source: LMDZ5/trunk/libf/phylmd/cdrag.F90 @ 2245

!
!$Id: cdrag.F90 ???? 2015-??-?? ??:??:??Z ? $
!
 SUBROUTINE cdrag( knon,  nsrf,   &
     speed, t1,    q1,    zgeop1, &
     psol,  tsurf, qsurf, z0m, z0h,  &
     pcfm,  pcfh,  zri,   pref )

  USE dimphy
  USE indice_sol_mod
  IMPLICIT NONE
! ================================================================= c
!
! Objet : calcul des cdrags pour le moment (pcfm) et 
!         les flux de chaleur sensible et latente (pcfh).   
!
! Modified histroy: 
!   27-Jan-2014: richardson number inconsistant between
!   coefcdrag.F90 and clcdrag.F90, Fuxing WANG wrote this subroutine
!   by merging coefcdrag and clcdrag.
!
! References:
!   Louis, J. F., 1979: A parametric model of vertical eddy fluxes in the
!     atmosphere. Boundary-Layer Meteorology. 01/1979; 17(2):187-202. 
!   Louis, J. F., Tiedtke, M. and Geleyn, J. F., 1982: `A short history of the
!     operational PBL parametrization at ECMWF'. Workshop on boundary layer
!     parametrization, November 1981, ECMWF, Reading, England. 
!     Page: 19. Equations in Table 1.
!   Anton Beljaars. May 1992. The parametrization of the planetary boundary layer.  
!     European Centre for Medium-Range Weather Forecasts.
!     Equations: 110-113. Page 40.
!   Miller,M.J., A.C.M.Beljaars, T.N.Palmer. 1992. The sensitivity of the ECMWF
!     model to the parameterization of evaporation from the tropical oceans. J.
!     Climate, 5:418-434.
!
! ================================================================= c
!
! knon----input-I- nombre de points pour un type de surface
! nsrf----input-I- indice pour le type de surface; voir indicesol.h
! speed---input-R- module du vent au 1er niveau du modele
! t1------input-R- temperature de l'air au 1er niveau du modele
! q1------input-R- humidite de l'air au 1er niveau du modele
! zgeop---input-R- geopotentiel au 1er niveau du modele
! psol----input-R- pression au sol
! tsurf---input-R- temperature de l'air a la surface 
! qsurf---input-R- humidite de l'air a la surface
! z0m, z0h---input-R- rugosite
!! u1, v1 are removed, speed is used. Fuxing WANG, 04/03/2015,
!! u1------input-R- vent zonal au 1er niveau du modele
!! v1------input-R- vent meridien au 1er niveau du modele
!
! pcfm---output-R- cdrag pour le moment 
! pcfh---output-R- cdrag pour les flux de chaleur latente et sensible
! zri----output-R- Richardson number
! pref---output-R- pression au niveau zgeop/RG
!
! Parameters: 
! ckap-----Karman constant
! cb,cc,cd-parameters in Louis et al., 1982
! ================================================================= c
!
!
! Parametres d'entree
!***************************************************************** 
  INTEGER, INTENT(IN)                      :: knon, nsrf
  REAL, DIMENSION(klon), INTENT(IN)        :: speed ! module du vent au 1er niveau du modele
  REAL, DIMENSION(klon), INTENT(IN)        :: zgeop1! geopotentiel au 1er niveau du modele
  REAL, DIMENSION(klon), INTENT(IN)        :: psol  ! pression au sol
  REAL, DIMENSION(klon), INTENT(IN)        :: t1    ! temperature at 1st level
  REAL, DIMENSION(klon), INTENT(IN)        :: q1    ! humidity at 1st level
  REAL, DIMENSION(klon), INTENT(IN)        :: tsurf ! Surface temperature (K)
  REAL, DIMENSION(klon), INTENT(IN)        :: qsurf ! Surface humidity (Kg/Kg)
  REAL, DIMENSION(klon), INTENT(IN)        :: z0m, z0h ! Rugosity at surface (m) 
!  paprs, pplay u1, v1: to be deleted
!  they were in the old clcdrag. Fuxing WANG, 04/03/2015
!  REAL, DIMENSION(klon,klev+1), INTENT(IN) :: paprs
!  REAL, DIMENSION(klon,klev), INTENT(IN)   :: pplay
!  REAL, DIMENSION(klon), INTENT(IN)        :: u1, v1

