spgrady.f File Reference

Compute y-gradient in spectral space. More...

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Functions/Subroutines
subroutine	spgrady (I, M, ENN1, EON, EONTOP, Q, QDY, QDYTOP)
	Computes the horizontal vector y-gradient of a scalar field in spectral space. More...

Detailed Description

Compute y-gradient in spectral space.

Author

IREDELL

Date

92-10-31

Definition in file spgrady.f.

Function/Subroutine Documentation

spgrady()

subroutine spgrady	(		I,
			M,
		real, dimension((m+1)*((i+1)*m+2)/2)	ENN1,
		real, dimension((m+1)*((i+1)*m+2)/2)	EON,
		real, dimension(m+1)	EONTOP,
		real, dimension((m+1)*((i+1)*m+2))	Q,
		real, dimension((m+1)*((i+1)*m+2))	QDY,
		real, dimension(2*(m+1))	QDYTOP
	)

Computes the horizontal vector y-gradient of a scalar field in spectral space.

Subprogram speps should be called already.

If L is the zonal wavenumber, N is the total wavenumber, EPS(L,N)=SQRT((N**2-L**2)/(4*N**2-1)) and A is Earth radius, then the meridional gradient of Q(L,N) is computed as EPS(L,N+1)*(N+2)/A*Q(L,N+1)-EPS(L,N+1)*(N-1)/A*Q(L,N-1).

Extra terms are computed over top of the spectral domain.

Advantage is taken of the fact that EPS(L,L)=0 in order to vectorize over the entire spectral domain.

Parameters

I	spectral domain shape (0 for triangular, 1 for rhomboidal)
M	spectral truncation
ENN1	N*(N+1)/A**2
EON	EPSILON/N*A
EONTOP	EPSILON/N*A over top
Q	scalar field
QDY	merid gradient (times coslat)
QDYTOP	merid gradient (times coslat) over top

Author

IREDELL

Date

92-10-31

Definition at line 31 of file spgrady.f.

Referenced by sptgptsd().