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icethd_dh.F90 @ 11954

Last change on this file since 11954 was 11355, checked in by dancopsey, 5 years ago
Add lots of print statements printing out values of files throughout the ocean_ice timestep.. New output will be in files crash_stats_419.out and crash_stats_68.out.
File size: 36.5 KB

Rev	Line
[8586]	1	MODULE icethd_dh
	2	!!======================================================================
	3	!! * MODULE icethd_dh *
	4	!! seaice : thermodynamic growth and melt
	5	!!======================================================================
[9604]	6	!! History : ! 2003-05 (M. Vancoppenolle) Original code in 1D
	7	!! ! 2005-06 (M. Vancoppenolle) 3D version
	8	!! 4.0 ! 2018 (many people) SI3 [aka Sea Ice cube]
[8586]	9	!!----------------------------------------------------------------------
[9570]	10	#if defined key_si3
[8586]	11	!!----------------------------------------------------------------------
[9570]	12	!! 'key_si3' SI3 sea-ice model
[8586]	13	!!----------------------------------------------------------------------
	14	!! ice_thd_dh : vertical sea-ice growth and melt
	15	!! ice_thd_snwblow : distribute snow fall between ice and ocean
	16	!!----------------------------------------------------------------------
	17	USE dom_oce ! ocean space and time domain
	18	USE phycst ! physical constants
	19	USE ice ! sea-ice: variables
	20	USE ice1D ! sea-ice: thermodynamics variables
	21	USE icethd_sal ! sea-ice: salinity profiles
	22	!
	23	USE in_out_manager ! I/O manager
	24	USE lib_mpp ! MPP library
	25	USE lib_fortran ! fortran utilities (glob_sum + no signed zero)
	26
	27	IMPLICIT NONE
	28	PRIVATE
	29
	30	PUBLIC ice_thd_dh ! called by ice_thd
[9274]	31	PUBLIC ice_thd_snwblow ! called in sbcblk/sbccpl and here
[8586]	32
	33	INTERFACE ice_thd_snwblow
	34	MODULE PROCEDURE ice_thd_snwblow_1d, ice_thd_snwblow_2d
	35	END INTERFACE
	36
	37	!!----------------------------------------------------------------------
[9598]	38	!! NEMO/ICE 4.0 , NEMO Consortium (2018)
[10069]	39	!! $Id$
[10068]	40	!! Software governed by the CeCILL license (see ./LICENSE)
[8586]	41	!!----------------------------------------------------------------------
	42	CONTAINS
	43
	44	SUBROUTINE ice_thd_dh
	45	!!------------------------------------------------------------------
	46	!! * ROUTINE ice_thd_dh *
	47	!!
[9274]	48	!! ** Purpose : compute ice and snow thickness changes due to growth/melting
[8586]	49	!!
	50	!! ** Method : Ice/Snow surface melting arises from imbalance in surface fluxes
[9274]	51	!! Bottom accretion/ablation arises from flux budget
	52	!! Snow thickness can increase by precipitation and decrease by sublimation
	53	!! If snow load excesses Archmiede limit, snow-ice is formed by
	54	!! the flooding of sea-water in the snow
[8586]	55	!!
[9274]	56	!! - Compute available flux of heat for surface ablation
	57	!! - Compute snow and sea ice enthalpies
	58	!! - Surface ablation and sublimation
	59	!! - Bottom accretion/ablation
	60	!! - Snow ice formation
[8586]	61	!!
	62	!! References : Bitz and Lipscomb, 1999, J. Geophys. Res.
	63	!! Fichefet T. and M. Maqueda 1997, J. Geophys. Res., 102(C6), 12609-12646
	64	!! Vancoppenolle, Fichefet and Bitz, 2005, Geophys. Res. Let.
	65	!! Vancoppenolle et al.,2009, Ocean Modelling
	66	!!------------------------------------------------------------------
	67	INTEGER :: ji, jk ! dummy loop indices
	68	INTEGER :: iter ! local integer
	69
	70	REAL(wp) :: ztmelts ! local scalar
	71	REAL(wp) :: zdum
	72	REAL(wp) :: zfracs ! fractionation coefficient for bottom salt entrapment
	73	REAL(wp) :: zswi1 ! switch for computation of bottom salinity
	74	REAL(wp) :: zswi12 ! switch for computation of bottom salinity
	75	REAL(wp) :: zswi2 ! switch for computation of bottom salinity
	76	REAL(wp) :: zgrr ! bottom growth rate
	77	REAL(wp) :: zt_i_new ! bottom formation temperature
[9935]	78	REAL(wp) :: z1_rho ! 1/(rhos+rau0-rhoi)
[8586]	79
	80	REAL(wp) :: zQm ! enthalpy exchanged with the ocean (J/m2), >0 towards the ocean
	81	REAL(wp) :: zEi ! specific enthalpy of sea ice (J/kg)
	82	REAL(wp) :: zEw ! specific enthalpy of exchanged water (J/kg)
	83	REAL(wp) :: zdE ! specific enthalpy difference (J/kg)
	84	REAL(wp) :: zfmdt ! exchange mass flux x time step (J/m2), >0 towards the ocean
	85
	86	REAL(wp), DIMENSION(jpij) :: zqprec ! energy of fallen snow (J.m-3)
[9922]	87	REAL(wp), DIMENSION(jpij) :: zq_top ! heat for surface ablation (J.m-2)
	88	REAL(wp), DIMENSION(jpij) :: zq_bot ! heat for bottom ablation (J.m-2)
