spgradq.f File Reference

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Functions/Subroutines
subroutine	spgradq (I, M, ENN1, ELONN1, EON, EONTOP, Q, QDX, QDY, QDYTOP)
	COMPUTES THE HORIZONTAL VECTOR GRADIENT OF A SCALAR FIELD IN SPECTRAL SPACE. More...

Detailed Description

Compute gradient in spectral space

Author

IREDELL

Date

92-10-31

Definition in file spgradq.f.

Function/Subroutine Documentation

spgradq()

subroutine spgradq	(		I,
			M,
		real, dimension((m+1)*((i+1)*m+2)/2)	ENN1,
		real, dimension((m+1)*((i+1)*m+2)/2)	ELONN1,
		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))	QDX,
		real, dimension((m+1)*((i+1)*m+2))	QDY,
		real, dimension(2*(m+1))	QDYTOP
	)

COMPUTES THE HORIZONTAL VECTOR 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 ZONAL GRADIENT OF Q(L,N) IS SIMPLY I*L/A*Q(L,N) WHILE 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	- INTEGER SPECTRAL DOMAIN SHAPE (0 FOR TRIANGULAR, 1 FOR RHOMBOIDAL)
M	- INTEGER SPECTRAL TRUNCATION
ENN1	- REAL ((M+1)*((I+1)*M+2)/2) N*(N+1)/A**2
ELONN1	- REAL ((M+1)*((I+1)*M+2)/2) L/(N*(N+1))*A
EON	- REAL ((M+1)*((I+1)*M+2)/2) EPSILON/N*A
EONTOP	- REAL (M+1) EPSILON/N*A OVER TOP
Q	- REAL ((M+1)*((I+1)*M+2)) SCALAR FIELD
QDX	- REAL ((M+1)*((I+1)*M+2)) ZONAL GRADIENT (TIMES COSLAT)
QDY	- REAL ((M+1)*((I+1)*M+2)) MERID GRADIENT (TIMES COSLAT)
QDYTOP	- REAL (2*(M+1)) MERID GRADIENT (TIMES COSLAT) OVER TOP

Definition at line 30 of file spgradq.f.