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C Copyright 1981-2007 ECMWF
C
C Licensed under the GNU Lesser General Public License which
C incorporates the terms and conditions of version 3 of the GNU
C General Public License.
C See LICENSE and gpl-3.0.txt for details.
C
INTEGER FUNCTION KINTRG(OLDGEO,NEWGEO,OLDFLD,NEWFLD)
C
C---->
C**** KINTRG
C
C Purpose
C -------
C Interpolate a reduced gaussian field a reduced gaussian field
C with a different resolution.
C
C
C Interface
C ---------
C IRET = KINTRG(OLDGEO,NEWGEO,OLDFLD,NEWFLD)
C
C Input
C -----
C OLDGEO - GRIB section 2 describing grid of old field.
C NEWGEO - GRIB section 2 describing grid of new field.
C OLDFLD - Array of values for old field.
C
C
C Output
C ------
C NEWFLD - Array of values for new field.
C
C Function returns:
C - number of points in the new field, if all is well
C - negative, otherwise.
C
C
C Method
C ------
C Build up field offsets from input geometries.
C For each point of the new field, find in the old field the four
C nearest neighbours' positions and values.
C Calculate new value from the neighbours.
C
C
C Externals
C ---------
C IGGLAT - Compute gaussian lines of latitude.
C JNORSGG - Find gaussian latitudes to north and south of latitude.
C KNFROM4 - Calculate value of new field point.
C INTLOG - Log messages
C
C
C Author
C ------
C J.D.Chambers ECMWF November 2000
C
C Modifications
C -------------
C
C Force nearest neighbour processing with env variable or
C INTOUT parameter
C S.Curic ECMWF September 2005
C
C Add fudging factor for computation of index in original field
C S.Curic ECMWF October 2006
C
C----<
C
IMPLICIT NONE
C
C Function arguments
C
INTEGER OLDGEO(*),NEWGEO(*)
REAL OLDFLD(*),NEWFLD(*)
C
#include "intisl.h"
#include "parim.h"
#include "nifld.common"
#include "nofld.common"
C
C Parameters
C
INTEGER JPMAXNG
PARAMETER (JPMAXNG=1280)
REAL*8 FFACTOR
PARAMETER (FFACTOR=0.00001)
C
C Local variables
C
LOGICAL LVEGGY, LCOMPAT
INTEGER TOTAL, NEXT, LOOP, NEWOFF(JPMAXNG), OLDOFF(JPMAXNG)
INTEGER LATIT, LONG, NEWTYPE, IRET, NPTS
INTEGER LAT(2), LON(4)
INTEGER PT(4), TYPE(4)
REAL OLAT(2), OLON(4)
REAL RLATOLD(JPMAXNG), RLATNEW(JPMAXNG), RLAT, RLON
CHARACTER*12 YFLAG,YFLAG1
C
C Externals
C
INTEGER IGGLAT, JNORSGG
REAL KNFROM4
EXTERNAL IGGLAT, JNORSGG, KNFROM4
C
C -----------------------------------------------------------------|
C* Section 1. Build working values using input geometries.
C -----------------------------------------------------------------|
C
100 CONTINUE
C
KINTRG = 0
C
IF( (NEWGEO(NGAUSS)*2).GT.JPMAXNG ) THEN
CALL INTLOG(JP_ERROR,
X 'KINTRG: Gaussian N too big = ',NEWGEO(NGAUSS))
CALL INTLOG(JP_ERROR,'KINTRG: Maximum handled = ',(JPMAXNG/2))
KINTRG = -1
GOTO 900
ENDIF
C
LVEGGY = (NITABLE.EQ.128).AND.
X ((NIPARAM.EQ.27).OR.
X (NIPARAM.EQ.28).OR.
X (NIPARAM.EQ.29).OR.
X (NIPARAM.EQ.30).OR.
X (NIPARAM.EQ.43) )
C Force nearest neighbour processing with env variable
CALL GETENV('NEAREST_NEIGHBOUR', YFLAG)
IF( YFLAG(1:1).EQ.'1' ) LVEGGY = .TRUE.
C Force nearest neighbour processing with INTOUT parameter
IF( LMETHOD ) LVEGGY = .TRUE.
IF( LVEGGY ) CALL INTLOG(JP_DEBUG,
X 'KINTRG: nearest neighbour processing (vegetation)',JPQUIET)
C
LCOMPAT = .FALSE.
C Force fix calculating neighbouring longitude
CALL GETENV('RG2RG_COMP', YFLAG1)
IF( YFLAG1(1:1).EQ.'1' ) LCOMPAT = .TRUE.