[8586]	89	REAL(wp), DIMENSION(jpij) :: zq_rema ! remaining heat at the end of the routine (J.m-2)
	90	REAL(wp), DIMENSION(jpij) :: zf_tt ! Heat budget to determine melting or freezing(W.m-2)
	91	REAL(wp), DIMENSION(jpij) :: zevap_rema ! remaining mass flux from sublimation (kg.m-2)
	92
	93	REAL(wp), DIMENSION(jpij) :: zdh_s_mel ! snow melt
	94	REAL(wp), DIMENSION(jpij) :: zdh_s_pre ! snow precipitation
	95	REAL(wp), DIMENSION(jpij) :: zdh_s_sub ! snow sublimation
	96
[9271]	97	REAL(wp), DIMENSION(jpij,nlay_s) :: zh_s ! snw layer thickness
	98	REAL(wp), DIMENSION(jpij,nlay_i) :: zh_i ! ice layer thickness
[8586]	99	REAL(wp), DIMENSION(jpij,nlay_i) :: zdeltah
	100	INTEGER , DIMENSION(jpij,nlay_i) :: icount ! number of layers vanished by melting
	101
	102	REAL(wp), DIMENSION(jpij) :: zsnw ! distribution of snow after wind blowing
	103
	104	REAL(wp) :: zswitch_sal
	105
	106	INTEGER :: num_iter_max ! Heat conservation
[11355]	107	INTEGER, DIMENSION(1) :: imax
[8586]	108	!!------------------------------------------------------------------
	109
	110	! Discriminate between time varying salinity and constant
	111	SELECT CASE( nn_icesal ) ! varying salinity or not
	112	CASE( 1 , 3 ) ; zswitch_sal = 0._wp ! prescribed salinity profile
	113	CASE( 2 ) ; zswitch_sal = 1._wp ! varying salinity profile
	114	END SELECT
	115
	116	! initialize layer thicknesses and enthalpies
	117	h_i_old (1:npti,0:nlay_i+1) = 0._wp
	118	eh_i_old(1:npti,0:nlay_i+1) = 0._wp
	119	DO jk = 1, nlay_i
	120	DO ji = 1, npti
	121	h_i_old (ji,jk) = h_i_1d(ji) * r1_nlay_i
	122	eh_i_old(ji,jk) = e_i_1d(ji,jk) * h_i_old(ji,jk)
	123	END DO
	124	END DO
	125	!
[9604]	126	! ! ============================================== !
	127	! ! Available heat for surface and bottom ablation !
	128	! ! ============================================== !
[8813]	129	!
[10534]	130	IF( ln_cndflx .AND. .NOT.ln_cndemulate ) THEN
[8813]	131	!
	132	DO ji = 1, npti
[9922]	133	zq_top(ji) = MAX( 0._wp, qml_ice_1d(ji) * rdt_ice )
[8813]	134	END DO
	135	!
[10534]	136	ELSE
[8813]	137	!
	138	DO ji = 1, npti
[9916]	139	zdum = qns_ice_1d(ji) + qsr_ice_1d(ji) - qtr_ice_top_1d(ji) - qcn_ice_top_1d(ji)
[9274]	140	qml_ice_1d(ji) = zdum * MAX( 0._wp , SIGN( 1._wp, t_su_1d(ji) - rt0 ) )
[9922]	141	zq_top(ji) = MAX( 0._wp, qml_ice_1d(ji) * rdt_ice )
[8813]	142	END DO
	143	!
[10534]	144	ENDIF
[8813]	145	!
[8586]	146	DO ji = 1, npti
[9916]	147	zf_tt(ji) = qcn_ice_bot_1d(ji) + qsb_ice_bot_1d(ji) + fhld_1d(ji)
[9922]	148	zq_bot(ji) = MAX( 0._wp, zf_tt(ji) * rdt_ice )
[8586]	149	END DO
	150
[9274]	151	! Ice and snow layer thicknesses
	152	!-------------------------------
[9271]	153	DO jk = 1, nlay_i
	154	DO ji = 1, npti
	155	zh_i(ji,jk) = h_i_1d(ji) * r1_nlay_i
	156	END DO
	157	END DO
	158
	159	DO jk = 1, nlay_s
	160	DO ji = 1, npti
	161	zh_s(ji,jk) = h_s_1d(ji) * r1_nlay_s
	162	END DO
	163	END DO
	164
[9274]	165	! ! ============ !
	166	! ! Snow !
	167	! ! ============ !
	168	!
	169	! Internal melting
	170	! ----------------
	171	! IF snow temperature is above freezing point, THEN snow melts (should not happen but sometimes it does)
[9271]	172	DO jk = 1, nlay_s
[8586]	173	DO ji = 1, npti
[9274]	174	IF( t_s_1d(ji,jk) > rt0 ) THEN
	175	hfx_res_1d (ji) = hfx_res_1d (ji) + e_s_1d(ji,jk) * zh_s(ji,jk) * a_i_1d(ji) * r1_rdtice ! heat flux to the ocean [W.m-2], < 0
[9935]	176	wfx_snw_sum_1d(ji) = wfx_snw_sum_1d(ji) + rhos * zh_s(ji,jk) * a_i_1d(ji) * r1_rdtice ! mass flux
[9271]	177	! updates
[9274]	178	dh_s_mlt(ji) = dh_s_mlt(ji) - zh_s(ji,jk)
	179	h_s_1d (ji) = h_s_1d(ji) - zh_s(ji,jk)
	180	zh_s (ji,jk) = 0._wp
	181	e_s_1d (ji,jk) = 0._wp
	182	t_s_1d (ji,jk) = rt0
[9271]	183	END IF
[8586]	184	END DO
[11355]	185	END DO
[8586]	186
[11355]	187	IF(narea == 419) THEN
	188	WRITE(9419,*) 'max wfx_snw_sum_1d icethd_dh after inte5rnal melting = ',MAXVAL( ABS( wfx_snw_sum_1d(:) ) )
	189	imax = MAXLOC( ABS( wfx_snw_sum_1d(:) ) )
	190	WRITE(9419,*) 'at location = ',imax
	191	WRITE(9419,*) 'zh_s = ',zh_s(imax,:)
	192	WRITE(9419,*) 'a_i_1d = ',a_i_1d(imax)
	193	ENDIF
	194
	195	IF(narea == 68) THEN
	196	WRITE(968,*) 'max wfx_snw_sum_1d icethd_dh after inte5rnal melting = ',MAXVAL( ABS( wfx_snw_sum_1d(:) ) )
	197	imax = MAXLOC( ABS( wfx_snw_sum_1d(:) ) )
	198	WRITE(968,*) 'at location = ',imax
	199	WRITE(968,*) 'zh_s = ',zh_s(imax,:)
	200	WRITE(968,*) 'a_i_1d = ',a_i_1d(imax)
	201	ENDIF
	202
[9274]	203	! Snow precipitation
	204	!-------------------
	205	CALL ice_thd_snwblow( 1. - at_i_1d(1:npti), zsnw(1:npti) ) ! snow distribution over ice after wind blowing
[8586]	206
	207	zdeltah(1:npti,:) = 0._wp
	208	DO ji = 1, npti
[9274]	209	IF( sprecip_1d(ji) > 0._wp ) THEN
	210	!
