*IF DEF,A03_7A EXCOEF7A.2
C *****************************COPYRIGHT****************************** EXCOEF7A.3
C (c) CROWN COPYRIGHT 1998, METEOROLOGICAL OFFICE, All Rights Reserved. EXCOEF7A.4
C EXCOEF7A.5
C Use, duplication or disclosure of this code is subject to the EXCOEF7A.6
C restrictions as set forth in the contract. EXCOEF7A.7
C EXCOEF7A.8
C Meteorological Office EXCOEF7A.9
C London Road EXCOEF7A.10
C BRACKNELL EXCOEF7A.11
C Berkshire UK EXCOEF7A.12
C RG12 2SZ EXCOEF7A.13
C EXCOEF7A.14
C If no contract has been raised with this copy of the code, the use, EXCOEF7A.15
C duplication or disclosure of it is strictly prohibited. Permission EXCOEF7A.16
C to do so must first be obtained in writing from the Head of Numerical EXCOEF7A.17
C Modelling at the above address. EXCOEF7A.18
C ******************************COPYRIGHT****************************** EXCOEF7A.19
!!! SUBROUTINE EX_COEF------------------------------------------------ EXCOEF7A.20
!!! EXCOEF7A.21
!!! Purpose: To calculate exchange coefficients for boundary layer EXCOEF7A.22
!!! subroutine KMKH. EXCOEF7A.23
!!! EXCOEF7A.24
!!! Suitable for single column use. EXCOEF7A.25
!!! EXCOEF7A.26
!!! Model Modification history: EXCOEF7A.27
!!! version Date EXCOEF7A.28
!!! EXCOEF7A.29
!!! 4.5 13/05/98 New deck. Richard Betts EXCOEF7A.30
!!! EXCOEF7A.31
!!! Documentation: UMDP No.24 EXCOEF7A.32
!!! EXCOEF7A.33
!!!--------------------------------------------------------------------- EXCOEF7A.34
EXCOEF7A.35
!! Arguments :- EXCOEF7A.36
SUBROUTINE EX_COEF ( 5,6EXCOEF7A.37
& P_FIELD,P1,P_POINTS,BL_LEVELS EXCOEF7A.38
&,CCB,CCT,NTML,L_MOM EXCOEF7A.39
&,CCA,DZL,RDZ,RI,U_P,V_P EXCOEF7A.40
&,RHO,ZH,ZLB,Z0M,H_BLEND EXCOEF7A.41
&,RHOKM,RHOKH,LTIMER EXCOEF7A.42
& ) EXCOEF7A.43
EXCOEF7A.44
IMPLICIT NONE EXCOEF7A.45
EXCOEF7A.46
LOGICAL LTIMER EXCOEF7A.47
LOGICAL EXCOEF7A.48
& L_MOM ! IN Switch for convective momentum transport. EXCOEF7A.49
EXCOEF7A.50
INTEGER EXCOEF7A.51
& P_FIELD ! IN No. of P-grid points in whole field. EXCOEF7A.52
&,P1 ! IN First P-grid point to be processed. EXCOEF7A.53
&,P_POINTS ! IN No. of P-grid points to be processed. EXCOEF7A.54
&,BL_LEVELS ! IN maximum number of boundary layer levels EXCOEF7A.55
EXCOEF7A.56
INTEGER EXCOEF7A.57
& CCB(P_FIELD) ! IN Convective Cloud Base. EXCOEF7A.58
&,CCT(P_FIELD) ! IN Convective Cloud Top. EXCOEF7A.59
&,NTML(P_FIELD) ! IN Number of turbulently mixed EXCOEF7A.60
! layers. EXCOEF7A.61
EXCOEF7A.62
REAL EXCOEF7A.63
& CCA(P_FIELD) ! IN Convective Cloud Amount. EXCOEF7A.64
&,DZL(P_FIELD,BL_LEVELS) ! IN Layer depths (m). DZL(,K) is the EXCOEF7A.65
! distance from layer boundary K-1/2 EXCOEF7A.66
! to layer boundary K+1/2. For K=1 EXCOEF7A.67
! the lower boundary is the surface. EXCOEF7A.68
&,RDZ(P_FIELD,BL_LEVELS) ! IN Reciprocal of distance between EXCOEF7A.69
! hybrid levels (m-1). 1/RDZ(,K) is EXCOEF7A.70
! the vertical distance from level EXCOEF7A.71
! K-1 to level K, except that for EXCOEF7A.72
! K=1 it is just the height of the EXCOEF7A.73
! lowest atmospheric level. EXCOEF7A.74