C -----------------------------------------------------------------|
C* Section 2. Calculate number of points in new field and offset
C to start of each latitude in the new grid
C -----------------------------------------------------------------|
C
200 CONTINUE
C
NEWOFF(1) = 0
TOTAL = NEWGEO(NPOINTS)
DO LOOP = 2, NEWGEO(NJ)
NEWOFF(LOOP) = NEWOFF(LOOP-1) + NEWGEO(NPOINTS-2+LOOP)
TOTAL = TOTAL + NEWGEO(NPOINTS-1+LOOP)
ENDDO
C
C Get the gaussian latitudes for the new field
C
IRET = IGGLAT(NEWGEO(NGAUSS)*2,RLATNEW,0,-1)
IF( IRET.NE.0 ) THEN
WRITE(*,*) 'KINTRG: Problem call igglat for new grid'
KINTRG = -1
RETURN
ENDIF
C
CALL INTLOG(JP_DEBUG,'KINTRG: No. of pts in new field = ',TOTAL)
C
C -----------------------------------------------------------------|
C* Section 3. Get the gaussian latitudes for the old field and
C setup the offsets to the start of each latitude.
C -----------------------------------------------------------------|
C
300 CONTINUE
C
OLDOFF(1) = 0
DO LOOP = 2, OLDGEO(NJ)
OLDOFF(LOOP) = OLDOFF(LOOP-1) + OLDGEO(NPOINTS-2+LOOP)
ENDDO
C
IRET = IGGLAT(OLDGEO(NGAUSS)*2,RLATOLD,0,-1)
IF( IRET.NE.0 ) THEN
WRITE(*,*) 'KINTRG: Problem call igglat for old grid'
KINTRG = -1
RETURN
ENDIF
C
C -----------------------------------------------------------------|
C* Section 4. Work through the points in the new field.
C -----------------------------------------------------------------|
C
400 CONTINUE
C
DO NEXT = 1, TOTAL
C
C Calculate lat/long
C
DO LOOP = 1, NEWGEO(NJ)
IF( NEWOFF(LOOP).GE.NEXT ) THEN
LATIT = LOOP - 1
GOTO 410
ENDIF
ENDDO
LATIT = NEWGEO(NJ)
C
410 CONTINUE
C
LONG = NEXT - NEWOFF(LATIT)
C
RLAT = RLATNEW(LATIT)
RLON = (REAL(LONG-1)*360.0)/REAL(NEWGEO(NPOINTS+LATIT-1))
C
C Find four neighbours in the old field with their types
C (Find NW neighbour and deduce the others).
C
LAT(NORTH) = JNORSGG(RLAT,RLATOLD,OLDGEO(NGAUSS),1)
LAT(SOUTH) = JNORSGG(RLAT,RLATOLD,OLDGEO(NGAUSS),0)
C
OLAT(NORTH) = RLATOLD(LAT(NORTH))
OLAT(SOUTH) = RLATOLD(LAT(SOUTH))
C
NPTS = OLDGEO(NPOINTS-1+LAT(NORTH))
IF( LCOMPAT ) THEN
LON(NWEST) = 1 + INT(RLON/(360.0/REAL(NPTS)))
ELSE
LON(NWEST) = 1 + INT((RLON/(360.0/REAL(NPTS))) + FFACTOR)
ENDIF
LON(NEAST) = LON(NWEST) + 1
IF( LON(NEAST).GT.NPTS ) LON(NEAST) = 1
C
OLON(NWEST) = (REAL(LON(NWEST)-1)*360.0)/REAL(NPTS)
IF( LON(NEAST).EQ.1 ) THEN
OLON(NEAST) = 360.0
ELSE
OLON(NEAST) = (REAL(LON(NEAST)-1)*360.0)/REAL(NPTS)
ENDIF
C
NPTS = OLDGEO(NPOINTS-1+LAT(SOUTH))
IF( LCOMPAT ) THEN
LON(SWEST) = 1 + INT(RLON/(360.0/REAL(NPTS)))
ELSE
LON(SWEST) = 1 + INT((RLON/(360.0/REAL(NPTS))) + FFACTOR)
ENDIF
LON(SEAST) = LON(SWEST) + 1
IF( LON(SEAST).GT.NPTS ) LON(SEAST) = 1
C
OLON(SWEST) = (REAL(LON(SWEST)-1)*360.0)/REAL(NPTS)
IF( LON(SEAST).EQ.1 ) THEN
OLON(SEAST) = 360.0
ELSE
OLON(SEAST) = (REAL(LON(SEAST)-1)*360.0)/REAL(NPTS)
ENDIF
C
PT(NWEST) = OLDOFF(LAT(NORTH)) + LON(NWEST)
PT(NEAST) = OLDOFF(LAT(NORTH)) + LON(NEAST)
PT(SWEST) = OLDOFF(LAT(SOUTH)) + LON(SWEST)
PT(SEAST) = OLDOFF(LAT(SOUTH)) + LON(SEAST)
C
C Interpolate the new value
C
NEWFLD(NEXT) = KNFROM4(LVEGGY,RLAT,RLON,OLAT,OLON,PT,OLDFLD)
C
ENDDO
C
KINTRG = TOTAL
C
C -----------------------------------------------------------------|
C* Section 9. Return
C -----------------------------------------------------------------|
C
900 CONTINUE
C
RETURN
END
|
