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SUBROUTINE ICECLOUD &
! Input :
& ( NP,PP,PZ,PDZ,PT,PR,PTSTEP,PPBLH,PWCLD,XW2D, &
! Output :
& SIFRC,SSIO,SSIU,W2D,RSI)
USE PARKIND1, ONLY : JPRB
USE YOMHOOK , ONLY : LHOOK, DR_HOOK
USE MODD_CST,ONLY : XCPD,XCPV,XLVTT,XLSTT,XG,XRD,XEPSILO
USE MODD_TIWMX
USE MODI_TIWMX
IMPLICIT NONE
!-----------------------------------------------------------------------
!
! Purpose:
! calculate subgridscale fraction of supersaturation with respect to ice.
! Method:
! Assume a linear distubution of relative humidity and let the variability
! of humidity be a function of model level thickness.
! (Also a function of of humidity itself in the boundary layer)
! Interface: subroutine ICECLOUD is called
! ------------ from subroutine 'rain_ice'
!
! variable type content
! ======== ==== =======
!
! INPUT arguments (arguments d'entree)
!----------------------------------------------
! PP : pressure at model level (Pa)
! PZ : model level height (m)
! PDZ : model level thickness (m)
! PT : temperature (K)
! PR : model level humidity mixing ratio (kg/kg)
! PTSTEP : timestep
! PPBLH : plantetary layer height (m) (negative value means unknown)
! PWCLD : water and / mixed phase cloud cover (negative means unknown)
! XW2D : quota between ice crystal concentration between dry and wet
! part of a gridbox
! OUTPUT arguments (arguments d'sortie)
!---------------------------------------------
! SIFRC : subgridscale fraction with supersaturation with respect to ice.
! SSIO : Super-saturation with respect to ice in the
! supersaturated fraction
! SSIU : Sub-saturation with respect to ice in the sub-saturated
! fraction
! W2D : Factor used to get consistncy between the mean value of
! the gridbox and parts of the gridbox
! RSI : Saturation mixing ratio over ice
INTEGER, INTENT(IN) :: NP
REAL, INTENT(IN) :: PP(NP)
REAL, INTENT(IN) :: PZ(NP)
REAL, INTENT(IN) :: PDZ(NP)
REAL, INTENT(IN) :: PT(NP)
REAL, INTENT(IN) :: PR(NP)
REAL, INTENT(IN) :: PTSTEP
REAL, INTENT(IN) :: PPBLH
REAL, INTENT(IN) :: PWCLD(NP)
REAL, INTENT(IN) :: XW2D
! OUTPUT arguments (arguments d'sortie)
!---------------------------------------------
REAL, INTENT(OUT) :: SIFRC(NP)
REAL, INTENT(OUT) :: SSIO(NP)
REAL, INTENT(OUT) :: SSIU(NP)
REAL, INTENT(OUT) :: W2D(NP)
REAL, INTENT(OUT) :: RSI(NP)
! Working variables:
REAL :: ZSIGMAX,ZSIGMAY,ZSIGMAZ,ZXDIST,ZYDIST,&
& ZRSW,ZRHW,ZRHIN,ZDRHDZ,ZZ,ZRHDIST,ZRHLIM, &
& ZRHDIF,ZWCLD,ZI2W,ZRHLIMICE,ZRHLIMINV,ZA,ZRHI,ZR
INTEGER :: JK
! External function
REAL :: QSATMX_TAB
REAL(KIND=JPRB) :: ZHOOK_HANDLE
IF (LHOOK) CALL DR_HOOK('ICECLOUD',0,ZHOOK_HANDLE)
ZSIGMAX=3.E-4 ! assumed rh variation in x axis direction
ZSIGMAY=ZSIGMAX ! assumed rh variation in y axis direction
ZSIGMAZ=1.6E-2 ! t5
!ZXDIST=DTHETA*110000.
ZXDIST=2500.
! gridsize in x axis (m) Avoid too low
! since the model has a tendency to become
! drier at high horizontal resolution
! due to stronger vertical velocities.
ZYDIST=ZXDIST ! gridsize in y axis (m)
DO JK = 1, NP
ZR = MAX(0.,PR(JK)*PTSTEP)
SIFRC(JK) = 0.
ZA = ZR*PP(JK)/(XEPSILO + ZR)
ZRHW = ZA/ESATW(PT(JK))
RSI(JK) = QSATMX_TAB(PP(JK),PT(JK),1.)
ZRHI = ZA/ESATI(PT(JK))
ZI2W = ESATW(PT(JK))/ESATI(PT(JK))
SSIU(JK) = MIN(ZI2W,ZRHI)
SSIO(JK) = SSIU(JK)
W2D(JK) = 1.
IF (PT(JK)>273.1 .OR. ZR<=0. .OR. ESATI(PT(JK)) >= PP(JK)*0.5) THEN
SSIU(JK) = SSIU(JK) - 1.