&,RHO(P_FIELD,BL_LEVELS) ! IN Density at theta_levels EXCOEF7A.75
&,RI(P_FIELD,2:BL_LEVELS) ! IN Richardson number for lower EXCOEF7A.76
! interface of layer. EXCOEF7A.77
&,U_P(P_FIELD,BL_LEVELS) ! IN Westerly wind component on P-grid EXCOEF7A.78
! (m per s). EXCOEF7A.79
&,V_P(P_FIELD,BL_LEVELS) ! IN Southerly wind component on P-grid EXCOEF7A.80
! (m per s). EXCOEF7A.81
&,ZH(P_FIELD) ! IN Boundary layer height (m). EXCOEF7A.82
&,ZLB(P_FIELD,BL_LEVELS) ! IN ZLB(,K) is height above surface of EXCOEF7A.83
! lower boundary of layer K (m). EXCOEF7A.84
&,Z0M(P_FIELD) ! IN Roughness length for momentum (m). EXCOEF7A.85
&,H_BLEND(P_FIELD) ! IN Blending height for effective EXCOEF7A.86
! roughness length scheme EXCOEF7A.87
EXCOEF7A.88
REAL EXCOEF7A.89
& RHOKM(P_FIELD,BL_LEVELS) ! INOUT Layer K-1 - to - layer K EXCOEF7A.90
! exchange coefficient for EXCOEF7A.91
! momentum, on UV-grid with first EXCOEF7A.92
! and last rows set to "missing EXCOEF7A.93
! data".Output as GAMMA*RHOKM* EXCOEF7A.94
! RDZUV for P244 (IMPL_CAL). EXCOEF7A.95
&,RHOKH(P_FIELD,BL_LEVELS) ! OUT Layer K-1 - to - layer K EXCOEF7A.96
! exchange coefficient for FTL, EXCOEF7A.97
! on P-grid.Output as GAMMA* EXCOEF7A.98
! *RHOKH*RDZ for P244(IMPL_CAL) EXCOEF7A.99
EXCOEF7A.100
!----------------------------------------------------------------------- EXCOEF7A.101
EXTERNAL TIMER EXCOEF7A.102
EXCOEF7A.103
!----------------------------------------------------------------------- EXCOEF7A.104
EXCOEF7A.105
! Local and other symbolic constants :- EXCOEF7A.106
*CALL C_LHEAT 
EXCOEF7A.107
*CALL C_R_CP EXCOEF7A.108
*CALL C_EPSLON EXCOEF7A.109
*CALL C_VKMAN EXCOEF7A.110
EXCOEF7A.111
REAL EH,EM,G0,DH,DM,LAMBDA_MIN,A_LAMBDA EXCOEF7A.112
PARAMETER ( EXCOEF7A.113
& EH=25.0 ! Used in calc of stability function FH. EXCOEF7A.114
&,EM=4.0 ! Used in calc of stability function FM. EXCOEF7A.115
&,G0=10.0 ! Used in stability function calcs. EXCOEF7A.116
&,DH=G0/EH ! Used in calc of stability function FH. EXCOEF7A.117
&,DM=G0/EM ! Used in calc of stability function FM. EXCOEF7A.118
&,LAMBDA_MIN=40.0 ! Minimum value of length scale LAMBDA. EXCOEF7A.119
&,A_LAMBDA=2.0 ! used in calc of LAMBDA_EFF EXCOEF7A.120
&) EXCOEF7A.121
EXCOEF7A.122
EXCOEF7A.123
! Define local storage. EXCOEF7A.124
EXCOEF7A.125
! Scalars. EXCOEF7A.126
EXCOEF7A.127
REAL EXCOEF7A.128
& DVDZM ! Modulus of wind shear gradient across lower level bdy EXCOEF7A.129
&,DZU ! Westerly wind shear between adjacent levels. EXCOEF7A.130
&,DZV ! Southerly wind shear between adjacent levels. EXCOEF7A.131
&,DVMOD2 ! Square of modulus of wind shear between adjacent EXCOEF7A.132
! levels EXCOEF7A.133
&,ELH ! Mixing length for heat & moisture at lower layer bdy. EXCOEF7A.134
&,ELM ! Mixing length for momentum at lower layer boundary. EXCOEF7A.135
&,FH ! (Value of) stability function for heat & moisture. EXCOEF7A.136
&,FM ! (Value of) stability function for momentum transport. EXCOEF7A.137
&,RTMRI ! Temporary in stability function calculation. EXCOEF7A.138
&,VKZ ! Temporary in calculation of ELH. EXCOEF7A.139
