| 1 | SUBROUTINE co2snow (ngrid,nlayer,ptimestep, |
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| 2 | & emisref,condsub,pplev, |
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| 3 | & pcondicea,pcondices,pfallice,pemisurf) |
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| 4 | |
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| 5 | IMPLICIT NONE |
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| 6 | |
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| 7 | |
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| 8 | c*****WRF: ligne trop longue |
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| 9 | |
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| 10 | c======================================================================= |
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| 11 | c Program for simulate the impact of the CO2 snow fall on |
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| 12 | c the surface infrared emission (emissivity) and on |
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| 13 | c the airborne dust |
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| 14 | c F.Forget 1996 |
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| 15 | c======================================================================= |
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| 16 | |
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| 17 | c Declarations |
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| 18 | c ------------ |
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| 19 | |
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| 20 | #include "dimensions.h" |
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| 21 | #include "dimphys.h" |
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| 22 | #include "comcstfi.h" |
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| 23 | #include "surfdat.h" |
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| 24 | #include "callkeys.h" |
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| 25 | |
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| 26 | c input |
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| 27 | c ----- |
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| 28 | |
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| 29 | INTEGER ngrid,nlayer |
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| 30 | REAL ptimestep , emisref(ngrid) ! grd or ice emissivity without snow |
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| 31 | logical condsub(ngrid) |
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| 32 | |
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| 33 | REAL pplev(ngrid,nlayer+1) |
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| 34 | REAL pcondicea(ngrid,nlayer), pcondices(ngrid) |
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| 35 | REAL pfallice(ngrid,nlayer+1) |
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| 36 | |
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| 37 | c output |
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| 38 | c ------ |
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| 39 | |
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| 40 | REAL pemisurf(ngrid) |
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| 41 | |
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| 42 | c local |
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| 43 | c ----- |
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| 44 | integer ig , l , icap |
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| 45 | |
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| 46 | REAL zdemisurf ,dtemis |
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| 47 | REAL sumdaer |
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| 48 | |
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| 49 | c saved |
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| 50 | c ----- |
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| 51 | REAL Kscat(2), scaveng |
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| 52 | LOGICAL firstcall |
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| 53 | SAVE firstcall |
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| 54 | save Kscat , scaveng |
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| 55 | DATA firstcall/.true./ |
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| 56 | |
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| 57 | c -------------- |
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| 58 | c Initialisation |
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| 59 | c -------------- |
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| 60 | |
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| 61 | if (firstcall) then |
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| 62 | |
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| 63 | c Kscat : coefficient for decreasing the surface emissivity |
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| 64 | c =(0.001/3.)*alpha/iceradius , |
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| 65 | c with 0.3< alpha < 0.6, set to 0.45 (coeff from emis = f (tau)) |
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| 66 | c and iceradius the mean radius of the |
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| 67 | c scaterring particles (200.e-6<iceradius<10.e-6) |
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| 68 | |
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| 69 | Kscat(1)=(0.001/3.)*0.45/iceradius(1) |
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| 70 | Kscat(2)=(0.001/3.)*0.45/iceradius(2) |
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| 71 | |
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| 72 | c Scavenging Ratio (dust concentration in the air / in the snow) |
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| 73 | scaveng = 100.0 |
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| 74 | |
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| 75 | c Collision Scavenging coefficient (m2.kg-1) |
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| 76 | c Csca = 2.3 ! not used yet !!!!!!!!!!! |
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| 77 | firstcall = .false. |
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| 78 | |
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| 79 | end if |
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| 80 | |
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| 81 | |
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| 82 | c LOOP on grid points |
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| 83 | c ------------------- |
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| 84 | do ig=1,ngrid |
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| 85 | if (condsub(ig)) then |
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| 86 | |
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| 87 | c IF (scavenging) then |
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| 88 | c Airborne Dust |
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| 89 | c ------------- |
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| 90 | c sumdaer=0. |
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| 91 | c do l=nlayer, 1, -1 |
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| 92 | c pdaerosol(ig,l)= -paerosol(ig,l,1)* |
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| 93 | c & (1-exp(-scaveng*pcondicea(ig,l)*ptimestep*g/ |
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| 94 | c & (pplev(ig,l)-pplev(ig,l+1))))/ptimestep |
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| 95 | |
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| 96 | c & - Csca*paerosol(ig,l,1) ! Scavenging by collision |
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| 97 | c & * 0.5*(pfallice(ig,l)) ! not included |
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| 98 | |
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| 99 | c test to avoid releasing to much dust when subliming: |
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| 100 | c if(pdaerosol(ig,l).gt.-sumdaer)pdaerosol(ig,l)=-sumdaer |
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| 101 | c sumdaer=sumdaer + pdaerosol(ig,l) |
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| 102 | |
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| 103 | c if (-pdaerosol(ig,l)*ptimestep.gt.paerosol(ig,l,1)) then |
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| 104 | c write(*,*) 'ds co2snow: aerosol < 0.0 !!!' |
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| 105 | c write(*,*) 'ig =' , ig |
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| 106 | c end if |
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| 107 | c end do |
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| 108 | c END IF |
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| 109 | |
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| 110 | c Surface emissivity |
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| 111 | c ------------------ |
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| 112 | c dtemis: Time scale for increasing the ice emissivity |
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| 113 | |
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| 114 | IF(ig.GT.ngrid/2+1) THEN |
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| 115 | icap=2 |
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| 116 | ELSE |
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| 117 | icap=1 |
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| 118 | ENDIF |
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| 119 | |
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| 120 | zdemisurf = |
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| 121 | & (emisref(ig)-pemisurf(ig))/(dtemisice(icap)*daysec) |
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| 122 | c Using directly the diferential equation: |
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| 123 | c & -Kscat(icap)*emisref(ig)* |
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| 124 | c & (pemisurf(ig)/emisref(ig))**4 *pfallice(ig,1) |
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| 125 | c Using an integrated form for numerical safety instead |
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| 126 | & +(emisref(ig)* ((pemisurf(ig)/emisref(ig))**(-3)+3.*Kscat(icap)* |
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| 127 | & pfallice(ig,1)*ptimestep)**(-1/3.) -pemisurf(ig))/ptimestep |
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| 128 | |
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| 129 | |
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| 130 | pemisurf(ig) = pemisurf(ig) + zdemisurf*ptimestep |
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| 131 | |
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| 132 | if (pemisurf(ig).lt.0.1) then |
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| 133 | write(*,*) 'ds co2snow: emis < 0.1 !!!' |
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| 134 | write(*,*) 'ig =' , ig |
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| 135 | write(*,*)'pemisurf(ig)',pemisurf(ig) |
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| 136 | write(*,*) 'zdemisurf*ptimestep',zdemisurf*ptimestep |
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| 137 | end if |
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| 138 | else |
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| 139 | pemisurf(ig) = emisref(ig) |
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| 140 | end if |
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| 141 | end do |
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| 142 | |
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| 143 | return |
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| 144 | end |
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