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limthd_dh.F90 in trunk/NEMOGCM/NEMO/LIM_SRC_3 – NEMO

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source: trunk/NEMOGCM/NEMO/LIM_SRC_3/limthd_dh.F90 @ 2733

Last change on this file since 2733 was 2715, checked in by rblod, 13 years ago
First attempt to put dynamic allocation on the trunk
Property svn:keywords set to `Id`
File size: 35.3 KB

Rev	Line
[825]	1	MODULE limthd_dh
[1572]	2	!!======================================================================
	3	!! * MODULE limthd_dh *
	4	!! LIM-3 : thermodynamic growth and decay of the ice
	5	!!======================================================================
	6	!! History : LIM ! 2003-05 (M. Vancoppenolle) Original code in 1D
	7	!! ! 2005-06 (M. Vancoppenolle) 3D version
	8	!! 3.2 ! 2009-07 (M. Vancoppenolle, Y. Aksenov, G. Madec) bug correction in rdmsnif & rdmicif
[2715]	9	!! 4.0 ! 2011-02 (G. Madec) dynamical allocation
[1572]	10	!!----------------------------------------------------------------------
[825]	11	#if defined key_lim3
[834]	12	!!----------------------------------------------------------------------
	13	!! 'key_lim3' LIM3 sea-ice model
	14	!!----------------------------------------------------------------------
[1572]	15	!! lim_thd_dh : vertical accr./abl. and lateral ablation of sea ice
[825]	16	!!----------------------------------------------------------------------
	17	USE par_oce ! ocean parameters
	18	USE phycst ! physical constants (OCE directory)
[888]	19	USE sbc_oce ! Surface boundary condition: ocean fields
[2715]	20	USE ice ! LIM variables
	21	USE par_ice ! LIM parameters
	22	USE thd_ice ! LIM thermodynamics
	23	USE wrk_nemo ! workspace manager
	24	USE in_out_manager ! I/O manager
	25	USE lib_mpp ! MPP library
[921]	26
[825]	27	IMPLICIT NONE
	28	PRIVATE
	29
[1572]	30	PUBLIC lim_thd_dh ! called by lim_thd
[825]	31
[1572]	32	REAL(wp) :: epsi20 = 1e-20 ! constant values
	33	REAL(wp) :: epsi13 = 1e-13 !
	34	REAL(wp) :: epsi16 = 1e-16 !
	35	REAL(wp) :: zzero = 0.e0 !
	36	REAL(wp) :: zone = 1.e0 !
[825]	37
	38	!!----------------------------------------------------------------------
[2715]	39	!! NEMO/LIM3 4.0 , UCL - NEMO Consortium (2010)
[1156]	40	!! $Id$
[2715]	41	!! Software governed by the CeCILL licence (NEMOGCM/NEMO_CeCILL.txt)
[825]	42	!!----------------------------------------------------------------------
	43	CONTAINS
	44
[2715]	45	SUBROUTINE lim_thd_dh( kideb, kiut, jl )
[921]	46	!!------------------------------------------------------------------
	47	!! * ROUTINE lim_thd_dh *
	48	!!
[1572]	49	!! ** Purpose : determines variations of ice and snow thicknesses.
[921]	50	!!
[1572]	51	!! ** Method : Ice/Snow surface melting arises from imbalance in surface fluxes
	52	!! Bottom accretion/ablation arises from flux budget
	53	!! Snow thickness can increase by precipitation and decrease by sublimation
	54	!! If snow load excesses Archmiede limit, snow-ice is formed by
	55	!! the flooding of sea-water in the snow
[921]	56	!!
[1572]	57	!! 1) Compute available flux of heat for surface ablation
	58	!! 2) Compute snow and sea ice enthalpies
	59	!! 3) Surface ablation and sublimation
	60	!! 4) Bottom accretion/ablation
	61	!! 5) Case of Total ablation
	62	!! 6) Snow ice formation
[921]	63	!!
[1572]	64	!! References : Bitz and Lipscomb, 1999, J. Geophys. Res.
	65	!! Fichefet T. and M. Maqueda 1997, J. Geophys. Res., 102(C6), 12609-12646
	66	!! Vancoppenolle, Fichefet and Bitz, 2005, Geophys. Res. Let.
	67	!! Vancoppenolle et al.,2009, Ocean Modelling
[921]	68	!!------------------------------------------------------------------
[1572]	69	INTEGER , INTENT(in) :: kideb, kiut ! Start/End point on which the the computation is applied
	70	INTEGER , INTENT(in) :: jl ! Thickness cateogry number
	71	!!
	72	INTEGER :: ji , jk ! dummy loop indices
	73	INTEGER :: zji, zjj ! 2D corresponding indices to ji
	74	INTEGER :: isnow ! switch for presence (1) or absence (0) of snow
	75	INTEGER :: isnowic ! snow ice formation not
	76	INTEGER :: i_ice_switch ! ice thickness above a certain treshold or not
	77	INTEGER :: iter
[2715]	78	INTEGER :: num_iter_max, numce_dh
[825]	79
[2715]	80	REAL(wp) :: meance_dh
	81	REAL(wp) :: zzfmass_i, zihgnew ! local scalar
	82	REAL(wp) :: zzfmass_s, zhsnew, ztmelts ! local scalar
[1572]	83	REAL(wp) :: zhn, zdhcf, zdhbf, zhni, zhnfi, zihg !
[2715]	84	REAL(wp) :: zdhnm, zhnnew, zhisn, zihic, zzc !
[1572]	85	REAL(wp) :: zfracs ! fractionation coefficient for bottom salt entrapment
	86	REAL(wp) :: zds ! increment of bottom ice salinity
	87	REAL(wp) :: zcoeff ! dummy argument for snowfall partitioning over ice and leads
	88	REAL(wp) :: zsm_snowice ! snow-ice salinity
	89	REAL(wp) :: zswi1 ! switch for computation of bottom salinity
	90	REAL(wp) :: zswi12 ! switch for computation of bottom salinity
	91	REAL(wp) :: zswi2 ! switch for computation of bottom salinity
	92	REAL(wp) :: zgrr ! bottom growth rate
	93	REAL(wp) :: ztform ! bottom formation temperature
[2715]	94	!
