NETCDF descriptor file problem: gadsdf: SDF file does not have any non-coordinate variables.

Kevin M Levey klevey at CUSTOMWEATHER.COM
Tue Nov 17 22:52:20 EST 2009


TUE 17NOV09: 1945PST

I am having problems opening trying to open a netcdf file of elevation data created by GMT. I am getting an error I've never seen before and don't understand.

The output from ncdump -h is:

netcdf topo2 {
dimensions:
        lat = 101 ;
        lon = 151 ;
variables:
        double lat(lat) ;
                lat:long_name = "latitude" ;
                lat:units = "degrees_north" ;
                lat:actual_range = 36.9, 37. ;
        double lon(lon) ;
                lon:long_name = "longitude" ;
                lon:units = "degrees_north" ;
                lon:actual_range = -120.18, -120.03 ;
        float elevation(lat, lon) ;
                elevation:long_name = "elevation" ;
                elevation:units = "meters" ;
                elevation:_FillValue = -999.f ;
                elevation:actual_range = 57.8879890441895, 96.9689636230469 ;

// global attributes:
                :Conventions = "COARDS/CF-1.0" ;
                :title = "../grids/madera/mapdata/topo/topo.grd" ;
                :history = "grdsample -R-120.18/-120.03/36.90/37 -I0.06m ../grids/DATA/tmp/madera_topo250.grd -G../grids/madera/mapdata/topo/topo.grd" ;
                :GMT_version = "4.5.0 [64-bit]" ;
}


My CTL file is as follows:

DSET /prod/custom/Input/modelplots/GRADS/reference/topo2.grd
TITLE This is a sample USL grid box for Central California
UNDEF -9999
XDEF lon 151 LINEAR -120.18 0.001
YDEF lat 101 LINEAR 36.9 0.001
VARS 3
alt=>elevation 1 99 Altitude in meters
lon=>lon 1 99 longitude
lat=>lat 1 99  Latitude
ENDVARS

However, here is the output I get when opening the CTL file (GRADS Version 2.0.a7.oga.2)

ga-> xdfopen usl_topo.ctl
Scanning Descriptor File:  usl_topo.ctl
SDF file has no discernable time coordinate -- using default values.
gadsdf: SDF file does not have any non-coordinate variables.
SDF Descriptor file usl_topo.ctl was not successfully opened & parsed.

Obviously I am doing something wrong here. I've had success before opening up WRF netcdf data files using this method, but if anyone has any suggestions here, I'd love to hear from you.

Thanks.

Regards,

Kevin M Levey, MSc in Oceans and Atmospheric Sciences (University of Cape Town)
Director of Meteorological Operations
CustomWeather, Inc.
San Francisco, California, USA

"Taking the World by Storm!"

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email: klevey at customweather.com



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