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C $Header: /u/gcmpack/MITgcm/pkg/land/land_stepfwd.F,v 1.3 2004/05/14 16:14:48 jmc Exp $ |
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C $Name: $ |
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|
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#include "LAND_OPTIONS.h" |
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|
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CBOP |
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C !ROUTINE: LAND_STEPFWD |
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C !INTERFACE: |
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SUBROUTINE LAND_STEPFWD( |
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I land_frc, bi, bj, myTime, myIter, myThid) |
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|
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C !DESCRIPTION: \bv |
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C *==========================================================* |
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C | S/R LAND_STEPFWD |
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C | o Land model main S/R: step forward land variables |
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C *==========================================================* |
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C \ev |
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|
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C !USES: |
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IMPLICIT NONE |
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|
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C == Global variables === |
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C-- size for MITgcm & Land package : |
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#include "LAND_SIZE.h" |
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|
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#include "EEPARAMS.h" |
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#include "LAND_PARAMS.h" |
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#include "LAND_VARS.h" |
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|
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C !INPUT/OUTPUT PARAMETERS: |
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C == Routine arguments == |
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C land_frc :: land fraction [0-1] |
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C bi,bj :: Tile index |
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C myTime :: Current time of simulation ( s ) |
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C myIter :: Current iteration number in simulation |
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C myThid :: Number of this instance of the routine |
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_RS land_frc(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy) |
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INTEGER bi, bj, myIter, myThid |
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_RL myTime |
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CEOP |
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|
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#ifdef ALLOW_LAND |
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C == Local variables == |
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C i,j,k :: loop counters |
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C kp1 :: k+1 |
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C grd_HeatCp :: Heat capacity of the ground [J/m3/K] |
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C enthalpGrdW :: enthalpy of ground water [J/m3] |
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C fieldCapac :: field capacity (of water) [m] |
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C mWater :: water content of the ground [kg/m3] |
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C groundWnp1 :: hold temporary future soil moisture [] |
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C grdWexcess :: ground water in excess [m/s] |
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C fractRunOff :: fraction of water in excess which leaves as runoff |
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C flxkup :: downward flux of water, upper interface (k-1,k) |
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C flxdwn :: downward flux of water, lower interface (k,k+1) |
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C flxEngU :: downward energy flux associated with water flux (W/m2) |
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C upper interface (k-1,k) |
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C flxEngL :: downward energy flux associated with water flux (W/m2) |
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C lower interface (k,k+1) |
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C temp_af :: ground temperature if above freezing |
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C temp_bf :: ground temperature if below freezing |
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C mPmE :: hold temporary (liquid) Precip minus Evap [kg/m2/s] |
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C enWfx :: hold temporary energy flux of Precip [W/m2] |
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C enGr1 :: ground enthalpy of level 1 [J/m2] |