	95	REAL(wp), POINTER, DIMENSION(:) :: zh_i, ztfs , zqfont_su, zqprec , zhgnew
	96	REAL(wp), POINTER, DIMENSION(:) :: zh_s, zhsold, zqfont_bo, z_f_surf, zfmass_i
	97	REAL(wp), POINTER, DIMENSION(:) :: zdh_s_mel, zdh_s_sub , zfdt_init , zqt_i, zqt_dummy, zdq_i
	98	REAL(wp), POINTER, DIMENSION(:) :: zdh_s_pre, zfsalt_melt, zfdt_final, zqt_s, zfbase , zinnermelt
	99	!
	100	REAL(wp), DIMENSION(jpij,jkmax) :: zdeltah
[1572]	101	REAL(wp), DIMENSION(jpij,jkmax) :: zqt_i_lay ! total ice heat content
	102	!!------------------------------------------------------------------
[825]	103
[2715]	104	IF( wrk_in_use(1, 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22) ) THEN
	105	CALL ctl_stop('lim_thd_dh: requestead workspace arrays unavailable') ; RETURN
	106	ENDIF
	107	! Set-up pointers to sub-arrays of workspace arrays
	108	zh_i => wrk_1d_1 (1:jpij) ! ice layer thickness
	109	zh_s => wrk_1d_2 (1:jpij) ! snow layer thickness
	110	ztfs => wrk_1d_3 (1:jpij) ! melting point
	111	zhsold => wrk_1d_4 (1:jpij) ! old snow thickness
	112	zqprec => wrk_1d_5 (1:jpij) ! energy of fallen snow
	113	zqfont_su => wrk_1d_6 (1:jpij) ! incoming, remaining surface energy
	114	zqfont_bo => wrk_1d_7 (1:jpij) ! incoming, bottom energy
	115	z_f_surf => wrk_1d_8 (1:jpij) ! surface heat for ablation
	116	zhgnew => wrk_1d_9 (1:jpij) ! new ice thickness
	117	zfmass_i => wrk_1d_10(1:jpij) !
	118	!
	119	zdh_s_mel => wrk_1d_11(1:jpij) ! snow melt
	120	zdh_s_pre => wrk_1d_12(1:jpij) ! snow precipitation
	121	zdh_s_sub => wrk_1d_13(1:jpij) ! snow sublimation
	122	zfsalt_melt => wrk_1d_14(1:jpij) ! salt flux due to ice melt
	123	!
	124	! ! Pathological cases
	125	zfdt_init => wrk_1d_15(1:jpij) ! total incoming heat for ice melt
	126	zfdt_final => wrk_1d_16(1:jpij) ! total remaing heat for ice melt
	127	zqt_i => wrk_1d_17(1:jpij) ! total ice heat content
	128	zqt_s => wrk_1d_18(1:jpij) ! total snow heat content
	129	zqt_dummy => wrk_1d_19(1:jpij) ! dummy heat content
	130
	131	zfbase => wrk_1d_20(1:jpij)
	132	zdq_i => wrk_1d_21(1:jpij)
	133	zinnermelt => wrk_1d_22(1:jpij)
[825]	134
[2715]	135	zfsalt_melt(:) = 0._wp
	136	ftotal_fin(:) = 0._wp
	137	zfdt_init(:) = 0._wp
	138	zfdt_final(:) = 0._wp
	139
[825]	140	DO ji = kideb, kiut
	141	old_ht_i_b(ji) = ht_i_b(ji)
	142	old_ht_s_b(ji) = ht_s_b(ji)
	143	END DO
[921]	144	!
	145	!------------------------------------------------------------------------------!
	146	! 1) Calculate available heat for surface ablation !
	147	!------------------------------------------------------------------------------!
	148	!
[2715]	149	DO ji = kideb, kiut
[825]	150	isnow = INT( 1.0 - MAX ( 0.0 , SIGN ( 1.0 , - ht_s_b(ji) ) ) )
	151	ztfs(ji) = isnow * rtt + ( 1.0 - isnow ) * rtt
[1572]	152	z_f_surf(ji) = qnsr_ice_1d(ji) + ( 1.0 - i0(ji) ) * qsr_ice_1d(ji) - fc_su(ji)
	153	z_f_surf(ji) = MAX( zzero , z_f_surf(ji) ) * MAX( zzero , SIGN( zone , t_su_b(ji) - ztfs(ji) ) )
	154	zfdt_init(ji) = ( z_f_surf(ji) + MAX( fbif_1d(ji) + qlbbq_1d(ji) + fc_bo_i(ji),0.0 ) ) * rdt_ice
[825]	155	END DO ! ji
	156
[2715]	157	zqfont_su (:) = 0._wp
	158	zqfont_bo (:) = 0._wp
	159	dsm_i_se_1d(:) = 0._wp
	160	dsm_i_si_1d(:) = 0._wp
[921]	161	!
	162	!------------------------------------------------------------------------------!
	163	! 2) Computing layer thicknesses and snow and sea-ice enthalpies. !
	164	!------------------------------------------------------------------------------!
	165	!
[2715]	166	DO ji = kideb, kiut ! Layer thickness
[825]	167	zh_i(ji) = ht_i_b(ji) / nlay_i
	168	zh_s(ji) = ht_s_b(ji) / nlay_s
	169	END DO
[2715]	170	!
	171	zqt_s(:) = 0._wp ! Total enthalpy of the snow
[825]	172	DO jk = 1, nlay_s
[2715]	173	DO ji = kideb, kiut
[1572]	174	zqt_s(ji) = zqt_s(ji) + q_s_b(ji,jk) * ht_s_b(ji) / nlay_s
[825]	175	END DO
	176	END DO
[2715]	177	!
