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surf_landice_mod.F90 @ 5020

Last change on this file since 5020 was 4947, checked in by evignon, 6 months ago
ajout de la parameterisation de rugosite de la neige sur les calottes de Amory et al. 2017
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: 24.3 KB

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1	!
2	MODULE surf_landice_mod
3
4	IMPLICIT NONE
5
6	CONTAINS
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	REAL :: ta1, ta2, ta3, z01, z02, z03, coefa, coefb, coefc, coefd
149
150
151	! End definition
152	!****************************************************************************************
153	!FC
154	!FC
155	REAL,SAVE :: alb_vis_sno_lic
156	!$OMP THREADPRIVATE(alb_vis_sno_lic)
157	REAL,SAVE :: alb_nir_sno_lic
158	!$OMP THREADPRIVATE(alb_nir_sno_lic)
159	LOGICAL, SAVE :: firstcall = .TRUE.
160	!$OMP THREADPRIVATE(firstcall)
161
162
163	!FC firtscall initializations
164	!******************************************************************************************
165	IF (firstcall) THEN
166	alb_vis_sno_lic=0.77
167	CALL getin_p('alb_vis_sno_lic',alb_vis_sno_lic)
168	PRINT*, 'alb_vis_sno_lic',alb_vis_sno_lic
169	alb_nir_sno_lic=0.77
170	CALL getin_p('alb_nir_sno_lic',alb_nir_sno_lic)
171	PRINT*, 'alb_nir_sno_lic',alb_nir_sno_lic
172
173	firstcall=.false.
174	ENDIF
175	!******************************************************************************************
176
177	! Initialize output variables
178	alb3(:) = 999999.
179	alb2(:) = 999999.
180	alb1(:) = 999999.
181	fluxbs(:)=0.
182	runoff(:) = 0.
183	!****************************************************************************************
184	! Calculate total absorbed radiance at surface
185	!
186	!****************************************************************************************
187	radsol(:) = 0.0
188	radsol(1:knon) = swnet(1:knon) + lwnet(1:knon)
189
190	!****************************************************************************************
191
192	!****************************************************************************************
193	! landice_opt = 0 : soil_model, calcul_flux, fonte_neige, ...
194	! landice_opt = 1 : prepare and call INterace Lmdz SISvat (INLANDSIS)
195	!****************************************************************************************
196
197
198	IF (landice_opt .EQ. 1) THEN
199
200	!****************************************************************************************
201	! CALL to INLANDSIS interface
202	!****************************************************************************************
203	#ifdef CPP_INLANDSIS
204
205	debut_is=debut
206	lafin_is=.false.
207	! Suppose zero surface speed
208	u0(:) = 0.0
209	v0(:) = 0.0
210
211
212	CALL calcul_flux_wind(knon, dtime, &
213	u0, v0, u1, v1, gustiness, cdragm, &
214	AcoefU, AcoefV, BcoefU, BcoefV, &
215	p1lay, temp_air, &
216	flux_u1, flux_v1)
217
218
219	! Set constants and compute some input for SISVAT
220	! = 1000 hPa
221	! and calculate incoming flux for SW and LW interval: swdown, lwdown
222	swdown(:) = 0.0
223	lwdown(:) = 0.0
224	snow_cont_air(:) = 0. ! the snow content in air is not a prognostic variable of the model
225	alb_soil(:) = 0.4 ! before albedo(:) but here it is the ice albedo that we have to set
226	ustar(:) = 0.
227	pref = 100000.
228	DO i = 1, knon
229	swdown(i) = swnet(i)/(1-albedo(i))
230	lwdown(i) = lwdownm(i)
231	wind_velo(i) = u1(i)2 + v1(i)2
232	wind_velo(i) = wind_velo(i)**0.5
233	pexner(i) = (p1lay(i)/pref)**(RD/RCPD)
234	dens_air(i) = p1lay(i)/RD/temp_air(i) ! dry air density
235	zsl_height(i) = pphi1(i)/RG
236	tsoil0(i,:) = tsoil(i,:)
237	ustar(i)= (cdragm(i)(wind_velo(i)2))*0.5
238	END DO
239
240
241
242	dtis=dtime
243
244	IF (lafin) THEN
245	lafin_is=.true.
