Contouring "strangely" gridded data

["Mark Verschell" <markv@xxxxxxxxxxxxxxxxxxx>]

I have a data set on an interesting grid that I am trying to contour.

The grid is not only irregularly spaced in x and y, but it is also rotated with
respect to the Earth. A rough example would be:

                                   *


                             *          *


                       *         *          *

                  *       *          *        *

                      *         *          *


                           *          *


                                *


The question is, what is the best/easiest way to handle this? I want to be able
to contour this and also overlay other data that is on a regular grid, e.g.
ELTOPO elevation data.

One idea I have come up with is this: the PPLUS manual discusses contouring of
ungridded data (Page 5-5) by use of X,Y,Z triplets, i.e. X-location,
Y-location, value. Does ferret allow access to this feature. This would be easy
to set-up.

Another idea is similar, but invovles regridding. The idea is that if you can
define a regular grid over the region of interest, and then do an automatic
regrid from X,Y,Z triplets (as above) to the new regular grid, with the caveat
that regions in the new regular grid that do not overlap with the original grid
are marked as missing/bad values. E.g.:

Data file for variable "Var" (which I would prefer to be in NetCDF format)
  100 30 3.4455
   99 27 2.4556
etc...

then
define axis/x=70:110:1 ......
define axis/y.....
define grid..... newg
contour Var[g=newg]


Thanks, Mark

-- 
-------------------------------------------------------------------------------

	      Mark Verschell (verschell@coaps.fsu.edu)
	      Center for Ocean and Atmospheric Prediction Studies
	      Florida State University
              2035 E. Paul Dirac Drive
              R.M. Johnson Bldg. - Suite 200
	      Tallahassee, FL  32310
	      (904) 644-6532              (904) 644-4841 (fax)