source: LMDZ6/branches/cirrus/libf/phylmd/surf_landice_mod.F90 @ 5185

Last change on this file since 5185 was 4916, checked in by evignon, 8 months ago

correction formulation de l'erosion de la neige soufflee suite aux investigations de Nicolas Chiabrando,
prise en compte d'un temps d'erosion de la neige fraiche nouvellement accumulee

  • Property copyright set to
    Name of program: LMDZ
    Creation date: 1984
    Version: LMDZ5
    License: CeCILL version 2
    Holder: Laboratoire de m\'et\'eorologie dynamique, CNRS, UMR 8539
    See the license file in the root directory
  • Property svn:eol-style set to native
  • Property svn:keywords set to Author Date Id Revision
File size: 23.4 KB
Line 
1!
2MODULE surf_landice_mod
3 
4  IMPLICIT NONE
5
6CONTAINS
7!
8!****************************************************************************************
9!
10  SUBROUTINE surf_landice(itime, dtime, knon, knindex, &
11       rlon, rlat, debut, lafin, &
12       rmu0, lwdownm, albedo, pphi1, &
13       swnet, lwnet, tsurf, p1lay, &
14       cdragh, cdragm, precip_rain, precip_snow, precip_bs, temp_air, spechum, &
15       AcoefH, AcoefQ, BcoefH, BcoefQ, &
16       AcoefU, AcoefV, BcoefU, BcoefV, &
17       AcoefQBS, BcoefQBS, &
18       ps, u1, v1, gustiness, rugoro, pctsrf, &
19       snow, qsurf, qsol, qbs1, agesno, &
20       tsoil, z0m, z0h, SFRWL, alb_dir, alb_dif, evap, fluxsens, fluxlat, fluxbs, &
21       tsurf_new, dflux_s, dflux_l, &
22       alt, slope, cloudf, &
23       snowhgt, qsnow, to_ice, sissnow, &
24       alb3, runoff, &
25       flux_u1, flux_v1)
26
27    USE dimphy
28    USE geometry_mod,     ONLY : longitude,latitude
29    USE surface_data,     ONLY : type_ocean, calice, calsno, landice_opt, iflag_albcalc
30    USE fonte_neige_mod,  ONLY : fonte_neige,run_off_lic,fqcalving_global,ffonte_global,fqfonte_global,runofflic_global
31    USE cpl_mod,          ONLY : cpl_send_landice_fields
32    USE calcul_fluxs_mod
33    USE phys_local_var_mod, ONLY : zxrhoslic, zxustartlic, zxqsaltlic
34    USE phys_output_var_mod, ONLY : snow_o,zfra_o
35!FC
36    USE ioipsl_getin_p_mod, ONLY : getin_p
37    USE lmdz_blowing_snow_ini, ONLY : c_esalt_bs, zeta_bs, pbst_bs, prt_bs, rhoice_bs, rhohard_bs
38    USE lmdz_blowing_snow_ini, ONLY : rhofresh_bs, tau_eqsalt_bs, tau_dens0_bs, tau_densmin_bs
39#ifdef CPP_INLANDSIS
40    USE surf_inlandsis_mod,  ONLY : surf_inlandsis
41#endif
42
43    USE indice_sol_mod
44
45!    INCLUDE "indicesol.h"
46    INCLUDE "dimsoil.h"
47    INCLUDE "YOMCST.h"
48    INCLUDE "clesphys.h"
49
50! Input variables
51!****************************************************************************************
52    INTEGER, INTENT(IN)                           :: itime, knon
53    INTEGER, DIMENSION(klon), INTENT(in)          :: knindex
54    REAL, INTENT(in)                              :: dtime
55    REAL, DIMENSION(klon), INTENT(IN)             :: swnet ! net shortwave radiance
56    REAL, DIMENSION(klon), INTENT(IN)             :: lwnet ! net longwave radiance
57    REAL, DIMENSION(klon), INTENT(IN)             :: tsurf
58    REAL, DIMENSION(klon), INTENT(IN)             :: p1lay
59    REAL, DIMENSION(klon), INTENT(IN)             :: cdragh, cdragm
60    REAL, DIMENSION(klon), INTENT(IN)             :: precip_rain, precip_snow, precip_bs
61    REAL, DIMENSION(klon), INTENT(IN)             :: temp_air, spechum
62    REAL, DIMENSION(klon), INTENT(IN)             :: AcoefH, AcoefQ
63    REAL, DIMENSION(klon), INTENT(IN)             :: BcoefH, BcoefQ
64    REAL, DIMENSION(klon), INTENT(IN)             :: AcoefU, AcoefV, BcoefU, BcoefV
