fo2fsh

Interpolates a scalar quantity from a fixed-offset grid to a fixed grid.

Prototype

	function fo2fsh (
		grid  : numeric   
	)

	return_val  :  float or double

Arguments

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

Return value

The return array dimensions are the same as grid's dimensions, except the latitude dimension (nlata) is increased by one. For example, a 5 degree fixed-offset grid would have dimensions nlata=36, nlona=72 and the return fixed grid would have dimensions nlatb=37, nlonb=72. The type will be double if the input is double, and float otherwise.

Description

fo2fsh interpolates a scalar quantity on a fixed-offset grid to a fixed grid 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 fo2fsh via:

  z = fo2fsh ( 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 fo2fsh_Wrap function if metadata retention is desired. The interface is identical.

See Also

fo2fsh_Wrap, f2fosh, f2fsh, f2gsh, g2fsh, g2gsh

Examples

Assume x is dimensioned nt x nlat x nlon. The code below interpolates from a fixed offset 2.5 degree grid (nlat=72, nlon=144) to a fixed grid with 2.5 degree resolution (jlat=73, ilon=144):

  X = fo2fsh (x)        ; ==> X(nt,jlat,ilon)

  ; Use fo2fsh_Wrap if metadata retention is desired
  ; X = fo2fsh_Wrap (x)        ; ==> X(nt,jlat,ilon)

Errors

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