*IF DEF,A05_2A,OR,DEF,A05_2C                                               AJX1F405.155    
C ******************************COPYRIGHT******************************    GTS2F400.1747   
C (c) CROWN COPYRIGHT 1995, METEOROLOGICAL OFFICE, All Rights Reserved.    GTS2F400.1748   
C                                                                          GTS2F400.1749   
C Use, duplication or disclosure of this code is subject to the            GTS2F400.1750   
C restrictions as set forth in the contract.                               GTS2F400.1751   
C                                                                          GTS2F400.1752   
C                Meteorological Office                                     GTS2F400.1753   
C                London Road                                               GTS2F400.1754   
C                BRACKNELL                                                 GTS2F400.1755   
C                Berkshire UK                                              GTS2F400.1756   
C                RG12 2SZ                                                  GTS2F400.1757   
C                                                                          GTS2F400.1758   
C If no contract has been raised with this copy of the code, the use,      GTS2F400.1759   
C duplication or disclosure of it is strictly prohibited.  Permission      GTS2F400.1760   
C to do so must first be obtained in writing from the Head of Numerical    GTS2F400.1761   
C Modelling at the above address.                                          GTS2F400.1762   
C ******************************COPYRIGHT******************************    GTS2F400.1763   
C                                                                          GTS2F400.1764   
CLL  SUBROUTINE DD_INIT------------------------------------------------    DDINIT2A.3      
CLL                                                                        DDINIT2A.4      
CLL  PURPOSE : ROUTINE TO INITIALISE THE DOWNDRAUGHT                       DDINIT2A.5      
CLL                                                                        DDINIT2A.6      
CLL  SUITABLE FOR SINGLE COLUMN MODEL USE                                  DDINIT2A.7      
CLL                                                                        DDINIT2A.8      
CLL  CODE WRITTEN FOR CRAY Y-MP BY S.BETT AND D.GREGORY AUTUMN 1991        DDINIT2A.9      
CLL                                                                        DDINIT2A.10     
CLL  MODEL            MODIFICATION HISTORY FROM MODEL VERSION 3.0:         DDINIT2A.11     
CLL VERSION  DATE                                                          DDINIT2A.12     
CLL   4.5    Jul. 98  Kill the IBM specific lines (JCThil)                 AJC1F405.5      
CLL                                                                        DDINIT2A.13     
CLL  PROGRAMMING STANDARDS : UNIFIED MODEL DOCUMENTATION PAPER NO. 3       DDINIT2A.14     
CLL  VERSION NO. 4  DATED 5/2/92                                           DDINIT2A.15     
CLL                                                                        DDINIT2A.16     
CLL  LOGICAL COMPONENTS COVERED:                                           DDINIT2A.17     
CLL                                                                        DDINIT2A.18     
CLL  SYSTEM TASK : P27                                                     DDINIT2A.19     
CLL                                                                        DDINIT2A.20     
CLL  DOCUMENTATION : UNIFIED MODEL DOCUMENTATION PAPER P27                 DDINIT2A.21     
CLL                                                                        DDINIT2A.22     
CLLEND-----------------------------------------------------------------    DDINIT2A.23     
C                                                                          DDINIT2A.24     
C*L  ARGUMENTS---------------------------------------------------------    DDINIT2A.25     
C                                                                          DDINIT2A.26     

      SUBROUTINE DD_INIT(NPNTS,TH_UD_K,Q_UD_K,THE_K,QE_K,PK,EXK,THDD_K,     4,2DDINIT2A.27     
     &                   QDD_K,DELTD,DELQD,BDD_START,K,BDDI,BDD_ON)        DDINIT2A.28     
C                                                                          DDINIT2A.29     
      IMPLICIT NONE                                                        DDINIT2A.30     
C                                                                          DDINIT2A.31     
C-----------------------------------------------------------------------   DDINIT2A.32     
C VECTOR LENGTHS AND LOOP COUNTERS                                         DDINIT2A.33     
C-----------------------------------------------------------------------   DDINIT2A.34     
C                                                                          DDINIT2A.35     
C                                                                          DDINIT2A.39     
      INTEGER I                 ! LOOP COUNTER                             DDINIT2A.40     
C                                                                          DDINIT2A.41     
      INTEGER NPNTS             ! VECTOR LENGTH                            DDINIT2A.42     
C                                                                          DDINIT2A.43     
      INTEGER K                 ! IN PRESENT MODEL LAYER                   DDINIT2A.44     
C                                                                          DDINIT2A.45     
C-----------------------------------------------------------------------   DDINIT2A.46     
C VARIABLES WHICH ARE INPUT                                                DDINIT2A.47     
C-----------------------------------------------------------------------   DDINIT2A.48     
C                                                                          DDINIT2A.49     
      REAL THE_K(NPNTS)         ! IN POTENTIAL TEMPERATURE OF              DDINIT2A.50     
                                !    ENVIRONMENT IN LAYER K (K)            DDINIT2A.51     
C                                                                          DDINIT2A.52     
