]

Hi,

I run the MM5 model which provides data output files every 8 days so I  
have many files. To read the variables over the whole time I use a  
description file (*.des). This has worked fine but now I am getting  
some problems. When I open the MM5 output files individually, I have  
no problem reading the data and it is well converted from short to  
float automatically by ferret. However, when I open the files using  
the description file, the values listed are incoherent, and do not  
even correspond the short values before the conversion using the scale  
factor and offset. I welcome any comments on this problem.
Erwan

Here are the commands I use in ferret:

When using the MM5 output file individually:
************************************************

yes? use out.90053118.nc
 *** NOTE: Units on axis "sigma_level" are not recognized: sigma
 *** NOTE: They will not be convertible:
yes? say `u,RETURN=nc_scale`
 !-> MESSAGE/CONTINUE 0.01
0.01
yes? say `u,RETURN=nc_offset`
 !-> MESSAGE/CONTINUE 0
0
yes? list u[d=1,T="01-JUN-1990:00:00:00",X=55.0,Y=0,K=1:4]
             VARIABLE : zonal component of horizontal wind (m/s)
             DATA SET : Output from MM5 v.3-4-0
             FILENAME : out.90053118.nc
             SUBSET   : 4 points (Z (sigma))
             LONGITUDE: 54.8E(54.8)
             LATITUDE : 0.3S
             TIME     : 01-JUN-1990 00:00
             54.81E
              82
 0.012 / 1:   8.57
 0.037 / 2:  -1.57
 0.075 / 3: -16.98
 0.125 / 4: -18.24

When using the description file:
**********************************

yes? use run.des
 *** NOTE: Units on axis "sigma_level" are not recognized: sigma
 *** NOTE: They will not be convertible:
yes? say `u,RETURN=nc_scale`
 !-> MESSAGE/CONTINUE 0.01
0.01
yes? say `u,RETURN=nc_offset`
 !-> MESSAGE/CONTINUE 0
0
yes? list u[d=2,T="01-JUN-1990:00:00:00",X=55.0,Y=0,K=1:4]
             VARIABLE : zonal component of horizontal wind (m/s)
             DATA SET : MM5 Model Output
             FILENAME : run.des
             SUBSET   : 4 points (Z (sigma))
             LONGITUDE: 54.8E(54.8)
             LATITUDE : 0.3S
             TIME     : 01-JUN-1990 00:00
              54.81E
               82
 0.012 / 1:   70700.
 0.037 / 2:  -31800.
 0.075 / 3: -188900.
 0.125 / 4: -303300.

Here is the description file run.des:
*****************************

 &FORMAT_RECORD
  D_TYPE               = '  MC',
  D_FORMAT             = '  1A',
  D_SOURCE_CLASS       = 'MODEL OUTPUT',
 /
 &BACKGROUND_RECORD
  D_EXPNUM             = '0000',
  D_MODNUM             = '  AA',
  D_TITLE              = 'MM5 Model Output',
  D_T0TIME             = '31-MAY-1990 18:00:00',
  D_TIME_UNIT          = 3600,
  D_TIME_MODULO        = .FALSE.,
 /
 &MESSAGE_RECORD
  D_MESSAGE            = ' ',
  D_ALERT_ON_OPEN      = F,
  D_ALERT_ON_OUTPUT    = F,
 /

 &EXTRA_RECORD
 /

 &STEPFILE_RECORD
  s_filename           = '/data/emonier/mm5_mjo/mm5_lon180_ERA_cntrl/ 
MM5/Run/out.90053118.nc'
,
  S_AUX_SET_NUM        = 0,
  S_START              = 0,
  S_END                = 192,
  S_DELTA              = 6,
  S_NUM_OF_FILES       = 1,
  S_REGVARFLAG         = ' ',
 /
 &STEPFILE_RECORD
  s_filename           = '**END OF STEPFILES**'
 /