[gradsusr] changing grid from 0-360 to -180-180 lon

[P. R.M.]

I have a problem with longitude ranges not matching when opening multiple grib2 files.
- the first grib2 file (gfs) has a longitude range defined by g2ctl.pl as:
xdef 720 linear 0 0.5

- the second grib2 file has a longitude range defined by g2ctl.pl as:
xdef 586 linear 261 0.066667

when opening both files, setting an arbitrary longitude range, and displaying a variable from the 2nd file, I get the following error:
ga-> set lon -100 -50
LON set to -100 -50
ga-> d myvar.2
Data Request Warning:  Request is completely outside file limits
  Entire grid contents are set to missing data
  Grid limits of file:     X = 1 586  Y = 1 481  Z = 1 1  T = 1 61  E = 1 1
  Grid limits of request:  X = -3914 1486  Y = -1724 -1123  Z = 1 1  T = 1 1  E = 1 1

the problem occurs because the first (gfs) grib2 longitude range gets set from -180 to 180, while the second file's longitude range is in the 0-360 range. grads doesnt seem to understand that the ranges overlap and are, in fact, valid.

I need set the 2nd file's longitude range to the -180-180 range, without manually editing the .ctl file created by g2ctl.pl.
is this possible to do through either grads or through wgrib2/g2ctl.pl?

please help,
thanks,
P.R.

 		 	   		  
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