C-----------------------------------------------------------------------
SUBROUTINE IPOLATES(IP,IPOPT,KGDSI,KGDSO,MI,MO,KM,IBI,LI,GI,
& NO,RLAT,RLON,IBO,LO,GO,IRET)
C$$$ SUBPROGRAM DOCUMENTATION BLOCK
C
C SUBPROGRAM: IPOLATES IREDELL'S POLATE FOR SCALAR FIELDS
C PRGMMR: IREDELL ORG: W/NMC23 DATE: 96-04-10
C
C ABSTRACT: THIS SUBPROGRAM INTERPOLATES SCALAR FIELDS
C FROM ANY GRID TO ANY GRID (JOE IRWIN'S DREAM).
C ONLY HORIZONTAL INTERPOLATION IS PERFORMED.
C THE FOLLOWING INTERPOLATION METHODS ARE POSSIBLE:
C (IP=0) BILINEAR
C (IP=1) BICUBIC
C (IP=2) NEIGHBOR
C (IP=3) BUDGET
C (IP=4) SPECTRAL
C (IP=6) NEIGHBOR-BUDGET
C SOME OF THESE METHODS HAVE INTERPOLATION OPTIONS AND/OR
C RESTRICTIONS ON THE INPUT OR OUTPUT GRIDS, BOTH OF WHICH
C ARE DOCUMENTED MORE FULLY IN THEIR RESPECTIVE SUBPROGRAMS.
C THE GRIDS ARE DEFINED BY THEIR GRID DESCRIPTION SECTIONS
C (PASSED IN INTEGER FORM AS DECODED BY SUBPROGRAM W3FI63).
C THE CURRENT CODE RECOGNIZES THE FOLLOWING PROJECTIONS:
C (KGDS(1)=000) EQUIDISTANT CYLINDRICAL
C (KGDS(1)=001) MERCATOR CYLINDRICAL
C (KGDS(1)=003) LAMBERT CONFORMAL CONICAL
C (KGDS(1)=004) GAUSSIAN CYLINDRICAL
C (KGDS(1)=005) POLAR STEREOGRAPHIC AZIMUTHAL
C (KGDS(1)=201) ROTATED EQUIDISTANT CYLINDRICAL
C (KGDS(1)=202) ROTATED EQUIDISTANT CYLINDRICAL
C WHERE KGDS COULD BE EITHER INPUT KGDSI OR OUTPUT KGDSO.
C AS AN ADDED BONUS THE NUMBER OF OUTPUT GRID POINTS
C AND THEIR LATITUDES AND LONGITUDES ARE ALSO RETURNED.
C ON THE OTHER HAND, THE OUTPUT CAN BE A SET OF STATION POINTS
C IF KGDSO(1)<0, IN WHICH CASE THE NUMBER OF POINTS
C AND THEIR LATITUDES AND LONGITUDES MUST BE INPUT.
C FOR THE BUDGET APPROACH, A SUBSECTION OF THE GRID MAY
C BE OUTPUT BY SUBTRACTING KGDSO(1) FROM 255 AND PASSING
C IN THE LATITUDES AND LONGITUDES OF THE POINTS.
C INPUT BITMAPS WILL BE INTERPOLATED TO OUTPUT BITMAPS.
C OUTPUT BITMAPS WILL ALSO BE CREATED WHEN THE OUTPUT GRID
C EXTENDS OUTSIDE OF THE DOMAIN OF THE INPUT GRID.
C THE OUTPUT FIELD IS SET TO 0 WHERE THE OUTPUT BITMAP IS OFF.
C
C PROGRAM HISTORY LOG:
C 96-04-10 IREDELL
C
C USAGE: CALL IPOLATES(IP,IPOPT,KGDSI,KGDSO,MI,MO,KM,IBI,LI,GI,
C & NO,RLAT,RLON,IBO,LO,GO,IRET)
C
C INPUT ARGUMENT LIST:
C IP - INTEGER INTERPOLATION METHOD
C (IP=0 FOR BILINEAR;
C IP=1 FOR BICUBIC;
C IP=2 FOR NEIGHBOR;
C IP=3 FOR BUDGET;
C IP=4 FOR SPECTRAL;
C IP=6 FOR NEIGHBOR-BUDGET)
C IPOPT - INTEGER (20) INTERPOLATION OPTIONS
C (IP=0: (NO OPTIONS)
C IP=1: CONSTRAINT OPTION
C IP=2: (NO OPTIONS)
C IP=3: NUMBER IN RADIUS, RADIUS WEIGHTS, SEARCH RADIUS
C IP=4: SPECTRAL SHAPE, SPECTRAL TRUNCATION
C IP=6: NUMBER IN RADIUS, RADIUS WEIGHTS ...)