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C mSnow :: mass of snow [kg/m2] |
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C dMsn :: mass of melting snow [kg/m2] |
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C snowPrec :: snow precipitation [kg/m2/s] |
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C hNewSnow :: fresh snow accumulation [m] |
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C dhSnowMx :: potential snow increase [m] |
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C dhSnow :: effective snow increase [m] |
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C mIceDt :: ground-ice growth rate (<- excess of snow) [kg/m2/s] |
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C ageFac :: snow aging factor [1] |
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_RL grd_HeatCp, enthalpGrdW |
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_RL fieldCapac, mWater |
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_RL groundWnp1, grdWexcess, fractRunOff |
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_RL flxkup(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL flxkdw(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL flxEngU(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL flxEngL, temp_af, temp_bf, mPmE, enWfx, enGr1 |
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_RL mSnow, dMsn, snowPrec |
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_RL hNewSnow, dhSnowMx, dhSnow, mIceDt, ageFac |
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INTEGER i,j,k,kp1 |
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|
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IF (land_calc_grT .AND. .NOT.land_impl_grT ) THEN |
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C-- Step forward ground temperature: |
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|
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DO k=1,land_nLev |
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kp1 = MIN(k+1,land_nLev) |
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|
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IF (k.EQ.1) THEN |
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DO j=1,sNy |
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DO i=1,sNx |
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flxkup(i,j) = land_HeatFlx(i,j,bi,bj) |
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ENDDO |
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ENDDO |
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ELSE |
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DO j=1,sNy |
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DO i=1,sNx |
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flxkup(i,j) = flxkdw(i,j) |
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ENDDO |
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ENDDO |
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ENDIF |
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|
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DO j=1,sNy |
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DO i=1,sNx |
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IF ( land_frc(i,j,bi,bj).GT.0. ) THEN |
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C- Thermal conductivity flux, lower interface (k,k+1): |
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flxkdw(i,j) = land_grdLambda* |
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& ( land_groundT(i,j,k,bi,bj) |
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& -land_groundT(i,j,kp1,bi,bj) ) |
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& *land_rec_dzC(kp1) |
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|
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C- Step forward ground enthalpy, level k : |
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land_enthalp(i,j,k,bi,bj) = land_enthalp(i,j,k,bi,bj) |
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& + land_deltaT * (flxkup(i,j)-flxkdw(i,j))/land_dzF(k) |
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|
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ENDIF |
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ENDDO |
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ENDDO |
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|
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ENDDO |
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C-- step forward ground temperature: end |
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ENDIF |
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|
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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|
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IF ( land_calc_grW .OR. land_calc_snow ) THEN |
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C-- Initialize run-off arrays. |
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DO j=1,sNy |
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DO i=1,sNx |
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land_runOff(i,j,bi,bj) = 0. _d 0 |
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land_enRnOf(i,j,bi,bj) = 0. _d 0 |
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ENDDO |
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ENDDO |
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ENDIF |