	211	! --- precipitation ---
[9935]	212	zdh_s_pre (ji) = zsnw(ji) * sprecip_1d(ji) * rdt_ice * r1_rhos / at_i_1d(ji) ! thickness change
[9274]	213	zqprec (ji) = - qprec_ice_1d(ji) ! enthalpy of the precip (>0, J.m-3)
	214	!
	215	hfx_spr_1d(ji) = hfx_spr_1d(ji) + zdh_s_pre(ji) * a_i_1d(ji) * zqprec(ji) * r1_rdtice ! heat flux from snow precip (>0, W.m-2)
[9935]	216	wfx_spr_1d(ji) = wfx_spr_1d(ji) - rhos * a_i_1d(ji) * zdh_s_pre(ji) * r1_rdtice ! mass flux, <0
[9274]	217
	218	! --- melt of falling snow ---
	219	rswitch = MAX( 0._wp , SIGN( 1._wp , zqprec(ji) - epsi20 ) )
[9922]	220	zdeltah (ji,1) = - rswitch * zq_top(ji) / MAX( zqprec(ji) , epsi20 ) ! thickness change
	221	zdeltah (ji,1) = MAX( - zdh_s_pre(ji), zdeltah(ji,1) ) ! bound melting
[9274]	222	hfx_snw_1d (ji) = hfx_snw_1d (ji) - zdeltah(ji,1) * a_i_1d(ji) * zqprec(ji) * r1_rdtice ! heat used to melt snow (W.m-2, >0)
[9935]	223	wfx_snw_sum_1d(ji) = wfx_snw_sum_1d(ji) - rhos * a_i_1d(ji) * zdeltah(ji,1) * r1_rdtice ! snow melting only = water into the ocean (then without snow precip), >0
[9274]	224
	225	! updates available heat + precipitations after melting
	226	dh_s_mlt (ji) = dh_s_mlt(ji) + zdeltah(ji,1)
[9922]	227	zq_top (ji) = MAX( 0._wp , zq_top (ji) + zdeltah(ji,1) * zqprec(ji) )
[9274]	228	zdh_s_pre(ji) = zdh_s_pre(ji) + zdeltah(ji,1)
	229
	230	! update thickness
	231	h_s_1d(ji) = MAX( 0._wp , h_s_1d(ji) + zdh_s_pre(ji) )
	232	!
	233	ELSE
	234	!
	235	zdh_s_pre(ji) = 0._wp
	236	zqprec (ji) = 0._wp
	237	!
	238	ENDIF
[8586]	239	END DO
	240
[9271]	241	! recalculate snow layers
	242	DO jk = 1, nlay_s
	243	DO ji = 1, npti
	244	zh_s(ji,jk) = h_s_1d(ji) * r1_nlay_s
	245	END DO
	246	END DO
	247
[9274]	248	! Snow melting
	249	! ------------
[9922]	250	! If heat still available (zq_top > 0), then melt more snow
[8586]	251	zdeltah(1:npti,:) = 0._wp
	252	zdh_s_mel(1:npti) = 0._wp
	253	DO jk = 1, nlay_s
	254	DO ji = 1, npti
[9922]	255	IF( zh_s(ji,jk) > 0._wp .AND. zq_top(ji) > 0._wp ) THEN
[9274]	256	!
	257	rswitch = MAX( 0._wp, SIGN( 1._wp, e_s_1d(ji,jk) - epsi20 ) )
[9922]	258	zdeltah (ji,jk) = - rswitch * zq_top(ji) / MAX( e_s_1d(ji,jk), epsi20 ) ! thickness change
	259	zdeltah (ji,jk) = MAX( zdeltah(ji,jk) , - zh_s(ji,jk) ) ! bound melting
[9274]	260	zdh_s_mel(ji) = zdh_s_mel(ji) + zdeltah(ji,jk)
	261
	262	hfx_snw_1d(ji) = hfx_snw_1d(ji) - zdeltah(ji,jk) * a_i_1d(ji) * e_s_1d (ji,jk) * r1_rdtice ! heat used to melt snow(W.m-2, >0)
[9935]	263	wfx_snw_sum_1d(ji) = wfx_snw_sum_1d(ji) - rhos * a_i_1d(ji) * zdeltah(ji,jk) * r1_rdtice ! snow melting only = water into the ocean (then without snow precip)
[9274]	264
	265	! updates available heat + thickness
	266	dh_s_mlt(ji) = dh_s_mlt(ji) + zdeltah(ji,jk)
[9922]	267	zq_top (ji) = MAX( 0._wp , zq_top(ji) + zdeltah(ji,jk) * e_s_1d(ji,jk) )
[9274]	268	h_s_1d (ji) = MAX( 0._wp , h_s_1d(ji) + zdeltah(ji,jk) )
	269	zh_s (ji,jk) = MAX( 0._wp , zh_s(ji,jk) + zdeltah(ji,jk) )
	270	!
