*IF DEF,A08_7A FRUNOF7A.2
C ******************************COPYRIGHT****************************** FRUNOF7A.3
C (c) CROWN COPYRIGHT 1997, METEOROLOGICAL OFFICE, All Rights Reserved. FRUNOF7A.4
C FRUNOF7A.5
C Use, duplication or disclosure of this code is subject to the FRUNOF7A.6
C restrictions as set forth in the contract. FRUNOF7A.7
C FRUNOF7A.8
C Meteorological Office FRUNOF7A.9
C London Road FRUNOF7A.10
C BRACKNELL FRUNOF7A.11
C Berkshire UK FRUNOF7A.12
C RG12 2SZ FRUNOF7A.13
C FRUNOF7A.14
C If no contract has been raised with this copy of the code, the use, FRUNOF7A.15
C duplication or disclosure of it is strictly prohibited. Permission FRUNOF7A.16
C to do so must first be obtained in writing from the Head of Numerical FRUNOF7A.17
C Modelling at the above address. FRUNOF7A.18
C ******************************COPYRIGHT****************************** FRUNOF7A.19
C FRUNOF7A.20
CLL SUBROUTINE FRUNOFF------------------------------------------------ FRUNOF7A.21
CLL FRUNOF7A.22
CLL PURPOSE : TO CALCULATE SURFACE RUNOFF FRUNOF7A.23
CLL FRUNOF7A.24
CLL SUITABLE FOR SINGLE COLUMN MODEL USE FRUNOF7A.25
CLL FRUNOF7A.26
CLL WRITTEN FOR CRAY-YMP BY S.ALLEN AND D.GREGORY FRUNOF7A.27
CLL DEC - FEB 1989/90 FRUNOF7A.28
CLL FRUNOF7A.29
CLL MODEL MODIFICATION HISTORY FROM MODEL VERSION 3.0: FRUNOF7A.30
CLL VERSION DATE FRUNOF7A.31
CLL FRUNOF7A.32
CLL PROGRAMMING STANDARDS : UNIFIED MODEL DOCUMENTATION PAPER NO. 4 FRUNOF7A.33
CLL VERSION NO. 1 18/1/90 FRUNOF7A.34
CLL FRUNOF7A.35
CLL LOGICAL COMPONENTS : P252 FRUNOF7A.36
CLL FRUNOF7A.37
CLL SYSTEM TASK : FRUNOF7A.38
CLL FRUNOF7A.39
CLL DOCUMENTATION : UNIFIED MODEL DOCUMENTATION PAPER NO 25 FRUNOF7A.40
CLL SECTION (3B(II)), EQN(P252.14) FRUNOF7A.41
CLL FRUNOF7A.42
CLLEND----------------------------------------------------------------- FRUNOF7A.43
C FRUNOF7A.44
C*L ARGUMENTS--------------------------------------------------------- FRUNOF7A.45
C FRUNOF7A.46
SUBROUTINE FRUNOFF ( 7FRUNOF7A.47
& NPNTS,TILE_PTS,TILE_INDEX,AREA, FRUNOF7A.48
& CAN_CPY,CAN_WCNT,INFIL,R,FRAC,TIMESTEP, FRUNOF7A.49
& SURF_ROFF FRUNOF7A.50
& ) FRUNOF7A.51
FRUNOF7A.52
IMPLICIT NONE FRUNOF7A.53
FRUNOF7A.54
INTEGER FRUNOF7A.55
& NPNTS ! IN Total number of land points. FRUNOF7A.56
&,TILE_PTS ! IN Number of tile points. FRUNOF7A.57