C KGDSI - INTEGER (200) INPUT GDS PARAMETERS AS DECODED BY W3FI63
C KGDSO - INTEGER (200) OUTPUT GDS PARAMETERS
C MI - INTEGER SKIP NUMBER BETWEEN INPUT GRID FIELDS IF KM>1
C OR DIMENSION OF INPUT GRID FIELDS IF KM=1
C MO - INTEGER SKIP NUMBER BETWEEN OUTPUT GRID FIELDS IF KM>1
C OR DIMENSION OF OUTPUT GRID FIELDS IF KM=1
C KM - INTEGER NUMBER OF FIELDS TO INTERPOLATE
C IBI - INTEGER (KM) INPUT BITMAP FLAGS
C LI - LOGICAL*1 (MI,KM) INPUT BITMAPS (IF RESPECTIVE IBI(K)=1)
C GI - REAL (MI,KM) INPUT FIELDS TO INTERPOLATE
C NO - INTEGER NUMBER OF OUTPUT POINTS (ONLY IF KGDSO(1)<0)
C RLAT - REAL (NO) OUTPUT LATITUDES IN DEGREES (IF KGDSO(1)<0)
C RLON - REAL (NO) OUTPUT LONGITUDES IN DEGREES (IF KGDSO(1)<0)
C
C OUTPUT ARGUMENT LIST:
C NO - INTEGER NUMBER OF OUTPUT POINTS (ONLY IF KGDSO(1)>=0)
C RLAT - REAL (MO) OUTPUT LATITUDES IN DEGREES (IF KGDSO(1)>=0)
C RLON - REAL (MO) OUTPUT LONGITUDES IN DEGREES (IF KGDSO(1)>=0)
C IBO - INTEGER (KM) OUTPUT BITMAP FLAGS
C LO - LOGICAL*1 (MO,KM) OUTPUT BITMAPS (ALWAYS OUTPUT)
C GO - REAL (MO,KM) OUTPUT FIELDS INTERPOLATED
C IRET - INTEGER RETURN CODE
C 0 SUCCESSFUL INTERPOLATION
C 1 UNRECOGNIZED INTERPOLATION METHOD
C 2 UNRECOGNIZED INPUT GRID OR NO GRID OVERLAP
C 3 UNRECOGNIZED OUTPUT GRID
C 1X INVALID BICUBIC METHOD PARAMETERS
C 3X INVALID BUDGET METHOD PARAMETERS
C 4X INVALID SPECTRAL METHOD PARAMETERS
C
C SUBPROGRAMS CALLED:
C POLATES0 INTERPOLATE SCALAR FIELDS (BILINEAR)
C POLATES1 INTERPOLATE SCALAR FIELDS (BICUBIC)
C POLATES2 INTERPOLATE SCALAR FIELDS (NEIGHBOR)
C POLATES3 INTERPOLATE SCALAR FIELDS (BUDGET)
C POLATES4 INTERPOLATE SCALAR FIELDS (SPECTRAL)
C
C REMARKS: EXAMPLES DEMONSTRATING RELATIVE CPU COSTS.
C THIS EXAMPLE IS INTERPOLATING 12 LEVELS OF TEMPERATURES
C FROM THE 360 X 181 GLOBAL GRID (NCEP GRID 3)
C TO THE 93 X 68 HAWAIIAN MERCATOR GRID (NCEP GRID 204).
C THE EXAMPLE TIMES ARE FOR THE C90. AS A REFERENCE, THE CP TIME
C FOR UNPACKING THE GLOBAL 12 TEMPERATURE FIELDS IS 0.04 SECONDS.