      REAL TH_UD_K(NPNTS)       ! IN PARCEL POTENTIAL TEMPERATURE OF       DDINIT2A.53     
                                !    UPDRAUGHT, LAYER K (K)                DDINIT2A.54     
C                                                                          DDINIT2A.55     
      REAL QE_K(NPNTS)          ! IN MIXING RATIO OF ENVIRONMENT IN        DDINIT2A.56     
                                !    LAYER K (KG/KG)                       DDINIT2A.57     
C                                                                          DDINIT2A.58     
      REAL Q_UD_K(NPNTS)        ! IN PARCEL MIXING RATIO OF UPDRAUGHT,     DDINIT2A.59     
                                !    LAYER K (KG/KG)                       DDINIT2A.60     
C                                                                          DDINIT2A.61     
      REAL EXK(NPNTS)           ! IN EXNER RATIO OF LAYER K                DDINIT2A.62     
C                                                                          DDINIT2A.63     
      REAL PK(NPNTS)            ! IN PRESSURE OF LAYER K (PA)              DDINIT2A.64     
C                                                                          DDINIT2A.65     
      LOGICAL BDDI(NPNTS)       ! IN MASK FOR THOSE POINTS WHERE           DDINIT2A.66     
                                !    DOWNDRAUGHT MAY INITIATE              DDINIT2A.67     
C                                                                          DDINIT2A.68     
      LOGICAL BDD_ON(NPNTS)     ! IN MASK FOR THOSE POINTS WHERE           DDINIT2A.69     
                                !    DOWNDRAUGHT IS ON                     DDINIT2A.70     
C                                                                          DDINIT2A.71     
C-----------------------------------------------------------------------   DDINIT2A.72     
C VARIABLES WHICH ARE INPUT AND OUTPUT                                     DDINIT2A.73     
C-----------------------------------------------------------------------   DDINIT2A.74     
C                                                                          DDINIT2A.75     
      LOGICAL BDD_START(NPNTS)  ! INOUT                                    DDINIT2A.76     
                                ! IN  MASK FOR THOSE POINT WHERE           DDINIT2A.77     
                                !     DOWNDRAUGHT MAY START                DDINIT2A.78     
                                ! OUT MASK FOR THOSE POINTS WHERE          DDINIT2A.79     
                                !                                          DDINIT2A.80     
C                                                                          DDINIT2A.81     
C-----------------------------------------------------------------------   DDINIT2A.82     
C VARIABLES WHICH ARE OUTPUT                                               DDINIT2A.83     
C-----------------------------------------------------------------------   DDINIT2A.84     
C                                                                          DDINIT2A.85     
      REAL THDD_K(NPNTS)        ! OUT DOWNDRAUGHT POTENTIAL TEMPERATURE    DDINIT2A.86     
                                !     OF LAYER K                           DDINIT2A.87     
C                                                                          DDINIT2A.88     
      REAL QDD_K(NPNTS)         ! OUT DOWNDRAUGHT MIXING RATIO OF          DDINIT2A.89     
                                !     LAYER K                              DDINIT2A.90     
C                                                                          DDINIT2A.91     
      REAL DELTD(NPNTS)         ! OUT COOLING NECESSARY TO ACHIEVE         DDINIT2A.92     
                                !     SATURATION                           DDINIT2A.93     
C                                                                          DDINIT2A.94     
      REAL DELQD(NPNTS)         ! OUT MOISTENING NECESSARY TO ACHIEVE      DDINIT2A.95     
                                !     SATURATION                           DDINIT2A.96     
C                                                                          DDINIT2A.97     
C-----------------------------------------------------------------------   DDINIT2A.98     
C VARIABLES WHICH ARE DEFINED LOCALLY                                      DDINIT2A.99     
C-----------------------------------------------------------------------   DDINIT2A.100    
C                                                                          DDINIT2A.101    
C                                                                          DDINIT2A.123    
      REAL TH_MEAN(NPNTS)       ! MEAN POTENTIAL TEMPERATURE USED IN       DDINIT2A.124    
                                ! CALCULATION OF SATURATED DOWNDRAUGHT     DDINIT2A.125    
                                ! POTENTIAL TEMPERATURE IN LAYER K         DDINIT2A.126    
C                                                                          DDINIT2A.127    
      REAL Q_MEAN(NPNTS)        ! MEAN MIXING RATIO USED IN CALCULATION    DDINIT2A.128    
                                ! OF SATURATED DOWNDRAUGHT                 DDINIT2A.129    
                                ! MIXING RATIO FOR LAYER K                 DDINIT2A.130    
C                                                                          DDINIT2A.131    
      REAL T_MEAN(NPNTS)        ! MEAN TEMPERATURE USED IN CALCULATION     DDINIT2A.132    
                                ! OF SATURATED DOWNDRAUGHT POTENTIAL       DDINIT2A.133    
                                ! TEMPERATURE OF LAYER K (K)               DDINIT2A.134    
C                                                                          DDINIT2A.135    
      REAL THDDS(NPNTS)         ! SATURATED DOWNDRAUGHT POTENTIAL          DDINIT2A.136    
                                ! TEMPERATURE IN LAYER K (K)               DDINIT2A.137    
C                                                                          DDINIT2A.138    
      REAL QDDS(NPNTS)          ! SATURATED DOWNDRAUGHT MIXING RATIO       DDINIT2A.139    
                                ! IN LAYER K (KG/KG)                       DDINIT2A.140    