&,LAMBDAM ! Asymptotic mixing length for turbulent transport EXCOEF7A.140
! of momentum. EXCOEF7A.141
&,LAMBDAH ! Asymptotic mixing length for turbulent transport EXCOEF7A.142
! of heat/moisture. EXCOEF7A.143
&,LAMBDA_EFF! Effective mixing length used with effective EXCOEF7A.144
! roughness length scheme. EXCOEF7A.145
INTEGER EXCOEF7A.146
& I ! Loop counter (horizontal field index). EXCOEF7A.147
&,K ! Loop counter (vertical level index). EXCOEF7A.148
&,KM1 ! K-1. EXCOEF7A.149
EXCOEF7A.150
! Layer interface K_LOG_LAYR-1/2 is the highest which requires log EXCOEF7A.151
! profile correction factors to the vertical finite differences. EXCOEF7A.152
! The value should be reassessed if the vertical resolution is changed. EXCOEF7A.153
! We could set K_LOG_LAYR = BL_LEVELS and thus apply the correction EXCOEF7A.154
! factors for all the interfaces treated by the boundary layer scheme; EXCOEF7A.155
! this would be desirable theoretically but expensive computationally EXCOEF7A.156
! because of the use of the log function. EXCOEF7A.157
EXCOEF7A.158
INTEGER K_LOG_LAYR EXCOEF7A.159
PARAMETER (K_LOG_LAYR=2) EXCOEF7A.160
EXCOEF7A.161
IF (LTIMER) THEN EXCOEF7A.162
CALL TIMER('EX_COEF ',103) EXCOEF7A.163
ENDIF EXCOEF7A.164
EXCOEF7A.165
!----------------------------------------------------------------------- EXCOEF7A.166
!! 1. Loop round "boundary" levels; calculate the stability- EXCOEF7A.167
!! dependent turbulent mixing coefficients. EXCOEF7A.168
!----------------------------------------------------------------------- EXCOEF7A.169
EXCOEF7A.170
DO K=2,BL_LEVELS EXCOEF7A.171
KM1 = K-1 EXCOEF7A.172
DO I=P1,P1+P_POINTS-1 EXCOEF7A.173
!----------------------------------------------------------------------- EXCOEF7A.174
!! 2.1 Calculate asymptotic mixing lengths LAMBDAM and LAMBDAH EXCOEF7A.175
!! (currently assumed equal). EXCOEF7A.176
!----------------------------------------------------------------------- EXCOEF7A.177
EXCOEF7A.178
LAMBDAM = MAX ( LAMBDA_MIN , 0.15*ZH(I) ) EXCOEF7A.179
LAMBDAH = LAMBDAM EXCOEF7A.180
LAMBDA_EFF = MAX (LAMBDAM, A_LAMBDA*H_BLEND(I) ) EXCOEF7A.181
IF ( K .GE. NTML(I) + 2) THEN EXCOEF7A.182
LAMBDAM = LAMBDA_MIN EXCOEF7A.183
LAMBDAH = LAMBDA_MIN EXCOEF7A.184
IF (ZLB(I,K) .GT. A_LAMBDA*H_BLEND(I)) LAMBDA_EFF = LAMBDA_MIN EXCOEF7A.185
ENDIF EXCOEF7A.186
EXCOEF7A.187
!----------------------------------------------------------------------- EXCOEF7A.188
!! 2.2 Calculate mixing lengths ELH, ELM at layer interface K-1/2. EXCOEF7A.189
!----------------------------------------------------------------------- EXCOEF7A.190
EXCOEF7A.191
! Incorporate log profile corrections to the vertical finite EXCOEF7A.192
! differences into the definitions of ELM and ELH. EXCOEF7A.193
! To save computing logarithms for all K, the values of ELM and ELH EXCOEF7A.194
! are unchanged for K > K_LOG_LAYR. EXCOEF7A.195
EXCOEF7A.196
IF (K .LE. K_LOG_LAYR) THEN EXCOEF7A.197
VKZ = VKMAN / RDZ(I,K) EXCOEF7A.198
ELM = VKZ / ( LOG( ( ZLB(I,K) + Z0M(I) + 0.5*DZL(I,K) ) / EXCOEF7A.199
& ( ZLB(I,K) + Z0M(I) - 0.5*DZL(I,KM1) ) ) EXCOEF7A.200
& + VKZ / LAMBDA_EFF ) EXCOEF7A.201