	178	zqt_i(:) = 0._wp ! Total enthalpy of the ice
[825]	179	DO jk = 1, nlay_i
[2715]	180	DO ji = kideb, kiut
	181	zzc = q_i_b(ji,jk) * ht_i_b(ji) / nlay_i
	182	zqt_i(ji) = zqt_i(ji) + zzc
	183	zqt_i_lay(ji,jk) = zzc
[825]	184	END DO
	185	END DO
[921]	186	!
	187	!------------------------------------------------------------------------------\|
	188	! 3) Surface ablation and sublimation \|
	189	!------------------------------------------------------------------------------\|
	190	!
[834]	191	!-------------------------
	192	! 3.1 Snow precips / melt
	193	!-------------------------
[825]	194	! Snow accumulation in one thermodynamic time step
	195	! snowfall is partitionned between leads and ice
	196	! if snow fall was uniform, a fraction (1-at_i) would fall into leads
	197	! but because of the winds, more snow falls on leads than on sea ice
	198	! and a greater fraction (1-at_i)^beta of the total mass of snow
[834]	199	! (beta < 1) falls in leads.
[825]	200	! In reality, beta depends on wind speed,
	201	! and should decrease with increasing wind speed but here, it is
[834]	202	! considered as a constant. an average value is 0.66
[825]	203	! Martin Vancoppenolle, December 2006
	204
	205	! Snow fall
	206	DO ji = kideb, kiut
	207	zcoeff = ( 1.0 - ( 1.0 - at_i_b(ji) )**betas ) / at_i_b(ji)
	208	zdh_s_pre(ji) = zcoeff * sprecip_1d(ji) * rdt_ice / rhosn
	209	END DO
[2715]	210	zdh_s_mel(:) = 0._wp
[825]	211
	212	! Melt of fallen snow
	213	DO ji = kideb, kiut
	214	! tatm_ice is now in K
[1572]	215	zqprec (ji) = rhosn * ( cpic * ( rtt - tatm_ice_1d(ji) ) + lfus )
	216	zqfont_su(ji) = z_f_surf(ji) * rdt_ice
	217	zdeltah (ji,1) = MIN( 0.e0 , - zqfont_su(ji) / MAX( zqprec(ji) , epsi13 ) )
	218	zqfont_su(ji) = MAX( 0.e0 , - zdh_s_pre(ji) - zdeltah(ji,1) ) * zqprec(ji)
	219	zdeltah (ji,1) = MAX( - zdh_s_pre(ji) , zdeltah(ji,1) )
	220	zdh_s_mel(ji) = zdh_s_mel(ji) + zdeltah(ji,1)
[825]	221	! heat conservation
[1572]	222	qt_s_in(ji,jl) = qt_s_in(ji,jl) + zqprec(ji) * zdh_s_pre(ji)
	223	zqt_s (ji) = zqt_s (ji) + zqprec(ji) * zdh_s_pre(ji)
	224	zqt_s (ji) = MAX( zqt_s(ji) - zqfont_su(ji) , 0.e0 )
[825]	225	END DO
	226
	227
	228	! Snow melt due to surface heat imbalance
	229	DO jk = 1, nlay_s
	230	DO ji = kideb, kiut
[1572]	231	zdeltah (ji,jk) = - zqfont_su(ji) / q_s_b(ji,jk)
	232	zqfont_su(ji) = MAX( 0.0 , - zh_s(ji) - zdeltah(ji,jk) ) * q_s_b(ji,jk)
	233	zdeltah (ji,jk) = MAX( zdeltah(ji,jk) , - zh_s(ji) )
	234	zdh_s_mel(ji) = zdh_s_mel(ji) + zdeltah(ji,jk) ! resulting melt of snow
[825]	235	END DO
	236	END DO
	237
	238	! Apply snow melt to snow depth
	239	DO ji = kideb, kiut
	240	dh_s_tot(ji) = zdh_s_mel(ji) + zdh_s_pre(ji)
	241	! Old and new snow depths
	242	zhsold(ji) = ht_s_b(ji)
	243	zhsnew = ht_s_b(ji) + dh_s_tot(ji)
	244	! If snow is still present zhn = 1, else zhn = 0
	245	zhn = 1.0 - MAX( zzero , SIGN( zone , - zhsnew ) )
	246	ht_s_b(ji) = MAX( zzero , zhsnew )
	247	! Volume and mass variations of snow
[1572]	248	dvsbq_1d (ji) = a_i_b(ji) * ( ht_s_b(ji) - zhsold(ji) - zdh_s_mel(ji) )
	249	dvsbq_1d (ji) = MIN( zzero, dvsbq_1d(ji) )
[1571]	250	rdmsnif_1d(ji) = rdmsnif_1d(ji) + rhosn * dvsbq_1d(ji)
[825]	251	END DO ! ji
	252
[834]	253	!--------------------------
	254	! 3.2 Surface ice ablation
	255	!--------------------------
[825]	256	DO ji = kideb, kiut
[2715]	257	dh_i_surf(ji) = 0._wp
[1572]	258	z_f_surf (ji) = zqfont_su(ji) / rdt_ice ! heat conservation test
[2715]	259	zdq_i (ji) = 0._wp
[825]	260	END DO ! ji
	261
	262	DO jk = 1, nlay_i
	263	DO ji = kideb, kiut
[1572]	264	! ! melt of layer jk
	265	zdeltah (ji,jk) = - zqfont_su(ji) / q_i_b(ji,jk)
	266	! ! recompute heat available
	267	zqfont_su(ji) = MAX( 0.0 , - zh_i(ji) - zdeltah(ji,jk) ) * q_i_b(ji,jk)
	268	! ! melt of layer jk cannot be higher than its thickness
	269	zdeltah (ji,jk) = MAX( zdeltah(ji,jk) , - zh_i(ji) )
	270	! ! update surface melt
	271	dh_i_surf(ji) = dh_i_surf(ji) + zdeltah(ji,jk)
	272	! ! for energy conservation
	273	zdq_i (ji) = zdq_i(ji) + zdeltah(ji,jk) * q_i_b(ji,jk) / rdt_ice
	274	!
