| 1 | MODULE hdo_surfex_mod |
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| 2 | |
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| 3 | IMPLICIT NONE |
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| 4 | |
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| 5 | CONTAINS |
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| 6 | |
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| 7 | subroutine hdo_surfex(ngrid,nlay,nq,ptimestep, |
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| 8 | & zt,pplay,zq,pqsurf, |
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| 9 | & old_h2o_vap,qsat,pdqsdif,dwatercap_dif, |
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| 10 | & hdoflux) |
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| 11 | |
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| 12 | use tracer_mod, only: igcm_h2o_vap, igcm_h2o_ice, |
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| 13 | & igcm_hdo_vap, igcm_hdo_ice, |
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| 14 | & qperemin |
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| 15 | use surfdat_h, only: watercaptag |
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| 16 | use geometry_mod, only: longitude_deg,latitude_deg |
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| 17 | use comcstfi_h, only: pi |
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| 18 | use write_output_mod, only: write_output |
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| 19 | |
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| 20 | implicit none |
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| 21 | c------------------------------------------------------------------ |
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| 22 | c Routine to compute the fluxes between air and surface |
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| 23 | c for HDO, based of the fluxes for H2O |
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| 24 | c L. Rossi.; M. Vals 2019 |
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| 25 | c------------------------------------------------------------------ |
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| 26 | include "callkeys.h" |
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| 27 | include "microphys.h" |
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| 28 | c------------------------------------------------------------------ |
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| 29 | c Arguments: |
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| 30 | c --------- |
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| 31 | c Inputs: |
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| 32 | INTEGER, INTENT(IN) :: ngrid,nlay |
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| 33 | INTEGER, INTENT(IN) :: nq ! nombre de traceurs |
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| 34 | |
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| 35 | REAL, INTENT(IN) :: ptimestep ! pas de temps physique (s) |
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| 36 | REAL, INTENT(IN) :: zt(ngrid,nlay) ! local value of temperature |
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| 37 | REAL, INTENT(IN) :: pplay(ngrid,nlay) ! pression au milieu des couches (Pa) |
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| 38 | REAL, INTENT(IN) :: zq(ngrid,nlay,nq) ! local value of tracers |
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| 39 | REAL, INTENT(IN) :: pqsurf(ngrid,nq) |
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| 40 | REAL, INTENT(IN) :: old_h2o_vap(ngrid) ! traceur d'eau avant |
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| 41 | !traitement de l'eau (kg/kg) |
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| 42 | REAL, INTENT(IN) :: qsat(ngrid) ! saturation mixing ratio |
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| 43 | REAL, INTENT(IN) :: dwatercap_dif(ngrid) ! trend related to permanent ice |
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| 44 | REAL, INTENT(INOUT) :: pdqsdif(ngrid,nq) ! tendance towards surface |
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| 45 | ! (kg/kg.s-1) |
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| 46 | |
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| 47 | c Output: |
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| 48 | REAL, INTENT(OUT) :: hdoflux(ngrid) ! value of vapour flux of HDO |
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| 49 | |
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| 50 | c------------------------------------------------------------------ |
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| 51 | c Local variables: |
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| 52 | |
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| 53 | REAL alpha(ngrid) ! equilibrium fractionation factor |
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| 54 | REAL alpha_c(ngrid) ! real fractionation factor |
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| 55 | REAL extrasublim ! sublimation in excess of surface ice |
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| 56 | REAL tmpratio(ngrid) ! D/H ratio in flux to surf |
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| 57 | REAL h2oflux(ngrid) ! value of vapour flux of H2O |
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| 58 | ! same sign as pdqsdif |
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| 59 | REAL*8 satu(ngrid) ! Water vapor saturation ratio over ice |
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| 60 | REAL zt1(ngrid),pplay1(ngrid) |
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| 61 | REAL Dv,Dv_hdo ! Water/HDO vapor diffusion coefficient |
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| 62 | INTEGER ig,l |
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| 63 | |
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| 64 | REAL DoH_vap(ngrid) |
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| 65 | |
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| 66 | c----------------------------------------------------------------------- |
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| 67 | c Calculation of the fluxes for HDO |
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| 68 | !! Calculation of the saturation ratio in the layer above the surface |
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| 69 | satu(1:ngrid)=old_h2o_vap(1:ngrid) / qsat(1:ngrid) |
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| 70 | !! Initialisation of the fractionation coefficient |
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| 71 | alpha(1:ngrid)=1. |
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| 72 | alpha_c(1:ngrid)=1. |
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| 73 | |
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| 74 | DO ig=1,ngrid |
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| 75 | |
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| 76 | h2oflux(ig) = pdqsdif(ig,igcm_h2o_ice) + |
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| 77 | & dwatercap_dif(ig) |
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| 78 | |
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| 79 | !! IF Sublimation |
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| 80 | if (h2oflux(ig).le.0.) then |
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| 81 | |
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| 82 | if (pqsurf(ig,igcm_h2o_ice).gt.qperemin) then |
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| 83 | pdqsdif(ig,igcm_hdo_ice) = |
