[idvusers] ascat data in netcdf in IDV

• To: IDV users list <idvusers@xxxxxxxxxxxxxxxx>
• Subject: [idvusers] ascat data in netcdf in IDV
• From: Hein Zelle <hein.zelle@xxxxxxxxxxxxx>
• Date: Thu, 26 Jun 2014 17:17:15 +0200
• Mail-followup-to: IDV users list <idvusers@xxxxxxxxxxxxxxxx>

Dear IDV users,

I'm at it again - struggling with netcdf file formats that will work
in IDV.  Any pointers will be appreciated!  I would like to put ascat
data (a left and right swath of data) in netcdf in such a way that IDV
will

- visualize the data as a colour shaded plan view
- skip trough time per orbit or per hour

The attached file dump (testout2.dump) almost works: I concatenate all
orbits onto a record (time) axis and use attributes to get IDV to
understand time.  IDV loads the file, shows the data variables and it
shows the time values but it won't plot anything (value plot nor color
shaded).  No error, just no plot.  (IDV version 3.1u1)

Can anyone spot what's wrong with testout2.dump?  The file is at
http://freja.argoss.nl/file-exchange/testout2.nc
Even better, does anyone have a working example of a file containing
satellite orbits with swaths?

Some observations:
- the record axis cannot be called 'time', IDV doesn't read the file.
- I don't know what's the proper featureType for this file, I can't
  find a relevant example in the CF conventions.
- I tried adding a third dimension (hourly time axis) with a separate
  record axis, but I couldn't get that to load in IDV at all.


Thanks for your help,
Kind regards

     Hein




-- 

Dr. Hein Zelle
Senior consultant meteorology & oceanography
BMT ARGOSS

Tel:        +31 (0)527-242299
Fax:        +31 (0)527-242016
E-mail:     hein.zelle@xxxxxxxxxxxxx
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netcdf testout2 {
dimensions:
        record = UNLIMITED ; // (1632 currently)
        x = 44 ;
variables:
        double x(x) ;
        double record(record) ;
        double time(record) ;
                time:_FillValue = -3.3e+33 ;
                time:units = "days since 1970-01-01 00:00:00" ;
                time:standard_name = "time" ;
                time:calendar = "standard" ;
        float longitude(record, x) ;
                longitude:_FillValue = -3.3e+33f ;
                longitude:units = "degrees_east" ;
                longitude:standard_name = "longitude" ;
        float latitude(record, x) ;
                latitude:_FillValue = -3.3e+33f ;
                latitude:units = "degrees_north" ;
                latitude:standard_name = "latitude" ;
        float wind_speed(record, x) ;
                wind_speed:_FillValue = -3.3e+33f ;
                wind_speed:units = "m/s" ;
                wind_speed:standard_name = "wind_speed" ;
                wind_speed:coordinates = "time latitude longitude" ;
        float zonal_wind_speed(record, x) ;
                zonal_wind_speed:_FillValue = -3.3e+33f ;
                zonal_wind_speed:units = "m/s" ;
                zonal_wind_speed:standard_name = "eastward_wind" ;
                zonal_wind_speed:coordinates = "time latitude longitude" ;
        float meridional_wind_speed(record, x) ;
                meridional_wind_speed:_FillValue = -3.3e+33f ;
                meridional_wind_speed:units = "m/s" ;
                meridional_wind_speed:standard_name = "northward_wind" ;
                meridional_wind_speed:coordinates = "time latitude longitude" ;

// global attributes:
                :title = "MetOp-A ASCAT 25.0 km Ocean Surface Winds" ;
                :Conventions = "CF-1.6" ;
                :featureType = "trajectory" ;
}