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| 2 | |
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| 3 | SUBROUTINE SISVAT_BSn |
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| 4 | |
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| 5 | ! +------------------------------------------------------------------------+ |
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| 6 | ! | MAR SISVAT_BSn 04-apr-2020 MAR | |
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| 7 | ! | SubRoutine SISVAT_BSn treats Snow Erosion | |
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| 8 | ! | (not deposition anymore since 2-jun 2018) | |
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| 9 | ! | | |
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| 10 | ! | SISVAT_bsn computes the snow erosion mass according to both the | |
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| 11 | ! | theoretical maximum erosion amount computed in inlandsis and the | |
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| 12 | ! | availability of snow (currently in the uppermost snow layer only) | |
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| 13 | ! | | |
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| 14 | ! +------------------------------------------------------------------------+ |
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| 15 | |
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| 16 | |
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| 17 | |
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| 18 | |
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| 19 | ! +--General Variables |
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| 20 | ! + ================= |
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| 21 | |
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| 22 | USE VARphy |
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| 23 | USE VAR_SV |
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| 24 | USE VARdSV |
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| 25 | USE VARxSV |
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| 26 | USE VARySV |
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| 27 | |
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| 28 | |
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| 29 | IMPLICIT NONE |
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| 30 | |
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| 31 | ! +--Local Variables |
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| 32 | ! + =============== |
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| 33 | |
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| 34 | |
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| 35 | INTEGER :: ikl ,isn |
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| 36 | REAL :: h_mmWE ! Eroded Snow Layer Min Thickness |
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| 37 | REAL :: dbsaux(knonv) ! Drift Amount (Dummy Variable) |
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| 38 | REAL :: dzweqo,dzweqn,bsno_x ! Conversion variables for erosion |
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| 39 | REAL :: dz_new,rho_new |
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| 40 | REAL :: snofOK ! Threshd Snow Fall |
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| 41 | REAL :: Fac ! Correction factor for erosion |
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| 42 | REAL :: densif ! Densification rate if erosion |
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| 43 | |
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| 44 | ! +--DATA |
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| 45 | ! + ==== |
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| 46 | |
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| 47 | data h_mmWE / 0.01e00 / ! Eroded Snow Layer Min Thickness |
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| 48 | |
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| 49 | ! +--EROSION |
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| 50 | ! + ======= |
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| 51 | |
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| 52 | !DO isn = nsno,2,-1 |
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| 53 | DO ikl = 1,knonv |
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| 54 | |
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| 55 | isn = isnoSV(ikl) |
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| 56 | dzweqo = dzsnSV(ikl,isn) *ro__SV(ikl,isn) ! [kg/m2, mm w.e.] |
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| 57 | |
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| 58 | bsno_x = min(0.,dbs_SV(ikl)) |
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| 59 | ! Fac = min(1.,max(1-(ro__SV(ikl,isn)/700.),0.)**2) |
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| 60 | ! Fac = min(1.,max(1-(qsnoSV(ikl)*1000/30.),0.)) |
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| 61 | ! bsno_x = bsno_x*Fac |
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| 62 | |
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| 63 | dzweqn = dzweqo + bsno_x |
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| 64 | dzweqn = max(dzweqn,h_mmWE) |
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| 65 | dzweqn = min(dzweqn,dzweqo) |
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| 66 | !XF |
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| 67 | dbs_SV(ikl) = dbs_SV(ikl) +(dzweqo -dzweqn) |
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| 68 | dbs_Er(ikl) = dbs_Er(ikl) +(dzweqo -dzweqn) |
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| 69 | dzsnSV(ikl,isn) = dzweqn & |
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| 70 | /max(epsi,ro__SV(ikl,isn)) |
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| 71 | |
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| 72 | ! Densification of the uppermost snow layer if erosion: |
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| 73 | IF((dzweqo-dzweqn)>0 .AND. & |
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| 74 | dzsnSV(ikl,isn)>0 .AND. & |
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| 75 | ro__SV(ikl,max(1,isnoSV(ikl)))<roBdSV) THEN |
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| 76 | !characteristic time scale for drifting snow compaction set to 24h |
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| 77 | !linear densification rate [kg/m3/s] over 24h |
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| 78 | densif = (450. - frsno) / (3600*24) |
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| 79 | |
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| 80 | !Attenuation of compaction rate from 450 to 500 kg/m3 |
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| 81 | Fac = 1-((ro__SV(ikl,max(1,isnoSV(ikl))) & |
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| 82 | -roBdSV)/(500.-roBdSV)) |
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| 83 | Fac = max(0.,min(1.,Fac)) |
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| 84 | |
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| 85 | IF (ro__SV(ikl,max(1,isnoSV(ikl)))>roBdSV) THEN |
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| 86 | densif=densif*Fac |
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| 87 | endif |
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| 88 | |
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| 89 | rho_new = min(roBdSV,ro__SV(ikl,isn)+densif*dt__SV) |
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| 90 | dz_new = dzsnSV(ikl,isn)*ro__SV(ikl,isn)/rho_new |
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| 91 | ro__SV(ikl,isn)=rho_new |
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| 92 | dzsnSV(ikl,isn)=dz_new |
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| 93 | endif |
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| 94 | |
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| 95 | IF(dzsnSV(ikl,isn)>0 .AND.dzsnSV(ikl,isn)<0.0001)THEN |
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| 96 | dbs_SV(ikl) = dbs_SV(ikl)+ dzsnSV(ikl,isn)*ro__SV(ikl,isn) |
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| 97 | dbs_Er(ikl) = dbs_Er(ikl)+ dzsnSV(ikl,isn)*ro__SV(ikl,isn) |
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| 98 | dzsnSV(ikl,isn) = 0 |
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| 99 | ro__SV(ikl,isn) = 0 |
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| 100 | isnoSV(ikl) = max(0,isnoSV(ikl) - 1) |
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| 101 | endif |
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| 102 | |
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| 103 | END DO |
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| 104 | !END DO |
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| 105 | |
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| 106 | |
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| 107 | END SUBROUTINE SISVAT_BSn |
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