sptrun.f File Reference

Truncate gridded scalar fields. More...

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Functions/Subroutines
subroutine	sptrun (iromb, maxwv, idrti, imaxi, jmaxi, idrto, imaxo, jmaxo, kmax, iprime, iskipi, jskipi, kskipi, iskipo, jskipo, kskipo, jcpu, gridi, grido)
	This subprogram spectrally truncates scalar fields on a global cylindrical grid, returning the fields to a possibly different global cylindrical grid.

Detailed Description

Truncate gridded scalar fields.

Author

IREDELL

Date

96-02-29

Definition in file sptrun.f.

Function/Subroutine Documentation

sptrun()

subroutine sptrun	(		iromb,
			maxwv,
			idrti,
			imaxi,
			jmaxi,
			idrto,
			imaxo,
			jmaxo,
			kmax,
			iprime,
			iskipi,
			jskipi,
			kskipi,
			iskipo,
			jskipo,
			kskipo,
			jcpu,
		real, dimension(*)	gridi,
		real, dimension(*)	grido
	)

This subprogram spectrally truncates scalar fields on a global cylindrical grid, returning the fields to a possibly different global cylindrical grid.

The wave-space can be either triangular or rhomboidal. either grid-space can be either an equally-spaced grid (with or without pole points) or a Gaussian grid. the grid fields may have general indexing. the transforms are all multiprocessed. Transform several fields at a time to improve vectorization. Subprogram can be called from a multiprocessing environment.

Remarks: Minimum grid dimensions for unaliased transforms to spectral:

Dimension	Linear	Quadratic
IMAX	2*MAXWV+2	3*MAXWV/2*2+2
JMAX (IDRT=4,IROMB=0)	1*MAXWV+1	3*MAXWV/2+1
JMAX (IDRT=4,IROMB=1)	2*MAXWV+1	5*MAXWV/2+1
JMAX (IDRT=0,IROMB=0)	2*MAXWV+3	3*MAXWV/2*2+3
JMAX (IDRT=0,IROMB=1)	4*MAXWV+3	5*MAXWV/2*2+3
JMAX (IDRT=256,IROMB=0)	2*MAXWV+1	3*MAXWV/2*2+1
JMAX (IDRT=256,IROMB=1)	4*MAXWV+1	5*MAXWV/2*2+1

Parameters

IROMB	Spectral domain shape (0 for triangular, 1 for rhomboidal)
MAXWV	Spectral truncation
IDRTI	Input grid identifier IDRTI=4 for Gaussian grid IDRTI=0 for equally-spaced grid including poles IDRTI=256 for equally-spaced grid excluding poles
IMAXI	Even number of input longitudes
JMAXI	Number of input latitudes
IDRTO	Output grid identifier IDRTO=4 for Gaussian grid IDRTO=0 for equally-spaced grid including poles IDRTO=256 for equally-spaced grid excluding poles
IMAXO	Even number of output longitudes
JMAXO	Number of output latitudes
KMAX	Number of fields to transform
IPRIME	Input longitude index for the prime meridian. Defaults to 1 if IPRIME=0 Output longitude index for prime meridian assumed 1
ISKIPI	Skip number between input longitudes (defaults to 1 if ISKIPI=0)
JSKIPI	Skip number between input latitudes from south (defaults to -IMAXI if JSKIPI=0)
KSKIPI	Skip number between input grid fields (defaults to IMAXI*JMAXI if KSKIPI=0)
ISKIPO	Skip number between output longitudes (defaults to 1 if ISKIPO=0)
JSKIPO	Skip number between output latitudes from south (defaults to -IMAXO if JSKIPO=0)
KSKIPO	Skip number between output grid fields (defaults to IMAXO*JMAXO if KSKIPO=0)
JCPU	Number of CPUs over which to multiprocess (defaults to environment NCPUS if JCPU=0)
GRIDI	Input grid fields
GRIDO	Output grid fields (may overlay input fields if grid shape is appropriate)

Author

IREDELL

Date

96-02-29

Definition at line 55 of file sptrun.f.

References ncpus(), and sptran().

Referenced by spectral_interp_mod::polates4::polates4_grib1(), and spectral_interp_mod::polates4::polates4_grib2().