[834]	275	! contribution to ice-ocean salt flux
[2715]	276	zji = MOD( npb(ji) - 1 , jpi ) + 1
	277	zjj = ( npb(ji) - 1 ) / jpi + 1
[1572]	278	zfsalt_melt(ji) = zfsalt_melt(ji) + ( sss_m(zji,zjj) - sm_i_b(ji) ) * a_i_b(ji) &
	279	& * MIN( zdeltah(ji,jk) , 0.e0 ) * rhoic / rdt_ice
	280	END DO
	281	END DO
[825]	282
[1572]	283	! !-------------------
	284	IF( con_i ) THEN ! Conservation test
	285	! !-------------------
	286	numce_dh = 0
[2715]	287	meance_dh = 0._wp
[921]	288	DO ji = kideb, kiut
	289	IF ( ( z_f_surf(ji) + zdq_i(ji) ) .GE. 1.0e-3 ) THEN
	290	numce_dh = numce_dh + 1
	291	meance_dh = meance_dh + z_f_surf(ji) + zdq_i(ji)
	292	ENDIF
[1572]	293	IF( z_f_surf(ji) + zdq_i(ji) .GE. 1.0e-3 ) THEN!
[921]	294	WRITE(numout,*) ' ALERTE heat loss for surface melt '
	295	WRITE(numout,*) ' zji, zjj, jl :', zji, zjj, jl
[2715]	296	WRITE(numout,*) ' ht_i_b : ', ht_i_b(ji)
	297	WRITE(numout,*) ' z_f_surf : ', z_f_surf(ji)
	298	WRITE(numout,*) ' zdq_i : ', zdq_i(ji)
	299	WRITE(numout,*) ' ht_i_b : ', ht_i_b(ji)
	300	WRITE(numout,*) ' fc_bo_i : ', fc_bo_i(ji)
	301	WRITE(numout,*) ' fbif_1d : ', fbif_1d(ji)
	302	WRITE(numout,*) ' qlbbq_1d : ', qlbbq_1d(ji)
	303	WRITE(numout,*) ' s_i_new : ', s_i_new(ji)
	304	WRITE(numout,*) ' sss_m : ', sss_m(zji,zjj)
[921]	305	ENDIF
[1572]	306	END DO
	307	!
	308	IF( numce_dh > 0 ) meance_dh = meance_dh / numce_dh
[921]	309	WRITE(numout,*) ' Error report - Category : ', jl
	310	WRITE(numout,*) ' ~~~~~~~~~~~~ '
	311	WRITE(numout,*) ' Number of points where there is sur. me. error : ', numce_dh
	312	WRITE(numout,*) ' Mean basal growth error on error points : ', meance_dh
[1572]	313	!
	314	ENDIF
[825]	315
[834]	316	!----------------------
	317	! 3.3 Snow sublimation
	318	!----------------------
[825]	319
	320	DO ji = kideb, kiut
	321	! if qla is positive (upwards), heat goes to the atmosphere, therefore
	322	! snow sublimates, if qla is negative (downwards), snow condensates
[1572]	323	zdh_s_sub(ji) = - parsub * qla_ice_1d(ji) / ( rhosn * lsub ) * rdt_ice
	324	dh_s_tot (ji) = dh_s_tot(ji) + zdh_s_sub(ji)
	325	zdhcf = ht_s_b(ji) + zdh_s_sub(ji)
	326	ht_s_b (ji) = MAX( zzero , zdhcf )
[825]	327	! we recompute dh_s_tot
[1572]	328	dh_s_tot (ji) = ht_s_b(ji) - zhsold(ji)
	329	qt_s_in (ji,jl) = qt_s_in(ji,jl) + zdh_s_sub(ji)*q_s_b(ji,1)
	330	END DO
[825]	331
[1572]	332	zqt_dummy(:) = 0.e0
[825]	333	DO jk = 1, nlay_s
	334	DO ji = kideb,kiut
[1572]	335	q_s_b (ji,jk) = rhosn * ( cpic * ( rtt - t_s_b(ji,jk) ) + lfus )
	336	zqt_dummy(ji) = zqt_dummy(ji) + q_s_b(ji,jk) * ht_s_b(ji) / nlay_s ! heat conservation
[825]	337	END DO
	338	END DO
	339
[1572]	340	DO jk = 1, nlay_s
	341	DO ji = kideb, kiut
	342	! In case of disparition of the snow, we have to update the snow temperatures
[825]	343	zhisn = MAX( zzero , SIGN( zone, - ht_s_b(ji) ) )
	344	t_s_b(ji,jk) = ( 1.0 - zhisn ) * t_s_b(ji,jk) + zhisn * rtt
	345	q_s_b(ji,jk) = ( 1.0 - zhisn ) * q_s_b(ji,jk)
	346	END DO
[921]	347	END DO
[825]	348
[921]	349	!
	350	!------------------------------------------------------------------------------!
	351	! 4) Basal growth / melt !
	352	!------------------------------------------------------------------------------!
	353	!
[825]	354	! Ice basal growth / melt is given by the ratio of heat budget over basal
	355	! ice heat content. Basal heat budget is given by the difference between
	356	! the inner conductive flux (fc_bo_i), from the open water heat flux
	357	! (qlbbqb) and the turbulent ocean flux (fbif).