	271	ENDIF
[8586]	272	END DO
	273	END DO
	274
[9274]	275	! Snow sublimation
	276	!-----------------
[8586]	277	! qla_ice is always >=0 (upwards), heat goes to the atmosphere, therefore snow sublimates
[8885]	278	! comment: not counted in mass/heat exchange in iceupdate.F90 since this is an exchange with atm. (not ocean)
[8586]	279	zdeltah(1:npti,:) = 0._wp
	280	DO ji = 1, npti
[9274]	281	IF( evap_ice_1d(ji) > 0._wp ) THEN
	282	!
[9935]	283	zdh_s_sub (ji) = MAX( - h_s_1d(ji) , - evap_ice_1d(ji) * r1_rhos * rdt_ice )
	284	zevap_rema(ji) = evap_ice_1d(ji) * rdt_ice + zdh_s_sub(ji) * rhos ! remaining evap in kg.m-2 (used for ice melting later on)
[9274]	285	zdeltah (ji,1) = MAX( zdh_s_sub(ji), - zdh_s_pre(ji) )
	286
	287	hfx_sub_1d (ji) = hfx_sub_1d(ji) + & ! Heat flux by sublimation [W.m-2], < 0 (sublimate snow that had fallen, then pre-existing snow)
	288	& ( zdeltah(ji,1) * zqprec(ji) + ( zdh_s_sub(ji) - zdeltah(ji,1) ) * e_s_1d(ji,1) ) &
	289	& * a_i_1d(ji) * r1_rdtice
[9935]	290	wfx_snw_sub_1d(ji) = wfx_snw_sub_1d(ji) - rhos * a_i_1d(ji) * zdh_s_sub(ji) * r1_rdtice ! Mass flux by sublimation
[9274]	291
	292	! new snow thickness
	293	h_s_1d(ji) = MAX( 0._wp , h_s_1d(ji) + zdh_s_sub(ji) )
	294	! update precipitations after sublimation and correct sublimation
	295	zdh_s_pre(ji) = zdh_s_pre(ji) + zdeltah(ji,1)
	296	zdh_s_sub(ji) = zdh_s_sub(ji) - zdeltah(ji,1)
	297	!
	298	ELSE
	299	!
	300	zdh_s_sub (ji) = 0._wp
	301	zevap_rema(ji) = 0._wp
	302	!
	303	ENDIF
[8586]	304	END DO
	305
	306	! --- Update snow diags --- !
	307	DO ji = 1, npti
	308	dh_s_tot(ji) = zdh_s_mel(ji) + zdh_s_pre(ji) + zdh_s_sub(ji)
	309	END DO
	310
[9274]	311	! Update temperature, energy
	312	!---------------------------
[8586]	313	! new temp and enthalpy of the snow (remaining snow precip + remaining pre-existing snow)
	314	DO jk = 1, nlay_s
	315	DO ji = 1,npti
	316	rswitch = MAX( 0._wp , SIGN( 1._wp, h_s_1d(ji) - epsi20 ) )
[9274]	317	e_s_1d(ji,jk) = rswitch / MAX( h_s_1d(ji), epsi20 ) * &
	318	& ( ( zdh_s_pre(ji) ) * zqprec(ji) + &
[9935]	319	& ( h_s_1d(ji) - zdh_s_pre(ji) ) * rhos * ( rcpi * ( rt0 - t_s_1d(ji,jk) ) + rLfus ) )
[8586]	320	END DO
	321	END DO
[9274]	322
	323	! ! ============ !
	324	! ! Ice !
	325	! ! ============ !
[8586]	326
[9274]	327	! Surface ice melting
	328	!--------------------
[8586]	329	zdeltah(1:npti,:) = 0._wp ! important
	330	DO jk = 1, nlay_i
	331	DO ji = 1, npti
[9935]	332	ztmelts = - rTmlt * sz_i_1d(ji,jk) ! Melting point of layer k [C]
[8586]	333
[9274]	334	IF( t_i_1d(ji,jk) >= (ztmelts+rt0) ) THEN !-- Internal melting
[8586]	335
[9935]	336	zEi = - e_i_1d(ji,jk) * r1_rhoi ! Specific enthalpy of layer k [J/kg, <0]
[9274]	337	zdE = 0._wp ! Specific enthalpy difference (J/kg, <0)
[8586]	338	! set up at 0 since no energy is needed to melt water...(it is already melted)
	339	zdeltah(ji,jk) = MIN( 0._wp , - zh_i(ji,jk) ) ! internal melting occurs when the internal temperature is above freezing
	340	! this should normally not happen, but sometimes, heat diffusion leads to this
[9935]	341	zfmdt = - zdeltah(ji,jk) * rhoi ! Mass flux x time step > 0
[8586]	342
[9750]	343	dh_i_itm(ji) = dh_i_itm(ji) + zdeltah(ji,jk) ! Cumulate internal melting
[8586]	344
[9935]	345	zfmdt = - rhoi * zdeltah(ji,jk) ! Recompute mass flux [kg/m2, >0]
[8586]	346
[9274]	347	hfx_res_1d(ji) = hfx_res_1d(ji) + zfmdt * a_i_1d(ji) * zEi * r1_rdtice ! Heat flux to the ocean [W.m-2], <0
	348	! ice enthalpy zEi is "sent" to the ocean
[9935]	349	sfx_res_1d(ji) = sfx_res_1d(ji) - rhoi * a_i_1d(ji) * zdeltah(ji,jk) * s_i_1d(ji) * r1_rdtice ! Salt flux
[9274]	350	! using s_i_1d and not sz_i_1d(jk) is ok
[9935]	351	wfx_res_1d(ji) = wfx_res_1d(ji) - rhoi * a_i_1d(ji) * zdeltah(ji,jk) * r1_rdtice ! Mass flux
[8586]	352
[9274]	353	ELSE !-- Surface melting
[8586]	354
