C----------------------------------------------------------------------- SUBROUTINE GDSWZD05(KGDS,IOPT,NPTS,FILL,XPTS,YPTS,RLON,RLAT,NRET, & LROT,CROT,SROT,LMAP,XLON,XLAT,YLON,YLAT,AREA) C$$$ SUBPROGRAM DOCUMENTATION BLOCK C C SUBPROGRAM: GDSWZD05 GDS WIZARD FOR POLAR STEREOGRAPHIC AZIMUTHAL C PRGMMR: IREDELL ORG: W/NMC23 DATE: 96-04-10 C C ABSTRACT: THIS SUBPROGRAM DECODES THE GRIB GRID DESCRIPTION SECTION C (PASSED IN INTEGER FORM AS DECODED BY SUBPROGRAM W3FI63) C AND RETURNS ONE OF THE FOLLOWING: C (IOPT=+1) EARTH COORDINATES OF SELECTED GRID COORDINATES C (IOPT=-1) GRID COORDINATES OF SELECTED EARTH COORDINATES C FOR POLAR STEREOGRAPHIC AZIMUTHAL PROJECTIONS. C IF THE SELECTED COORDINATES ARE MORE THAN ONE GRIDPOINT C BEYOND THE THE EDGES OF THE GRID DOMAIN, THEN THE RELEVANT C OUTPUT ELEMENTS ARE SET TO FILL VALUES. C THE ACTUAL NUMBER OF VALID POINTS COMPUTED IS RETURNED TOO. C OPTIONALLY, THE VECTOR ROTATIONS AND THE MAP JACOBIANS C FOR THIS GRID MAY BE RETURNED AS WELL. C C PROGRAM HISTORY LOG: C 96-04-10 IREDELL C 97-10-20 IREDELL INCLUDE MAP OPTIONS C 09-05-13 GAYNO ENSURE AREA ALWAYS POSITIVE C C USAGE: CALL GDSWZD05(KGDS,IOPT,NPTS,FILL,XPTS,YPTS,RLON,RLAT,NRET, C & LROT,CROT,SROT,LMAP,XLON,XLAT,YLON,YLAT,AREA) C C INPUT ARGUMENT LIST: C KGDS - INTEGER (200) GDS PARAMETERS AS DECODED BY W3FI63 C IOPT - INTEGER OPTION FLAG C (+1 TO COMPUTE EARTH COORDS OF SELECTED GRID COORDS) C (-1 TO COMPUTE GRID COORDS OF SELECTED EARTH COORDS) C NPTS - INTEGER MAXIMUM NUMBER OF COORDINATES C FILL - REAL FILL VALUE TO SET INVALID OUTPUT DATA C (MUST BE IMPOSSIBLE VALUE; SUGGESTED VALUE: -9999.) C XPTS - REAL (NPTS) GRID X POINT COORDINATES IF IOPT>0 C YPTS - REAL (NPTS) GRID Y POINT COORDINATES IF IOPT>0 C RLON - REAL (NPTS) EARTH LONGITUDES IN DEGREES E IF IOPT<0 C (ACCEPTABLE RANGE: -360. TO 360.) C RLAT - REAL (NPTS) EARTH LATITUDES IN DEGREES N IF IOPT<0 C (ACCEPTABLE RANGE: -90. TO 90.) C LROT - INTEGER FLAG TO RETURN VECTOR ROTATIONS IF 1 C LMAP - INTEGER FLAG TO RETURN MAP JACOBIANS IF 1 C C OUTPUT ARGUMENT LIST: C XPTS - REAL (NPTS) GRID X POINT COORDINATES