[834]	358	! fc_bo_i is positive downwards. fbif and qlbbq are positive to the ice
[825]	359
[834]	360	!-----------------------------------------------------
	361	! 4.1 Basal growth - (a) salinity not varying in time
	362	!-----------------------------------------------------
[1572]	363	IF( num_sal /= 2 .AND. num_sal /= 4 ) THEN
[825]	364	DO ji = kideb, kiut
[1572]	365	IF( ( fc_bo_i(ji) + fbif_1d(ji) + qlbbq_1d(ji) ) < 0.0 ) THEN
[825]	366	s_i_new(ji) = sm_i_b(ji)
	367	! Melting point in K
	368	ztmelts = - tmut * s_i_new(ji) + rtt
	369	! New ice heat content (Bitz and Lipscomb, 1999)
	370	ztform = t_i_b(ji,nlay_i) ! t_bo_b crashes in the
[921]	371	! Baltic
[1572]	372	q_i_b(ji,nlay_i+1) = rhoic * ( cpic * ( ztmelts - ztform ) &
	373	& + lfus * ( 1.0 - ( ztmelts - rtt ) / ( ztform - rtt ) ) &
	374	& - rcp * ( ztmelts - rtt ) )
[825]	375	! Basal growth rate = - F*dt / q
[1572]	376	dh_i_bott(ji) = - rdt_ice*( fc_bo_i(ji) + fbif_1d(ji) + qlbbq_1d(ji) ) / q_i_b(ji,nlay_i+1)
	377	ENDIF
	378	END DO
	379	ENDIF
[825]	380
[834]	381	!-------------------------------------------------
	382	! 4.1 Basal growth - (b) salinity varying in time
	383	!-------------------------------------------------
[1572]	384	IF( num_sal == 2 .OR. num_sal == 4 ) THEN
[825]	385	! the growth rate (dh_i_bott) is function of the new ice
	386	! heat content (q_i_b(nlay_i+1)). q_i_b depends on the new ice
	387	! salinity (snewice). snewice depends on dh_i_bott
	388	! it converges quickly, so, no problem
[834]	389	! See Vancoppenolle et al., OM08 for more info on this
[825]	390
	391	! Initial value (tested 1D, can be anything between 1 and 20)
	392	num_iter_max = 4
[1572]	393	s_i_new(:) = 4.0
[825]	394
	395	! Iterative procedure
	396	DO iter = 1, num_iter_max
	397	DO ji = kideb, kiut
[1572]	398	IF( fc_bo_i(ji) + fbif_1d(ji) + qlbbq_1d(ji) < 0.e0 ) THEN
[825]	399	zji = MOD( npb(ji) - 1, jpi ) + 1
	400	zjj = ( npb(ji) - 1 ) / jpi + 1
	401	! Melting point in K
	402	ztmelts = - tmut * s_i_new(ji) + rtt
	403	! New ice heat content (Bitz and Lipscomb, 1999)
[1572]	404	q_i_b(ji,nlay_i+1) = rhoic * ( cpic * ( ztmelts - t_bo_b(ji) ) &
	405	& + lfus * ( 1.0 - ( ztmelts - rtt ) / ( t_bo_b(ji) - rtt ) ) &
	406	& - rcp * ( ztmelts-rtt ) )
[825]	407	! Bottom growth rate = - F*dt / q
[1572]	408	dh_i_bott(ji) = - rdt_ice * ( fc_bo_i(ji) + fbif_1d(ji) + qlbbq_1d(ji) ) / q_i_b(ji,nlay_i+1)
[825]	409	! New ice salinity ( Cox and Weeks, JGR, 1988 )
	410	! zswi2 (1) if dh_i_bott/rdt .GT. 3.6e-7
	411	! zswi12 (1) if dh_i_bott/rdt .LT. 3.6e-7 and .GT. 2.0e-8
	412	! zswi1 (1) if dh_i_bott/rdt .LT. 2.0e-8
[1572]	413	zgrr = MIN( 1.0e-3, MAX ( dh_i_bott(ji) / rdt_ice , epsi13 ) )
[825]	414	zswi2 = MAX( zzero , SIGN( zone , zgrr - 3.6e-7 ) )
	415	zswi12 = MAX( zzero , SIGN( zone , zgrr - 2.0e-8 ) ) * ( 1.0 - zswi2 )
	416	zswi1 = 1. - zswi2 * zswi12
[1572]	417	zfracs = zswi1 * 0.12 + zswi12 * ( 0.8925 + 0.0568 * LOG( 100.0 * zgrr ) ) &
	418	& + zswi2 * 0.26 / ( 0.26 + 0.74 * EXP ( - 724300.0 * zgrr ) )
	419	zds = zfracs * sss_m(zji,zjj) - s_i_new(ji)
[888]	420	s_i_new(ji) = zfracs * sss_m(zji,zjj)
[825]	421	ENDIF ! fc_bo_i
	422	END DO ! ji
	423	END DO ! iter
	424
	425	! Final values
	426	DO ji = kideb, kiut
[1572]	427	IF( ( fc_bo_i(ji) + fbif_1d(ji) + qlbbq_1d(ji) ) .LT. 0.0 ) THEN
[825]	428	! New ice salinity must not exceed 15 psu
	429	s_i_new(ji) = MIN( s_i_new(ji), s_i_max )
	430	! Metling point in K
	431	ztmelts = - tmut * s_i_new(ji) + rtt
	432	! New ice heat content (Bitz and Lipscomb, 1999)
[1572]	433	q_i_b(ji,nlay_i+1) = rhoic * ( cpic * ( ztmelts - t_bo_b(ji) ) &
	434	& + lfus * ( 1.0 - ( ztmelts - rtt ) / ( t_bo_b(ji) - rtt ) ) &
	435	& - rcp * ( ztmelts - rtt ) )
