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C $Header: /u/gcmpack/MITgcm/pkg/bulk_force/bulkf_formula_aim.F,v 1.1 2006/01/22 15:50:37 jmc Exp $ |
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jmc |
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C $Name: $ |
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#include "BULK_FORCE_OPTIONS.h" |
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CBOP |
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C !ROUTINE: BULKF_FORMULA_AIM |
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C !INTERFACE: |
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SUBROUTINE BULKF_FORMULA_AIM( |
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I Tsurf, SLRD, |
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I T1, T0, Q0, Vsurf, |
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O SHF, EVAP, SLRU, |
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O dEvp, sFlx, |
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I iceornot, myThid ) |
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C !DESCRIPTION: \bv |
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C *==========================================================* |
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C | S/R BULKF_FORMULA_AIM |
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C | o compute surface flux over ocean and sea-ice, |
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C | using AIM surface flux formulation |
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C *==========================================================* |
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C *==========================================================* |
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C \ev |
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C !USES: |
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IMPLICIT NONE |
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C Resolution parameters |
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#include "EEPARAMS.h" |
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#include "SIZE.h" |
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#include "PARAMS.h" |
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#include "BULKF_PARAMS.h" |
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C !INPUT/OUTPUT PARAMETERS: |
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C == Routine Arguments == |
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C-- Input: |
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C FMASK :: fractional land-sea mask (2-dim) |
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C Tsurf :: surface temperature (2-dim) |
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C SSR :: sfc sw radiation (net flux) (2-dim) |
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C SLRD :: sfc lw radiation (downward flux)(2-dim) |
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C T1 :: near-surface air temperature (from Pot.temp) |
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C T0 :: near-surface air temperature (2-dim) |
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C Q0 :: near-surface sp. humidity [g/kg](2-dim) |
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C Vsurf :: surface wind speed [m/s] (2-dim,input) |
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C-- Output: |
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C SHF :: sensible heat flux (2-dim) |
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C EVAP :: evaporation [g/(m^2 s)] (2-dim) |
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C SLRU :: sfc lw radiation (upward flux) (2-dim) |
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C Shf0 :: sensible heat flux over freezing surf. |
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C dShf :: sensible heat flux derivative relative to surf. temp |
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C Evp0 :: evaporation computed over freezing surface (Ts=0.oC) |
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C dEvp :: evaporation derivative relative to surf. temp |
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C Slr0 :: upward long wave radiation over freezing surf. |
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C dSlr :: upward long wave rad. derivative relative to surf. temp |
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C sFlx :: net heat flux (+=down) except SW, function of surf. temp Ts: |
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C 0: Flux(Ts=0.oC) ; 1: Flux(Ts^n) ; 2: d.Flux/d.Ts(Ts^n) |
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C TSFC :: surface temperature (clim.) (2-dim) |
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C TSKIN :: skin surface temperature (2-dim) |
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C-- Input: |
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C iceornot :: 0=open water, 1=ice cover |
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C myThid :: Thread number for this instance of the routine |
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C-- |
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INTEGER NGP |
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PARAMETER ( NGP = 1 ) |
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c _RL PSA(NGP), FMASK(NGP), EMISloc |
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_RL Tsurf(NGP) |
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c _RL SSR(NGP) |
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_RL SLRD(NGP) |
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_RL T1(NGP), T0(NGP), Q0(NGP), Vsurf(NGP) |
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_RL SHF(NGP), EVAP(NGP), SLRU(NGP) |
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_RL dEvp(NGP), sFlx(NGP,0:2) |
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c _RL Shf0(NGP), dShf(NGP), Evp0(NGP), dEvp(NGP) |
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c _RL Slr0(NGP), dSlr(NGP), sFlx(NGP,0:2) |
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c _RL TSFC(NGP), TSKIN(NGP) |
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INTEGER iceornot |
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INTEGER myThid |
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CEOP |