SSIO(JK) = SSIU(JK)
IF(PWCLD(JK)>=0.) SIFRC(JK) = PWCLD(JK)
CYCLE
ENDIF
ZRHIN = MAX(0.05, MIN(1.,ZRHW))
ZDRHDZ=ZRHIN*XG /(PT(JK)*XRD)* &
& ( XEPSILO*XLVTT/(XCPD*PT(JK)) - 1.) ! correct
! & ( ZEPSILO*XLSTT/(XCPD*PT) -1.) ! incorrect
! more exact
! assumed rh variation in the z axis (rh/m) in the pbl .
! Also possible to just use
! zdrhdz=4.2e-4_jprb ! rh/m !
ZZ=0.
IF(PPBLH < 0. )THEN ! Assume boundary layer height is not available
ZZ = MIN(1.,MAX(0.,PZ(JK)*0.001))
ELSE
IF(PZ(JK) > 35. .AND. PZ(JK) > PPBLH) ZZ = 1.
ENDIF
! 1.6e-2 rh/m means variations is of order 0.5 for a 1km dept.
! sigmaz=4e-2 ! EO 140 lev.
! Compute rh-variation is x,y,z direction as approxmately
! independent, exept for the z variation in the pbl, where rh is
! assumed to be fairly constantly increasing with height
ZRHDIST = SQRT( ZXDIST*ZSIGMAX**2 + ZYDIST*ZSIGMAY**2 + &
& (1.-ZZ)* (PDZ(JK)*ZDRHDZ)**2 + ZZ*PDZ(JK)*ZSIGMAZ**2)
! z-variation of rh in the pbl z-variation of rh outside the pbl
! Safety for very coarse vertical resolution:
IF(ZZ > 0.1) ZRHDIST = ZRHDIST/(1.+ZRHDIST)
!!!! Note ZRHDIST is with respect to water ! !!!!!!!!!!!!
ZRHLIM = MAX(0.5,MIN(0.99,1.-0.5*ZRHDIST))
IF(PWCLD(JK) < 0.)THEN
! Assume water/mixed-phase cloud cover from e.g.
! statistical cloud scheme is not available
ZRHDIF = (1. - ZRHW)/(1.0-ZRHLIM)
ZRHDIF = 1. - SQRT(MAX(0.,ZRHDIF))
ZWCLD = MIN(1.,MAX(ZRHDIF,0.0))
ELSE
ZWCLD = PWCLD(JK)
! possible to backwards compute a critical relative humity consitent with
! input cloudcover:
! IF(PWCLD < 0.99 .AND. PWCLD > 0.01) ZRHLIM= 1. - (1.-ZRHW)/(1.-PWCLD)**2
ENDIF
SIFRC(JK) = ZWCLD
! relation rhlim with respect to water to that of ice:
!ZRHLIMICE = MAX(ZRHDMIN*ZI2W,1.+ ZI2W*( ZRHLIM - 1.))
ZRHLIMICE = 1.+ ZI2W*( ZRHLIM - 1.)
IF(ZRHLIM <= 0.999)THEN
! compute a 1/(1-rhlim) constistant with lstmp(i,k):
ZRHLIMINV = 1./(1. - ZRHLIMICE)
ZRHDIF = (ZRHI - ZRHLIMICE)*ZRHLIMINV
IF(ZWCLD==0.)THEN
SIFRC(JK) = MIN(1.,0.5*MAX(0.,ZRHDIF))
ELSE
ZA = 1. - 1./ZI2W
SIFRC(JK) = MIN(1.,ZA*0.5/ (1. - ZRHLIM))
SIFRC(JK) = MIN(1.,ZWCLD + SIFRC(JK))
ENDIF
ENDIF
IF(SIFRC(JK) > 0.01) THEN
SSIU(JK) = SIFRC(JK) + ZRHLIMICE*(1.-SIFRC(JK))
SSIO(JK) = (ZRHI - (1.- SIFRC(JK))*SSIU(JK))/SIFRC(JK)
ELSE
SIFRC(JK) = 0.! to aviod mismatch with output variables
ZA = MIN(0.,ZRHI-ZRHLIMICE)
SSIU(JK) = MAX(0.,SIFRC(JK) + ZRHLIMICE*(1.-SIFRC(JK)) + 2.*ZA )
ENDIF
SSIO(JK) = MIN(ZI2W,SSIO(JK))
SSIU(JK) = MAX(0.,SSIU(JK))
! Transform from relative humidity to degree of saturation:
SSIU(JK) = SSIU(JK) - 1.
SSIO(JK) = SSIO(JK) - 1.
IF (XW2D > 1.) W2D(JK) = 1./(1. - SIFRC(JK) + XW2D*SIFRC(JK))
ENDDO
IF (LHOOK) CALL DR_HOOK('ICECLOUD',1,ZHOOK_HANDLE)
END SUBROUTINE ICECLOUD