[gradsusr] problems plotting parts of netcdf file in GrADS from 20W to 30E longitude

[Jason Snyder]

I am trying to plot u velocity values from a netcdf file in GrADS from
longitude 20W (-20) to longitude 30E (30). The netcdf file is formated so
it only displays data from 0 to 360 where 0 is on the prime meridion. When
I tried to plot anything to the east of the dateline it says the data is
out of range. I also tried to add 360 to the negative longitude values and
it does not have data for this. How can I set up grads to plot both the
area east and west of the prime meridion (0 degrees) using GrADS?

I have the below gs script options:

'sdfopen file.nc'
'set lon 340 to 390'
'd u'

The above plots the map from 340 degrees to 390 but nothing east of 360
degrees.

or

'sdfopen file.nc'
'set lon -20 to 30'
'd u'

The above script gives an error message saying -20 is out of range.

Also how can I modify the netcdf file to that it can plot u values to the
east of 360 degrees. Should I use gdal (www.gdal.org) or cdo (
https://code.zmaw.de/projects/cdo,
https://www.unidata.ucar.edu/software/netcdf/workshops/2012/third_party/CDO.html
)

Thank you for your help.

Jason
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://gradsusr.org/pipermail/gradsusr/attachments/20151004/b908d5c1/attachment.html