SUBROUTINE PREPT(DRPTPS,DLONS,DLATS,DPRES,RTYPES,RSPRES,
     *  MTDAT,PSG,NLAT,NLON,NSIG,GLATS,GLONS,SIGL)
C$$$  SUBPROGRAM DOCUMENTATION BLOCK
C                .      .    .                                       .
C SUBPROGRAM:    PREPT       PRELIMINARY STUFF BEFORE RES. CALC. T
C   PRGMMR: PARRISH          ORG: W/NMC22    DATE: 90-10-11
C
C ABSTRACT: PRELIMINARY STUFF BEFORE RESIDUAL CALCULATION FOR TEMPS.
C
C PROGRAM HISTORY LOG:
C   90-10-11  PARRISH
C
C   INPUT ARGUMENT LIST:
C     DRPTPS   - OBS TYPE IN, OBS ERROR OUT (LN(PS) UNITS)
C     DLONS,DLATS - OBS LONGITUDES AND LATITUDES (RADIANS IN AND OUT)
C     DPRES    - PRES (MB*10+QM IN, GRID COORDS IN SIGMA OUT)
C     RTYPES   - PREPDA OBSERVATION TYPES
C     MTDAT    - NUMBER OF OBSERVATIONS
C     PSG      - MODEL GUESS LOG(PSFC), P IN CB
C     NLAT     - NUMBER OF GAUSSIAN LATS POLE TO POLE
C     NLON     - NUMBER OF LONGITUDES
C     NSIG     - NUMBER OF SIGMA LEVELS
C     GLATS,GLONS - GRID LATITUDES AND LONGITUDES
C     GLONS    - GRID LONGITUDES
C     SIGL     - SIGMA LAYER MIDPOINT VALUES
C
C   OUTPUT ARGUMENT LIST:
C     RSPRES   - OBSERVATION PRESSURES
C     AND AS INDICATED ABOVE
C
C ATTRIBUTES:
C   LANGUAGE: CFT77
C   MACHINE:  CRAY YMP
C
C$$$
C--------
C
C-CRA          DIMENSION DRPTPS(MTDAT),DLONS(MTDAT)
C-CRA          DIMENSION DLATS(MTDAT),DPRES(MTDAT)
C-CRA          DIMENSION PSG(NLAT+1,NLON+2)
C-CRA          DIMENSION GLATS(NLAT),GLONS(NLON),SIGL(NSIG)
C-CRA          DIMENSION RTYPES(MTDAT)
C-CRA          DIMENSION RSPRES(MTDAT)
C-CRA          DIMENSION RBPRES(MTDAT)
C-CRA          DIMENSION RBT(MTDAT)
C-CRA          DIMENSION RLOW(MTDAT),RHGH(MTDAT)
C-CRA          DIMENSION SIGLL(NSIG)
 
C          DIMENSION DRPTPS(_MTDAT_),DLONS(_MTDAT_)
          DIMENSION DRPTPS(60000),DLONS(60000)
C          DIMENSION DLATS(_MTDAT_),DPRES(_MTDAT_)
          DIMENSION DLATS(60000),DPRES(60000)
          DIMENSION PSG(96+1,192+2)
          DIMENSION GLATS(96),GLONS(192),SIGL(28)
C          DIMENSION RTYPES(_MTDAT_)
          DIMENSION RTYPES(60000)
C          DIMENSION RSPRES(_MTDAT_)
          DIMENSION RSPRES(60000)
C          DIMENSION RBPRES(_MTDAT_)
          DIMENSION RBPRES(60000)
C          DIMENSION RBT(_MTDAT_)
          DIMENSION RBT(60000)
C          DIMENSION RLOW(_MTDAT_),RHGH(_MTDAT_)
          DIMENSION RLOW(60000),RHGH(60000)
          DIMENSION SIGLL(28)
C--------
C-------- LOCAL SPACE
C--------
C--------
C-------- GET LOG(SIG)
C--------
C-CRA                SIGLL=LOG(SIGL)
C       DIMENSION SIGLL(NSIG)
           WRITE(6,*) 'SIGL'
           WRITE(6,*) (SIGL(ITMP),ITMP=1,NSIG)
          DO ITMP=1,NSIG
          SIGLL(ITMP)=LOG(SIGL(ITMP))
          ENDDO
C--------
C-------- CONVERT OBS LATS AND LONS TO GRID COORDINATES
C--------
      CALL GDCRDP(DLATS,MTDAT,GLATS,NLAT)
      CALL GDCRDP(DLONS,MTDAT,GLONS,NLON)
C--------
C-------- 3.  INTERPOLATE SURFACE PRESSURE
C--------
C-------- OBTAIN GUESS SURFACE PRESSURE AT OBS LOCATIONS
C--------
      CALL INTRP2(PSG,RBPRES,DLATS,DLONS,
     *  NLAT,NLON,MTDAT)
C--------
C-------- CONVERT OBS PRESSURE TO SIGMA, THEN GET GRID COORDINATES
C--------
C-CRA                RSPRES=10.*EXP(DPRES)
C       DIMENSION RSPRES(MTDAT)
          DO ITMP=1,MTDAT
          RSPRES(ITMP)=10.*EXP(DPRES(ITMP))
          ENDDO
C-CRA                DPRES=DPRES-RBPRES
C       DIMENSION DLATS(MTDAT),DPRES(MTDAT)
          DO ITMP=1,MTDAT
          DPRES(ITMP)=DPRES(ITMP)-RBPRES(ITMP)
          ENDDO
      CALL GDCRDN(DPRES,MTDAT,SIGLL,NSIG)
      DO 260 I=1,MTDAT
        IF(RTYPES(I) .GT. 179.5 .AND. RTYPES(I) .LT. 189.5)THEN
          IF(DPRES(I) .GT. 4.)DRPTPS(I)=1.E6
        END IF
 260  CONTINUE
      NUMLOW=0
      NUMHGH=0
      HGH=0.
      XLOW=0.
      DO 80 I=1,MTDAT
        RLOW(I)=DPRES(I)-1.
        RLOW(I)=MIN(0.,RLOW(I))
        RLOW(I)=-RLOW(I)
        IF(RLOW(I).NE.0.) NUMLOW=NUMLOW+1
        XLOW=MAX(RLOW(I),XLOW)
        RHGH(I)=DPRES(I)-NSIG-.05
        RHGH(I)=MAX(0.,RHGH(I))
        IF(RHGH(I).NE.0.) NUMHGH=NUMHGH+1
        HGH=MAX(RHGH(I),HGH)
80    CONTINUE
      WRITE(6,900)MTDAT,NUMHGH,NUMLOW,HGH,XLOW
900   FORMAT(' NUMBER OF TEMPS=',I8,' NUMBER EXTRAPOLATED ABOVE',
     *  ' TOP SIGMA LAYER=',I8,/,'  NUMBER EXTRAPOLATED BELOW',
     *  ' BOTTOM SIGMA LAYER=',I8,/,' LARGEST EXTRAPOLATION',
     *  ' ABOVE=',F12.2,/,' LARGEST EXTRAPOLATION BELOW=',F12.2)
      DO 90 I=1,MTDAT
        IF(DRPTPS(I) .LE. 0.)THEN
          PRINT *,I,DRPTPS(I),RTYPES(I),DLATS(I),DPRES(I)
          DRPTPS(I)=1.E9
          END IF
        DRPTPS(I)=1./(DRPTPS(I)+
     *     1.E6*RHGH(I)+4.*RLOW(I))**2
90    CONTINUE
      RETURN
      END