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|
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#ifdef LAND_OLD_VERSION |
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IF ( .TRUE. ) THEN |
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#else |
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IF ( land_calc_grW ) THEN |
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#endif |
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C-- need (later on) ground temp. to be consistent with updated enthalpy: |
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DO k=1,land_nLev |
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DO j=1,sNy |
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DO i=1,sNx |
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IF ( land_frc(i,j,bi,bj).GT.0. ) THEN |
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mWater = land_rhoLiqW*land_waterCap |
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& *land_groundW(i,j,k,bi,bj) |
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grd_HeatCp = land_heatCs + land_CpWater*mWater |
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temp_bf = (land_enthalp(i,j,k,bi,bj)+land_Lfreez*mWater) |
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& / grd_HeatCp |
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temp_af = land_enthalp(i,j,k,bi,bj) / grd_HeatCp |
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land_groundT(i,j,k,bi,bj) = |
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& MIN( temp_bf, MAX(temp_af, 0. _d 0) ) |
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ENDIF |
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ENDDO |
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ENDDO |
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ENDDO |
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ENDIF |
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|
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IF ( land_calc_snow ) THEN |
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C-- Step forward Snow thickness (also account for rain temperature) |
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ageFac = 1. _d 0 - land_deltaT/timeSnowAge |
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DO j=1,sNy |
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DO i=1,sNx |
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IF ( land_frc(i,j,bi,bj).GT.0. ) THEN |
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mPmE = land_Pr_m_Ev(i,j,bi,bj) |
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enWfx = land_EnWFlux(i,j,bi,bj) |
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enGr1 = land_enthalp(i,j,1,bi,bj)*land_dzF(1) |
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C- snow aging: |
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land_snowAge(i,j,bi,bj) = |
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& ( land_deltaT + land_snowAge(i,j,bi,bj)*ageFac ) |
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IF ( enWfx.LT.0. ) THEN |
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C- snow precip in excess (Snow > Evap) : |
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C => start to melt (until ground at freezing point) and then accumulate |
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snowPrec = -enWfx -MAX( enGr1/land_deltaT, 0. _d 0 ) |
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snowPrec = MAX( snowPrec*recip_Lfreez , 0. _d 0 ) |
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mPmE = mPmE - snowPrec |
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flxEngU(i,j) = enWfx + land_Lfreez*snowPrec |
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hNewSnow = land_deltaT * snowPrec / land_rhoSnow |
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C- refresh snow age: |
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land_snowAge(i,j,bi,bj) = land_snowAge(i,j,bi,bj) |
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& *EXP( -hNewSnow/hNewSnowAge ) |
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C- update snow thickness: |
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c land_hSnow(i,j,bi,bj) = land_hSnow(i,j,bi,bj) + hNewSnow |
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C glacier & ice-sheet missing: excess of snow put directly into run-off |
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dhSnowMx = MAX( 0. _d 0, |
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& land_hMaxSnow - land_hSnow(i,j,bi,bj) ) |
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dhSnow = MIN( hNewSnow, dhSnowMx ) |
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land_hSnow(i,j,bi,bj) = land_hSnow(i,j,bi,bj) + dhSnow |
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mIceDt = land_rhoSnow * (hNewSnow-dhSnow) / land_deltaT |
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land_runOff(i,j,bi,bj) = mIceDt/land_rhoLiqW |
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land_enRnOf(i,j,bi,bj) = -mIceDt*land_Lfreez |
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ELSE |
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C- rain precip (whatever Evap is) or Evap exceeds snow precip : |
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C => snow melts or sublimates |
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c snowMelt = MIN( enWfx*recip_Lfreez , |