&,TILE_INDEX(NPNTS) ! IN Index of tile points. FRUNOF7A.58
FRUNOF7A.59
REAL FRUNOF7A.60
& AREA ! IN Fractional area of gridbox over which FRUNOF7A.61
! water falls (%). FRUNOF7A.62
&,CAN_CPY(NPNTS) ! IN Canopy capacity (kg/m2). FRUNOF7A.63
&,CAN_WCNT(NPNTS) ! IN Canopy water content (kg/m2). FRUNOF7A.64
&,INFIL(NPNTS) ! IN Infiltration rate (kg/m2/s). FRUNOF7A.65
&,R(NPNTS) ! IN Water fall rate (kg/m2/s). FRUNOF7A.66
&,FRAC(NPNTS) ! IN Tile fraction. FRUNOF7A.67
&,TIMESTEP ! IN Timestep (s). FRUNOF7A.68
FRUNOF7A.69
REAL FRUNOF7A.70
& SURF_ROFF(NPNTS) ! OUT Cummulative surface runoff (kg/m2/s). FRUNOF7A.71
FRUNOF7A.72
! Workspace -------------------------------------------------------- FRUNOF7A.73
REAL FRUNOF7A.74
& AEXP ! Used in the calculation of exponential FRUNOF7A.75
&,AEXP1 ! terms in the surface runoff formula. FRUNOF7A.76
&,AEXP2 ! FRUNOF7A.77
&,CM ! (CAN_CPY - CAN_WCNT)/TIMESTEP FRUNOF7A.78
&,CAN_RATIO ! CAN_WCNT / CAN_CPY FRUNOF7A.79
&,RUNOFF ! Local runoff. FRUNOF7A.80
FRUNOF7A.81
INTEGER FRUNOF7A.82
& I ! Land point index. FRUNOF7A.83
&,J ! Counter for loop over tile points. FRUNOF7A.84
FRUNOF7A.85
DO J=1,TILE_PTS FRUNOF7A.86
I = TILE_INDEX(J) FRUNOF7A.87
RUNOFF = 0. FRUNOF7A.88
IF (R(I).GT.0.0) THEN FRUNOF7A.89
IF ( INFIL(I)*TIMESTEP.LE.CAN_WCNT(I) FRUNOF7A.90
& .AND. CAN_CPY(I).GT.0.0 ) THEN FRUNOF7A.91
! Infiltration in timestep < or = canopy water content FRUNOF7A.92
AEXP = AREA*CAN_CPY(I)/R(I) FRUNOF7A.93
IF (CAN_WCNT(I) .GT. 0.0) THEN FRUNOF7A.94
AEXP1 = EXP( -AEXP*INFIL(I)/CAN_WCNT(I)) FRUNOF7A.95
ELSE FRUNOF7A.96
AEXP1 = 0.0 FRUNOF7A.97
END IF FRUNOF7A.98
AEXP2 = EXP( -AEXP/TIMESTEP) FRUNOF7A.99
CAN_RATIO = CAN_WCNT(I)/CAN_CPY(I) FRUNOF7A.100
CAN_RATIO = MIN(CAN_RATIO,1.0) ABX1F405.967
RUNOFF = R(I) * ( CAN_RATIO*AEXP1 + FRUNOF7A.101
* (1. - CAN_RATIO)*AEXP2 ) FRUNOF7A.102
! ... P252.14A FRUNOF7A.103
ELSE FRUNOF7A.104
! Infiltration in timestep > canopy water content FRUNOF7A.105
CM = (CAN_CPY(I)-CAN_WCNT(I))/TIMESTEP FRUNOF7A.106
CM = MAX(CM,0.0) ABX1F405.968
AEXP = EXP( -AREA*(INFIL(I)+CM)/R(I)) FRUNOF7A.107
RUNOFF = R(I)*AEXP ! ... P252.14B FRUNOF7A.108
ENDIF FRUNOF7A.109
ENDIF FRUNOF7A.110
SURF_ROFF(I) = SURF_ROFF(I) + FRAC(I)*RUNOFF FRUNOF7A.111
ENDDO FRUNOF7A.112
FRUNOF7A.113
RETURN FRUNOF7A.114
END FRUNOF7A.115
*ENDIF FRUNOF7A.116