IF IOPT<0 C YPTS - REAL (NPTS) GRID Y POINT COORDINATES IF IOPT<0 C RLON - REAL (NPTS) EARTH LONGITUDES IN DEGREES E IF IOPT>0 C RLAT - REAL (NPTS) EARTH LATITUDES IN DEGREES N IF IOPT>0 C NRET - INTEGER NUMBER OF VALID POINTS COMPUTED C CROT - REAL (NPTS) CLOCKWISE VECTOR ROTATION COSINES IF LROT=1 C SROT - REAL (NPTS) CLOCKWISE VECTOR ROTATION SINES IF LROT=1 C (UGRID=CROT*UEARTH-SROT*VEARTH; C VGRID=SROT*UEARTH+CROT*VEARTH) C XLON - REAL (NPTS) DX/DLON IN 1/DEGREES IF LMAP=1 C XLAT - REAL (NPTS) DX/DLAT IN 1/DEGREES IF LMAP=1 C YLON - REAL (NPTS) DY/DLON IN 1/DEGREES IF LMAP=1 C YLAT - REAL (NPTS) DY/DLAT IN 1/DEGREES IF LMAP=1 C AREA - REAL (NPTS) AREA WEIGHTS IN M**2 IF LMAP=1 C (PROPORTIONAL TO THE SQUARE OF THE MAP FACTOR) C C ATTRIBUTES: C LANGUAGE: FORTRAN 77 C C$$$ INTEGER KGDS(200) REAL XPTS(NPTS),YPTS(NPTS),RLON(NPTS),RLAT(NPTS) REAL CROT(NPTS),SROT(NPTS) REAL XLON(NPTS),XLAT(NPTS),YLON(NPTS),YLAT(NPTS),AREA(NPTS) PARAMETER(RERTH=6.3712E6) PARAMETER(PI=3.14159265358979,DPR=180./PI) C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - IF(KGDS(1).EQ.005) THEN IM=KGDS(2) JM=KGDS(3) RLAT1=KGDS(4)*1.E-3 RLON1=KGDS(5)*1.E-3 IROT=MOD(KGDS(6)/8,2) ORIENT=KGDS(7)*1.E-3 DX=KGDS(8) DY=KGDS(9) IPROJ=MOD(KGDS(10)/128,2) ISCAN=MOD(KGDS(11)/128,2) JSCAN=MOD(KGDS(11)/64,2) NSCAN=MOD(KGDS(11)/32,2) H=(-1.)**IPROJ HI=(-1.)**ISCAN HJ=(-1.)**(1-JSCAN) DXS=DX*HI DYS=DY*HJ DE=(1.+SIN(60./DPR))*RERTH DR=DE*COS(RLAT1/DPR)/(1+H*SIN(RLAT1/DPR)) XP=1-H*SIN((RLON1-ORIENT)/DPR)*DR/DXS YP=1+COS((RLON1-ORIENT)/DPR)*DR/DYS DE2=DE**2 XMIN=0 XMAX=IM+1 YMIN=0 YMAX=JM+1 NRET=0 C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - C TRANSLATE GRID COORDINATES TO EARTH COORDINATES IF(IOPT.EQ.0.OR.IOPT.EQ.1) THEN DO N=1,NPTS IF(XPTS(N).GE.XMIN.AND.XPTS(N).LE.XMAX.AND. & YPTS(N).GE.YMIN.AND.YPTS(N).LE.YMAX) THEN DI=(XPTS(N)-XP)*DXS DJ=(YPTS(N)-YP)*DYS DR2=DI**2+DJ**2 IF(DR2.LT.DE2*1.E-6) THEN RLON(N)=0. RLAT(N)=H*90. ELSE RLON(N)=MOD(ORIENT+H*DPR*ATAN2(DI,-DJ)+3600,360.) RLAT(N)=H*DPR*ASIN((DE2-DR2)/(DE2+DR2)) ENDIF NRET=NRET+1 IF(LROT.EQ.1) THEN IF(IROT.EQ.1) THEN