[9935]	355	zEi = - e_i_1d(ji,jk) * r1_rhoi ! Specific enthalpy of layer k [J/kg, <0]
[8586]	356	zEw = rcp * ztmelts ! Specific enthalpy of resulting meltwater [J/kg, <0]
	357	zdE = zEi - zEw ! Specific enthalpy difference < 0
	358
[9922]	359	zfmdt = - zq_top(ji) / zdE ! Mass flux to the ocean [kg/m2, >0]
[8586]	360
[9935]	361	zdeltah(ji,jk) = - zfmdt * r1_rhoi ! Melt of layer jk [m, <0]
[8586]	362
	363	zdeltah(ji,jk) = MIN( 0._wp , MAX( zdeltah(ji,jk) , - zh_i(ji,jk) ) ) ! Melt of layer jk cannot exceed the layer thickness [m, <0]
	364
[9935]	365	zq_top(ji) = MAX( 0._wp , zq_top(ji) - zdeltah(ji,jk) * rhoi * zdE ) ! update available heat
[8586]	366
[9750]	367	dh_i_sum(ji) = dh_i_sum(ji) + zdeltah(ji,jk) ! Cumulate surface melt
[8586]	368
[9935]	369	zfmdt = - rhoi * zdeltah(ji,jk) ! Recompute mass flux [kg/m2, >0]
[8586]	370
	371	zQm = zfmdt * zEw ! Energy of the melt water sent to the ocean [J/m2, <0]
	372
[9935]	373	sfx_sum_1d(ji) = sfx_sum_1d(ji) - rhoi * a_i_1d(ji) * zdeltah(ji,jk) * s_i_1d(ji) * r1_rdtice ! Salt flux >0
[9274]	374	! using s_i_1d and not sz_i_1d(jk) is ok)
	375	hfx_thd_1d(ji) = hfx_thd_1d(ji) + zfmdt * a_i_1d(ji) * zEw * r1_rdtice ! Heat flux [W.m-2], < 0
	376	hfx_sum_1d(ji) = hfx_sum_1d(ji) - zfmdt * a_i_1d(ji) * zdE * r1_rdtice ! Heat flux used in this process [W.m-2], > 0
	377	!
[9935]	378	wfx_sum_1d(ji) = wfx_sum_1d(ji) - rhoi * a_i_1d(ji) * zdeltah(ji,jk) * r1_rdtice ! Mass flux
[8586]	379
	380	END IF
[9274]	381
	382	! Ice sublimation
	383	! ---------------
[9935]	384	zdum = MAX( - ( zh_i(ji,jk) + zdeltah(ji,jk) ) , - zevap_rema(ji) * r1_rhoi )
[9274]	385	zdeltah (ji,jk) = zdeltah (ji,jk) + zdum
	386	dh_i_sub(ji) = dh_i_sub(ji) + zdum
	387
[9935]	388	sfx_sub_1d(ji) = sfx_sub_1d(ji) - rhoi * a_i_1d(ji) * zdum * s_i_1d(ji) * r1_rdtice ! Salt flux >0
[9274]	389	! clem: flux is sent to the ocean for simplicity
	390	! but salt should remain in the ice except
	391	! if all ice is melted. => must be corrected
	392	hfx_sub_1d(ji) = hfx_sub_1d(ji) + zdum * e_i_1d(ji,jk) * a_i_1d(ji) * r1_rdtice ! Heat flux [W.m-2], < 0
[8586]	393
[9935]	394	wfx_ice_sub_1d(ji) = wfx_ice_sub_1d(ji) - rhoi * a_i_1d(ji) * zdum * r1_rdtice ! Mass flux > 0
[9274]	395
[8586]	396	! update remaining mass flux
[9935]	397	zevap_rema(ji) = zevap_rema(ji) + zdum * rhoi
[8586]	398
	399	! record which layers have disappeared (for bottom melting)
	400	! => icount=0 : no layer has vanished
	401	! => icount=5 : 5 layers have vanished
	402	rswitch = MAX( 0._wp , SIGN( 1._wp , - ( zh_i(ji,jk) + zdeltah(ji,jk) ) ) )
	403	icount(ji,jk) = NINT( rswitch )
	404	zh_i(ji,jk) = MAX( 0._wp , zh_i(ji,jk) + zdeltah(ji,jk) )
	405
	406	! update heat content (J.m-2) and layer thickness
	407	eh_i_old(ji,jk) = eh_i_old(ji,jk) + zdeltah(ji,jk) * e_i_1d(ji,jk)
	408	h_i_old (ji,jk) = h_i_old (ji,jk) + zdeltah(ji,jk)
	409	END DO
	410	END DO
[9274]	411
[8586]	412	! update ice thickness
	413	DO ji = 1, npti
[9750]	414	h_i_1d(ji) = MAX( 0._wp , h_i_1d(ji) + dh_i_sum(ji) + dh_i_itm(ji) + dh_i_sub(ji) )
[8586]	415	END DO
	416
	417	! remaining "potential" evap is sent to ocean
	418	DO ji = 1, npti
	419	wfx_err_sub_1d(ji) = wfx_err_sub_1d(ji) - zevap_rema(ji) * a_i_1d(ji) * r1_rdtice ! <=0 (net evap for the ocean in kg.m-2.s-1)
	420	END DO
	421
	422
[9274]	423	! Ice Basal growth
[8586]	424	!------------------
	425	! Basal growth is driven by heat imbalance at the ice-ocean interface,
[9916]	426	! between the inner conductive flux (qcn_ice_bot), from the open water heat flux
[9913]	427	! (fhld) and the sensible ice-ocean flux (qsb_ice_bot).
[9916]	428	! qcn_ice_bot is positive downwards. qsb_ice_bot and fhld are positive to the ice
[8586]	429
	430	! If salinity varies in time, an iterative procedure is required, because
	431	! the involved quantities are inter-dependent.