C
C METHOD IP IPOPT CP SECONDS
C -------- -- ------------- ----------
C BILINEAR 0 0.03
C BICUBIC 1 0 0.07
C BICUBIC 1 1 0.07
C NEIGHBOR 2 0.01
C BUDGET 3 -1,-1 0.48
C SPECTRAL 4 0,40 0.22
C SPECTRAL 4 1,40 0.24
C SPECTRAL 4 0,-1 0.42
C N-BUDGET 6 -1,-1 0.15
C
C THE SPECTRAL INTERPOLATION IS FAST FOR THE MERCATOR GRID.
C HOWEVER, FOR SOME GRIDS THE SPECTRAL INTERPOLATION IS SLOW.
C THE FOLLOWING EXAMPLE IS INTERPOLATING 12 LEVELS OF TEMPERATURES
C FROM THE 360 X 181 GLOBAL GRID (NCEP GRID 3)
C TO THE 93 X 65 CONUS LAMBERT CONFORMAL GRID (NCEP GRID 211).
C
C METHOD IP IPOPT CP SECONDS
C -------- -- ------------- ----------
C BILINEAR 0 0.03
C BICUBIC 1 0 0.07
C BICUBIC 1 1 0.07
C NEIGHBOR 2 0.01
C BUDGET 3 -1,-1 0.51
C SPECTRAL 4 0,40 3.94
C SPECTRAL 4 1,40 5.02
C SPECTRAL 4 0,-1 11.36
C N-BUDGET 6 -1,-1 0.18
C
C ATTRIBUTES:
C LANGUAGE: FORTRAN 77
C
C$$$
IMPLICIT NONE
C
INTEGER, INTENT(IN ) :: IP, IPOPT(20), KM, MI, MO
INTEGER, INTENT(IN ) :: IBI(KM), KGDSI(200), KGDSO(200)
INTEGER, INTENT(INOUT) :: NO
INTEGER, INTENT( OUT) :: IRET, IBO(KM)
C
LOGICAL*1, INTENT(IN ) :: LI(MI,KM)
LOGICAL*1, INTENT( OUT) :: LO(MO,KM)
C
REAL, INTENT(IN ) :: GI(MI,KM)
REAL, INTENT(INOUT) :: RLAT(MO),RLON(MO)
REAL, INTENT( OUT) :: GO(MO,KM)
C
INTEGER :: K, N
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C BILINEAR INTERPOLATION
IF(IP.EQ.0) THEN
CALL POLATES0(IPOPT,KGDSI,KGDSO,MI,MO,KM,IBI,LI,GI,
& NO,RLAT,RLON,IBO,LO,GO,IRET)
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C BICUBIC INTERPOLATION
ELSEIF(IP.EQ.1) THEN
CALL POLATES1(IPOPT,KGDSI,KGDSO,MI,MO,KM,IBI,LI,GI,
& NO,RLAT,RLON,IBO,LO,GO,IRET)
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C NEIGHBOR INTERPOLATION
ELSEIF(IP.EQ.2) THEN
CALL POLATES2(IPOPT,KGDSI,KGDSO,MI,MO,KM,IBI,LI,GI,
& NO,RLAT,RLON,IBO,LO,GO,IRET)
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C BUDGET INTERPOLATION
ELSEIF(IP.EQ.3) THEN
CALL POLATES3(IPOPT,KGDSI,KGDSO,MI,MO,KM,IBI,LI,GI,
& NO,RLAT,RLON,IBO,LO,GO,IRET)
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C SPECTRAL INTERPOLATION
ELSEIF(IP.EQ.4) THEN
CALL POLATES4(IPOPT,KGDSI,KGDSO,MI,MO,KM,IBI,LI,GI,
& NO,RLAT,RLON,IBO,LO,GO,IRET)
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C NEIGHBOR-BUDGET INTERPOLATION
ELSEIF(IP.EQ.6) THEN
CALL POLATES6(IPOPT,KGDSI,KGDSO,MI,MO,KM,IBI,LI,GI,
& NO,RLAT,RLON,IBO,LO,GO,IRET)
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C UNRECOGNIZED INTERPOLATION METHOD
ELSE
IF(KGDSO(1).GE.0) NO=0
CMIC$ DO ALL AUTOSCOPE
DO K=1,KM
IBO(K)=1
DO N=1,NO
LO(N,K)=.FALSE.
GO(N,K)=0.
ENDDO
ENDDO
IRET=1
ENDIF
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
END