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c & land_hSnow(i,j,bi,bj)*land_rhoSnow/land_deltaT ) |
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mSnow = land_hSnow(i,j,bi,bj)*land_rhoSnow |
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dMsn = enWfx*recip_Lfreez*land_deltaT |
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IF ( dMsn .GE. mSnow ) THEN |
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dMsn = mSnow |
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land_hSnow(i,j,bi,bj) = 0. _d 0 |
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flxEngU(i,j) = enWfx - land_Lfreez*mSnow/land_deltaT |
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ELSE |
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flxEngU(i,j) = 0. _d 0 |
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land_hSnow(i,j,bi,bj) = land_hSnow(i,j,bi,bj) |
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& - dMsn / land_rhoSnow |
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ENDIF |
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c IF (mPmE.GT.0.) land_snowAge(i,j,bi,bj) = timeSnowAge |
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mPmE = mPmE + dMsn/land_deltaT |
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ENDIF |
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flxkup(i,j) = mPmE/land_rhoLiqW |
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c land_Pr_m_Ev(i,j,bi,bj) = mPmE |
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IF ( land_hSnow(i,j,bi,bj).LE. 0. _d 0 ) |
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& land_snowAge(i,j,bi,bj) = 0. _d 0 |
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C- avoid negative (but very small, < 1.e-34) hSnow that occurs because |
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C of truncation error. Might need to rewrite this part. |
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c IF ( land_hSnow(i,j,bi,bj).LE. 0. _d 0 ) THEN |
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c land_hSnow(i,j,bi,bj) = 0. _d 0 |
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c land_snowAge(i,j,bi,bj) = 0. _d 0 |
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c ENDIF |
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ENDIF |
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ENDDO |
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ENDDO |
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ELSE |
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DO j=1,sNy |
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DO i=1,sNx |
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flxkup(i,j) = land_Pr_m_Ev(i,j,bi,bj)/land_rhoLiqW |
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flxEngU(i,j) = 0. _d 0 |
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ENDDO |
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ENDDO |
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ENDIF |
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|
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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|
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IF (land_calc_grW) THEN |
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C-- Step forward ground Water: |
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|
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DO k=1,land_nLev |
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IF (k.EQ.land_nLev) THEN |
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kp1 = k |
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fractRunOff = 1. _d 0 |
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ELSE |
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kp1 = k+1 |
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fractRunOff = land_fractRunOff |
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ENDIF |
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fieldCapac = land_waterCap*land_dzF(k) |
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|
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DO j=1,sNy |
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DO i=1,sNx |
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IF ( land_frc(i,j,bi,bj).GT.0. ) THEN |
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|
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#ifdef LAND_OLD_VERSION |
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IF ( .TRUE. ) THEN |
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IF ( k.EQ.land_nLev ) THEN |
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#else |
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IF ( land_groundT(i,j,k,bi,bj).LT.0. _d 0 ) THEN |
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C- Frozen level: only account for upper level fluxes |
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IF ( flxkup(i,j) .LT. 0. _d 0 ) THEN |
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C- Step forward soil moisture (& enthapy), level k : |
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land_groundW(i,j,k,bi,bj) = land_groundW(i,j,k,bi,bj) |
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& + land_deltaT * flxkup(i,j) / fieldCapac |
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IF ( land_calc_snow ) |
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& land_enthalp(i,j,k,bi,bj) = land_enthalp(i,j,k,bi,bj) |