! Parametres de sortie
!******************************************************************
  REAL, DIMENSION(klon), INTENT(OUT)       :: pcfm  ! Drag coefficient for heat flux
  REAL, DIMENSION(klon), INTENT(OUT)       :: pcfh  ! Drag coefficient for momentum
  REAL, DIMENSION(klon), INTENT(OUT)       :: zri   ! Richardson number
  REAL, DIMENSION(klon), INTENT(OUT)       :: pref  ! Pression au niveau zgeop/RG

! Parametres local
  INTEGER                                  :: ng_q1    ! Number of grids that q1 < 0.0
  INTEGER                                  :: ng_qsurf ! Number of grids that qsurf < 0.0
!  zgeop1, psol: to be deleted, they are inputs now. Fuxing WANG, 04/03/2015
!  REAL, DIMENSION(klon)                    :: zgeop1! geopotentiel au 1er niveau du modele
!  REAL, DIMENSION(klon)                    :: psol  ! pression au sol
!
! ================================================================= c
!
  INCLUDE "YOMCST.h"
  INCLUDE "YOETHF.h"
!  INCLUDE "indicesol.h"
  INCLUDE "clesphys.h"
  INCLUDE "iniprint.h"
!
! Quelques constantes et options:
!!$PB      REAL, PARAMETER :: ckap=0.35, cb=5.0, cc=5.0, cd=5.0, cepdu2=(0.1)**2
  REAL, PARAMETER :: CKAP=0.40, CB=5.0, CC=5.0, CD=5.0, CEPDU2 = (0.1)**2
!
! Variables locales :
  INTEGER               :: i
  REAL                  :: zdu2, ztsolv
  REAL                  :: ztvd, zscf
  REAL                  :: zucf, zcr
  REAL                  :: friv, frih
  REAL, DIMENSION(klon) :: zcfm1, zcfm2 ! Drag coefficient for momentum
  REAL, DIMENSION(klon) :: zcfh1, zcfh2 ! Drag coefficient for heat flux
  LOGICAL, PARAMETER    :: zxli=.FALSE. ! calcul des cdrags selon Laurent Li
  REAL, DIMENSION(klon) :: zcdn_m, zcdn_h         ! Drag coefficient in neutral conditions
!
! Fonctions thermodynamiques et fonctions d'instabilite
  REAL                  :: fsta, fins, x
  fsta(x) = 1.0 / (1.0+10.0*x*(1+8.0*x))
  fins(x) = SQRT(1.0-18.0*x)

! ================================================================= c
! Fuxing WANG, 04/03/2015, delete the calculation of zgeop1 
! (le geopotentiel du premier couche de modele).
! zgeop1 is an input ivariable in this subroutine.
!  DO i = 1, knon
!     zgeop1(i) = RD * t1(i) / (0.5*(paprs(i,1)+pplay(i,1))) &
!          * (paprs(i,1)-pplay(i,1))
!  END DO
! ================================================================= c
!
! Fuxing WANG, 04/03/2015
! To check if there are negative q1, qsurf values.
  ng_q1 = 0     ! Initialization
  ng_qsurf = 0  ! Initialization
  DO i = 1, knon
     IF (q1(i).LT.0.0)     ng_q1 = ng_q1 + 1
     IF (qsurf(i).LT.0.0)  ng_qsurf = ng_qsurf + 1
  ENDDO
  IF (ng_q1.GT.0) THEN
      WRITE(lunout,*)" *** Warning: Negative q1(humidity at 1st level) values in cdrag.F90 !"
      WRITE(lunout,*)" The total number of the grids is: ", ng_q1
      WRITE(lunout,*)" The negative q1 is set to zero "
!      abort_message="voir ci-dessus"
!      CALL abort_gcm(modname,abort_message,1)
  ENDIF
  IF (ng_qsurf.GT.0) THEN
      WRITE(lunout,*)" *** Warning: Negative qsurf(humidity at surface) values in cdrag.F90 !"
      WRITE(lunout,*)" The total number of the grids is: ", ng_qsurf
      WRITE(lunout,*)" The negative qsurf is set to zero "
!      abort_message="voir ci-dessus"
!      CALL abort_gcm(modname,abort_message,1)
  ENDIF