[825]	436	! Basal growth rate = - F*dt / q
[1572]	437	dh_i_bott(ji) = - rdt_ice*( fc_bo_i(ji) + fbif_1d(ji) + qlbbq_1d(ji) ) / q_i_b(ji,nlay_i+1)
[834]	438	! Salinity update
[825]	439	! entrapment during bottom growth
[1572]	440	dsm_i_se_1d(ji) = ( s_i_new(ji) * dh_i_bott(ji) + sm_i_b(ji) * ht_i_b(ji) ) &
	441	& / MAX( ht_i_b(ji) + dh_i_bott(ji) ,epsi13 ) - sm_i_b(ji)
[825]	442	ENDIF ! heat budget
[1572]	443	END DO
	444	ENDIF
[825]	445
[834]	446	!----------------
	447	! 4.2 Basal melt
	448	!----------------
[2715]	449	meance_dh = 0._wp
[1572]	450	numce_dh = 0
[2715]	451	zinnermelt(:) = 0._wp
[825]	452
	453	DO ji = kideb, kiut
	454	! heat convergence at the surface > 0
[2715]	455	IF( ( fc_bo_i(ji) + fbif_1d(ji) + qlbbq_1d(ji) ) >= 0._wp ) THEN
[825]	456	s_i_new(ji) = s_i_b(ji,nlay_i)
	457	zqfont_bo(ji) = rdt_ice * ( fc_bo_i(ji) + fbif_1d(ji) + qlbbq_1d(ji) )
[2715]	458	zfbase(ji) = zqfont_bo(ji) / rdt_ice ! heat conservation test
	459	zdq_i(ji) = 0._wp
	460	dh_i_bott(ji) = 0._wp
[825]	461	ENDIF
	462	END DO
	463
	464	DO jk = nlay_i, 1, -1
	465	DO ji = kideb, kiut
	466	IF ( ( fc_bo_i(ji) + fbif_1d(ji) + qlbbq_1d(ji) ) .GE. 0.0 ) THEN
[2715]	467	ztmelts = - tmut * s_i_b(ji,jk) + rtt
	468	IF( t_i_b(ji,jk) >= ztmelts ) THEN
[825]	469	zdeltah(ji,jk) = - zh_i(ji)
	470	dh_i_bott(ji) = dh_i_bott(ji) + zdeltah(ji,jk)
[2715]	471	zinnermelt(ji) = 1._wp
[825]	472	ELSE ! normal ablation
	473	zdeltah(ji,jk) = - zqfont_bo(ji) / q_i_b(ji,jk)
[1572]	474	zqfont_bo(ji) = MAX( 0.0 , - zh_i(ji) - zdeltah(ji,jk) ) * q_i_b(ji,jk)
[825]	475	zdeltah(ji,jk) = MAX(zdeltah(ji,jk), - zh_i(ji) )
	476	dh_i_bott(ji) = dh_i_bott(ji) + zdeltah(ji,jk)
[1572]	477	zdq_i(ji) = zdq_i(ji) + zdeltah(ji,jk) * q_i_b(ji,jk) / rdt_ice
[921]	478	! contribution to salt flux
[825]	479	zji = MOD( npb(ji) - 1, jpi ) + 1
	480	zjj = ( npb(ji) - 1 ) / jpi + 1
[1572]	481	zfsalt_melt(ji) = zfsalt_melt(ji) + ( sss_m(zji,zjj) - sm_i_b(ji) ) * a_i_b(ji) &
	482	& * MIN( zdeltah(ji,jk) , 0.0 ) * rhoic / rdt_ice
[825]	483	ENDIF
	484	ENDIF
	485	END DO ! ji
	486	END DO ! jk
	487
[1572]	488	! !-------------------
	489	IF( con_i ) THEN ! Conservation test
	490	! !-------------------
[921]	491	DO ji = kideb, kiut
[1572]	492	IF( ( fc_bo_i(ji) + fbif_1d(ji) + qlbbq_1d(ji) ) >= 0.e0 ) THEN
	493	IF( ( zfbase(ji) + zdq_i(ji) ) >= 1.e-3 ) THEN
	494	numce_dh = numce_dh + 1
[921]	495	meance_dh = meance_dh + zfbase(ji) + zdq_i(ji)
	496	ENDIF
	497	IF ( zfbase(ji) + zdq_i(ji) .GE. 1.0e-3 ) THEN
[2715]	498	WRITE(numout,*) ' ALERTE heat loss for basal melt : zji, zjj, jl :', zji, zjj, jl
	499	WRITE(numout,*) ' ht_i_b : ', ht_i_b(ji)
	500	WRITE(numout,*) ' zfbase : ', zfbase(ji)
	501	WRITE(numout,*) ' zdq_i : ', zdq_i(ji)
	502	WRITE(numout,*) ' ht_i_b : ', ht_i_b(ji)
	503	WRITE(numout,*) ' fc_bo_i : ', fc_bo_i(ji)
	504	WRITE(numout,*) ' fbif_1d : ', fbif_1d(ji)
	505	WRITE(numout,*) ' qlbbq_1d : ', qlbbq_1d(ji)
	506	WRITE(numout,*) ' s_i_new : ', s_i_new(ji)
	507	WRITE(numout,*) ' sss_m : ', sss_m(zji,zjj)
[921]	508	WRITE(numout,*) ' dh_i_bott : ', dh_i_bott(ji)
[2715]	509	WRITE(numout,*) ' innermelt : ', INT( zinnermelt(ji) )
[921]	510	ENDIF
[1572]	511	ENDIF
	512	END DO
	513	IF( numce_dh > 0 ) meance_dh = meance_dh / numce_dh
[921]	514	WRITE(numout,*) ' Number of points where there is bas. me. error : ', numce_dh
	515	WRITE(numout,*) ' Mean basal melt error on error points : ', meance_dh
	516	WRITE(numout,*) ' Remaining bottom heat : ', zqfont_bo(jiindex_1d)
[1572]	517	!
	518	ENDIF
[825]	519
[921]	520	!
	521	!------------------------------------------------------------------------------!
	522	! 5) Pathological cases !
	523	!------------------------------------------------------------------------------!
	524	!
