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Interpolates a scalar quantity from one fixed grid to another.


	function f2fsh (
		grid        : numeric,                       
		outdims [2] : byte, short, integer or long   

	return_val  :  float or double



An array of 2 or more dimensions whose rightmost two dimensions must be latitude x longitude. The values must be in ascending latitude order.


An array indicating the dimensions of the rightmost two dimensions of the output grid (outdims[0] = nlatb, outdims[1] = nlonb).

As of version 6.0.0, this can be of type byte, short, integer or long.

Return value

The return array's dimensions are the same as grid's dimensions, except the rightmost two dimensions, nlata and nlona, are replaced by nlatb and nlonb. The type will be double if the input is double, and float otherwise.


f2fsh interpolates a scalar quantity from one fixed grid to another using spherical harmonics (via the Spherepack code). Values will be in ascending latitude order.

If missing values are encountered in a 2D subsection of the input array, then no interpolation will be performed on that 2D array, and the corresponding 2D subsection of the return array will be filled with missing values.

Arrays which have dimensions [...] x nlata x nlona should not include the cyclic (wrap-around) points when invoking this function. For example, if an array x has dimensions nlata = 64 and nlona = 129, where the "129" represents the cyclic point, then the user should pass the data to f2fsh via:

  z = f2fsh ( x(...,0:nlona-2) )  ; does not include cyclic points

This function can only be used on grids that span the globe. It cannot be used for limited area grids.

Please read the caveats that you should be aware of when using spherical harmonic regridding.

Use the f2fsh_Wrap function if metadata retention is desired. The interface is identical.

See Also

f2fsh_Wrap, f2fosh, f2gsh, fo2fsh, g2fsh, g2gsh


Assume x is dimensioned nt x nlat x nlon. The code below interpolates from a fixed 2.5 degree grid (nlat=73, nlon=144) to a one degree grid (jlat=181,ilon=360):

  X = f2fsh (x, (/jlat,ilon/) )    ; ==> X(nt,jlat,ilon)

  ; Use f2fsh_Wrap if metadata retention is desired
  ; X = f2fsh_Wrap (x, (/jlat,ilon/) )    ; ==> X(nt,jlat,ilon)


ier is equal to:

4 or 10 if nlona is less than 4
5 or 10 if nlata is less than 3
8 if nlonb is less than 4
9 if nlatb is less than 3