spgradx.f File Reference

Compute x-gradient in Fourier space. More...

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Functions/Subroutines
subroutine	spgradx (M, INCW, KMAX, MP, CLAT, W, WX)
	This subprogram computes the x-gradient of fields in complex Fourier space. More...

Detailed Description

Compute x-gradient in Fourier space.

Author

IREDELL

Date

96-02-20

Definition in file spgradx.f.

Function/Subroutine Documentation

spgradx()

subroutine spgradx	(	integer, intent(in)	M,
		integer, intent(in)	INCW,
		integer, intent(in)	KMAX,
		integer, dimension(kmax), intent(in)	MP,
		real, intent(in)	CLAT,
		real, dimension(2*incw,kmax), intent(inout)	W,
		real, dimension(2*incw,kmax), intent(out)	WX
	)

This subprogram computes the x-gradient of fields in complex Fourier space.

The x-gradient of a vector field W is WX=CONJG(W)*L/RERTH where L is the wavenumber and RERTH is the Earth radius, so that the result is the x-gradient of the pseudo-vector.

The x-gradient of a scalar field W is WX=CONJG(W)*L/(RERTH*CLAT) where CLAT is the cosine of latitude.

At the pole this is undefined, so the way to get the x-gradient at the pole is by passing both the weighted wavenumber 0 and the unweighted wavenumber 1 amplitudes at the pole and setting MP=10. In this case, the wavenumber 1 amplitudes are used to compute the x-gradient and then zeroed out.

Note

This subprogram is thread-safe.

Parameters

	M	Fourier wavenumber truncation
	INCW	first dimension of the complex amplitude array (INCW >= M+1)
	KMAX	number of Fourier fields
	MP	identifiers (0 or 10 for scalar, 1 for vector)
	CLAT	cosine of latitude
[out]	W	Fourier amplitudes corrected when MP=10 and CLAT=0
[out]	WX	complex amplitudes of x-gradients

Author

IREDELL

Date

96-02-20

Definition at line 37 of file spgradx.f.

Referenced by sptgptsd(), and sptgptvd().