CROT(N)=H*COS((RLON(N)-ORIENT)/DPR) SROT(N)=SIN((RLON(N)-ORIENT)/DPR) ELSE CROT(N)=1 SROT(N)=0 ENDIF ENDIF IF(LMAP.EQ.1) THEN IF(DR2.LT.DE2*1.E-6) THEN XLON(N)=0. XLAT(N)=-SIN((RLON(N)-ORIENT)/DPR)/DPR*DE/DXS/2 YLON(N)=0. YLAT(N)=H*COS((RLON(N)-ORIENT)/DPR)/DPR*DE/DYS/2 AREA(N)=RERTH**2*ABS(DXS)*ABS(DYS)*4/DE2 ELSE DR=SQRT(DR2) CLAT=COS(RLAT(N)/DPR) XLON(N)=H*COS((RLON(N)-ORIENT)/DPR)/DPR*DR/DXS XLAT(N)=-SIN((RLON(N)-ORIENT)/DPR)/DPR*DR/DXS/CLAT YLON(N)=SIN((RLON(N)-ORIENT)/DPR)/DPR*DR/DYS YLAT(N)=H*COS((RLON(N)-ORIENT)/DPR)/DPR*DR/DYS/CLAT AREA(N)=RERTH**2*CLAT**2*ABS(DXS)*ABS(DYS)/DR2 ENDIF ENDIF ELSE RLON(N)=FILL RLAT(N)=FILL ENDIF ENDDO C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - C TRANSLATE EARTH COORDINATES TO GRID COORDINATES ELSEIF(IOPT.EQ.-1) THEN DO N=1,NPTS IF(ABS(RLON(N)).LE.360.AND.ABS(RLAT(N)).LE.90.AND. & H*RLAT(N).NE.-90) THEN DR=DE*TAN((90-H*RLAT(N))/2/DPR) XPTS(N)=XP+H*SIN((RLON(N)-ORIENT)/DPR)*DR/DXS YPTS(N)=YP-COS((RLON(N)-ORIENT)/DPR)*DR/DYS IF(XPTS(N).GE.XMIN.AND.XPTS(N).LE.XMAX.AND. & YPTS(N).GE.YMIN.AND.YPTS(N).LE.YMAX) THEN NRET=NRET+1 IF(LROT.EQ.1) THEN IF(IROT.EQ.1) THEN CROT(N)=H*COS((RLON(N)-ORIENT)/DPR) SROT(N)=SIN((RLON(N)-ORIENT)/DPR) ELSE CROT(N)=1 SROT(N)=0 ENDIF ENDIF IF(LMAP.EQ.1) THEN DR2=DR**2 IF(DR2.LT.DE2*1.E-6) THEN XLON(N)=0. XLAT(N)=-SIN((RLON(N)-ORIENT)/DPR)/DPR*DE/DXS/2 YLON(N)=0. YLAT(N)=H*COS((RLON(N)-ORIENT)/DPR)/DPR*DE/DYS/2 AREA(N)=RERTH**2*ABS(DXS)*ABS(DYS)*4/DE2 ELSE CLAT=COS(RLAT(N)/DPR) XLON(N)=H*COS((RLON(N)-ORIENT)/DPR)/DPR*DR/DXS XLAT(N)=-SIN((RLON(N)-ORIENT)/DPR)/DPR*DR/DXS/CLAT YLON(N)=SIN((RLON(N)-ORIENT)/DPR)/DPR*DR/DYS YLAT(N)=H*COS((RLON(N)-ORIENT)/DPR)/DPR*DR/DYS/CLAT AREA(N)=RERTH**2*CLAT**2*ABS(DXS)*ABS(DYS)/DR2 ENDIF ENDIF ELSE XPTS(N)=FILL YPTS(N)=FILL ENDIF ELSE XPTS(N)=FILL YPTS(N)=FILL ENDIF ENDDO ENDIF C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - C PROJECTION UNRECOGNIZED ELSE IRET=-1 IF(IOPT.GE.0) THEN DO N=1,NPTS RLON(N)=FILL RLAT(N)=FILL ENDDO ENDIF IF(IOPT.LE.0) THEN DO N=1,NPTS XPTS(N)=FILL YPTS(N)=FILL ENDDO ENDIF ENDIF C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - END