Re: ncl_convert2nc problem

Hi Steve,
Sorry for the delay getting back to you. It appears that the algorithm
we were using had a problem with southern hemisphere grids. I have
replaced it with one that seems to work for your grid and that I
believe is more reliable in general. Let us know if you would like a
new binary to test out. The test file now produces these values for
lat and lon:

float g5_lat_0 ( g5_x_0, g5_y_1 )
         corners : ( -78.358, -79.22246, -75.78817, -75.12761 )
         long_name : latitude
         GridType : Polar Stereographic Projection Grid
         units : degrees_north
         ProjectionCenter : south
         Dy : 1598
         Dx : 1598
         Lov : 180
         Lo1 : 156.607
         La1 : -78.358

      float g5_lon_1 ( g5_x_0, g5_y_1 )
         corners : ( 156.607, 172.7067, 174.4876, 161.9337 )
         long_name : longitude
         GridType : Polar Stereographic Projection Grid
         units : degrees_east
         ProjectionCenter : south
         Dy : 1598
         Dx : 1598
         Lov : 180
         Lo1 : 156.607
         La1 : -78.358

  -dave

On Feb 8, 2010, at 7:45 PM, Steve George wrote:

> Hi there
>
> I'm trying to convert some AMPS forecast data (in GRIB format; see
> http://www.mmm.ucar.edu/rt/amps/wrf_grib/) into netCDF using
> ncl_convert2nc.
>
> I'm having a problem with the resulting g5_lon_1 and g5_lat_0 fields.
> The calculated latitudes/longitudes are stepping South and West from
> the
> origin, rather than North and East. i.e. from a grid definition of:
>
> Nx = 213 ;
> Ny = 228 ;
> La1 = -78.358002 ;
> Lo1 = 156.606995 ;
> Lov = 180.000000 ;
> Dx = 1598.000000 ;
> Dy = 1598.000000 ;
> // Pole in proj. plane = South ;
> ProjFlag = 1 ;
> ResCompFlag = 8 ;
>
>
> I end up with corners of: lat ( -78.358, -76.73927, -79.32224,
> -81.42978
> ), lon (156.606, 143.6038, 132.4332, 147.3015)...where the lat/lon
> range
> should be ~ (-78 -> -75) and ( 156 -> 180).
>
> Any ideas? Or could someone point me towards the transformation
> algorithm, so that I can encode it myself.
>
> Thanks
>
> Steve
>
> --
> Dr Steve George
> University of Canterbury
> Christchurch, NZ
>
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Received on Fri Feb 19 10:54:50 2010