resig.f

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C*********************************************************************
        SUBROUTINE resig
C*********************************************************************
C
C  REDEFINES THE HEIGHTS OF THE FLOW SURFACES BASED ON WIND SPEED OVER
C  THE LOWEST TERRRAIN HEIGHTS & LAPSE RATES AT THE VARIOUS FLOW LEVELS
C  --THE UNDERLYING CONCEPT IS SIMILAR TO THAT OF THE 'CRITICAL STREAM-
C  LINE'. WEIGHTED AVERAGES ARE USED TO CALCULATE FLOW SURFACE HEIGHTS 
C  AT EACH GRID POINT, GIVING GREATEST WEIGHT TO VALUES APPROPRIATE TO 
C  THE NEAREST SOUNDINGS. 
C
C    --LUDWIG, JANUARY 1988.
C
          include 'NGRIDS.PAR'
C
          include 'ANCHOR.CMM'
          include 'FLOWER.CMM'
          include 'LIMITS.CMM'
          include 'STALOC.CMM'
          include 'TSONDS.CMM'
C
       REAL COMPDZ
C
C  MAKE SURE STUFF IS HERE WHEN YOU COME BACK
C
        SAVE
C
C  OVERS(DPTDZ,DZTOP) IS A STATEMENT FUNCTION THAT CAN BE USED TO 
C  DEFINE MAXIMUM RISE OF A FLOW SURFACE IN TERMS OF THE POTENTIAL 
C  TEMPERATURE LAPSE RATE (DPTDZ) RATE AND THE MAXIMUM DIFFERENCE IN 
C  TERRAIN ELEVATION (DZMAX). THE VERSION INCLUDED HERE ASSUMES  THAT 
C  FLOW FOLLOWS UNDER-LYING TERRAIN FOR NEUTRAL OR UNSTABLE CONDITIONS 
C  & THAT THERE IS NO OVERSHOOT OR UNDERSHOOT.
C  
C
        overs(dptdz,dztop)=dztop
C
           DO 200 it = 1,numtmp
C
C  CHECK THAT THERE WAS DATA FROM T-SONDE STATION (NTHTS >0)
C
              IF (nthts(it).GT.0) THEN
C
C  FIND NEAREST LOW REFERENCE POINT AND THE WINDS ABOVE IT
C
         idis2=(nint(xtmp(it))-lowix(1))**2+
     $                        (nint(ytmp(it))-lowiy(1))**2
         jnear(it)=1
             DO 30 jl=2,5
           IF ((nint(xtmp(it))-lowix(jl))**2+
     $                 (nint(ytmp(it))-lowiy(jl))**2 .LT. idis2) THEN
                      idis2=(nint(xtmp(it))-lowix(jl))**2+
     $                           (nint(ytmp(it))-lowiy(jl))**2
                      jnear(it)=jl
                   END IF
30       CONTINUE
         lx=lowix(jnear(it))
         ly=lowiy(jnear(it))
                 DO 100 l=1,nlvl
                    rhslo(it,l)=rhs(lx,ly,l)
                    spd=sqrt(u(lx,ly,l)**2+v(lx,ly,l)**2)
C
C  PUT LOWER LIMIT ON POTENTIAL TEMPERATURE LAPSE RATE AND CALCULATE
C  MAXIMUM RISE CORRESPONDING TO THE WIND SPEED & LAPSE FOR THIS 
C  T-SONDE.
C
                    dtheta=ptlaps(it,l)
            IF (dtheta .GT.-998.) THEN
                       IF (dtheta.LE.dpotmin) dtheta=dpotmin
                       dzmax(it,l)=spd/sqrt(9.8*dtheta/tsigl(it,l))
C
C   FLOW AMPLITUDES ARE LIMITED USING A STATEMENT FUNCTION (OVERS)
C   OF THE POT TMP LAPSE & TERR. AMPLITUDE.
C
                       IF (dzmax(it,l).GT. overs(dtheta,zrise))
     $                            dzmax(it,l)=overs(dtheta,zrise)
            ELSE
               dzmax(it,l)=-9999.
            END IF
 100             CONTINUE
C
C  DEFINE MINIMUM ALLOWABLE FLOW SURFACE SEPARATIONS FOR EACH T-SONDE'S
C  DOMAIN OF INFLUENCE. MINIMUM SEPARATION DEFINED AS A FRACTION 
C  (CMPRES) OF THEIR SEPARATION OVER THE TERRAIN LOW POINT FOR THE 
C  T-SONDE. DO NOT LET SEPARATION BETWEEN SURFACES COMPRESS BY MORE 
C  THAN CMPRES FACTOR OR BE GREATER THAN DEFINED BY OVERS(DPTDZ,DZMAX).
C
                 DO 150 l=nlvl-1,1,-1
            IF (dzmax(it,l).GT.-9998.) THEN
                       compdz=cmpres*(rhslo(it,l+1)-rhslo(it,l))
                       IF (dzmax(it,l).GT.(dzmax(it,l+1)+compdz))
     $                         dzmax(it,l)=dzmax(it,l+1) +compdz
            ELSE
               dzmax(it,l)=-9999.
            END IF
 150             CONTINUE
C
C  MAKE ONE MORE PASS TO ENSURE THAT UPPER SURFACES DO NOT RISE
C  MORE RAPIDLY THAN THE SURFACE OR TERRAIN BELOW, WHICHEVER IS HIGHER.
C
                DO 155 l=2,nlvl
           IF (dzmax(it,l).GT.-9998.) THEN
              IF (l.EQ.2) THEN
                         IF (dzmax(it,l).GT.overs(dtheta,zrise))
     $                             dzmax(it,l)=overs(dtheta,zrise)
              ELSE
             diff=zrise-rhs(lx,ly,l)
                         totryz=dzmax(it,l-1)
                         IF (totryz .LT. diff) totryz=diff
                         IF(dzmax(it,l).GT.totryz)
     $                              dzmax(it,l)=totryz
              END IF
           ELSE
              dzmax(it,l)=-9999.
           END IF
 155            CONTINUE
C
       ELSE
          WRITE (*,*) 'NO LEVELS IN RESIG FOR SOND ',it
          stop
           END IF
C
200     CONTINUE
C
C  NOW CALL FLOWHT TO DETERMINE THE WEIGHTED AVERAGE HTS FOR EACH FLOW 
C  SURFACE ABOVE EACH GRID POINT & REDEFINE LOW FLOW SFC HEIGHTS ON 
C  GRID
C
C
        CALL flowht
C
        RETURN
        END