[9750]	432	! Basal growth (dh_i_bog) depends upon new ice specific enthalpy (zEi),
	433	! which depends on forming ice salinity (s_i_new), which depends on dh/dt (dh_i_bog)
[8586]	434	! -> need for an iterative procedure, which converges quickly
	435
	436	num_iter_max = 1
	437	IF( nn_icesal == 2 ) num_iter_max = 5 ! salinity varying in time
	438
	439	DO ji = 1, npti
	440	IF( zf_tt(ji) < 0._wp ) THEN
[9274]	441	DO iter = 1, num_iter_max ! iterations
[8586]	442
	443	! New bottom ice salinity (Cox & Weeks, JGR88 )
	444	!--- zswi1 if dh/dt < 2.0e-8
	445	!--- zswi12 if 2.0e-8 < dh/dt < 3.6e-7
	446	!--- zswi2 if dh/dt > 3.6e-7
[9750]	447	zgrr = MIN( 1.0e-3, MAX ( dh_i_bog(ji) * r1_rdtice , epsi10 ) )
[9274]	448	zswi2 = MAX( 0._wp , SIGN( 1._wp , zgrr - 3.6e-7 ) )
	449	zswi12 = MAX( 0._wp , SIGN( 1._wp , zgrr - 2.0e-8 ) ) * ( 1.0 - zswi2 )
	450	zswi1 = 1. - zswi2 * zswi12
	451	zfracs = MIN( zswi1 * 0.12 + zswi12 * ( 0.8925 + 0.0568 * LOG( 100.0 * zgrr ) ) &
	452	& + zswi2 * 0.26 / ( 0.26 + 0.74 * EXP ( - 724300.0 * zgrr ) ) , 0.5 )
[8586]	453
[9274]	454	s_i_new(ji) = zswitch_sal * zfracs * sss_1d(ji) + ( 1. - zswitch_sal ) * s_i_1d(ji) ! New ice salinity
[8586]	455
[9935]	456	ztmelts = - rTmlt * s_i_new(ji) ! New ice melting point (C)
[9274]	457
	458	zt_i_new = zswitch_sal * t_bo_1d(ji) + ( 1. - zswitch_sal) * t_i_1d(ji, nlay_i)
[8586]	459
[9935]	460	zEi = rcpi * ( zt_i_new - (ztmelts+rt0) ) & ! Specific enthalpy of forming ice (J/kg, <0)
	461	& - rLfus * ( 1.0 - ztmelts / ( zt_i_new - rt0 ) ) + rcp * ztmelts
[8586]	462
[9274]	463	zEw = rcp * ( t_bo_1d(ji) - rt0 ) ! Specific enthalpy of seawater (J/kg, < 0)
[8586]	464
[9274]	465	zdE = zEi - zEw ! Specific enthalpy difference (J/kg, <0)
[8586]	466
[9935]	467	dh_i_bog(ji) = rdt_ice * MAX( 0._wp , zf_tt(ji) / ( zdE * rhoi ) )
[8586]	468
	469	END DO
	470	! Contribution to Energy and Salt Fluxes
[9935]	471	zfmdt = - rhoi * dh_i_bog(ji) ! Mass flux x time step (kg/m2, < 0)
[8586]	472
[9274]	473	hfx_thd_1d(ji) = hfx_thd_1d(ji) + zfmdt * a_i_1d(ji) * zEw * r1_rdtice ! Heat flux to the ocean [W.m-2], >0
	474	hfx_bog_1d(ji) = hfx_bog_1d(ji) - zfmdt * a_i_1d(ji) * zdE * r1_rdtice ! Heat flux used in this process [W.m-2], <0
[8586]	475
[9935]	476	sfx_bog_1d(ji) = sfx_bog_1d(ji) - rhoi * a_i_1d(ji) * dh_i_bog(ji) * s_i_new(ji) * r1_rdtice ! Salt flux, <0
[8586]	477
[9935]	478	wfx_bog_1d(ji) = wfx_bog_1d(ji) - rhoi * a_i_1d(ji) * dh_i_bog(ji) * r1_rdtice ! Mass flux, <0
[8586]	479
	480	! update heat content (J.m-2) and layer thickness
[9935]	481	eh_i_old(ji,nlay_i+1) = eh_i_old(ji,nlay_i+1) + dh_i_bog(ji) * (-zEi * rhoi)
[9750]	482	h_i_old (ji,nlay_i+1) = h_i_old (ji,nlay_i+1) + dh_i_bog(ji)
[8586]	483
	484	ENDIF
	485
	486	END DO
	487
[9274]	488	! Ice Basal melt
	489	!---------------
[8586]	490	zdeltah(1:npti,:) = 0._wp ! important
	491	DO jk = nlay_i, 1, -1
	492	DO ji = 1, npti
	493	IF( zf_tt(ji) > 0._wp .AND. jk > icount(ji,jk) ) THEN ! do not calculate where layer has already disappeared by surface melting
	494
[9935]	495	ztmelts = - rTmlt * sz_i_1d(ji,jk) ! Melting point of layer jk (C)
[8586]	496
[9274]	497	IF( t_i_1d(ji,jk) >= (ztmelts+rt0) ) THEN !-- Internal melting
[8586]	498
[9935]	499	zEi = - e_i_1d(ji,jk) * r1_rhoi ! Specific enthalpy of melting ice (J/kg, <0)
[8586]	500	zdE = 0._wp ! Specific enthalpy difference (J/kg, <0)
[9274]	501	! set up at 0 since no energy is needed to melt water...(it is already melted)
[8586]	502	zdeltah (ji,jk) = MIN( 0._wp , - zh_i(ji,jk) ) ! internal melting occurs when the internal temperature is above freezing
	503	! this should normally not happen, but sometimes, heat diffusion leads to this
	504
[9750]	505	dh_i_itm (ji) = dh_i_itm(ji) + zdeltah(ji,jk)
[8586]	506
