interpolation on rotated grid

[Nicolas Schneider <schneid@xxxxxxxxxxxxx>]

Hi ferret users

I'm a fairly new ferret user and not yet familiar with all of its 
concepts.
Thus, the following might be a fairly simple task for an experienced
user, however I haven't managed to solve it.

I have a multi-file NetCDF data set (NCEP geopotential height at several
levels) for a quite large region. This data is on a regular lat/lon grid.

What I am trying to do is to interpolate this data on a smaller grid
with a x-axis rotated by 22 deg to the west. I have the coordinates of
the 4 corner points of the smaller grid and its resolution (2x2 km). I
tried to show the situation in the pic below. X are the gridpoints of the
larger lat/lon-grid, + are the grid-points of the smaller, rotated grid.   

What I would like to have are the interpolated values at any grid point of
the small grid (+) at any level. Is this possible? Is there a way to
define axes which are not north-south or west-east oriented, respectively,
but some kind of southeast to northwest?

Thanks!!!

Nick


X----X----X----X----X----X
|    |    |+   |    |    |
|    |    / \  |    |    |
X----X---+X--+-X----X----X
|    |  / \ / \|    |    |
|    | +  |+   +    |    |
X----X/-\-/-\-/X\---X----X
|    +   +|  + | +  |    |
|    |\ / \ / \|/ \ |    |
X----X-+--X+---+---+X----X
|    |  \ / \ /|\ / |    |
|    |   +|  + | +  |    |
X----X----\-/-\X/---X----X
|    |    |+   +    |    |
|    |    | \ /|    |    |
X----X----X--+-X----X----X

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

Nicolas Schneider
University of Bern
Institute of Geography
Hallerstrasse 12
CH-3012 Bern

phone +41-31-631-8542
email schneid@giub.unibe.ch
-------------------------------------------------------------