| 1 | SUBROUTINE ch4surf(ngrid,nlayer,nq,ptimestep,tsurf,pdtsurf, |
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| 2 | & pplev,pdpsurf,pq,pdq,pqsurf,pdqsurf,pdqch4,pdqsch4) |
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| 3 | |
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| 4 | use callkeys_mod, only: dayfrac, thresh_non2 |
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| 5 | use comcstfi_mod, only: g, r |
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| 6 | use comgeomfi_h |
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| 7 | use comsaison_h, only: fract |
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| 8 | use planete_mod, only: z0 |
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| 9 | use tracer_h, only: igcm_ch4_gas,igcm_ch4_ice,igcm_n2,mmol |
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| 10 | IMPLICIT NONE |
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| 11 | |
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| 12 | c---------------- |
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| 13 | c declarations: |
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| 14 | c ------------- |
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| 15 | |
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| 16 | #include "dimensions.h" |
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| 17 | |
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| 18 | ! Routine for nogcm : sublimation/condensation scheme at the surface |
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| 19 | ! Output : tendancy for methane mixing ratio and surface reservoir : |
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| 20 | ! pdqch4, pdqs_ch4 |
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| 21 | |
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| 22 | !----------------------------------------------------------------------- |
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| 23 | ! Arguments |
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| 24 | |
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| 25 | |
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| 26 | INTEGER ngrid,nlayer,nq |
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| 27 | REAL ptimestep |
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| 28 | INTEGER ig,iq |
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| 29 | |
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| 30 | ! input : |
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| 31 | REAL tsurf(ngrid) |
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| 32 | REAL pplev(ngrid,nlayer+1) |
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| 33 | REAL pdpsurf(ngrid) |
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| 34 | REAL pq(ngrid,nlayer,nq) |
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| 35 | REAL pdq(ngrid,nlayer,nq) |
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| 36 | REAL pqsurf(ngrid,nq) |
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| 37 | REAL pdqsurf(ngrid,nq) |
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| 38 | REAL pdtsurf(ngrid) |
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| 39 | |
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| 40 | ! Output |
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| 41 | REAL pdqch4(ngrid) |
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| 42 | REAL pdqsch4(ngrid) |
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| 43 | |
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| 44 | ! local |
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| 45 | REAL qsat(ngrid) |
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| 46 | REAL zpsrf(ngrid) |
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| 47 | REAL zq_ch4(ngrid) |
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| 48 | REAL zq_n2surf(ngrid) |
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| 49 | REAL ztsurf(ngrid) |
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| 50 | REAL gamm(ngrid) ! activity coefficient |
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| 51 | REAL rho,u,v,uv,z00,cdrag,alt |
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| 52 | REAL vonk ! Von Karman Constant |
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| 53 | SAVE vonk |
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| 54 | DATA vonk/0.4/ |
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| 55 | |
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| 56 | ! Calculation of turbulent flux : F=rho*cdrag*uv*(qsat-zq) |
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| 57 | |
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| 58 | ! Calcul de cdrag |
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| 59 | alt=5. ! m |
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| 60 | !z00=1.e-2 ! rugosity |
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| 61 | z00=z0 |
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| 62 | cdrag=(vonk/log(alt/z00))**2 |
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| 63 | |
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| 64 | u=6. ! 6 |
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| 65 | v=3. ! 3 |
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| 66 | uv=sqrt(u**2+v**2) |
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| 67 | |
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| 68 | pdqsch4(:)=0. |
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| 69 | pdqch4(:)=0. |
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| 70 | |
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| 71 | !! Update CH4, pressure |
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| 72 | DO ig=1,ngrid |
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| 73 | zpsrf(ig)=pplev(ig,1) |
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| 74 | zq_ch4(ig)=pq(ig,1,igcm_ch4_gas) |