C                                                                          DDINIT2A.141    
C                                                                          DDINIT2A.143    
      REAL BUOY                 ! BUOYANCY OF PARCEL IN LAYER K            DDINIT2A.144    
C                                                                          DDINIT2A.145    
      REAL THDD_V               ! VIRTUAL POTENTIAL TEMPERATURE OF         DDINIT2A.146    
                                ! PARCEL IN LAYER K                        DDINIT2A.147    
C                                                                          DDINIT2A.148    
      REAL THE_V                ! VIRTUAL POTENTIAL TEMPERATURE OF         DDINIT2A.149    
                                ! ENVIRONMENT IN LAYER K                   DDINIT2A.150    
C                                                                          DDINIT2A.151    
C-----------------------------------------------------------------------   DDINIT2A.152    
C EXTERNAL ROUTINES CALLED                                                 DDINIT2A.153    
C-----------------------------------------------------------------------   DDINIT2A.154    
C                                                                          DDINIT2A.155    
      EXTERNAL SATCAL                                                      DDINIT2A.156    
C                                                                          DDINIT2A.157    
C-----------------------------------------------------------------------   DDINIT2A.158    
C CALCULATE MEAN TEMPERATURE AND MIXING RATIO                              DDINIT2A.159    
C-----------------------------------------------------------------------   DDINIT2A.160    
C                                                                          DDINIT2A.161    
      DO I=1,NPNTS                                                         DDINIT2A.162    
       TH_MEAN(I) = (THE_K(I)+TH_UD_K(I))*0.5                              DDINIT2A.163    
       Q_MEAN(I) = (QE_K(I)+Q_UD_K(I))*0.5                                 DDINIT2A.164    
       T_MEAN(I) = TH_MEAN(I)*EXK(I)                                       DDINIT2A.165    
      END DO                                                               DDINIT2A.166    
C                                                                          DDINIT2A.167    
C-----------------------------------------------------------------------   DDINIT2A.168    
C CALCULATE SATURATED DOWNDRAUGHT POTENTIAL TEMPERATURE FOR LAYER K        DDINIT2A.169    
C-----------------------------------------------------------------------   DDINIT2A.170    
C                                                                          DDINIT2A.171    
      CALL SATCAL(NPNTS,T_MEAN,TH_MEAN,PK,QDDS,THDDS,K,EXK,Q_MEAN,         DDINIT2A.172    
     *            THE_K)                                                   DDINIT2A.173    
C                                                                          DDINIT2A.174    
C-----------------------------------------------------------------------   DDINIT2A.175    
C IS SATURATED PARCEL NEGATIVELY BUOYANT COMPARED TO ENVIRONMENT           DDINIT2A.176    
C-----------------------------------------------------------------------   DDINIT2A.177    
C                                                                          DDINIT2A.178    
      DO I=1,NPNTS                                                         DDINIT2A.179    
       IF (.NOT. BDD_ON(I) .AND. BDDI(I) .AND. K.GE.4) THEN                DDINIT2A.180    
          THDD_V = THDDS(I)*(1.0+0.61*QDDS(I))                             DDINIT2A.181    
          THE_V = THE_K(I)*(1.0+0.61*QE_K(I))                              DDINIT2A.182    
          BUOY = THDD_V - THE_V                                            DDINIT2A.183    
C                                                                          DDINIT2A.184    
          IF (BUOY .LT. 0.5 ) THEN                                         DDINIT2A.185    
C                                                                          DDINIT2A.186    
C-----------------------------------------------------------------------   DDINIT2A.187    
C INITIATE DOWNDRAUGHT                                                     DDINIT2A.188    
C-----------------------------------------------------------------------   DDINIT2A.189    
C                                                                          DDINIT2A.190    
             THDD_K(I) = THDDS(I)                                          DDINIT2A.191    
             QDD_K(I) = QDDS(I)                                            DDINIT2A.192    
             BDD_START(I) = .TRUE.                                         DDINIT2A.193    
C                                                                          DDINIT2A.194    
C-----------------------------------------------------------------------   DDINIT2A.195    
C CALCULATE COOLING AND MOISTENING TO ACHIEVE SATURATION                   DDINIT2A.196    
C-----------------------------------------------------------------------   DDINIT2A.197    
C                                                                          DDINIT2A.198    
             DELTD(I) = THDDS(I)-THE_K(I)                                  DDINIT2A.199    
             DELQD(I) = QDDS(I)-QE_K(I)                                    DDINIT2A.200    
          END IF                                                           DDINIT2A.201    
       END IF                                                              DDINIT2A.202    
      END DO                                                               DDINIT2A.203    
C                                                                          DDINIT2A.204    
      RETURN                                                               DDINIT2A.205    
      END                                                                  DDINIT2A.206    
C                                                                          DDINIT2A.207    
*ENDIF                                                                     DDINIT2A.208