sptgpmd.f File Reference

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Functions/Subroutines
subroutine	sptgpmd (IROMB, MAXWV, KMAX, MI, MJ, KWSKIP, KGSKIP, NISKIP, NJSKIP, RLAT1, RLON1, DLAT, DLON, WAVE, XM, YM)
	This subprogram performs a spherical transform from spectral coefficients of scalar fields to gradient fields on a mercator grid. More...

Detailed Description

Transform spectral to mercator gradients

Author

IREDELL

Date

96-02-29

Definition in file sptgpmd.f.

Function/Subroutine Documentation

sptgpmd()

subroutine sptgpmd	(		IROMB,
			MAXWV,
			KMAX,
			MI,
			MJ,
			KWSKIP,
			KGSKIP,
			NISKIP,
			NJSKIP,
			RLAT1,
			RLON1,
			DLAT,
			DLON,
		real, dimension(*)	WAVE,
		real, dimension(*)	XM,
		real, dimension(*)	YM
	)

This subprogram performs a spherical transform from spectral coefficients of scalar fields to gradient fields on a mercator grid.

The wave-space can be either triangular or rhomboidal. The wave and grid fields may have general indexing, but each wave field is in sequential 'ibm order', i.e. with zonal wavenumber as the slower index. The mercator grid is identified by the location of its first point and by its respective increments. The transforms are all multiprocessed over sector points. 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
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
KWSKIP	- INTEGER SKIP NUMBER BETWEEN WAVE FIELDS (DEFAULTS TO (MAXWV+1)*((IROMB+1)*MAXWV+2) IF KWSKIP=0)
KGSKIP	- INTEGER SKIP NUMBER BETWEEN GRID FIELDS (DEFAULTS TO MI*MJ 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 MI IF NJSKIP=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.
WAVE	- REAL (*) WAVE FIELDS
XM	- REAL (*) MERCATOR X-GRADIENTS
YM	- REAL (*) MERCATOR Y-GRADIENTS

SUBPROGRAMS CALLED:

• SPWGET() GET WAVE-SPACE CONSTANTS
• SPLAPLAC() COMPUTE LAPLACIAN IN SPECTRAL SPACE
• SPTGPMV() TRANSFORM SPECTRAL VECTOR TO MERCATOR

Definition at line 56 of file sptgpmd.f.