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| 75 | & + pdq(ig,1,igcm_ch4_gas)*ptimestep |
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| 76 | zq_n2surf(ig)=pqsurf(ig,igcm_n2) |
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| 77 | & + pdqsurf(ig,igcm_n2)*ptimestep |
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| 78 | ztsurf(ig)=tsurf(ig) !+pdtsurf(ig)*ptimestep |
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| 79 | ENDDO |
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| 80 | |
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| 81 | !! Get qsat for CH4 |
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| 82 | call methanesat(ngrid,ztsurf,zpsrf,qsat,zq_n2surf(:)) |
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| 83 | |
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| 84 | !! Dayfrac: Fraction of the daytime where we do not condense CH4 in N2 |
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| 85 | ! corresponds to cold layer of N2 pushing CH4 or depleting CH4 near the surface |
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| 86 | ! By default, we do not take this into account : dayfrac=0. We condense all the time |
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| 87 | ! dayfrac = 1 : we do not condense CH4 in N2 during daytime |
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| 88 | ! dayfrac = 2 : all saturated, so we never condense CH4 in N2 |
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| 89 | ! dayfrac = 0.5 : we do not condense CH4 during half of the daytime (we condense during all night + half of daytime) |
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| 90 | |
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| 91 | !! Loop |
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| 92 | DO ig=1,ngrid |
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| 93 | |
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| 94 | !! Take into account activity coefficient |
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| 95 | gamm(ig)=499.9-21.8*ztsurf(ig)+0.249*ztsurf(ig)**2 |
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| 96 | & -1.3*(zq_ch4(ig)* |
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| 97 | & mmol(igcm_n2)/mmol(igcm_ch4_gas)*100.-0.6)/0.3 |
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| 98 | gamm(ig)=max(gamm(ig),1.) |
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| 99 | qsat(ig)=qsat(ig)*gamm(ig) |
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| 100 | |
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| 101 | rho = zpsrf(ig) / (r * tsurf(ig) ) |
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| 102 | !! Condensation Flux |
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| 103 | pdqsch4(ig)=(-rho*uv*cdrag*(qsat(ig)-zq_ch4(ig))) |
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| 104 | |
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| 105 | if (dayfrac.gt.0.and.zq_n2surf(ig).gt.thresh_non2) then |
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| 106 | if (dayfrac.gt.1.) then |
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| 107 | pdqsch4(ig)=min(pdqsch4(ig),0.) |
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| 108 | else |
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| 109 | if (pdqsch4(ig).gt.0.) then ! condensation |
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| 110 | pdqsch4(ig)=pdqsch4(ig)*(1.-fract(ig)*dayfrac) |
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| 111 | endif |
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| 112 | endif |
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| 113 | endif |
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| 114 | |
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| 115 | !! Conserve mass if reservoir depleted |
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| 116 | if ((-pdqsch4(ig)*ptimestep).gt. |
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| 117 | & (pqsurf(ig,igcm_ch4_ice))) then |
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| 118 | pdqsch4(ig)=-pqsurf(ig,igcm_ch4_ice)/ptimestep |
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| 119 | endif |
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| 120 | |
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| 121 | if (pdqsch4(ig)*ptimestep.gt.zq_ch4(ig)*zpsrf(ig)/g) then |
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| 122 | pdqsch4(ig)=zq_ch4(ig)/ptimestep*zpsrf(ig)/g |
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| 123 | endif |
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| 124 | |
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| 125 | !! Security to avoid large changes in temperatures due to |
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| 126 | !latent heat |
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| 127 | if (pdqsch4(ig)*ptimestep.gt.0.25) then |
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| 128 | pdqsch4(ig)=0.25/ptimestep |
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| 129 | endif |
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| 130 | if (pdqsch4(ig)*ptimestep.lt.-0.25) then |
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| 131 | pdqsch4(ig)=-0.25/ptimestep |
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| 132 | endif |
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| 133 | |
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| 134 | !! Atm tendency |
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| 135 | pdqch4(ig)=-pdqsch4(ig)*g/zpsrf(ig) |
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| 136 | |
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| 137 | ENDDO |
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| 138 | |
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| 139 | RETURN |
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| 140 | END |
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