[834]	525	!----------------------------------------------
	526	! 5.1 Excessive ablation in a 1-category model
	527	!----------------------------------------------
[825]	528
	529	DO ji = kideb, kiut
[1572]	530	! ! in a 1-category sea ice model, bottom ablation must not exceed hmelt (-0.15)
	531	IF( jpl == 1 ) THEN ; zdhbf = MAX( hmelt , dh_i_bott(ji) )
	532	ELSE ; zdhbf = dh_i_bott(ji)
	533	ENDIF
	534	! ! excessive energy is sent to lateral ablation
	535	fsup (ji) = rhoic * lfus * at_i_b(ji) / MAX( 1.0 - at_i_b(ji) , epsi13 ) &
	536	& * ( zdhbf - dh_i_bott(ji) ) / rdt_ice
[825]	537	dh_i_bott(ji) = zdhbf
[1572]	538	! !since ice volume is only used for outputs, we keep it global for all categories
	539	dvbbq_1d (ji) = a_i_b(ji) * dh_i_bott(ji)
	540	! !new ice thickness
	541	zhgnew (ji) = ht_i_b(ji) + dh_i_surf(ji) + dh_i_bott(ji)
	542	! ! diagnostic ( bottom ice growth )
	543	zji = MOD( npb(ji) - 1, jpi ) + 1
	544	zjj = ( npb(ji) - 1 ) / jpi + 1
	545	diag_bot_gr(zji,zjj) = diag_bot_gr(zji,zjj) + MAX(dh_i_bott(ji),0.0)*a_i_b(ji) / rdt_ice
	546	diag_sur_me(zji,zjj) = diag_sur_me(zji,zjj) + MIN(dh_i_surf(ji),0.0)*a_i_b(ji) / rdt_ice
	547	diag_bot_me(zji,zjj) = diag_bot_me(zji,zjj) + MIN(dh_i_bott(ji),0.0)*a_i_b(ji) / rdt_ice
[825]	548	END DO
	549
[834]	550	!-----------------------------------
	551	! 5.2 More than available ice melts
	552	!-----------------------------------
[825]	553	! then heat applied minus heat content at previous time step
	554	! should equal heat remaining
	555	!
	556	DO ji = kideb, kiut
	557	! Adapt the remaining energy if too much ice melts
	558	!--------------------------------------------------
	559	zihgnew = 1.0 - MAX( zzero , SIGN( zone , - zhgnew(ji) ) ) !1 if ice
	560	! 0 if no more ice
[1572]	561	zhgnew (ji) = zihgnew * zhgnew(ji) ! ice thickness is put to 0
[825]	562	! remaining heat
[834]	563	zfdt_final(ji) = ( 1.0 - zihgnew ) * ( zqfont_su(ji) + zqfont_bo(ji) )
[825]	564
	565	! If snow remains, energy is used to melt snow
[1572]	566	zhni = ht_s_b(ji) ! snow depth at previous time step
	567	zihg = MAX( zzero , SIGN ( zone , - ht_s_b(ji) ) ) ! 0 if snow
[825]	568
	569	! energy of melting of remaining snow
[1572]	570	zqt_s(ji) = ( 1. - zihg ) * zqt_s(ji) / MAX( zhni, epsi13 )
	571	zdhnm = - ( 1. - zihg ) * ( 1. - zihgnew ) * zfdt_final(ji) / MAX( zqt_s(ji) , epsi13 )
[825]	572	zhnfi = zhni + zdhnm
[1572]	573	zfdt_final(ji) = MAX( zfdt_final(ji) + zqt_s(ji) * zdhnm , 0.0 )
[825]	574	ht_s_b(ji) = MAX( zzero , zhnfi )
	575	zqt_s(ji) = zqt_s(ji) * ht_s_b(ji)
	576
	577	! Mass variations of ice and snow
	578	!---------------------------------
[1572]	579	! ! mass variation of the jl category
[1571]	580	zzfmass_s = - a_i_b(ji) * ( zhni - ht_s_b(ji) ) * rhosn ! snow
	581	zzfmass_i = a_i_b(ji) * ( zhgnew(ji) - ht_i_b(ji) ) * rhoic ! ice
	582	!
	583	zfmass_i(ji) = zzfmass_i ! ice variation saved to compute salt flux (see below)
	584	!
	585	! ! mass variation cumulated over category
	586	rdmsnif_1d(ji) = rdmsnif_1d(ji) + zzfmass_s ! snow
	587	rdmicif_1d(ji) = rdmicif_1d(ji) + zzfmass_i ! ice
[825]	588
	589	! Remaining heat to the ocean
	590	!---------------------------------
[1572]	591	focea(ji) = - zfdt_final(ji) / rdt_ice ! focea is in W.m-2 * dt
[825]	592
	593	END DO
	594
	595	ftotal_fin (:) = zfdt_final(:) / rdt_ice
	596
	597	!---------------------------
	598	! Salt flux and heat fluxes
	599	!---------------------------
	600	DO ji = kideb, kiut
[1572]	601	zihgnew = 1.0 - MAX( zzero , SIGN( zone , - zhgnew(ji) ) ) !1 if ice
[825]	602
	603	! Salt flux
[1572]	604	zji = MOD( npb(ji) - 1, jpi ) + 1
	605	zjj = ( npb(ji) - 1 ) / jpi + 1
[825]	606	! new lines
[1572]	607	IF( num_sal == 4 ) THEN
	608	fseqv_1d(ji) = fseqv_1d(ji) + zihgnew * zfsalt_melt(ji) &
	609	& + (1.0 - zihgnew) * zfmass_i(ji) * ( sss_m(zji,zjj) - bulk_sal ) / rdt_ice
	610	ELSE
	611	fseqv_1d(ji) = fseqv_1d(ji) + zihgnew * zfsalt_melt(ji) &
	612	& + (1.0 - zihgnew) * zfmass_i(ji) * ( sss_m(zji,zjj) - sm_i_b(ji) ) / rdt_ice
	613	ENDIF
[825]	614	! Heat flux
	615	! excessive bottom ablation energy (fsup) - 0 except if jpl = 1
	616	! excessive total ablation energy (focea) sent to the ocean
[1572]	617	qfvbq_1d(ji) = qfvbq_1d(ji) + fsup(ji) + ( 1.0 - zihgnew ) * focea(ji) * a_i_b(ji) * rdt_ice
[825]	618
	619	zihic = 1.0 - MAX( zzero , SIGN( zone , -ht_i_b(ji) ) )
	620	! equals 0 if ht_i = 0, 1 if ht_i gt 0
	621	fscbq_1d(ji) = a_i_b(ji) * fstbif_1d(ji)
[1572]	622	qldif_1d(ji) = qldif_1d(ji) + fsup(ji) + ( 1.0 - zihgnew ) * focea(ji) * a_i_b(ji) * rdt_ice &
	623	& + ( 1.0 - zihic ) * fscbq_1d(ji) * rdt_ice
[825]	624	END DO ! ji
	625
	626	!-------------------------------------------
	627	! Correct temperature, energy and thickness
	628	!-------------------------------------------
	629	DO ji = kideb, kiut
[1572]	630	zihgnew = 1.0 - MAX( zzero , SIGN( zone , - zhgnew(ji) ) )
	631	t_su_b(ji) = zihgnew * t_su_b(ji) + ( 1.0 - zihgnew ) * rtt
[825]	632	END DO ! ji
	633
	634	DO jk = 1, nlay_i
	635	DO ji = kideb, kiut
[1572]	636	zihgnew = 1.0 - MAX( zzero , SIGN( zone , - zhgnew(ji) ) )
	637	t_i_b(ji,jk) = zihgnew * t_i_b(ji,jk) + ( 1.0 - zihgnew ) * rtt
	638	q_i_b(ji,jk) = zihgnew * q_i_b(ji,jk)
[825]	639	END DO
	640	END DO ! ji
	641
	642	DO ji = kideb, kiut
	643	ht_i_b(ji) = zhgnew(ji)
	644	END DO ! ji
[921]	645	!