246	END IF
247
248	CALL surf_inlandsis(knon, rlon, rlat, knindex, itime, dtis, debut_is, lafin_is,&
249	rmu0, swdown, lwdown, albedo, pexner, ps, p1lay, precip_rain, precip_snow, &
250	zsl_height, wind_velo, ustar, temp_air, dens_air, spechum, tsurf,&
251	rugoro, snow_cont_air, alb_soil, alt, slope, cloudf, &
252	radsol, qsol, tsoil0, snow, zfra, snowhgt, qsnow, to_ice, sissnow,agesno, &
253	AcoefH, AcoefQ, BcoefH, BcoefQ, cdragm, cdragh, &
254	run_off_lic, fqfonte, ffonte, evap, erod, fluxsens, fluxlat,dflux_s, dflux_l, &
255	tsurf_new, alb1, alb2, alb3, alb6, &
256	emis_new, z0m, z0h, qsurf)
257
258	debut_is=.false.
259
260
261	! Treatment of snow melting and calving
262
263	! for consistency with standard LMDZ, add calving to run_off_lic
264	run_off_lic(:)=run_off_lic(:) + to_ice(:)
265
266	DO i = 1, knon
267	ffonte_global(knindex(i),is_lic) = ffonte(i)
268	fqfonte_global(knindex(i),is_lic) = fqfonte(i)! net melting= melting - refreezing
269	fqcalving_global(knindex(i),is_lic) = to_ice(i) ! flux
270	runofflic_global(knindex(i)) = run_off_lic(i)
271	ENDDO
272	! Here, we assume that the calving term is equal to the to_ice term
273	! (no ice accumulation)
274
275
276	#else
277	abort_message='Pb de coherence: landice_opt = 1 mais CPP_INLANDSIS = .false.'
278	CALL abort_physic(modname,abort_message,1)
279	#endif
280
281
282	ELSE
283
284	!****************************************************************************************
285	! Soil calculations
286	!
287	!****************************************************************************************
288
289	! EV: use calbeta
290	CALL calbeta(dtime, is_lic, knon, snow, qsol, beta, cal, dif_grnd)
291
292
293	! use soil model and recalculate properly cal
294	IF (soil_model) THEN
295	CALL soil(dtime, is_lic, knon, snow, tsurf, qsol, &
296	& longitude(knindex(1:knon)), latitude(knindex(1:knon)), tsoil, soilcap, soilflux)
297	cal(1:knon) = RCPD / soilcap(1:knon)
298	radsol(1:knon) = radsol(1:knon) + soilflux(1:knon)
299	ELSE
300	cal = RCPD * calice
301	WHERE (snow > 0.0) cal = RCPD * calsno
302	ENDIF
303
304
305	!****************************************************************************************
306	! Calulate fluxes
307	!
308	!****************************************************************************************
309	! beta(:) = 1.0
310	! dif_grnd(:) = 0.0
311
312	! Suppose zero surface speed
313	u0(:)=0.0
314	v0(:)=0.0
315	u1_lay(:) = u1(:) - u0(:)
316	v1_lay(:) = v1(:) - v0(:)
317
318	CALL calcul_fluxs(knon, is_lic, dtime, &
319	tsurf, p1lay, cal, beta, cdragh, cdragh, ps, &
320	precip_rain, precip_snow, snow, qsurf, &
321	radsol, dif_grnd, temp_air, spechum, u1_lay, v1_lay, gustiness, &
322	1.,AcoefH, AcoefQ, BcoefH, BcoefQ, &
323	tsurf_new, evap, fluxlat, fluxsens, dflux_s, dflux_l)
324
325	CALL calcul_flux_wind(knon, dtime, &
326	u0, v0, u1, v1, gustiness, cdragm, &
327	AcoefU, AcoefV, BcoefU, BcoefV, &
328	p1lay, temp_air, &
329	flux_u1, flux_v1)
330
331
332	!****************************************************************************************
333	! Calculate albedo
334	!
335	!****************************************************************************************
336
337	!
338	!IM: plusieurs choix/tests sur l'albedo des "glaciers continentaux"
339	! alb1(1 : knon) = 0.6 !IM cf FH/GK
340	! alb1(1 : knon) = 0.82
341	! alb1(1 : knon) = 0.77 !211003 Ksta0.77
342	! alb1(1 : knon) = 0.8 !KstaTER0.8 & LMD_ARMIP5
343	!IM: KstaTER0.77 & LMD_ARMIP6
344
345	! Attantion: alb1 and alb2 are not the same!