! Calculer le frottement au sol (Cdrag)
  DO i = 1, knon
!------------------------------------------------------------
! u1, v1 are replaced by speed. Fuxing WANG, 04/03/2015,
!     zdu2 = MAX(CEPDU2,u1(i)**2+v1(i)**2)
!------------------------------------------------------------
     zdu2 = MAX(CEPDU2, speed(i)**2)
!     psol(i) = paprs(i,1)
     pref(i) = EXP(LOG(psol(i)) - zgeop1(i)/(RD*t1(i)* &
                 (1.+ RETV * max(q1(i),0.0))))  ! negative q1 set to zero
!------------ the old calculations in clcdrag----------------
!     ztsolv = tsurf(i) * (1.0+RETV*qsurf(i)) 
!     ztvd = (t1(i)+zgeop1(i)/RCPD/(1.+RVTMP2*q1(i))) &
!          *(1.+RETV*q1(i)) 
!------------------------------------------------------------
! Fuxing WANG, 04/03/2015, in this revised version, 
! the negative qsurf and q1 are set to zero (as in coefcdrag)
     ztsolv = tsurf(i) * (1.0+RETV*max(qsurf(i),0.0)) ! negative qsurf set to zero
     ztvd = (t1(i)+zgeop1(i)/RCPD/(1.+RVTMP2*q1(i))) &
          *(1.+RETV*max(q1(i),0.0)) ! negative q1 set to zero
     zri(i) = zgeop1(i)*(ztvd-ztsolv)/(zdu2*ztvd)


! Coefficients CD neutres pour m et h
     zcdn_m(i) = (CKAP/LOG(1.+zgeop1(i)/(RG*z0m(i))))**2
     zcdn_h(i) = (CKAP/LOG(1.+zgeop1(i)/(RG*z0h(i))))**2

     IF (zri(i) .GT. 0.) THEN      ! situation stable
        zri(i) = MIN(20.,zri(i))
        IF (.NOT.zxli) THEN
           zscf = SQRT(1.+CD*ABS(zri(i)))
           friv = AMAX1(1. / (1.+2.*CB*zri(i)/ZSCF), f_ri_cd_min)
           zcfm1(i) = zcdn_m(i) * friv
           frih = AMAX1(1./ (1.+3.*CB*zri(i)*ZSCF), f_ri_cd_min )
!!$ PB     zcfh1(i) = zcdn(i) * frih
!!$ PB     zcfh1(i) = f_cdrag_stable * zcdn(i) * frih
           zcfh1(i) = f_cdrag_ter * zcdn_h(i) * frih
           IF(nsrf.EQ.is_oce) zcfh1(i) = f_cdrag_oce * zcdn_h(i) * frih
!!$ PB
           pcfm(i) = zcfm1(i)
           pcfh(i) = zcfh1(i)
        ELSE
           pcfm(i) = zcdn_m(i)* fsta(zri(i))
           pcfh(i) = zcdn_h(i)* fsta(zri(i))
        ENDIF
     ELSE                          ! situation instable
        IF (.NOT.zxli) THEN
           zucf = 1./(1.+3.0*CB*CC*zcdn_m(i)*SQRT(ABS(zri(i)) &
                *(1.0+zgeop1(i)/(RG*z0m(i)))))
           zcfm2(i) = zcdn_m(i)*amax1((1.-2.0*CB*zri(i)*zucf),f_ri_cd_min)
!!$ PB     zcfh2(i) = zcdn_h(i)*amax1((1.-3.0*cb*zri(i)*zucf),f_ri_cd_min)
           zcfh2(i) = f_cdrag_ter*zcdn_h(i)*amax1((1.-3.0*CB*zri(i)*zucf),f_ri_cd_min)
           pcfm(i) = zcfm2(i)
           pcfh(i) = zcfh2(i)
        ELSE
           pcfm(i) = zcdn_m(i)* fins(zri(i))
           pcfh(i) = zcdn_h(i)* fins(zri(i))
        ENDIF
! cdrah sur l'ocean cf. Miller et al. (1992)
        zcr = (0.0016/(zcdn_m(i)*SQRT(zdu2)))*ABS(ztvd-ztsolv)**(1./3.)
        IF(nsrf.EQ.is_oce) pcfh(i) =f_cdrag_oce* zcdn_h(i)*(1.0+zcr**1.25)**(1./1.25)
     ENDIF
  END DO

! ================================================================= c
     
  ! IM cf JLD : on seuille cdrag_m et cdrag_h
  IF (nsrf == is_oce) THEN
     DO i=1,knon
        pcfm(i)=MIN(pcfm(i),cdmmax)
        pcfh(i)=MIN(pcfh(i),cdhmax)
     END DO
  END IF

END SUBROUTINE cdrag