sptrunm.f File Reference

Spectrally interpolate scalars to Mercator. More...

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Functions/Subroutines
subroutine	sptrunm (iromb, maxwv, idrti, imaxi, jmaxi, kmax, mi, mj, iprime, iskipi, jskipi, kskipi, kgskip, niskip, njskip, jcpu, rlat1, rlon1, dlat, dlon, gridi, gm)
	This subprogram spectrally truncates scalar fields on a global cylindrical grid, returning the fields to a Mercator grid.

Detailed Description

Spectrally interpolate scalars to Mercator.

Author

IREDELL

Date

96-02-29

Definition in file sptrunm.f.

Function/Subroutine Documentation

sptrunm()

subroutine sptrunm	(		iromb,
			maxwv,
			idrti,
			imaxi,
			jmaxi,
			kmax,
			mi,
			mj,
			iprime,
			iskipi,
			jskipi,
			kskipi,
			kgskip,
			niskip,
			njskip,
			jcpu,
			rlat1,
			rlon1,
			dlat,
			dlon,
		real, dimension(*)	gridi,
		real, dimension(*)	gm )

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

The wave-space can be either triangular or rhomboidal. The 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.

Parameters

IROMB	- INTEGER SPECTRAL DOMAIN SHAPE (0 FOR TRIANGULAR, 1 FOR RHOMBOIDAL)
MAXWV	- INTEGER SPECTRAL TRUNCATION
IDRTI	- INTEGER 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	- INTEGER EVEN NUMBER OF INPUT LONGITUDES.
JMAXI	- INTEGER NUMBER OF INPUT LATITUDES.
KMAX	- INTEGER NUMBER OF FIELDS TO TRANSFORM.
MI	- INTEGER NUMBER OF POINTS IN THE FASTER ZONAL DIRECTION
MJ	- INTEGER NUMBER OF POINTS IN THE SLOWER MERID DIRECTION
IPRIME	- INTEGER INPUT LONGITUDE INDEX FOR THE PRIME MERIDIAN. (DEFAULTS TO 1 IF IPRIME=0) (OUTPUT LONGITUDE INDEX FOR PRIME MERIDIAN ASSUMED 1.)
ISKIPI	- INTEGER SKIP NUMBER BETWEEN INPUT LONGITUDES (DEFAULTS TO 1 IF ISKIPI=0)
JSKIPI	- INTEGER SKIP NUMBER BETWEEN INPUT LATITUDES FROM SOUTH (DEFAULTS TO -IMAXI IF JSKIPI=0)
KSKIPI	- INTEGER SKIP NUMBER BETWEEN INPUT GRID FIELDS (DEFAULTS TO IMAXI*JMAXI IF KSKIPI=0)
KGSKIP	- INTEGER SKIP NUMBER BETWEEN GRID FIELDS (DEFAULTS TO NPS*NPS IF KGSKIP=0)
NISKIP	- INTEGER SKIP NUMBER BETWEEN GRID I-POINTS (DEFAULTS TO 1 IF NISKIP=0)
NJSKIP	- INTEGER SKIP NUMBER BETWEEN GRID J-POINTS (DEFAULTS TO NPS IF NJSKIP=0)
JCPU	- INTEGER NUMBER OF CPUS OVER WHICH TO MULTIPROCESS (DEFAULTS TO ENVIRONMENT NCPUS IF JCPU=0)
RLAT1	- REAL LATITUDE OF THE FIRST GRID POINT IN DEGREES
RLON1	- REAL LONGITUDE OF THE FIRST GRID POINT IN DEGREES
DLAT	- REAL LATITUDE INCREMENT IN DEGREES SUCH THAT D(PHI)/D(J)=DLAT*COS(PHI) WHERE J IS MERIDIONAL INDEX. DLAT IS NEGATIVE FOR GRIDS INDEXED SOUTHWARD. (IN TERMS OF GRID INCREMENT DY VALID AT LATITUDE RLATI, THE LATITUDE INCREMENT DLAT IS DETERMINED AS DLAT=DPR*DY/(RERTH*COS(RLATI/DPR)) WHERE DPR=180/PI AND RERTH IS EARTH'S RADIUS)
DLON	- REAL LONGITUDE INCREMENT IN DEGREES SUCH THAT D(LAMBDA)/D(I)=DLON WHERE I IS ZONAL INDEX. DLON IS NEGATIVE FOR GRIDS INDEXED WESTWARD.
GRIDI	- REAL (*) INPUT GRID FIELDS
GM	- REAL (*) MERCATOR FIELDS

SUBPROGRAMS CALLED:

• sptran() Perform a scalar spherical transform
• sptgpm() Transform spectral scalar to Mercator
• ncpus() Gets environment number of cpus

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

Definition at line 76 of file sptrunm.f.

References ncpus(), sptgpm(), and sptran().

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