346	alb1(1:knon) = alb_vis_sno_lic
347	alb2(1:knon) = alb_nir_sno_lic
348
349
350	!****************************************************************************************
351	! Rugosity
352	!
353	!****************************************************************************************
354
355	if (z0m_landice .GT. 0.) then
356	z0m(1:knon) = z0m_landice
357	z0h(1:knon) = z0h_landice
358	else
359	! parameterization of z0=f(T) following measurements in Adelie Land by Amory et al 2018
360	coefa = 0.1658 !0.1862 !Ant
361	coefb = -50.3869 !-55.7718 !Ant
362	ta1 = 253.15 !255. Ant
363	ta2 = 273.15
364	ta3 = 273.15+3
365	z01 = exp(coefa*ta1 + coefb) !~0.2 ! ~0.25 mm
366	z02 = exp(coefa*ta2 + coefb) !~6 !~7 mm
367	z03 = z01
368	coefc = log(z03/z02)/(ta3-ta2)
369	coefd = log(z03)-coefc*ta3
370	do j=1,knon
371	if (temp_air(j) .lt. ta1) then
372	z0m(j) = z01
373	else if (temp_air(j).ge.ta1 .and. temp_air(j).lt.ta2) then
374	z0m(j) = exp(coefa*temp_air(j) + coefb)
375	else if (temp_air(j).ge.ta2 .and. temp_air(j).lt.ta3) then
376	! if st > 0, melting induce smooth surface
377	z0m(j) = exp(coefc*temp_air(j) + coefd)
378	else
379	z0m(j) = z03
380	endif
381	z0h(j)=z0m(j)
382	enddo
383
384	endif
385
386
387	!****************************************************************************************
388	! Simple blowing snow param
389	!****************************************************************************************
390	! we proceed in 2 steps:
391	! first we erode - if possible -the accumulated snow during the time step
392	! then we update the density of the underlying layer and see if we can also erode
393	! this layer
394
395
396	if (ok_bs) then
397	fluxbs(:)=0.
398	do j=1,knon
399	ws1(j)=(u1(j)2+v1(j)2)**0.5
400	ustar(j)=(cdragm(j)(u1(j)2+v1(j)2))*0.5
401	rhod(j)=p1lay(j)/RD/temp_air(j)
402	ustart0(j) =(log(2.868)-log(1.625))/0.085*sqrt(cdragm(j))
403	enddo
404
405	! 1st step: erosion of fresh snow accumulated during the time step
406	do j=1, knon
407	if (precip_snow(j) .GT. 0.) then
408	rhos(j)=rhofresh_bs
409	! blowing snow flux formula used in MAR
410	ustart(j)=ustart0(j)exp(max(rhoice_bs/rhofresh_bs-rhoice_bs/rhos(j),0.))exp(max(0.,rhos(j)-rhohard_bs))
411	! we have multiplied by exp to prevent erosion when rhos>rhohard_bs
412	! computation of qbs at the top of the saltation layer
413	! default formulation from MAR model (Amory et al. 2021, Gallee et al. 2001)
414	esalt=1./(c_esalt_bs*max(1.e-6,ustar(j)))
415	hsalt(j)=0.08436(max(1.e-6,ustar(j))*1.27)
416	qsalt(j)=(max(ustar(j)2-ustart(j)2,0.))/(RGhsalt(j))esalt
417	! calculation of erosion (flux positive towards the surface here)
418	! consistent with implicit resolution of turbulent mixing equation
419	! Nemoto and Nishimura 2004 show that steady-state saltation is achieved within a time tau_eqsalt_bs of about 10s
420	! we thus prevent snowerosion (snow particle transfer from the saltation layer to the first model level)
421	! integrated over tau_eqsalt_bs to exceed the total mass of snow particle in the saltation layer
422	! (rhoqsalthsalt)
423	! during this first step we also lower bound the erosion to the amount of fresh snow accumulated during the time step
424	maxerosion=min(precip_snow(j),hsalt(j)qsalt(j)rhod(j)/tau_eqsalt_bs)
425
426	fluxbs_1(j)=rhod(j)ws1(j)cdragh(j)zeta_bs(AcoefQBS(j)-qsalt(j)) &
427	/ (1.-rhod(j)ws1(j)cdragh(j)zeta_bsBcoefQBS(j)*dtime)
428	fluxbs_1(j)=max(-maxerosion,fluxbs_1(j))
429
430	if (precip_snow(j) .gt. abs(fluxbs_1(j))) then
431	ok_remaining_freshsnow(j)=.true.