65    REAL, DIMENSION(klon), INTENT(IN)             :: AcoefQBS, BcoefQBS
66    REAL, DIMENSION(klon), INTENT(IN)             :: ps
67    REAL, DIMENSION(klon), INTENT(IN)             :: u1, v1, gustiness, qbs1
68    REAL, DIMENSION(klon), INTENT(IN)             :: rugoro
69    REAL, DIMENSION(klon,nbsrf), INTENT(IN)       :: pctsrf
70
71    LOGICAL,  INTENT(IN)                          :: debut   !true if first step
72    LOGICAL,  INTENT(IN)                          :: lafin   !true if last step
73    REAL, DIMENSION(klon), INTENT(IN)             :: rlon, rlat
74    REAL, DIMENSION(klon), INTENT(IN)             :: rmu0
75    REAL, DIMENSION(klon), INTENT(IN)             :: lwdownm !ylwdown
76    REAL, DIMENSION(klon), INTENT(IN)             :: albedo  !mean albedo
77    REAL, DIMENSION(klon), INTENT(IN)             :: pphi1   
78    REAL, DIMENSION(klon), INTENT(IN)             :: alt   !mean altitude of the grid box 
79    REAL, DIMENSION(klon), INTENT(IN)             :: slope   !mean slope in grid box 
80    REAL, DIMENSION(klon), INTENT(IN)             :: cloudf  !total cloud fraction
81
82! In/Output variables
83!****************************************************************************************
84    REAL, DIMENSION(klon), INTENT(INOUT)          :: snow, qsol
85    REAL, DIMENSION(klon), INTENT(INOUT)          :: agesno
86    REAL, DIMENSION(klon, nsoilmx), INTENT(INOUT) :: tsoil
87
88! Output variables
89!****************************************************************************************
90    REAL, DIMENSION(klon), INTENT(OUT)            :: qsurf
91    REAL, DIMENSION(klon), INTENT(OUT)            :: z0m, z0h
92!albedo SB >>>
93!    REAL, DIMENSION(klon), INTENT(OUT)            :: alb1  ! new albedo in visible SW interval
94!    REAL, DIMENSION(klon), INTENT(OUT)            :: alb2  ! new albedo in near IR interval
95    REAL, DIMENSION(6), INTENT(IN)                :: SFRWL
96    REAL, DIMENSION(klon,nsw), INTENT(OUT)        :: alb_dir,alb_dif
97!albedo SB <<<
98    REAL, DIMENSION(klon), INTENT(OUT)            :: evap, fluxsens, fluxlat
99    REAL, DIMENSION(klon), INTENT(OUT)            :: fluxbs
100    REAL, DIMENSION(klon), INTENT(OUT)            :: tsurf_new
101    REAL, DIMENSION(klon), INTENT(OUT)            :: dflux_s, dflux_l     
102    REAL, DIMENSION(klon), INTENT(OUT)            :: flux_u1, flux_v1
103
104    REAL, DIMENSION(klon), INTENT(OUT)           :: alb3
105    REAL, DIMENSION(klon), INTENT(OUT)           :: qsnow   !column water in snow [kg/m2]
106    REAL, DIMENSION(klon), INTENT(OUT)           :: snowhgt !Snow height (m)
107    REAL, DIMENSION(klon), INTENT(OUT)           :: to_ice
108    REAL, DIMENSION(klon), INTENT(OUT)           :: sissnow
109    REAL, DIMENSION(klon), INTENT(OUT)           :: runoff  !Land ice runoff
110 
111
112! Local variables
113!****************************************************************************************
114    REAL, DIMENSION(klon)    :: soilcap, soilflux
115    REAL, DIMENSION(klon)    :: cal, beta, dif_grnd
116    REAL, DIMENSION(klon)    :: zfra, alb_neig
117    REAL, DIMENSION(klon)    :: radsol
118    REAL, DIMENSION(klon)    :: u0, v0, u1_lay, v1_lay, ustar
119    INTEGER                  :: i,j,nt
120    REAL, DIMENSION(klon)    :: fqfonte,ffonte
121    REAL, DIMENSION(klon)    :: run_off_lic_frac
122    REAL, DIMENSION(klon)    :: emis_new                  !Emissivity
123    REAL, DIMENSION(klon)    :: swdown,lwdown
124    REAL, DIMENSION(klon)    :: precip_snow_adv, snow_adv !Snow Drift precip./advection (not used in inlandsis)
