Performs forward spectral transformation by successively carrying out SHTG2W and SHTW2S.
The definitions of ISW and arrays S, W, and G are the same as for SHTG2W and SHTW2S. This subroutine performs SHTG2W and SHTW2S successively, with the following results.
When ISW=0, a normal forward spectral transformation is carried out.
(4.32)
When ISW=1, the latitudinal derivative of the forward spectral transform is calculated.
(4.33)
When ISW=-1, the meridional derivative of the forward spectral transform is calculated.
(4.34)
SHTG2S(MM,JM,IM,ISW,G,W,S,WORK)
MM (I) Input parameter. The cut-off wavenumber (M). JM (I) Input parameter. 1/2 of the NS partition number (J) IM (I) Input parameter. 1/2 of the EW partition number(I) ISW (I) Input parameter. Specifies the type of transformation. (See above definition.) G (R) Input parameter. Grid data. (For length and arrangement, see SHTW2G.) W (R) Output parameter. Wave data (For length and arrangement, see SHTS2W.)S (R) Output parameter. Spectral data. (For length and arrangement, see SHTNML.) WORK (R) Working area initialized by SHTINT
- (a)
- The present subroutine is equivalent to successively calling SHTG2W and SHTW2S.
- (b)
- By using the two transforms for ISW=1 and ISW=-1, the divergence of the vector field can be calculated.