C-----------------------------------------------------------------------
SUBROUTINE POLATES4(IPOPT,KGDSI,KGDSO,MI,MO,KM,IBI,LI,GI,
& NO,RLAT,RLON,IBO,LO,GO,IRET)
C$$$ SUBPROGRAM DOCUMENTATION BLOCK
C
C SUBPROGRAM: POLATES4 INTERPOLATE SCALAR FIELDS (SPECTRAL)
C PRGMMR: IREDELL ORG: W/NMC23 DATE: 96-04-10
C
C ABSTRACT: THIS SUBPROGRAM PERFORMS SPECTRAL INTERPOLATION
C FROM ANY GRID TO ANY GRID FOR SCALAR FIELDS.
C IT REQUIRES THAT THE INPUT FIELDS BE UNIFORMLY GLOBAL.
C OPTIONS ALLOW CHOICES BETWEEN TRIANGULAR SHAPE (IPOPT(1)=0)
C AND RHOMBOIDAL SHAPE (IPOPT(1)=1) WHICH HAS NO DEFAULT;
C A SECOND OPTION IS THE TRUNCATION (IPOPT(2)) WHICH DEFAULTS
C TO A SENSIBLE TRUNCATION FOR THE INPUT GRID (IF OPT(2)=-1).
C NOTE THAT IF THE OUTPUT GRID IS NOT FOUND IN A SPECIAL LIST,
C THEN THE TRANSFORM BACK TO GRID IS NOT VERY FAST.
C THIS SPECIAL LIST CONTAINS GLOBAL CYLINDRICAL GRIDS,
C POLAR STEREOGRAPHIC GRIDS CENTERED AT THE POLE
C AND MERCATOR GRIDS.
C ONLY HORIZONTAL INTERPOLATION IS PERFORMED.
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 (SPECTRAL NATIVE)
C (KGDS(1)=005) POLAR STEREOGRAPHIC AZIMUTHAL
C (KGDS(1)=202) ROTATED EQUIDISTANT CYLINDRICAL (ETA NATIVE)
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 OUTPUT BITMAPS WILL NOT BE CREATED.
C
C PROGRAM HISTORY LOG:
C 96-04-10 IREDELL
C 2001-06-18 IREDELL IMPROVE DETECTION OF SPECIAL FAST TRANSFORM
C
C USAGE: CALL POLATES4(IPOPT,KGDSI,KGDSO,MI,MO,KM,IBI,LI,GI,
C & NO,RLAT,RLON,IBO,LO,GO,IRET)
C
C INPUT ARGUMENT LIST:
C IPOPT - INTEGER (20) INTERPOLATION OPTIONS
C IPOPT(1)=0 FOR TRIANGULAR, IPOPT(1)=1 FOR RHOMBOIDAL;
C IPOPT(2) IS TRUNCATION NUMBER
C (DEFAULTS TO SENSIBLE IF IPOPT(2)=-1).
C KGDSI - INTEGER (200) INPUT GDS PARAMETERS AS DECODED BY W3FI63
C KGDSO - INTEGER (200) OUTPUT GDS PARAMETERS
C (KGDSO(1)<0 IMPLIES RANDOM STATION POINTS)
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 (MUST BE ALL 0)
C LI - LOGICAL*1 (MI,KM) INPUT BITMAPS (IF SOME 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 2 UNRECOGNIZED INPUT GRID OR NO GRID OVERLAP
C 3 UNRECOGNIZED OUTPUT GRID
C 41 INVALID NONGLOBAL INPUT GRID
C 42 INVALID SPECTRAL METHOD PARAMETERS
C
C SUBPROGRAMS CALLED:
C GDSWIZ GRID DESCRIPTION SECTION WIZARD
C SPTRUN SPECTRALLY TRUNCATE GRIDDED SCALAR FIELDS
C SPTRUNS SPECTRALLY INTERPOLATE SCALARS TO POLAR STEREO.
C SPTRUNM SPECTRALLY INTERPOLATE SCALARS TO MERCATOR
C SPTRUNG SPECTRALLY INTERPOLATE SCALARS TO STATIONS
C
C ATTRIBUTES:
C LANGUAGE: FORTRAN 77
C
C$$$
INTEGER IPOPT(20)
INTEGER KGDSI(200),KGDSO(200)
INTEGER IBI(KM),IBO(KM)
LOGICAL*1 LI(MI,KM),LO(MO,KM)
REAL GI(MI,KM),GO(MO,KM)
REAL RLAT(MO),RLON(MO),CROT(MO),SROT(MO)
REAL XPTS(MO),YPTS(MO)
REAL GO2(MO,KM)
PARAMETER(FILL=-9999.)
