vhsec, vhsgc

Procedures for computing vector spherical harmonic syntheses via Spherepack.

Synopsis

    procedure vhsec(
        br : float,
        bi : float,
        cr : float,
        ci : float,
        u  : float,
        v  : float
    )

    procedure vhsgc(
        br : float,
        bi : float,
        cr : float,
        ci : float,
        u  : float,
        v  : float
    )

Arguments

br, bi, cr, ci
vector spherical harmonic coefficients (input, array with two or more dimensions, last two dimensions must be nlat x nlat and values must be in ascending latitude order, but see note below)
u, v
vector spherical harmonic synthesis arrays (input/output, same dimensions as br, bi, cr, ci, except the last two dimensions must be nlat x nlon and values must/will be in ascending latitude order, but see note below)

Description

Note: If you have version 4.1 of NCL, these procedures will not work with arrays greater than two dimensions. In order to use arrays with more than two dimensions, you need to run version 4.1.1 of NCL. If your site is licensed for version 4.1, then you can get version 4.1.1 for free. To get version 4.1.1 of NCAR Graphics software, please contact your site representative. If you don't know who your site representative is, then send email to ncarginf@ucar.edu or call (303) 497-1201.

vhsec and vhsgc both perform the vector spherical harmonic synthesis on the arrays br, bi, cr, and ci and store the results in the arrays u and v. vhsec operates on an equal (fixed) grid, and vhsgc operates on a Gaussian grid.

For the arrays whose last two dimensions are nlat x nlon, the rest of the dimensions (if any) are collectively referred to as nt. If the input/output arrays are just two dimensions, then nt can either be considered equal to 1 or nothing at all.

Arrays which have dimensions nt x nlat x nlon should not include the cyclic (wraparound) points when invoking the procedures and functions which use spherical harmonics (Spherepack).

For example, if an array x has dimensions nlat = 64 and nlon = 129, where the "129" represents the cyclic points, then the user should pass the data to the procedure/function via: 

    z = sample ( x([...],:,0:nlon-2) )  ; does not include cyclic points

Error messages

If jer or ker is equal to:
1 : error in the specification of nlat
2 : error in the specification of nlon
4 : error in the specification of nt (jer only)

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$Revision: 1.13 $ $Date: 1999/04/29 21:32:21 $