	646	!------------------------------------------------------------------------------\|
	647	! 6) Snow-Ice formation \|
	648	!------------------------------------------------------------------------------\|
[1572]	649	! When snow load excesses Archimede's limit, snow-ice interface goes down under sea-level,
	650	! flooding of seawater transforms snow into ice dh_snowice is positive for the ice
[825]	651	DO ji = kideb, kiut
[1572]	652	!
	653	dh_snowice(ji) = MAX( zzero , ( rhosn * ht_s_b(ji) + (rhoic-rau0) * ht_i_b(ji) ) / ( rhosn+rau0-rhoic ) )
	654	zhgnew(ji) = MAX( zhgnew(ji) , zhgnew(ji) + dh_snowice(ji) )
	655	zhnnew = MIN( ht_s_b(ji) , ht_s_b(ji) - dh_snowice(ji) )
[825]	656
[921]	657	! Changes in ice volume and ice mass.
[1572]	658	dvnbq_1d (ji) = a_i_b(ji) * ( zhgnew(ji)-ht_i_b(ji) )
	659	dmgwi_1d (ji) = dmgwi_1d(ji) + a_i_b(ji) * ( ht_s_b(ji) - zhnnew ) * rhosn
[825]	660
[1572]	661	rdmicif_1d(ji) = rdmicif_1d(ji) + a_i_b(ji) * ( zhgnew(ji) - ht_i_b(ji) ) * rhoic
	662	rdmsnif_1d(ji) = rdmsnif_1d(ji) + a_i_b(ji) * ( zhnnew - ht_s_b(ji) ) * rhosn
[825]	663
[921]	664	! Equivalent salt flux (1) Snow-ice formation component
	665	! -----------------------------------------------------
[1572]	666	zji = MOD( npb(ji) - 1, jpi ) + 1
	667	zjj = ( npb(ji) - 1 ) / jpi + 1
[825]	668
[1572]	669	IF( num_sal /= 2 ) THEN ; zsm_snowice = sm_i_b(ji)
	670	ELSE ; zsm_snowice = ( rhoic - rhosn ) / rhoic * sss_m(zji,zjj)
	671	ENDIF
	672	IF( num_sal == 4 ) THEN
	673	fseqv_1d(ji) = fseqv_1d(ji) + ( sss_m(zji,zjj) - bulk_sal ) * a_i_b(ji) &
	674	& * ( zhgnew(ji) - ht_i_b(ji) ) * rhoic / rdt_ice
	675	ELSE
	676	fseqv_1d(ji) = fseqv_1d(ji) + ( sss_m(zji,zjj) - zsm_snowice ) * a_i_b(ji) &
	677	& * ( zhgnew(ji) - ht_i_b(ji) ) * rhoic / rdt_ice
	678	ENDIF
[825]	679	! entrapment during snow ice formation
[1572]	680	i_ice_switch = 1.0 - MAX( 0.e0 , SIGN( 1.0 , - ht_i_b(ji) + 1.0e-6 ) )
	681	isnowic = 1.0 - MAX( 0.e0 , SIGN( 1.0 , - dh_snowice(ji) ) ) * i_ice_switch
	682	IF( num_sal == 2 .OR. num_sal == 4 ) &
	683	dsm_i_si_1d(ji) = ( zsm_snowice*dh_snowice(ji) &
	684	& + sm_i_b(ji) * ht_i_b(ji) / MAX( ht_i_b(ji) + dh_snowice(ji), epsi13) &
	685	& - sm_i_b(ji) ) * isnowic
[825]	686
[921]	687	! Actualize new snow and ice thickness.
[825]	688	ht_s_b(ji) = zhnnew
	689	ht_i_b(ji) = zhgnew(ji)
	690
	691	! Total ablation ! new lines added to debug
[2715]	692	IF( ht_i_b(ji) <= 0._wp ) a_i_b(ji) = 0._wp
[825]	693
	694	! diagnostic ( snow ice growth )
[1572]	695	zji = MOD( npb(ji) - 1, jpi ) + 1
	696	zjj = ( npb(ji) - 1 ) / jpi + 1
	697	diag_sni_gr(zji,zjj) = diag_sni_gr(zji,zjj) + dh_snowice(ji)*a_i_b(ji) / rdt_ice
	698	!
[825]	699	END DO !ji
[2715]	700	!
	701	IF( wrk_not_released(1, 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21) ) &
	702	CALL ctl_stop('lim_thd_dh : failed to release workspace arrays')
	703	!
[921]	704	END SUBROUTINE lim_thd_dh
[1572]	705
[825]	706	#else
[1572]	707	!!----------------------------------------------------------------------
	708	!! Default option NO LIM3 sea-ice model
	709	!!----------------------------------------------------------------------
[825]	710	CONTAINS
	711	SUBROUTINE lim_thd_dh ! Empty routine
	712	END SUBROUTINE lim_thd_dh
	713	#endif
[1572]	714
	715	!!======================================================================
[921]	716	END MODULE limthd_dh

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