432	bsweight_fresh(j)=1.
433	else
434	ok_remaining_freshsnow(j)=.false.
435	bsweight_fresh(j)=exp(-(abs(fluxbs_1(j))-precip_snow(j))/precip_snow(j))
436	endif
437	else
438	ok_remaining_freshsnow(j)=.false.
439	fluxbs_1(j)=0.
440	bsweight_fresh(j)=0.
441	endif
442	enddo
443
444
445	! we now compute the snow age of the overlying layer (snow surface after erosion of the fresh snow accumulated during the time step)
446	! this is done through the routine albsno
447	CALL albsno(klon,knon,dtime,agesno(:),alb_neig(:), precip_snow(:)+fluxbs_1(:))
448
449	! 2nd step:
450	! computation of threshold friction velocity
451	! which depends on surface snow density
452	do j = 1, knon
453	if (ok_remaining_freshsnow(j)) then
454	fluxbs_2(j)=0.
455	else
456	! we start eroding the underlying layer
457	! estimation of snow density
458	! snow density increases with snow age and
459	! increases even faster in case of sedimentation of blowing snow or rain
460	tau_dens=max(tau_densmin_bs, tau_dens0_bs*exp(-abs(precip_bs(j))/pbst_bs - &
461	abs(precip_rain(j))/prt_bs)*exp(-max(tsurf(j)-RTT,0.)))
462	rhos(j)=rhofresh_bs+(rhohard_bs-rhofresh_bs)(1.-exp(-agesno(j)86400.0/tau_dens))
463	! blowing snow flux formula used in MAR
464	ustart(j)=ustart0(j)exp(max(rhoice_bs/rhofresh_bs-rhoice_bs/rhos(j),0.))exp(max(0.,rhos(j)-rhohard_bs))
465	! we have multiplied by exp to prevent erosion when rhos>rhohard_bs
466	! computation of qbs at the top of the saltation layer
467	! default formulation from MAR model (Amory et al. 2021, Gallee et al. 2001)
468	esalt=1./(c_esalt_bs*max(1.e-6,ustar(j)))
469	hsalt(j)=0.08436(max(1.e-6,ustar(j))*1.27)
470	qsalt(j)=(max(ustar(j)2-ustart(j)2,0.))/(RGhsalt(j))esalt
471	! calculation of erosion (flux positive towards the surface here)
472	! consistent with implicit resolution of turbulent mixing equation
473	! Nemoto and Nishimura 2004 show that steady-state saltation is achieved within a time tau_eqsalt_bs of about 10s
474	! we thus prevent snowerosion (snow particle transfer from the saltation layer to the first model level)
475	! integrated over tau_eqsalt_bs to exceed the total mass of snow particle in the saltation layer
476	! (rhoqsalthsalt)
477	maxerosion=hsalt(j)qsalt(j)rhod(j)/tau_eqsalt_bs
478	fluxbs_2(j)=rhod(j)ws1(j)cdragh(j)zeta_bs(AcoefQBS(j)-qsalt(j)) &
479	/ (1.-rhod(j)ws1(j)cdragh(j)zeta_bsBcoefQBS(j)*dtime)
480	fluxbs_2(j)=max(-maxerosion,fluxbs_2(j))
481	endif
482	enddo
483
484
485
486
487	! final flux and outputs
488	do j=1, knon
489	! total flux is the erosion of fresh snow +
490	! a fraction of the underlying snow (if all the fresh snow has been eroded)
491	! the calculation of the fraction is quite delicate since we do not know
492	! how much time was needed to erode the fresh snow. We assume that this time
493	! is dtexp(-(abs(fluxbs1)-precipsnow)/precipsnow)=dtbsweight_fresh
494
495	fluxbs(j)=fluxbs_1(j)+fluxbs_2(j)*(1.-bsweight_fresh(j))
496	i = knindex(j)
497	zxustartlic(i) = ustart(j)
498	zxrhoslic(i) = rhos(j)
499	zxqsaltlic(i)=qsalt(j)
500	enddo
501
502
503	else ! not ok_bs
504	! those lines are useful to calculate the snow age
505	CALL albsno(klon,knon,dtime,agesno(:),alb_neig(:), precip_snow(:))
506
507	endif ! if ok_bs
508
509
510
511	!****************************************************************************************
512	! Calculate snow amount
513	!