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| 84 | & pdqsdif(ig,igcm_h2o_ice)* |
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| 85 | & (pqsurf(ig,igcm_hdo_ice)/ |
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| 86 | & pqsurf(ig,igcm_h2o_ice) ) |
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| 87 | else |
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| 88 | pdqsdif(ig,igcm_hdo_ice) = 0. |
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| 89 | endif |
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| 90 | |
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| 91 | pdqsdif(ig,igcm_hdo_ice)= |
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| 92 | & max(pdqsdif(ig,igcm_hdo_ice), |
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| 93 | & -pqsurf(ig,igcm_hdo_ice)/ptimestep) |
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| 94 | |
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| 95 | hdoflux(ig) = pdqsdif(ig,igcm_hdo_ice) |
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| 96 | |
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| 97 | if(watercaptag(ig)) then |
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| 98 | |
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| 99 | !if we sublimate more than qsurf |
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| 100 | if ((-h2oflux(ig)*ptimestep) |
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| 101 | & .gt.pqsurf(ig,igcm_h2o_ice)) then |
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| 102 | |
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| 103 | C dwatercap_dif is how much we sublimate in excess of |
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| 104 | C pqsurf for H2O |
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| 105 | C hdoflux(ig) is the flux of HDO from atm. to surf. |
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| 106 | c The D/H of the old ice is supposed to be 5 SMOW |
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| 107 | c We need D/H of the flux to be 5, so we need |
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| 108 | c dwatercap_dif* 5 * 2 * 155.76e-6 (=1 SMOW) |
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| 109 | hdoflux(ig)= hdoflux(ig) |
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| 110 | & +(dwatercap_dif(ig)*(2.*155.76e-6)*5.) |
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| 111 | endif |
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| 112 | endif ! watercap |
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| 113 | |
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| 114 | else ! condensation |
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| 115 | |
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| 116 | if (hdofrac) then !do we use fractionation? |
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| 117 | !! Calculation of the H2O vapor diffusion coefficient |
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| 118 | Dv = 1./3. * sqrt( 8*kbz*zt(ig,1)/(pi*mh2o/nav) ) |
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| 119 | & * kbz * zt(ig,1) / |
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| 120 | & ( pi * pplay(ig,1) * (molco2+molh2o)*(molco2+molh2o) |
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| 121 | & * sqrt(1.+mh2o/mco2) ) |
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| 122 | !! Calculation of the HDO vapor diffusion coefficient |
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| 123 | Dv_hdo = 1./3. * sqrt( 8*kbz*zt(ig,1)/(pi*mhdo/nav) ) |
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| 124 | & * kbz * zt(ig,1) / |
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| 125 | & ( pi * pplay(ig,1) * (molco2+molhdo)*(molco2+molhdo) |
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| 126 | & * sqrt(1.+mhdo/mco2) ) |
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| 127 | !! Calculation of the "equilibrium" fractionation coefficient |
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| 128 | c alpha(ig) = exp(16288./zt(ig,1)**2.-9.34e-2) |
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| 129 | alpha(ig) = exp(13525./zt(ig,1)**2.-5.59e-2) !Lamb |
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| 130 | !! Calculation of the 'real' fractionnation coefficient (effect of kinetics, see Jouzel and Merlivat, 1984) |
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| 131 | alpha_c(ig) = (alpha(ig)*satu(ig))/ |
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| 132 | & ( (alpha(ig)*(Dv/Dv_hdo)*(satu(ig)-1.)) + 1.) |
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| 133 | else |
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| 134 | alpha_c(ig) = 1. |
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| 135 | endif |
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| 136 | |
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| 137 | if (old_h2o_vap(ig).gt.qperemin) then |
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| 138 | pdqsdif(ig,igcm_hdo_ice)= |
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| 139 | & alpha_c(ig)*pdqsdif(ig,igcm_h2o_ice)* |
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| 140 | & (zq(ig,1,igcm_hdo_vap)/ |
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| 141 | & old_h2o_vap(ig)) |
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| 142 | else |
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| 143 | pdqsdif(ig,igcm_hdo_ice)= 0. |
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| 144 | endif |
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| 145 | |
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| 146 | if (hdofrac) then !do we use fractionation? |
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| 147 | pdqsdif(ig,igcm_hdo_ice)= |
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| 148 | & min( pdqsdif(ig,igcm_hdo_ice), |
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| 149 | & (zq(ig,1,igcm_hdo_vap)/ptimestep) ) |
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| 150 | endif |
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| 151 | |
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| 152 | hdoflux(ig)=pdqsdif(ig,igcm_hdo_ice) |
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| 153 | |
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| 154 | endif !sublimation |
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| 155 | |
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| 156 | ENDDO ! of DO ig=1,ngrid |
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| 157 | |
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| 158 | c CALL write_output('extrasublim', |
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| 159 | c & 'extrasublimation', |
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| 160 | c & ' ',tmpratio) |
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| 161 | c CALL write_output('alpha_c_s', |
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| 162 | c & 'alpha_c_s', |
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| 163 | c & ' ',alpha_c) |
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| 164 | |
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| 165 | return |
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| 166 | end subroutine hdo_surfex |
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| 167 | c------------------------------------------------------------------ |
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| 168 | |
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| 169 | end module hdo_surfex_mod |
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