125    REAL, DIMENSION(klon)    :: erod                      !erosion of surface snow (flux, kg/m2/s like evap)
126    REAL, DIMENSION(klon)    :: zsl_height, wind_velo     !surface layer height, wind spd
127    REAL, DIMENSION(klon)    :: dens_air,  snow_cont_air  !air density; snow content air
128    REAL, DIMENSION(klon)    :: alb_soil                  !albedo of underlying ice
129    REAL, DIMENSION(klon)    :: pexner                    !Exner potential
130    REAL                     :: pref
131    REAL, DIMENSION(klon,nsoilmx) :: tsoil0               !modif
132    REAL                          :: dtis                ! subtimestep
133    LOGICAL                       :: debut_is, lafin_is  ! debut and lafin for inlandsis
134
135    CHARACTER (len = 20)                      :: modname = 'surf_landice'
136    CHARACTER (len = 80)                      :: abort_message
137
138
139    REAL,DIMENSION(klon) :: alb1,alb2
140    REAL,DIMENSION(klon) :: precip_totsnow, evap_totsnow
141    REAL, DIMENSION (klon,6) :: alb6
142    REAL                   :: esalt
143    REAL                   :: lambdasalt,fluxsalt, csalt, nunu, aa, bb, cc
144    REAL                   :: tau_dens, maxerosion
145    REAL, DIMENSION(klon)  :: ws1, rhod, rhos, ustart0, ustart, qsalt, hsalt
146    REAL, DIMENSION(klon)  :: fluxbs_1, fluxbs_2, bsweight_fresh
147    LOGICAL, DIMENSION(klon) :: ok_remaining_freshsnow
148
149! End definition
150!****************************************************************************************
151!FC
152!FC
153   REAL,SAVE :: alb_vis_sno_lic
154  !$OMP THREADPRIVATE(alb_vis_sno_lic)
155   REAL,SAVE :: alb_nir_sno_lic
156  !$OMP THREADPRIVATE(alb_nir_sno_lic)
157  LOGICAL, SAVE :: firstcall = .TRUE.
158  !$OMP THREADPRIVATE(firstcall)
159
160
161!FC firtscall initializations
162!******************************************************************************************
163  IF (firstcall) THEN
164  alb_vis_sno_lic=0.77
165  CALL getin_p('alb_vis_sno_lic',alb_vis_sno_lic)
166           PRINT*, 'alb_vis_sno_lic',alb_vis_sno_lic
167  alb_nir_sno_lic=0.77
168  CALL getin_p('alb_nir_sno_lic',alb_nir_sno_lic)
169           PRINT*, 'alb_nir_sno_lic',alb_nir_sno_lic
170 
171  firstcall=.false.
172  ENDIF
173!******************************************************************************************
174
175! Initialize output variables
176    alb3(:) = 999999.
177    alb2(:) = 999999.
178    alb1(:) = 999999.
179    fluxbs(:)=0. 
180    runoff(:) = 0.
181!****************************************************************************************
182! Calculate total absorbed radiance at surface
183!
184!****************************************************************************************
185    radsol(:) = 0.0
186    radsol(1:knon) = swnet(1:knon) + lwnet(1:knon)
187
188!****************************************************************************************
189
190!****************************************************************************************
191!  landice_opt = 0 : soil_model, calcul_flux, fonte_neige, ... 
192!  landice_opt = 1  : prepare and call INterace Lmdz SISvat (INLANDSIS)
193!****************************************************************************************
194
195
196    IF (landice_opt .EQ. 1) THEN
197
198!****************************************************************************************   
199! CALL to INLANDSIS interface
200!****************************************************************************************
201#ifdef CPP_INLANDSIS
202
203        debut_is=debut
204        lafin_is=.false.
