How to draw data on multi-grid

[Zhi Liang <Zhi.Liang@xxxxxxxx>]

Hi,

  I have global data sets that are splitted into four files (the grid 
in each file is part of
the global grid). I want to plot the data in one picture using those 
four files (like using shade).
The grid is curvilinear. Is this possible?

  Thanks!

Zhi