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#ifdef ALLOW_FORMULA_AIM |
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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C FWIND0 = ratio of near-sfc wind to lowest-level wind |
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C CHS = heat exchange coefficient over sea |
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C VGUST = wind speed for sub-grid-scale gusts |
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C DTHETA = Potential temp. gradient for stability correction |
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C dTstab = potential temp. increment for stability function derivative |
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C FSTAB = Amplitude of stability correction (fraction) |
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C P0 = reference pressure [Pa=N/m2] |
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C GG = gravity accel. [m/s2] |
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C RD = gas constant for dry air [J/kg/K] |
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C CP = specific heat at constant pressure [J/kg/K] |
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C ALHC = latent heat of condensation [J/g] |
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C ALHF = latent heat of freezing [J/g] |
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C SBC = Stefan-Boltzmann constant |
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C EMISloc :: longwave surface emissivity |
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c _RL FWIND0, CHS, VGUST, DTHETA, dTstab, FSTAB |
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_RL P0, ALHC, ALHF, RD, CP, SBC, EMISloc |
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EQUIVALENCE ( ocean_emissivity , EMISloc ) |
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EQUIVALENCE ( Lvap , ALHC ) |
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EQUIVALENCE ( Lfresh , ALHF ) |
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EQUIVALENCE ( Rgas , RD ) |
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EQUIVALENCE ( cpair , CP ) |
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EQUIVALENCE ( stefan , SBC ) |
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C-- Local variables: |
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C PSA :: norm. surface pressure [p/p0] (2-dim) |
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C DENVV :: surface flux (sens,lat.) coeff. (=Rho*|V|) [kg/m2/s] |
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C CDENVV :: surf. heat flux (sens.,lat.) coeff including stability effect |
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C ALHevp :: Latent Heat of evaporation |
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_RL PSA(NGP) |
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_RL DENVV(NGP), PRD |
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_RL Shf0(NGP), dShf(NGP), Evp0(NGP) |
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_RL Slr0(NGP), dSlr(NGP) |
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_RL TSFC(NGP), TSKIN(NGP) |
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_RL CDENVV(NGP), RDTH, FSSICE |
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_RL ALHevp, Fstb0, dTstb, dFstb |
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_RL QSAT0(NGP,2) |
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_RL QDUMMY(1), RDUMMY(1), TS2 |
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INTEGER J |
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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PSA(1) = 1. _d 0 |
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P0 = 1. _d +5 |
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C--- |
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ALHevp = ALHC |
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C Evap of snow/ice: account for Latent Heat of freezing : |
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c IF ( aim_energPrecip .OR. useThSIce ) ALHevp = ALHC + ALHF |
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IF ( iceornot.GE.1 ) ALHevp = ALHC + ALHF |
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C 1.4 Density * wind speed (including gustiness factor) |
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PRD = P0/RD |
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c VG2 = VGUST*VGUST |
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c factWind2 = FWIND0*FWIND0 |
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DO J=1,NGP |
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c SPEED0(J)=SQRT(factWind2*Vsurf2(J)+VG2) |
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c DENVV(J)=(PRD*PSA(J)/T0(J))*SPEED0(J) |
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C-- assuming input file "WspeedFile" contains the time-average "SPEED0" |
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C from AIM output (aimPhytave: fields # 15 ; aimDiag: WINDS ) : |
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DENVV(J)=(PRD*PSA(J)/T0(J))*Vsurf(J) |
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ENDDO |
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C 1.5 Define effective skin temperature to compensate for |
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C non-linearity of heat/moisture fluxes during the daily cycle |
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DO J=1,NGP |
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TSKIN(J) = Tsurf(J) + celsius2K |
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TSFC(J)=273.16 _d 0 |
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ENDDO |
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C-- 2. Computation of fluxes over land and sea |
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C 2.1 Stability correction |
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RDTH = FSTAB/DTHETA |
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DO J=1,NGP |
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FSSICE=1.+MIN(DTHETA,MAX(-DTHETA,TSKIN(J)-T1(J)))*RDTH |
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CDENVV(J)=CHS*DENVV(J)*FSSICE |
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ENDDO |