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& + land_deltaT * flxEngU(i,j) / land_dzF(k) |
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ELSE |
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C- Frozen level: incoming water flux goes directly into run-off |
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land_runOff(i,j,bi,bj) = land_runOff(i,j,bi,bj) |
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& + flxkup(i,j) |
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land_enRnOf(i,j,bi,bj) = land_enRnOf(i,j,bi,bj) |
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& + flxEngU(i,j) |
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ENDIF |
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C- prepare fluxes for next level: |
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flxkup(i,j) = 0. _d 0 |
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flxEngU(i,j) = 0. _d 0 |
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|
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ELSE |
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|
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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C- Diffusion flux of water, lower interface (k,k+1): |
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IF ( k.EQ.land_nLev .OR. |
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& land_groundT(i,j,kp1,bi,bj).LT.0. _d 0 ) THEN |
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#endif /* LAND_OLD_VERSION */ |
| 284 |
C- no Diffusion of water if one level is frozen : |
| 285 |
flxkdw(i,j) = 0. _d 0 |
| 286 |
flxEngL = 0. _d 0 |
| 287 |
ELSE |
| 288 |
flxkdw(i,j) = fieldCapac* |
| 289 |
& ( land_groundW(i,j,k,bi,bj) |
| 290 |
& -land_groundW(i,j,kp1,bi,bj) ) |
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& / land_wTauDiff |
| 292 |
C- energy flux associated with water flux: take upwind Temp |
| 293 |
IF ( flxkdw(i,j).GE.0. ) THEN |
| 294 |
flxEngL = flxkdw(i,j)*land_rhoLiqW*land_CpWater |
| 295 |
& *land_groundT(i,j,k,bi,bj) |
| 296 |
ELSE |
| 297 |
flxEngL = flxkdw(i,j)*land_rhoLiqW*land_CpWater |
| 298 |
& *land_groundT(i,j,kp1,bi,bj) |
| 299 |
ENDIF |
| 300 |
ENDIF |
| 301 |
|
| 302 |
C- Step forward soil moisture, level k : |
| 303 |
groundWnp1 = land_groundW(i,j,k,bi,bj) |
| 304 |
& + land_deltaT * (flxkup(i,j)-flxkdw(i,j)) / fieldCapac |
| 305 |
|
| 306 |
C- Water in excess will leave as run-off or go to level below |
| 307 |
land_groundW(i,j,k,bi,bj) = MIN(1. _d 0, groundWnp1) |
| 308 |
grdWexcess = ( groundWnp1 - MIN(1. _d 0, groundWnp1) ) |
| 309 |
& *fieldCapac/land_deltaT |
| 310 |
|
| 311 |
C- Run off: fraction 1-fractRunOff enters level below |
| 312 |
land_runOff(i,j,bi,bj) = land_runOff(i,j,bi,bj) |
| 313 |
& + fractRunOff*grdWexcess |
| 314 |
C- prepare fluxes for next level: |
| 315 |
flxkup(i,j) = flxkdw(i,j) |
| 316 |
& + (1. _d 0-fractRunOff)*grdWexcess |
| 317 |
|
| 318 |
IF ( land_calc_snow ) THEN |
| 319 |
enthalpGrdW = land_rhoLiqW*land_CpWater |
| 320 |
& *land_groundT(i,j,k,bi,bj) |
| 321 |
C-- Account for water fluxes in energy budget: update ground Enthalpy |
| 322 |
land_enthalp(i,j,k,bi,bj) = land_enthalp(i,j,k,bi,bj) |
| 323 |
& + ( flxEngU(i,j) - flxEngL - grdWexcess*enthalpGrdW |
| 324 |
& )*land_deltaT/land_dzF(k) |
| 325 |
|
| 326 |
land_enRnOf(i,j,bi,bj) = land_enRnOf(i,j,bi,bj) |
| 327 |
& + fractRunOff*grdWexcess*enthalpGrdW |
| 328 |
C- prepare fluxes for next level: |
| 329 |
flxEngU(i,j) = flxEngL |
| 330 |
& + (1. _d 0-fractRunOff)*grdWexcess*enthalpGrdW |
| 331 |
ENDIF |
| 332 |
ENDIF |
| 333 |
C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
| 334 |
|
| 335 |
ENDIF |
| 336 |
ENDDO |
| 337 |
ENDDO |
| 338 |
|
| 339 |
ENDDO |
| 340 |
C-- step forward ground Water: end |
| 341 |
ENDIF |
| 342 |
|
| 343 |
C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
| 344 |
|
| 345 |
IF ( land_calc_grT ) THEN |
| 346 |
C-- Compute ground temperature from enthalpy (if not already done): |
| 347 |
|
| 348 |
DO k=1,land_nLev |
| 349 |
DO j=1,sNy |
| 350 |
DO i=1,sNx |
| 351 |
C- Ground Heat capacity, layer k: |
| 352 |
mWater = land_rhoLiqW*land_waterCap |
| 353 |
& *land_groundW(i,j,k,bi,bj) |
| 354 |
grd_HeatCp = land_heatCs + land_CpWater*mWater |
| 355 |
C temperature below freezing: |
| 356 |
temp_bf = (land_enthalp(i,j,k,bi,bj)+land_Lfreez*mWater) |
| 357 |
& / grd_HeatCp |
| 358 |
C temperature above freezing: |
| 359 |
temp_af = land_enthalp(i,j,k,bi,bj) / grd_HeatCp |
| 360 |
#ifdef LAND_OLD_VERSION |
| 361 |
land_enthalp(i,j,k,bi,bj) = |
| 362 |
& grd_HeatCp*land_groundT(i,j,k,bi,bj) |
| 363 |
#else |
| 364 |
land_groundT(i,j,k,bi,bj) = |
| 365 |
& MIN( temp_bf, MAX(temp_af, 0. _d 0) ) |
| 366 |
#endif |
| 367 |
ENDDO |
| 368 |
ENDDO |
| 369 |
ENDDO |
| 370 |
|
| 371 |
IF ( land_impl_grT ) THEN |
| 372 |
DO j=1,sNy |
| 373 |
DO i=1,sNx |
| 374 |
IF ( land_hSnow(i,j,bi,bj).GT.0. _d 0 ) THEN |
| 375 |
land_skinT(i,j,bi,bj) = MIN(land_skinT(i,j,bi,bj), 0. _d 0) |
| 376 |
ELSE |
| 377 |
land_skinT(i,j,bi,bj) = land_groundT(i,j,1,bi,bj) |
| 378 |
ENDIF |
| 379 |
ENDDO |
| 380 |
ENDDO |
| 381 |
ELSE |
| 382 |
DO j=1,sNy |
| 383 |
DO i=1,sNx |
| 384 |
land_skinT(i,j,bi,bj) = land_groundT(i,j,1,bi,bj) |
| 385 |
ENDDO |
| 386 |
ENDDO |
| 387 |
ENDIF |
| 388 |
|
| 389 |
C-- Compute ground temperature: end |
| 390 |
ENDIF |
| 391 |
|
| 392 |
#endif /* ALLOW_LAND */ |
| 393 |
|
| 394 |
RETURN |
| 395 |
END |
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