205        ! Suppose zero surface speed
206        u0(:)            = 0.0
207        v0(:)            = 0.0
208
209
210        CALL calcul_flux_wind(knon, dtime, &
211         u0, v0, u1, v1, gustiness, cdragm, &
212         AcoefU, AcoefV, BcoefU, BcoefV, &
213         p1lay, temp_air, &
214         flux_u1, flux_v1)
215
216       
217       ! Set constants and compute some input for SISVAT
218       ! = 1000 hPa
219       ! and calculate incoming flux for SW and LW interval: swdown, lwdown
220       swdown(:)        = 0.0
221       lwdown(:)        = 0.0
222       snow_cont_air(:) = 0.  ! the snow content in air is not a prognostic variable of the model     
223       alb_soil(:)      = 0.4 ! before albedo(:) but here it is the ice albedo that we have to set
224       ustar(:)         = 0.
225       pref             = 100000.       
226       DO i = 1, knon
227          swdown(i)        = swnet(i)/(1-albedo(i))
228          lwdown(i)        = lwdownm(i)
229          wind_velo(i)     = u1(i)**2 + v1(i)**2
230          wind_velo(i)     = wind_velo(i)**0.5
231          pexner(i)        = (p1lay(i)/pref)**(RD/RCPD)
232          dens_air(i)      = p1lay(i)/RD/temp_air(i)  ! dry air density
233          zsl_height(i)    = pphi1(i)/RG     
234          tsoil0(i,:)      = tsoil(i,:) 
235          ustar(i)= (cdragm(i)*(wind_velo(i)**2))**0.5   
236       END DO
237       
238
239
240        dtis=dtime
241
242          IF (lafin) THEN
243            lafin_is=.true.
244          END IF
245
246          CALL surf_inlandsis(knon, rlon, rlat, knindex, itime, dtis, debut_is, lafin_is,&
247            rmu0, swdown, lwdown, albedo, pexner, ps, p1lay, precip_rain, precip_snow,   &
248            zsl_height, wind_velo, ustar, temp_air, dens_air, spechum, tsurf,&
249            rugoro, snow_cont_air, alb_soil, alt, slope, cloudf, &
250            radsol, qsol, tsoil0, snow, zfra, snowhgt, qsnow, to_ice, sissnow,agesno,   &
251            AcoefH, AcoefQ, BcoefH, BcoefQ, cdragm, cdragh, &
252            run_off_lic, fqfonte, ffonte, evap, erod, fluxsens, fluxlat,dflux_s, dflux_l, &
253            tsurf_new, alb1, alb2, alb3, alb6, &
254            emis_new, z0m, z0h, qsurf)
255
256          debut_is=.false.
257
258
259        ! Treatment of snow melting and calving
260
261        ! for consistency with standard LMDZ, add calving to run_off_lic
262        run_off_lic(:)=run_off_lic(:) + to_ice(:)
263
264        DO i = 1, knon
265           ffonte_global(knindex(i),is_lic)    = ffonte(i)
266           fqfonte_global(knindex(i),is_lic)   = fqfonte(i)! net melting= melting - refreezing
267           fqcalving_global(knindex(i),is_lic) = to_ice(i) ! flux
268           runofflic_global(knindex(i)) = run_off_lic(i)
269        ENDDO
270        ! Here, we assume that the calving term is equal to the to_ice term
271        ! (no ice accumulation)
272
273
274#else
275       abort_message='Pb de coherence: landice_opt = 1  mais CPP_INLANDSIS = .false.'
276       CALL abort_physic(modname,abort_message,1)
277#endif
278
279
280    ELSE
281
282!****************************************************************************************
283! Soil calculations
284!
285!****************************************************************************************
286
287    ! EV: use calbeta
288    CALL calbeta(dtime, is_lic, knon, snow, qsol, beta, cal, dif_grnd)
289
290
291    ! use soil model and recalculate properly cal
292    IF (soil_model) THEN
293       CALL soil(dtime, is_lic, knon, snow, tsurf, qsol, &
294        & longitude(knindex(1:knon)), latitude(knindex(1:knon)), tsoil, soilcap, soilflux)
295       cal(1:knon) = RCPD / soilcap(1:knon)
296       radsol(1:knon)  = radsol(1:knon) + soilflux(1:knon)
297    ELSE
298       cal = RCPD * calice
299       WHERE (snow > 0.0) cal = RCPD * calsno
300    ENDIF
301
302
303!****************************************************************************************
304! Calulate fluxes
305!