[9935]	507	zfmdt = - zdeltah(ji,jk) * rhoi ! Mass flux x time step > 0
[8586]	508
[9274]	509	hfx_res_1d(ji) = hfx_res_1d(ji) + zfmdt * a_i_1d(ji) * zEi * r1_rdtice ! Heat flux to the ocean [W.m-2], <0
	510	! ice enthalpy zEi is "sent" to the ocean
[9935]	511	sfx_res_1d(ji) = sfx_res_1d(ji) - rhoi * a_i_1d(ji) * zdeltah(ji,jk) * s_i_1d(ji) * r1_rdtice ! Salt flux
[9274]	512	! using s_i_1d and not sz_i_1d(jk) is ok
[9935]	513	wfx_res_1d(ji) = wfx_res_1d(ji) - rhoi * a_i_1d(ji) * zdeltah(ji,jk) * r1_rdtice ! Mass flux
[8586]	514
	515	! update heat content (J.m-2) and layer thickness
	516	eh_i_old(ji,jk) = eh_i_old(ji,jk) + zdeltah(ji,jk) * e_i_1d(ji,jk)
	517	h_i_old (ji,jk) = h_i_old (ji,jk) + zdeltah(ji,jk)
	518
[9274]	519	ELSE !-- Basal melting
[8586]	520
[9935]	521	zEi = - e_i_1d(ji,jk) * r1_rhoi ! Specific enthalpy of melting ice (J/kg, <0)
[9274]	522	zEw = rcp * ztmelts ! Specific enthalpy of meltwater (J/kg, <0)
	523	zdE = zEi - zEw ! Specific enthalpy difference (J/kg, <0)
[8586]	524
[9922]	525	zfmdt = - zq_bot(ji) / zdE ! Mass flux x time step (kg/m2, >0)
[8586]	526
[9935]	527	zdeltah(ji,jk) = - zfmdt * r1_rhoi ! Gross thickness change
[8586]	528
[9274]	529	zdeltah(ji,jk) = MIN( 0._wp , MAX( zdeltah(ji,jk), - zh_i(ji,jk) ) ) ! bound thickness change
[8586]	530
[9935]	531	zq_bot(ji) = MAX( 0._wp , zq_bot(ji) - zdeltah(ji,jk) * rhoi * zdE ) ! update available heat. MAX is necessary for roundup errors
[8586]	532
[9922]	533	dh_i_bom(ji) = dh_i_bom(ji) + zdeltah(ji,jk) ! Update basal melt
[8586]	534
[9935]	535	zfmdt = - zdeltah(ji,jk) * rhoi ! Mass flux x time step > 0
[8586]	536
[9274]	537	zQm = zfmdt * zEw ! Heat exchanged with ocean
[8586]	538
[9274]	539	hfx_thd_1d(ji) = hfx_thd_1d(ji) + zfmdt * a_i_1d(ji) * zEw * r1_rdtice ! Heat flux to the ocean [W.m-2], <0
	540	hfx_bom_1d(ji) = hfx_bom_1d(ji) - zfmdt * a_i_1d(ji) * zdE * r1_rdtice ! Heat used in this process [W.m-2], >0
[8586]	541
[9935]	542	sfx_bom_1d(ji) = sfx_bom_1d(ji) - rhoi * a_i_1d(ji) * zdeltah(ji,jk) * s_i_1d(ji) * r1_rdtice ! Salt flux
[9274]	543	! using s_i_1d and not sz_i_1d(jk) is ok
[8586]	544
[9935]	545	wfx_bom_1d(ji) = wfx_bom_1d(ji) - rhoi * a_i_1d(ji) * zdeltah(ji,jk) * r1_rdtice ! Mass flux
[8586]	546
	547	! update heat content (J.m-2) and layer thickness
	548	eh_i_old(ji,jk) = eh_i_old(ji,jk) + zdeltah(ji,jk) * e_i_1d(ji,jk)
	549	h_i_old (ji,jk) = h_i_old (ji,jk) + zdeltah(ji,jk)
	550	ENDIF
	551
	552	ENDIF
	553	END DO
	554	END DO
	555
	556	! Update temperature, energy
[9274]	557	! --------------------------
[8586]	558	DO ji = 1, npti
[9750]	559	h_i_1d(ji) = MAX( 0._wp , h_i_1d(ji) + dh_i_bog(ji) + dh_i_bom(ji) )
[8586]	560	END DO
	561
[9274]	562	! If heat still available then melt more snow
[8586]	563	!-------------------------------------------
	564	zdeltah(1:npti,:) = 0._wp ! important
	565	DO ji = 1, npti
[9922]	566	zq_rema (ji) = zq_top(ji) + zq_bot(ji)
[9274]	567	rswitch = 1._wp - MAX( 0._wp, SIGN( 1._wp, - h_s_1d(ji) ) ) ! =1 if snow
	568	rswitch = rswitch * MAX( 0._wp, SIGN( 1._wp, e_s_1d(ji,1) - epsi20 ) )
	569	zdeltah (ji,1) = - rswitch * zq_rema(ji) / MAX( e_s_1d(ji,1), epsi20 )
	570	zdeltah (ji,1) = MIN( 0._wp , MAX( zdeltah(ji,1) , - h_s_1d(ji) ) ) ! bound melting
	571	dh_s_tot(ji) = dh_s_tot(ji) + zdeltah(ji,1)
	572	h_s_1d (ji) = h_s_1d (ji) + zdeltah(ji,1)
[8586]	573
[9274]	574	zq_rema(ji) = zq_rema(ji) + zdeltah(ji,1) * e_s_1d(ji,1) ! update available heat (J.m-2)
	575	hfx_snw_1d(ji) = hfx_snw_1d(ji) - zdeltah(ji,1) * a_i_1d(ji) * e_s_1d(ji,1) * r1_rdtice ! Heat used to melt snow, W.m-2 (>0)
[9935]	576	wfx_snw_sum_1d(ji) = wfx_snw_sum_1d(ji) - rhos * a_i_1d(ji) * zdeltah(ji,1) * r1_rdtice ! Mass flux
[8637]	577	dh_s_mlt(ji) = dh_s_mlt(ji) + zdeltah(ji,1)
[8586]	578	!
