Regridding/interpolation

[Glenn Carver <Glenn.Carver@xxxxxxxxxxxxxxxx>]

I have a variables, say tr,  on a regular lat/long/theta grid (theta is
potential temperature). I also have pressure, p, on this same grid. I need
to regrid the variables onto a new grid which has the vertical coordinate
replaced by pressure. To be able to do this requires a linear vertical
interpolation using the values of pressure in p. However, since p for each
lat/lon is different I cannot figure out a way of getting ferret to do this.

e.g.
define/axis/z=500:0:-10 paxis   ! defines the regular pressure axis I want
define grid/like=tr/z=paxis newgrid  ! sets up the grid I eventually want tr on

I can't use the normal regridding as this uses the variable's underlying
grid whereas I need a lookup to the pressure variable to find the z
coordinate value. I can't use an objective analysis ext. fn. because that's
going to do a 2D interpolation and I only need a 1d (vertical in this case)
interpolation.

  Thanks,

          Glenn


--
Dr. Glenn Carver, Senior Research Associate,
Centre for Atmospheric Science, Chemistry Dept., Cambridge University, UK
mailto:Glenn.Carver@atm.ch.cam.ac.uk   http://www.atm.ch.cam.ac.uk/~glenn/

              "I never think of the future, it comes soon enough"
                   - Albert Einstein