306!****************************************************************************************
307!    beta(:) = 1.0
308!    dif_grnd(:) = 0.0
309
310! Suppose zero surface speed
311    u0(:)=0.0
312    v0(:)=0.0
313    u1_lay(:) = u1(:) - u0(:)
314    v1_lay(:) = v1(:) - v0(:)
315
316    CALL calcul_fluxs(knon, is_lic, dtime, &
317         tsurf, p1lay, cal, beta, cdragh, cdragh, ps, &
318         precip_rain, precip_snow, snow, qsurf,  &
319         radsol, dif_grnd, temp_air, spechum, u1_lay, v1_lay, gustiness, &
320         1.,AcoefH, AcoefQ, BcoefH, BcoefQ, &
321         tsurf_new, evap, fluxlat, fluxsens, dflux_s, dflux_l)
322
323    CALL calcul_flux_wind(knon, dtime, &
324         u0, v0, u1, v1, gustiness, cdragm, &
325         AcoefU, AcoefV, BcoefU, BcoefV, &
326         p1lay, temp_air, &
327         flux_u1, flux_v1)
328
329
330!****************************************************************************************
331! Calculate albedo
332!
333!****************************************************************************************
334
335!
336!IM: plusieurs choix/tests sur l'albedo des "glaciers continentaux"
337!       alb1(1 : knon)  = 0.6 !IM cf FH/GK
338!       alb1(1 : knon)  = 0.82
339!       alb1(1 : knon)  = 0.77 !211003 Ksta0.77
340!       alb1(1 : knon)  = 0.8 !KstaTER0.8 & LMD_ARMIP5
341!IM: KstaTER0.77 & LMD_ARMIP6   
342
343! Attantion: alb1 and alb2 are not the same!
344    alb1(1:knon)  = alb_vis_sno_lic
345    alb2(1:knon)  = alb_nir_sno_lic
346
347
348!****************************************************************************************
349! Rugosity
350!
351!****************************************************************************************
352    z0m = z0m_landice
353    z0h = z0h_landice
354    !z0m = SQRT(z0m**2+rugoro**2)
355
356
357!****************************************************************************************
358! Simple blowing snow param
359!****************************************************************************************
360! we proceed in 2 steps:
361! first we erode - if possible -the accumulated snow during the time step
362! then we update the density of the underlying layer and see if we can also erode
363! this layer
364
365
366   if (ok_bs) then
367       fluxbs(:)=0.
368       do j=1,klon
369          ws1(j)=(u1(j)**2+v1(j)**2)**0.5
370          ustar(j)=(cdragm(j)*(u1(j)**2+v1(j)**2))**0.5
371          rhod(j)=p1lay(j)/RD/temp_air(j)
372          ustart0(j) =(log(2.868)-log(1.625))/0.085*sqrt(cdragm(j))
373       enddo
374
375       ! 1st step: erosion of fresh snow accumulated during the time step
376       do j=1, knon
377       if (precip_snow(j) .GT. 0.) then
378           rhos(j)=rhofresh_bs
379           ! blowing snow flux formula used in MAR
380           ustart(j)=ustart0(j)*exp(max(rhoice_bs/rhofresh_bs-rhoice_bs/rhos(j),0.))*exp(max(0.,rhos(j)-rhohard_bs))
381           ! we have multiplied by exp to prevent erosion when rhos>rhohard_bs
382           ! computation of qbs at the top of the saltation layer
383           ! default formulation from MAR model (Amory et al. 2021, Gallee et al. 2001)
384           esalt=1./(c_esalt_bs*max(1.e-6,ustar(j)))
385           hsalt(j)=0.08436*(max(1.e-6,ustar(j))**1.27)
386           qsalt(j)=(max(ustar(j)**2-ustart(j)**2,0.))/(RG*hsalt(j))*esalt
387           ! calculation of erosion (flux positive towards the surface here)
388           ! consistent with implicit resolution of turbulent mixing equation
389           ! Nemoto and Nishimura 2004 show that steady-state saltation is achieved within a time tau_eqsalt_bs of about 10s
390           ! we thus prevent snowerosion (snow particle transfer from the saltation layer to the first model level)
391           ! integrated over tau_eqsalt_bs to exceed the total mass of snow particle in the saltation layer
392           ! (rho*qsalt*hsalt)
393           ! during this first step we also lower bound the erosion to the amount of fresh snow accumulated during the time step
394           maxerosion=min(precip_snow(j),hsalt(j)*qsalt(j)*rhod(j)/tau_eqsalt_bs)
395
396           fluxbs_1(j)=rhod(j)*ws1(j)*cdragh(j)*zeta_bs*(AcoefQBS(j)-qsalt(j)) &
397                   / (1.-rhod(j)*ws1(j)*cdragh(j)*zeta_bs*BcoefQBS(j)*dtime)
398           fluxbs_1(j)=max(-maxerosion,fluxbs_1(j))
399
400           if (precip_snow(j) .gt. abs(fluxbs_1(j))) then
401               ok_remaining_freshsnow(j)=.true.