PARAMETER(RERTH=6.3712E6)
PARAMETER(PI=3.14159265358979,DPR=180./PI)
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C COMPUTE NUMBER OF OUTPUT POINTS AND THEIR LATITUDES AND LONGITUDES.
IRET=0
IF(KGDSO(1).GE.0) THEN
CALL GDSWIZ(KGDSO, 0,MO,FILL,XPTS,YPTS,RLON,RLAT,NO,0,
& CROT,SROT)
IF(NO.EQ.0) IRET=3
ENDIF
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C AFFIRM APPROPRIATE INPUT GRID
C LAT/LON OR GAUSSIAN
C NO BITMAPS
C FULL ZONAL COVERAGE
C FULL MERIDIONAL COVERAGE
IDRTI=KGDSI(1)
IM=KGDSI(2)
JM=KGDSI(3)
RLON1=KGDSI(5)*1.E-3
RLON2=KGDSI(8)*1.E-3
ISCAN=MOD(KGDSI(11)/128,2)
JSCAN=MOD(KGDSI(11)/64,2)
NSCAN=MOD(KGDSI(11)/32,2)
IF(IDRTI.NE.0.AND.IDRTI.NE.4) IRET=41
DO K=1,KM
IF(IBI(K).NE.0) IRET=41
ENDDO
IF(IRET.EQ.0) THEN
IF(ISCAN.EQ.0) THEN
DLON=(MOD(RLON2-RLON1-1+3600,360.)+1)/(IM-1)
ELSE
DLON=-(MOD(RLON1-RLON2-1+3600,360.)+1)/(IM-1)
ENDIF
IG=NINT(360/ABS(DLON))
IPRIME=1+MOD(-NINT(RLON1/DLON)+IG,IG)
IMAXI=IG
JMAXI=JM
IF(MOD(IG,2).NE.0.OR.IM.LT.IG) IRET=41
ENDIF
IF(IRET.EQ.0.AND.IDRTI.EQ.0) THEN
RLAT1=KGDSI(4)*1.E-3
RLAT2=KGDSI(7)*1.E-3
DLAT=(RLAT2-RLAT1)/(JM-1)
JG=NINT(180/ABS(DLAT))
IF(JM.EQ.JG) IDRTI=256
IF(JM.NE.JG.AND.JM.NE.JG+1) IRET=41
ELSEIF(IRET.EQ.0.AND.IDRTI.EQ.4) THEN
JG=KGDSI(10)*2
IF(JM.NE.JG) IRET=41
ENDIF
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C SET PARAMETERS
IF(IRET.EQ.0) THEN
IROMB=IPOPT(1)
MAXWV=IPOPT(2)
IF(MAXWV.EQ.-1) THEN
IF(IROMB.EQ.0.AND.IDRTI.EQ.4) MAXWV=(JMAXI-1)
IF(IROMB.EQ.1.AND.IDRTI.EQ.4) MAXWV=(JMAXI-1)/2
IF(IROMB.EQ.0.AND.IDRTI.EQ.0) MAXWV=(JMAXI-3)/2
IF(IROMB.EQ.1.AND.IDRTI.EQ.0) MAXWV=(JMAXI-3)/4
IF(IROMB.EQ.0.AND.IDRTI.EQ.256) MAXWV=(JMAXI-1)/2
IF(IROMB.EQ.1.AND.IDRTI.EQ.256) MAXWV=(JMAXI-1)/4
ENDIF
IF((IROMB.NE.0.AND.IROMB.NE.1).OR.MAXWV.LT.0) IRET=42
ENDIF
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C INTERPOLATE
IF(IRET.EQ.0) THEN
IF(NSCAN.EQ.0) THEN
ISKIPI=1
JSKIPI=IM
ELSE
ISKIPI=JM
JSKIPI=1
ENDIF
IF(ISCAN.EQ.1) ISKIPI=-ISKIPI
IF(JSCAN.EQ.0) JSKIPI=-JSKIPI
ISPEC=0
C SPECIAL CASE OF GLOBAL CYLINDRICAL GRID
IF((KGDSO(1).EQ.0.OR.KGDSO(1).EQ.4).AND.
& MOD(KGDSO(2),2).EQ.0.AND.KGDSO(5).EQ.0.AND.
