ERA-Interim and regrid2 v. xdef/ydef

[Tara J. Troy]

You can't do that - the number of grid points tells grads how to read
the data.

You can imagine if you had one degree data, you would tell it there were
360 points in the x direction. If you still had the same dataset and
told it you had 720 points at 0.5 degree resolution, basically what it
would do is read rows 1 and 2 and think that it was all data belonging
to row 1. You have to regrid the data yourself.

Tara

Matt Jeglum wrote:
> I have been using the ERA-Interim dataset, and after running it through grib2ctl I get control files
> that work, but do not include any sort of PDEF specification.  I am ultimately interested in
> interpolating the 1.5 degree grid on the ERA-Interim to a higher resolution.  I have heard of two
> methods to do this.  One is to use the regrid2 function, but since I am computer illiterate and the
> other option is quite easy, I am avoiding that.  It seems possible to change the xdef and ydef
> specifications in the ctl file to interpolate to the higher resolution to begin with.  All you would need
> to change is the # of grid points and the increment.  This has worked for others but not for me, and I
> suspect it may be due to the lack of PDEF.  Is this method legitimate? If so, anyone know the ERA-
> Interim projection specs for PDEF?
>