402               bsweight_fresh(j)=1.
403           else
404               ok_remaining_freshsnow(j)=.false.
405               bsweight_fresh(j)=exp(-(abs(fluxbs_1(j))-precip_snow(j))/precip_snow(j))
406           endif
407       else
408           ok_remaining_freshsnow(j)=.false.
409           fluxbs_1(j)=0.
410           bsweight_fresh(j)=0.
411       endif
412       enddo
413
414
415       ! we now compute the snow age of the overlying layer (snow surface after erosion of the fresh snow accumulated during the time step)
416       ! this is done through the routine albsno
417       CALL albsno(klon,knon,dtime,agesno(:),alb_neig(:), precip_snow(:)+fluxbs_1(:))
418
419       ! 2nd step:
420       ! computation of threshold friction velocity
421       ! which depends on surface snow density
422       do j = 1, knon
423        if (ok_remaining_freshsnow(j)) then
424           fluxbs_2(j)=0.
425        else
426           ! we start eroding the underlying layer
427           ! estimation of snow density
428           ! snow density increases with snow age and
429           ! increases even faster in case of sedimentation of blowing snow or rain
430           tau_dens=max(tau_densmin_bs, tau_dens0_bs*exp(-abs(precip_bs(j))/pbst_bs - &
431                    abs(precip_rain(j))/prt_bs)*exp(-max(tsurf(j)-RTT,0.)))
432           rhos(j)=rhofresh_bs+(rhohard_bs-rhofresh_bs)*(1.-exp(-agesno(j)*86400.0/tau_dens))
433           ! blowing snow flux formula used in MAR
434           ustart(j)=ustart0(j)*exp(max(rhoice_bs/rhofresh_bs-rhoice_bs/rhos(j),0.))*exp(max(0.,rhos(j)-rhohard_bs))
435           ! we have multiplied by exp to prevent erosion when rhos>rhohard_bs
436           ! computation of qbs at the top of the saltation layer
437           ! default formulation from MAR model (Amory et al. 2021, Gallee et al. 2001)
438           esalt=1./(c_esalt_bs*max(1.e-6,ustar(j)))
439           hsalt(j)=0.08436*(max(1.e-6,ustar(j))**1.27)
440           qsalt(j)=(max(ustar(j)**2-ustart(j)**2,0.))/(RG*hsalt(j))*esalt
441           ! calculation of erosion (flux positive towards the surface here)
442           ! consistent with implicit resolution of turbulent mixing equation
443           ! Nemoto and Nishimura 2004 show that steady-state saltation is achieved within a time tau_eqsalt_bs of about 10s
444           ! we thus prevent snowerosion (snow particle transfer from the saltation layer to the first model level)
445           ! integrated over tau_eqsalt_bs to exceed the total mass of snow particle in the saltation layer
446           ! (rho*qsalt*hsalt)
447           maxerosion=hsalt(j)*qsalt(j)*rhod(j)/tau_eqsalt_bs
448           fluxbs_2(j)=rhod(j)*ws1(j)*cdragh(j)*zeta_bs*(AcoefQBS(j)-qsalt(j)) &
449                   / (1.-rhod(j)*ws1(j)*cdragh(j)*zeta_bs*BcoefQBS(j)*dtime)
450           fluxbs_2(j)=max(-maxerosion,fluxbs_2(j))
451         endif
452       enddo
453
454
455
456
457       ! final flux and outputs       
458        do j=1, knon
459              ! total flux is the erosion of fresh snow +
460              ! a fraction of the underlying snow (if all the fresh snow has been eroded)
461              ! the calculation of the fraction is quite delicate since we do not know
462              ! how much time was needed to erode the fresh snow. We assume that this time
463              ! is dt*exp(-(abs(fluxbs1)-precipsnow)/precipsnow)=dt*bsweight_fresh
464
465              fluxbs(j)=fluxbs_1(j)+fluxbs_2(j)*(1.-bsweight_fresh(j))
466              i = knindex(j)
467              zxustartlic(i) = ustart(j)
468              zxrhoslic(i) = rhos(j)
469              zxqsaltlic(i)=qsalt(j)
470        enddo
471
472
473  else ! not ok_bs
474  ! those lines are useful to calculate the snow age
475       CALL albsno(klon,knon,dtime,agesno(:),alb_neig(:), precip_snow(:))
476
477  endif ! if ok_bs
478
479
480
481!****************************************************************************************
482! Calculate snow amount
483!   
