NetCDF Xdfopen problem

[Karin Meier-Fleischer]

Hello Mike,

if you have a non COARDS netCDF file your entries for the xdfopen
is correct except the levels line. There is no number of levels.

It should be

       ZDEF levels_1 1 LINEAR 1 1

But for one level there is no need to have this line in the descriptor
file.

Cia, Karin


On Thu, 8 Nov 2007, Mike Johnson wrote:
> I've just recently returned to the GRADS community from an extended
> absence and was hoping someone could give some advice on reading a
> netcdf file (of which I have no previous experience).  Anyway, I've
> tried a number of things relative to online documentation and examples
> from the users group.  So far I've been unsuccessful in opening the
> file. I am using GrADS v1.9b4.  thanks in advance...
>
> Mike Johnson
>
> Here's symptoms of what I thought was the most promising methodology.
>
> *1.  I created a data descriptor file "20070824_1200.ddf" with following:*
>
> DSET  ^20070824_1200.nc
> TITLE Example NetCDF File
> UNDEF -99999.
> XDEF x 200 LINEAR -125.117 2.5
> YDEF y 200 LINEAR 40.2711 2.5
> ZDEF levels_1 LINEAR 1 1
> TDEF n_valtimes 39 LINEAR 12Z24AUG2007 1HR
> VARS 2
> ws=>ws 1 t,z,y,x Wind Speed
> wd=>wd 1 t,z,y,x Wind Direction
> ENDVARS
>
> *2.  error produced:*
> xdfopen 20070824_1200.ddf
> Scanning Description File: 20070824_1200.ddf
> XDFopen Error:  Missing or invalid dimension size.
> --> The invalid description file record is:
> --> zdef levels_1 linear 1 1
> The data file was not opened.
>
> *3.  partial ncdump output of 20070824_1200.nc:*
> netcdf 20070824_1200 {
> dimensions:
>            record = UNLIMITED ; // (39 currently)
>            n_valtimes = 39 ;
>            data_variables = 2 ;
>            charsPerLevel = 11 ;
>            namelen = 132 ;
>            x = 200 ;
>            y = 200 ;
>            levels_1 = 1 ;
> variables:
>            float ws(record, levels_1, y, x)
>                        ws:long_name = "Wind Speed" ;
>                        ws:units = "m/s" ;
>                        ws:udunits = "meter/sec" ;
>                        ws:uiname = "windSpeed" ;
>                        ws:valid_range = -150.f, 150.f ;
>                        ws:_FillValue = -99999.f ;
>                        ws:_n3d = 1 ;
>                        ws:levels = "FHAG 10" ;
>           char wsLevels(levels_1, charsPerLevel) ;
>           char wsInventory(n_valtimes, levels_1) ;
>           float wd(record, levels_1, y, x) ;
>                        wd:long_name = "Wind Direction" ;
>                        wd:units = "degree_True" ;
>                        wd:udunits = "degree_True" ;
>                        wd:uiname = "windDir" ;
>                        wd:valid_range = 0.f, 360.f ;
>                        wd:_FillValue = -99999.f ;
>                        wd:_n3d = 1 ;
>                        wd:levels = "FHAG 10"
>            char wdlevels(levels_1, charsPerLevel) ;
>            char wdInventory(n_valtimes, levels_1) ;
>            int valtimeMINUSreftime(n_valtimes) ;
>                         valtimeMINUSreftime:units = "seconds"
>            double reftime ;
>                         reftime:long_name = "reference time" ;
>                         reftime:units = "seconds since (1970-1-1
> 00:00:00:0)" ;
>            char origin(namelen) ;
>            char model(namelen) ;
> // global attributes:
>                         :projIndex = 3 ;
>                         :projName = "LATLON"
>                         :centralLat = 42.5392f ;
>                         :centralLon = -122.1475f ;
>                         :rotation = 25.f ;
>                         :lat00 = 40.2711f ;
>                         :lon00 = -125.117f ;
>                         :latNxNy = 44.7219f ;
>                         :lonNxNy = -118.9594f ;
>                         :dxKm = 2.5f ;
>                         :dyKm = 2.5f ;
> data:
>
> ws =
> 8., 8.6,...............................
>