& KGDSO(11).EQ.0) THEN
IDRTO=KGDSO(1)
IMO=KGDSO(2)
JMO=KGDSO(3)
RLON2=KGDSO(8)*1.E-3
DLONO=(MOD(RLON2-1+3600,360.)+1)/(IMO-1)
IGO=NINT(360/ABS(DLONO))
IF(IMO.EQ.IGO.AND.IDRTO.EQ.0) THEN
RLAT1=KGDSO(4)*1.E-3
RLAT2=KGDSO(7)*1.E-3
DLAT=(RLAT2-RLAT1)/(JMO-1)
JGO=NINT(180/ABS(DLAT))
IF(JMO.EQ.JGO) IDRTO=256
IF(JMO.EQ.JGO.OR.JMO.EQ.JGO+1) ISPEC=1
ELSEIF(IMO.EQ.IGO.AND.IDRTO.EQ.4) THEN
JGO=KGDSO(10)*2
IF(JMO.EQ.JGO) ISPEC=1
ENDIF
IF(ISPEC.EQ.1) THEN
CALL SPTRUN(IROMB,MAXWV,IDRTI,IMAXI,JMAXI,IDRTO,IMO,JMO,
& KM,IPRIME,ISKIPI,JSKIPI,MI,0,0,MO,0,GI,GO)
ENDIF
C SPECIAL CASE OF POLAR STEREOGRAPHIC GRID
ELSEIF(KGDSO(1).EQ.5.AND.
& KGDSO(2).EQ.KGDSO(3).AND.MOD(KGDSO(2),2).EQ.1.AND.
& KGDSO(8).EQ.KGDSO(9).AND.KGDSO(11).EQ.64) THEN
NPS=KGDSO(2)
RLAT1=KGDSO(4)*1.E-3
RLON1=KGDSO(5)*1.E-3
IROT=MOD(KGDSO(6)/8,2)
ORIENT=KGDSO(7)*1.E-3
XMESH=KGDSO(8)
IPROJ=MOD(KGDSO(10)/128,2)
IP=(NPS+1)/2
H=(-1.)**IPROJ
DE=(1.+SIN(60./DPR))*RERTH
DR=DE*COS(RLAT1/DPR)/(1+H*SIN(RLAT1/DPR))
XP=1-H*SIN((RLON1-ORIENT)/DPR)*DR/XMESH
YP=1+COS((RLON1-ORIENT)/DPR)*DR/XMESH
IF(NINT(XP).EQ.IP.AND.NINT(YP).EQ.IP) THEN
IF(IPROJ.EQ.0) THEN
CALL SPTRUNS(IROMB,MAXWV,IDRTI,IMAXI,JMAXI,KM,NPS,
& IPRIME,ISKIPI,JSKIPI,MI,MO,0,0,0,
& 60.,XMESH,ORIENT,GI,GO,GO2)
ELSE
CALL SPTRUNS(IROMB,MAXWV,IDRTI,IMAXI,JMAXI,KM,NPS,
& IPRIME,ISKIPI,JSKIPI,MI,MO,0,0,0,
& 60.,XMESH,ORIENT,GI,GO2,GO)
ENDIF
ISPEC=1
ENDIF
C SPECIAL CASE OF MERCATOR GRID
ELSEIF(KGDSO(1).EQ.1) THEN
NI=KGDSO(2)
NJ=KGDSO(3)
RLAT1=KGDSO(4)*1.E-3
RLON1=KGDSO(5)*1.E-3
RLON2=KGDSO(8)*1.E-3
RLATI=KGDSO(9)*1.E-3
ISCANO=MOD(KGDSO(11)/128,2)
JSCANO=MOD(KGDSO(11)/64,2)
NSCANO=MOD(KGDSO(11)/32,2)
DY=KGDSO(13)
HI=(-1.)**ISCANO
HJ=(-1.)**(1-JSCANO)
DLONO=HI*(MOD(HI*(RLON2-RLON1)-1+3600,360.)+1)/(NI-1)
DLATO=HJ*DY/(RERTH*COS(RLATI/DPR))*DPR
IF(NSCANO.EQ.0) THEN
CALL SPTRUNM(IROMB,MAXWV,IDRTI,IMAXI,JMAXI,KM,NI,NJ,
& IPRIME,ISKIPI,JSKIPI,MI,MO,0,0,0,
& RLAT1,RLON1,DLATO,DLONO,GI,GO)
ISPEC=1
ENDIF
ENDIF
C GENERAL SLOW CASE
IF(ISPEC.EQ.0) THEN
CALL SPTRUNG(IROMB,MAXWV,IDRTI,IMAXI,JMAXI,KM,NO,
& IPRIME,ISKIPI,JSKIPI,MI,MO,0,0,0,RLAT,RLON,GI,GO)
ENDIF
CMIC$ DO ALL AUTOSCOPE
DO K=1,KM
IBO(K)=0
DO N=1,NO
LO(N,K)=.TRUE.
ENDDO
ENDDO
ELSE
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
ENDIF
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
END