Re: loading point-data to idv

Heiko Klein wrote:

I would like to load point data to the idv for the first time. The data I'm using is in NetCDF CF-1.0 convention, having a station axis connected to longitude/latitude coordinates, i.e. :

netcdf test {
dimensions:
        station = UNLIMITED ; // (94 currently)
        time = 366 ;
        dim_charlen = 4 ;
variables:
        float EPDL5(station, time) ;
                EPDL5:_FillValue = -9999.f ;
                EPDL5:component = "ammonium" ;
                EPDL5:component_id = "5" ;
                EPDL5:long_name = "ammonium, precip" ;
                EPDL5:matrix = "precip" ;
        char station(station, dim_charlen) ;
        short time(time) ;
                time:units = "days since 2002-01-01 00:00:00 UTC" ;
        double lon(station) ;
                lon:long_name = "station longitude" ;
                lon:units = "degrees_east" ;
                lon:_FillValue = -999999. ;
        double lat(station) ;
                lat:lat_name = "station latitude" ;
                lat:units = "degrees_north" ;
                lat:_FillValue = -999999. ;

// global attributes:
                :Conventions = "CF-1.0" ;
}

Trying to read it as URL->Point Data gave me just one field 'Point Data', and while trying to 'Create Display', I get the error message:
Unable to make PointObsDataset from file

Trying to read it as File didn't gave me a field at all.

I tried also to connect to one of the point-data servers, to look for an example, but I haven't been allowed to access the servers.

So, what do I have to do to display point data in IDV, and compare it i.e. as timeseries to one of my grid-cells.

Best regards,

Heiko

We dont yet have a Point-Data reader for CF-1, partly because I havent seen a real file yet (until now), and partly because Im not sure the CF spec is complete enough. Theres been some discussion of this on the CF list that I need to review. From my POV, its not obvious what the String valued "station" coordinate means. The CF spec doesnt mention such a beast explicitly.

Anyway, looking at your file "NATTOT_year_cf.nc" , I would expect an attribute coordinate = "lat lon" on each data variable; see CF section 5.4.

Ill look at the feasibility of adding a CF station reader when i get back next week and see about reading your files into it ( I probably need you to add the coordinate attribute). You might want to add altitude info also if you can.

You might find this interesting:

http://www.unidata.ucar.edu/software/netcdf-java/formats/UnidataObsConvention.html