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| 2 | |
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| 3 | subroutine SISVAT_BSn |
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| 4 | |
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| 5 | C +------------------------------------------------------------------------+ |
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| 6 | C | MAR SISVAT_BSn 04-apr-2020 MAR | |
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| 7 | C | SubRoutine SISVAT_BSn treats Snow Erosion | |
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| 8 | C | (not deposition anymore since 2-jun 2018) | |
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| 9 | C | | |
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| 10 | C | SISVAT_bsn computes the snow erosion mass according to both the | |
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| 11 | C | theoretical maximum erosion amount computed in SISVATesbl and the | |
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| 12 | C | availability of snow (currently in the uppermost snow layer only) | |
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| 13 | C | | |
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| 14 | C | Preprocessing Option: SISVAT IO (not always a standard preprocess.) | |
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| 15 | C | ^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^ | |
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| 16 | C | FILE | CONTENT | |
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| 17 | C | ~~~~~~~~~~~~~~~~~~~~~+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
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| 18 | C | # stdout | #sb: OUTPUT of Snow Erosion | |
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| 19 | C | | unit 6, SubRoutine SISVAT_BSn **ONLY** | |
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| 20 | C +------------------------------------------------------------------------+ |
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| 21 | |
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| 22 | |
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| 23 | |
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| 24 | |
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| 25 | C +--General Variables |
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| 26 | C + ================= |
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| 27 | |
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| 28 | use VARphy |
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| 29 | use VAR_SV |
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| 30 | use VARdSV |
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| 31 | use VARxSV |
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| 32 | use VARySV |
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| 33 | |
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| 34 | |
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| 35 | IMPLICIT NONE |
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| 36 | |
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| 37 | C +--Local Variables |
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| 38 | C + =============== |
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| 39 | |
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| 40 | |
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| 41 | integer ikl ,isn |
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| 42 | real h_mmWE ! Eroded Snow Layer Min Thickness |
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| 43 | real dbsaux(knonv) ! Drift Amount (Dummy Variable) |
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| 44 | real dzweqo,dzweqn,bsno_x ! Conversion variables for erosion |
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| 45 | real dz_new,rho_new |
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| 46 | real snofOK ! Threshd Snow Fall |
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| 47 | real Fac ! Correction factor for erosion |
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| 48 | real densif ! Densification rate if erosion |
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| 49 | |
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| 50 | C +--DATA |
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| 51 | C + ==== |
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| 52 | |
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| 53 | data h_mmWE / 0.01e00 / ! Eroded Snow Layer Min Thickness |
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| 54 | |
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| 55 | C +--EROSION |
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| 56 | C + ======= |
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| 57 | |
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| 58 | !DO isn = nsno,2,-1 |
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| 59 | DO ikl = 1,knonv |
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| 60 | |
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| 61 | isn = isnoSV(ikl) |
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| 62 | dzweqo = dzsnSV(ikl,isn) *ro__SV(ikl,isn) ! [kg/m2, mm w.e.] |
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| 63 | |
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| 64 | bsno_x = min(0.,dbs_SV(ikl)) |
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| 65 | c Fac = min(1.,max(1-(ro__SV(ikl,isn)/700.),0.)**2) |
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| 66 | c Fac = min(1.,max(1-(qsnoSV(ikl)*1000/30.),0.)) |
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| 67 | c bsno_x = bsno_x*Fac |
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| 68 | |
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| 69 | dzweqn = dzweqo + bsno_x |
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| 70 | dzweqn = max(dzweqn,h_mmWE) |
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| 71 | dzweqn = min(dzweqn,dzweqo) |
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| 72 | cXF |
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| 73 | dbs_SV(ikl) = dbs_SV(ikl) +(dzweqo -dzweqn) |
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| 74 | dbs_Er(ikl) = dbs_Er(ikl) +(dzweqo -dzweqn) |
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| 75 | dzsnSV(ikl,isn) = dzweqn |
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| 76 | . /max(epsi,ro__SV(ikl,isn)) |
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| 77 | |
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| 78 | ! Densification of the uppermost snow layer if erosion: |
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| 79 | if((dzweqo-dzweqn)>0 .and. |
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| 80 | . dzsnSV(ikl,isn)>0 .and. |
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| 81 | . ro__SV(ikl,max(1,isnoSV(ikl)))<roBdSV) then |
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| 82 | |
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| 83 | !characteristic time scale for drifting snow compaction set to 24h |
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| 84 | !linear densification rate [kg/m3/s] over 24h |
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| 85 | densif = (450. - frsno) / (3600*24) |
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| 86 | |
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| 87 | !Attenuation of compaction rate from 450 to 500 kg/m3 |
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| 88 | Fac = 1-((ro__SV(ikl,max(1,isnoSV(ikl))) |
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| 89 | . -roBdSV)/(500.-roBdSV)) |
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| 90 | Fac = max(0.,min(1.,Fac)) |
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| 91 | |
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| 92 | if (ro__SV(ikl,max(1,isnoSV(ikl)))>roBdSV) then |
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| 93 | densif=densif*Fac |
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| 94 | endif |
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| 95 | |
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| 96 | rho_new = min(roBdSV,ro__SV(ikl,isn)+densif*dt__SV) |
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| 97 | dz_new = dzsnSV(ikl,isn)*ro__SV(ikl,isn)/rho_new |
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| 98 | ro__SV(ikl,isn)=rho_new |
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| 99 | dzsnSV(ikl,isn)=dz_new |
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| 100 | endif |
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| 101 | |
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| 102 | if(dzsnSV(ikl,isn)>0 .and.dzsnSV(ikl,isn)<0.0001)then |
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| 103 | dbs_SV(ikl) = dbs_SV(ikl)+ dzsnSV(ikl,isn)*ro__SV(ikl,isn) |
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| 104 | dbs_Er(ikl) = dbs_Er(ikl)+ dzsnSV(ikl,isn)*ro__SV(ikl,isn) |
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| 105 | dzsnSV(ikl,isn) = 0 |
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| 106 | ro__SV(ikl,isn) = 0 |
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| 107 | isnoSV(ikl) = max(0,isnoSV(ikl) - 1) |
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| 108 | endif |
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| 109 | |
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| 110 | END DO |
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| 111 | !END DO |
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| 112 | |
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| 113 | return |
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| 114 | END |
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