Change values in a .nc file

[Mark Schus]

Hi everyone!

I had asked this before, and someone replied with a solution to my
problem...only, that was months ago, and I need to do it again and I forget how
to.

I want to make a contour plot in grads using my own data, but I don't know how
to make grads read my data.  Someone suggested that I open up a .nc file, such
as a surface pressure file pres.nc, and manually change the values in that file
to the ones that I want to plot.

Basically, I want to plot moisture flux convergence values in northwestern
Canada, so if I open up the pres.nc file, how can I manually change all of the
gridpoint values?

Any help would be great!

Thanks a lot,

Mark