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