484!****************************************************************************************
485    IF (ok_bs) THEN
486      precip_totsnow(:)=precip_snow(:)+precip_bs(:)
487      evap_totsnow(:)=evap(:)-fluxbs(:) ! flux bs is positive towards the surface (snow erosion)
488    ELSE
489      precip_totsnow(:)=precip_snow(:)
490      evap_totsnow(:)=evap(:)
491    ENDIF
492   
493 
494    CALL fonte_neige(knon, is_lic, knindex, dtime, &
495         tsurf, precip_rain, precip_totsnow,  &
496         snow, qsol, tsurf_new, evap_totsnow)
497   
498   
499    WHERE (snow(1 : knon) .LT. 0.0001) agesno(1 : knon) = 0.                                         
500    zfra(1:knon) = MAX(0.0,MIN(1.0,snow(1:knon)/(snow(1:knon)+10.0))) 
501
502
503    END IF ! landice_opt
504
505
506!****************************************************************************************
507! Send run-off on land-ice to coupler if coupled ocean.
508! run_off_lic has been calculated in fonte_neige or surf_inlandsis
509! If landice_opt>=2, corresponding call is done from surf_land_orchidee
510!****************************************************************************************
511    IF (type_ocean=='couple' .AND. landice_opt .LT. 2) THEN
512       ! Compress fraction where run_off_lic is active (here all pctsrf(is_lic))
513       run_off_lic_frac(:)=0.0
514       DO j = 1, knon
515          i = knindex(j)
516          run_off_lic_frac(j) = pctsrf(i,is_lic)
517       ENDDO
518
519       CALL cpl_send_landice_fields(itime, knon, knindex, run_off_lic, run_off_lic_frac)
520    ENDIF
521
522 ! transfer runoff rate [kg/m2/s](!) to physiq for output
523    runoff(1:knon)=run_off_lic(1:knon)/dtime
524
525       snow_o=0.
526       zfra_o = 0.
527       DO j = 1, knon
528           i = knindex(j)
529           snow_o(i) = snow(j)
530           zfra_o(i) = zfra(j)
531       ENDDO
532
533
534!albedo SB >>>
535     select case(NSW)
536     case(2)
537       alb_dir(1:knon,1)=alb1(1:knon)
538       alb_dir(1:knon,2)=alb2(1:knon)
539     case(4)
540       alb_dir(1:knon,1)=alb1(1:knon)
541       alb_dir(1:knon,2)=alb2(1:knon)
542       alb_dir(1:knon,3)=alb2(1:knon)
543       alb_dir(1:knon,4)=alb2(1:knon)
544     case(6)
545       alb_dir(1:knon,1)=alb1(1:knon)
546       alb_dir(1:knon,2)=alb1(1:knon)
547       alb_dir(1:knon,3)=alb1(1:knon)
548       alb_dir(1:knon,4)=alb2(1:knon)
549       alb_dir(1:knon,5)=alb2(1:knon)
550       alb_dir(1:knon,6)=alb2(1:knon)
551
552       IF ((landice_opt .EQ. 1) .AND. (iflag_albcalc .EQ. 2)) THEN
553       alb_dir(1:knon,1)=alb6(1:knon,1)
554       alb_dir(1:knon,2)=alb6(1:knon,2)
555       alb_dir(1:knon,3)=alb6(1:knon,3)
556       alb_dir(1:knon,4)=alb6(1:knon,4)
557       alb_dir(1:knon,5)=alb6(1:knon,5)
558       alb_dir(1:knon,6)=alb6(1:knon,6)
559       ENDIF
560
561     end select
562alb_dif=alb_dir
563!albedo SB <<<
564
565
566  END SUBROUTINE surf_landice
567!
568!****************************************************************************************
569!
570END MODULE surf_landice_mod
571
572
573
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