514	!****************************************************************************************
515	IF (ok_bs) THEN
516	precip_totsnow(:)=precip_snow(:)+precip_bs(:)
517	evap_totsnow(:)=evap(:)-fluxbs(:) ! flux bs is positive towards the surface (snow erosion)
518	ELSE
519	precip_totsnow(:)=precip_snow(:)
520	evap_totsnow(:)=evap(:)
521	ENDIF
522
523
524	CALL fonte_neige(knon, is_lic, knindex, dtime, &
525	tsurf, precip_rain, precip_totsnow, &
526	snow, qsol, tsurf_new, evap_totsnow)
527
528
529	WHERE (snow(1 : knon) .LT. 0.0001) agesno(1 : knon) = 0.
530	zfra(1:knon) = MAX(0.0,MIN(1.0,snow(1:knon)/(snow(1:knon)+10.0)))
531
532
533	END IF ! landice_opt
534
535
536	!****************************************************************************************
537	! Send run-off on land-ice to coupler if coupled ocean.
538	! run_off_lic has been calculated in fonte_neige or surf_inlandsis
539	! If landice_opt>=2, corresponding call is done from surf_land_orchidee
540	!****************************************************************************************
541	IF (type_ocean=='couple' .AND. landice_opt .LT. 2) THEN
542	! Compress fraction where run_off_lic is active (here all pctsrf(is_lic))
543	run_off_lic_frac(:)=0.0
544	DO j = 1, knon
545	i = knindex(j)
546	run_off_lic_frac(j) = pctsrf(i,is_lic)
547	ENDDO
548
549	CALL cpl_send_landice_fields(itime, knon, knindex, run_off_lic, run_off_lic_frac)
550	ENDIF
551
552	! transfer runoff rate [kg/m2/s](!) to physiq for output
553	runoff(1:knon)=run_off_lic(1:knon)/dtime
554
555	snow_o=0.
556	zfra_o = 0.
557	DO j = 1, knon
558	i = knindex(j)
559	snow_o(i) = snow(j)
560	zfra_o(i) = zfra(j)
561	ENDDO
562
563
564	!albedo SB >>>
565	select case(NSW)
566	case(2)
567	alb_dir(1:knon,1)=alb1(1:knon)
568	alb_dir(1:knon,2)=alb2(1:knon)
569	case(4)
570	alb_dir(1:knon,1)=alb1(1:knon)
571	alb_dir(1:knon,2)=alb2(1:knon)
572	alb_dir(1:knon,3)=alb2(1:knon)
573	alb_dir(1:knon,4)=alb2(1:knon)
574	case(6)
575	alb_dir(1:knon,1)=alb1(1:knon)
576	alb_dir(1:knon,2)=alb1(1:knon)
577	alb_dir(1:knon,3)=alb1(1:knon)
578	alb_dir(1:knon,4)=alb2(1:knon)
579	alb_dir(1:knon,5)=alb2(1:knon)
580	alb_dir(1:knon,6)=alb2(1:knon)
581
582	IF ((landice_opt .EQ. 1) .AND. (iflag_albcalc .EQ. 2)) THEN
583	alb_dir(1:knon,1)=alb6(1:knon,1)
584	alb_dir(1:knon,2)=alb6(1:knon,2)
585	alb_dir(1:knon,3)=alb6(1:knon,3)
586	alb_dir(1:knon,4)=alb6(1:knon,4)
587	alb_dir(1:knon,5)=alb6(1:knon,5)
588	alb_dir(1:knon,6)=alb6(1:knon,6)
589	ENDIF
590
591	end select
592	alb_dif=alb_dir
593	!albedo SB <<<
594
595
596	END SUBROUTINE surf_landice
597	!
598	!****************************************************************************************
599	!
600	END MODULE surf_landice_mod
601
602
603

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