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IF ( dTstab.GT.0. _d 0 ) THEN |
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C- account for stability function derivative relative to Tsurf: |
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C note: to avoid discontinuity in the derivative (because of min,max), compute |
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C the derivative using the discrete form: F(Ts+dTstab)-F(Ts-dTstab)/2.dTstab |
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DO J=1,NGP |
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Fstb0 = 1.+MIN(DTHETA,MAX(-DTHETA,TSFC(J) -T1(J)))*RDTH |
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Shf0(J) = CHS*DENVV(J)*Fstb0 |
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dTstb = ( DTHETA+dTstab-ABS(TSKIN(J)-T1(J)) )/dTstab |
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dFstb = RDTH*MIN(1. _d 0, MAX(0. _d 0, dTstb*0.5 _d 0)) |
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dShf(J) = CHS*DENVV(J)*dFstb |
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ENDDO |
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ENDIF |
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C 2.2 Evaporation |
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CALL BULKF_SH2RH_AIM( 2, NGP, TSKIN, PSA, 1. _d 0, |
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& QDUMMY, dEvp, QSAT0(1,1), myThid ) |
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CALL BULKF_SH2RH_AIM( 0, NGP, TSFC, PSA, 1. _d 0, |
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& QDUMMY, RDUMMY,QSAT0(1,2), myThid ) |
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IF ( dTstab.GT.0. _d 0 ) THEN |
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C- account for stability function derivative relative to Tsurf: |
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DO J=1,NGP |
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EVAP(J) = CDENVV(J)*(QSAT0(J,1)-Q0(J)) |
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Evp0(J) = Shf0(J)*(QSAT0(J,2)-Q0(J)) |
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dEvp(J) = CDENVV(J)*dEvp(J) |
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& + dShf(J)*(QSAT0(J,1)-Q0(J)) |
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ENDDO |
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ELSE |
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DO J=1,NGP |
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EVAP(J) = CDENVV(J)*(QSAT0(J,1)-Q0(J)) |
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Evp0(J) = CDENVV(J)*(QSAT0(J,2)-Q0(J)) |
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dEvp(J) = CDENVV(J)*dEvp(J) |
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ENDDO |
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ENDIF |
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C 2.3 Sensible heat flux |
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IF ( dTstab.GT.0. _d 0 ) THEN |
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C- account for stability function derivative relative to Tsurf: |
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DO J=1,NGP |
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SHF(J) = CDENVV(J)*CP*(TSKIN(J)-T0(J)) |
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Shf0(J) = Shf0(J)*CP*(TSFC(J) -T0(J)) |
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dShf(J) = CDENVV(J)*CP |
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& + dShf(J)*CP*(TSKIN(J)-T0(J)) |
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dShf(J) = MAX( dShf(J), 0. _d 0 ) |
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C-- do not allow negative derivative vs Ts of Sensible+Latent H.flux: |
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C a) quiet unrealistic ; |
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C b) garantee positive deriv. of total H.flux (needed for implicit solver) |
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dEvp(J) = MAX( dEvp(J), -dShf(J)/ALHevp ) |
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ENDDO |
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ELSE |
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DO J=1,NGP |
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SHF(J) = CDENVV(J)*CP*(TSKIN(J)-T0(J)) |
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Shf0(J) = CDENVV(J)*CP*(TSFC(J) -T0(J)) |
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dShf(J) = CDENVV(J)*CP |
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ENDDO |
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ENDIF |
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C 2.4 Emission of lw radiation from the surface |
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DO J=1,NGP |
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TS2 = TSFC(J)*TSFC(J) |
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Slr0(J) = SBC*TS2*TS2 |
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TS2 = TSKIN(J)*TSKIN(J) |
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SLRU(J) = SBC*TS2*TS2 |
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dSlr(J) = 4. _d 0 *SBC*TS2*TSKIN(J) |
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ENDDO |
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C-- Compute net surface heat flux and its derivative ./. surf. temp. |
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DO J=1,NGP |
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sFlx(J,0)= ( SLRD(J) - EMISloc*Slr0(J) ) |
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& - ( Shf0(J) + ALHevp*Evp0(J) ) |
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sFlx(J,1)= ( SLRD(J) - EMISloc*SLRU(J) ) |
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& - ( SHF(J) + ALHevp*EVAP(J) ) |
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sFlx(J,2)= -EMISloc*dSlr(J) |
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& - ( dShf(J) + ALHevp*dEvp(J) ) |
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ENDDO |
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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#endif /* ALLOW_FORMULA_AIM */ |
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RETURN |
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END |
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