Could not retrieve add offset

Sat May 20 19:25:35 EDT 2006

Jennifer, et al.,

As it turns out, the original descriptor file that I sent was fine, as you
and Diane have determined.  Upon my debugging of another problem, I
discovered I had incorrectly defined my $GADDIR environment variable.  I
have since tested the descriptor file without problem.

I am a GrADS newbie and have a lot to learn.  My apologies that you all
spent some time on what turned out to be pilot error.

By the way, I have successfully followed Hoop's 'sdfopen'.  However, yes,
I have experienced a number of core dumps.  I am too inexperienced to make
an assessment; could be nothing to do with this method and more to some
other misconfiguration on my part.   But I will try the two different
methods over the course of the next two weeks and may have some comments
of value.

Thanks.

-pw

On Sat, 20 May 2006 16:14:58 -0400, Jennifer M. Adams <jma at COLA.IGES.ORG>
wrote:

>Dear Paul, et al.,
>OK, so you could read this file with sdfopen and do it the way Hoop
>suggests. But if templating with sdfopen often leads to core dumps on
>your operating system, then it's perfectly reasonable to do it with a
>'dtype netcdf' descriptor. User's choice. My greater concern is why
>the 'dtype netcdf' interface isn't retrieving the 'add_offset' or the
>'missing_value' attributes properly for you.
>
>I downloaded a NetCDF file from CDC -- daily means of SLP for 1999
>with the identical ncdump output -- and used your descriptor file
>with this data set and it read the slp data on my mac without any
>problems at all:
>
>ga-> open /data/netcdf/rean/slp.ctl
>Scanning description file:  /data/netcdf/rean/slp.ctl
>Data file /data/netcdf/rean/slp.%y4.nc is open as file 1
>LON set to 0 360
>LAT set to -90 90
>LEV set to 1 1
>Time values set: 1999:1:1:0 1999:1:1:0
>ga-> q file
>File 1 : NCEP Reanalysis Daily Averages
>   Descriptor: /data/netcdf/rean/slp.ctl
>   Binary: /data/netcdf/rean/slp.%y4.nc
>   Type = Gridded
>   Xsize = 144  Ysize = 73  Zsize = 1  Tsize = 731
>   Number of Variables = 1
>     slp 0 -103 mean Daily Sea Level Pressure [Pa]
>ga-> d slp
>Contouring: 97000 to 105000 interval 1000
>ga->
>
>
>The attributes of this file are exactly the same, so ... why doesn't
>it work for you???
>
>On May 18, 2006, at 8:42 PM, Willis, Paul ENV:EX wrote:
>> Running GrADS 1.9b4 on linux.
>Which executable are you using:  gradsnc, gradshdf, or gradsdods?
>Which linux: RH7.1, RH9, or RHE3?
>
>  Jennifer
>
>>
>>
>> Thanks in advance for any guidance.
>>
>> -paul
>> *********************
>>
>>
>> ga-> q dim
>>
>> Default file number is: 1
>>
>> X is varying   Lon = 0 to 360   X = 1 to 145
>>
>> Y is varying   Lat = -90 to 90   Y = 0.999999 to 73
>>
>> Z is fixed     Lev = 1  Z = 1
>>
>> T is fixed     Time = 00Z01JAN1999  T = 1
>>
>> ga-> d slp
>> "  -- using -1e+15 insteade data type for "missing_value
>> " not handled
>> -- using -1e+15 instead
>>
>> Warning: Could not retrieve add offset data type -- setting add
>> offset to
>> 0.0
>>
>> Contouring: -20000 to -16500
>>  interval 500
>>
>> *********************
>> here is my descriptor file
>> *********************
>> dset /home/pfwillis/2006/Grads/circulation/Climate/data/slp_daily.%
>> y4.nc
>> dtype netcdf
>> options yrev template
>> undef -1e15 missing_value
>> unpack scale_factor add_offset
>> title NCEP Reanalysis Daily Averages
>> xdef 144 linear 0 2.5
>> ydef 73 linear -90 2.5
>> zdef   1 linear 1 1
>> tdef 731 linear 00Z01jan1999 24hr
>> vars 1
>> slp 0 t,y,x mean Daily Sea Level Pressure [Pa]
>> endvars
>>
>>
>> *********************
>> should an ncdump provide useful information on this, see below.
>> *********************
>>
>>
>> netcdf slp_daily.1999 {
>> dimensions:
>>  lon = 144 ;
>>  lat = 73 ;
>>  time = UNLIMITED ;
>>  // (365 currently)
>> variables:
>>  float lat(lat) ;
>>   lat:units = "degrees_north" ;
>>
>>   lat:actual_range = 90.f, -90.f ;
>>   lat:long_name = "Latitude" ;
>>
>>  float lon(lon) ;
>>   lon:units = "degrees_east" ;
>>
>>   lon:long_name = "Longitude" ;
>>
>>   lon:actual_range = 0.f, 357.5f ;
>>  double time(time) ;
>>
>>   time:units = "hours since 1-1-1 00:00:0.0" ;
>>
>>   time:long_name = "Time" ;
>>   time:actual_range = 17514144., 17522880. ;
>>
>>   time:delta_t = "0000-00-01 00:00:00" ;
>>
>> time:avg_period = "0000-00-01 00:00:00" ;
>>  short slp(time, lat, lon) ;
>>
>> slp:long_name = "mean Daily Sea Level Pressure" ;
>>
>>   slp:valid_range = 87000.f, 115000.f ;
>>
>>   slp:actual_range = 92970.f, 110552.f ;
>>
>>   slp:units = "Pascals" ;
>>
>>   slp:add_offset = 119765.f ;
>>
>>   slp:scale_factor = 1.f ;
>>
>>   slp:missing_value = 32766s ;
>>
>>   slp:precision = 0s ;
>>
>>   slp:least_significant_digit = -1s ;
>>
>>  slp:GRIB_id = 2s ;
>>
>>   slp:GRIB_name = "PRMSL" ;
>>
>>   slp:var_desc = "Sea Level Pressure\n",
>>    "P" ;
>>
>>   slp:dataset = "NCEP Reanalysis Daily Averages\n",
>>    "AJ" ;
>>
>>   slp:level_desc = "Sea Level\n",
>>    "I" ;
>>
>>   slp:statistic = "Mean\n",
>>    "M" ;
>>
>>   slp:parent_stat = "Individual Obs\n",
>>    "I" ;
>>
>>
>> // global attributes:
>>   :Conventions = "COARDS" ;
>>
>>   :title = "mean daily NMC reanalysis (1999)" ;
>>
>>   :base_date = 1999s, 1s, 1s ;
>>
>>   :history = "created 99/01/04 by Hoop (netCDF2.3)" ;
>>
>>   :description = "Data is from NMC initialized reanalysis\n",
>>
>>    "(4x/day).  It consists of most variables
>> interpolated to\n",
>>
>>    "pressure surfaces from model (sigma) surfaces." ;
>>
>>   :platform = "Model" ;
>>
>>
>> data:
>>
>>  lat = .......
>>
>
>Jennifer M. Adams
>IGES/COLA
>4041 Powder Mill Road, Suite 302
>Beltsville, MD 20705
>jma at cola.iges.org