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fo2fshv_Wrap

Interpolates a vector quantity from a fixed-offset grid to a fixed grid (retains metadata).

Prototype

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"

	procedure fo2fshv_Wrap (
		uoff  : numeric,  
		voff  : numeric,  
		ureg  : float,    ; or double
		vreg  : float     ; or double
	)

Arguments

uoff
voff

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

ureg
vreg

(output)
Vector arrays of 2 or more dimensions whose rightmost two dimensions must be latitude x longitude. Values will be in ascending latitude order.

The arrays must be the same size as the uoff and voff arrays, except the latitude dimension must have one extra element.

Since fo2fshv_Wrap is a procedure, the user must explicitly preallocate memory for these return arrays.

Description

fo2fshv_Wrap interpolates a vector pair on a fixed-offset grid (uoff,voff) (including pole points) to a fixed grid (ureg,vreg) using spherical harmonics (via the Spherepack code). The output array dimensions must be the same as the input array dimensions, except jlat is replaced by jlat+1. 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.

Arrays which have dimensions [...] x nlata x nlona should not include the cyclic (wrap-around) points when invoking this procedure. For example, if arrays u and v have dimensions nlata = 64 and nlona = 129, where the "129" represents the cyclic point, then the user should pass the data to fo2fshv_Wrap via:

  z = fo2fshv_Wrap(u(...,0:nlona-2), v(...,0:nlona-2),...)  ; does not include cyclic points

This procedure 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.

This function is identical to the built-in function fo2fshv except it retains metadata.

See Also

f2foshv_Wrap, f2fshv_Wrap, f2gshv_Wrap, g2fshv_Wrap, g2gshv_Wrap

Examples

Example 1

Assume u and v are dimensioned nt x nlat x nlon, and that they are of type float or double.

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):

  uNew = new ( (/nt,jlat,ilon/), typeof(u) ) 
  vNew = new ( (/nt,jlat,ilon/), typeof(v) ) 

  fo2fshv_Wrap (u,v, uNew,vNew)

Errors

ier is equal to:

4 or 10 if nlona (ilon) is less than 4
5 or 10 if nlata (jlat) is less than 3
8 if nlonb is less than 4
9 if nlatb is less than 3