ELH = VKZ / ( LOG( ( ZLB(I,K) + Z0M(I) + 0.5*DZL(I,K) ) / EXCOEF7A.202
& ( ZLB(I,K) + Z0M(I) - 0.5*DZL(I,KM1) ) ) EXCOEF7A.203
& + VKZ / LAMBDAH ) EXCOEF7A.204
ELSE EXCOEF7A.205
VKZ = VKMAN * ( ZLB(I,K) + Z0M(I) ) EXCOEF7A.206
ELM = VKZ / (1.0 + VKZ/LAMBDA_EFF ) EXCOEF7A.207
ELH = VKZ / (1.0 + VKZ/LAMBDAH ) EXCOEF7A.208
ENDIF EXCOEF7A.209
EXCOEF7A.210
!----------------------------------------------------------------------- EXCOEF7A.211
!! 2.3 Calculate wind shear and magnitude of gradient thereof across EXCOEF7A.212
!! interface K-1/2. EXCOEF7A.213
!----------------------------------------------------------------------- EXCOEF7A.214
EXCOEF7A.215
! Repeat of KMKH calculation, could be passed in from KMKH. EXCOEF7A.216
DZU = U_P(I,K) - U_P(I,KM1) EXCOEF7A.217
DZV = V_P(I,K) - V_P(I,KM1) EXCOEF7A.218
DVMOD2 = MAX ( 1.0E-12 , DZU*DZU + DZV*DZV ) EXCOEF7A.219
DVDZM = SQRT (DVMOD2) * RDZ(I,K) EXCOEF7A.220
EXCOEF7A.221
!----------------------------------------------------------------------- EXCOEF7A.222
!! 2.4 Calculate (values of) stability functions FH, FM. EXCOEF7A.223
!----------------------------------------------------------------------- EXCOEF7A.224
EXCOEF7A.225
IF (RI(I,K) .GE. 0.0) THEN EXCOEF7A.226
RTMRI = 0.0 EXCOEF7A.227
FM = 1.0 / ( 1.0 + G0*RI(I,K) ) EXCOEF7A.228
FH = FM EXCOEF7A.229
EXCOEF7A.230
! !----------------------------------------------------------- EXCOEF7A.231
! ! If convective cloud exists in layer K allow neutral mixing EXCOEF7A.232
! ! of momentum between layers K-1 and K. This is to ensure EXCOEF7A.233
! ! that a reasonable amount of momentum is mixed in the EXCOEF7A.234
! ! presence of convection; it is not be required when EXCOEF7A.235
! ! momentum transport is included in the convection scheme. EXCOEF7A.236
! !----------------------------------------------------------- EXCOEF7A.237
EXCOEF7A.238
IF ( .NOT.L_MOM .AND. (CCA(I) .GT. 0.0) .AND. EXCOEF7A.239
& (K .GE. CCB(I)) .AND. (K .LT. CCT(I)) ) EXCOEF7A.240
& FM = 1.0 EXCOEF7A.241
ELSE EXCOEF7A.242
RTMRI = (ELM/ELH) * SQRT ( -RI(I,K) ) EXCOEF7A.243
FM = 1.0 - ( G0*RI(I,K) / ( 1.0 + DM*RTMRI ) ) EXCOEF7A.244
FH = 1.0 - ( G0*RI(I,K) / ( 1.0 + DH*RTMRI ) ) EXCOEF7A.245
ENDIF EXCOEF7A.246
EXCOEF7A.247
!----------------------------------------------------------------------- EXCOEF7A.248
!! 2.5 Calculate exchange coefficients RHO*KM, RHO*KH for interface EXCOEF7A.249
!! K-1/2. EXCOEF7A.250
!----------------------------------------------------------------------- EXCOEF7A.251
EXCOEF7A.252
RHOKM(I,K) = RHO(I, K) * ELM * ELM * DVDZM * FM EXCOEF7A.253
RHOKH(I,K) = RHO (I, K)* ELH * ELM * DVDZM * FH EXCOEF7A.254
EXCOEF7A.255
ENDDO ! p_points EXCOEF7A.256
ENDDO ! bl_levels EXCOEF7A.257
EXCOEF7A.258
! Initialise unused 1st level of RHOKH to prevent compilation error EXCOEF7A.259
DO I=P1,P1+P_POINTS-1 EXCOEF7A.260
RHOKH(I,1)=0.0 EXCOEF7A.261
ENDDO EXCOEF7A.262
EXCOEF7A.263
IF (LTIMER) THEN EXCOEF7A.264
CALL TIMER('EX_COEF ',104) EXCOEF7A.265
ENDIF EXCOEF7A.266
EXCOEF7A.267
RETURN EXCOEF7A.268
END EXCOEF7A.269
*ENDIF EXCOEF7A.270