	579	! Remaining heat flux (W.m-2) is sent to the ocean heat budget
[9912]	580	qt_oce_ai_1d(ji) = qt_oce_ai_1d(ji) + ( zq_rema(ji) * a_i_1d(ji) ) * r1_rdtice
[8586]	581
	582	IF( ln_icectl .AND. zq_rema(ji) < 0. .AND. lwp ) WRITE(numout,*) 'ALERTE zq_rema <0 = ', zq_rema(ji)
	583	END DO
	584
	585	!
[9274]	586	! Snow-Ice formation
	587	! ------------------
[8586]	588	! When snow load excesses Archimede's limit, snow-ice interface goes down under sea-level,
	589	! flooding of seawater transforms snow into ice dh_snowice is positive for the ice
[9935]	590	z1_rho = 1._wp / ( rhos+rau0-rhoi )
[8586]	591	DO ji = 1, npti
	592	!
[9935]	593	dh_snowice(ji) = MAX( 0._wp , ( rhos * h_s_1d(ji) + (rhoi-rau0) * h_i_1d(ji) ) * z1_rho )
[8586]	594
	595	h_i_1d(ji) = h_i_1d(ji) + dh_snowice(ji)
	596	h_s_1d(ji) = h_s_1d(ji) - dh_snowice(ji)
	597
	598	! Contribution to energy flux to the ocean [J/m2], >0 (if sst<0)
[9935]	599	zfmdt = ( rhos - rhoi ) * dh_snowice(ji) ! <0
[8586]	600	zEw = rcp * sst_1d(ji)
	601	zQm = zfmdt * zEw
	602
[9274]	603	hfx_thd_1d(ji) = hfx_thd_1d(ji) + zfmdt * a_i_1d(ji) * zEw * r1_rdtice ! Heat flux
[8586]	604
[9274]	605	sfx_sni_1d(ji) = sfx_sni_1d(ji) + sss_1d(ji) * a_i_1d(ji) * zfmdt * r1_rdtice ! Salt flux
[8586]	606
	607	! Case constant salinity in time: virtual salt flux to keep salinity constant
[8637]	608	IF( nn_icesal /= 2 ) THEN
[8586]	609	sfx_bri_1d(ji) = sfx_bri_1d(ji) - sss_1d (ji) * a_i_1d(ji) * zfmdt * r1_rdtice & ! put back sss_m into the ocean
[9935]	610	& - s_i_1d(ji) * a_i_1d(ji) * dh_snowice(ji) * rhoi * r1_rdtice ! and get rn_icesal from the ocean
[8586]	611	ENDIF
	612
[9274]	613	! Mass flux: All snow is thrown in the ocean, and seawater is taken to replace the volume
[9935]	614	wfx_sni_1d(ji) = wfx_sni_1d(ji) - a_i_1d(ji) * dh_snowice(ji) * rhoi * r1_rdtice
	615	wfx_snw_sni_1d(ji) = wfx_snw_sni_1d(ji) + a_i_1d(ji) * dh_snowice(ji) * rhos * r1_rdtice
[8586]	616
	617	! update heat content (J.m-2) and layer thickness
	618	eh_i_old(ji,0) = eh_i_old(ji,0) + dh_snowice(ji) * e_s_1d(ji,1) + zfmdt * zEw
	619	h_i_old (ji,0) = h_i_old (ji,0) + dh_snowice(ji)
	620
	621	END DO
	622
	623	!
	624	! Update temperature, energy
[9274]	625	! --------------------------
[8586]	626	DO ji = 1, npti
[9274]	627	rswitch = 1._wp - MAX( 0._wp , SIGN( 1._wp , - h_i_1d(ji) ) )
	628	t_su_1d(ji) = rswitch * t_su_1d(ji) + ( 1._wp - rswitch ) * rt0
[8586]	629	END DO
	630
	631	DO jk = 1, nlay_s
	632	DO ji = 1,npti
[10785]	633	! where there is no ice or no snow
	634	rswitch = ( 1._wp - MAX( 0._wp, SIGN( 1._wp, - h_s_1d(ji) ) ) ) * ( 1._wp - MAX( 0._wp, SIGN(1._wp, - h_i_1d(ji) ) ) )
	635	! mass & energy loss to the ocean
	636	hfx_res_1d(ji) = hfx_res_1d(ji) + ( 1._wp - rswitch ) * &
	637	& ( e_s_1d(ji,jk) * h_s_1d(ji) * r1_nlay_s * a_i_1d(ji) * r1_rdtice ) ! heat flux to the ocean [W.m-2], < 0
	638	wfx_res_1d(ji) = wfx_res_1d(ji) + ( 1._wp - rswitch ) * &
	639	& ( rhos * h_s_1d(ji) * r1_nlay_s * a_i_1d(ji) * r1_rdtice ) ! mass flux
	640	! update energy (mass is updated in the next loop)
[8586]	641	e_s_1d(ji,jk) = rswitch * e_s_1d(ji,jk)
	642	! recalculate t_s_1d from e_s_1d
[9935]	643	t_s_1d(ji,jk) = rt0 + rswitch * ( - e_s_1d(ji,jk) * r1_rhos * r1_rcpi + rLfus * r1_rcpi )
[8586]	644	END DO
	645	END DO
	646
[10785]	647	! --- ensure that a_i = 0 & h_s = 0 where h_i = 0 ---
	648	WHERE( h_i_1d(1:npti) == 0._wp )
	649	a_i_1d(1:npti) = 0._wp
	650	h_s_1d(1:npti) = 0._wp
	651	END WHERE
[8586]	652	!
	653	END SUBROUTINE ice_thd_dh
	654
	655
	656	!!--------------------------------------------------------------------------
	657	!! INTERFACE ice_thd_snwblow
[9274]	658	!!
[8586]	659	!! ** Purpose : Compute distribution of precip over the ice
[9274]	660	!!
	661	!! Snow accumulation in one thermodynamic time step
	662	!! snowfall is partitionned between leads and ice.
	663	!! If snow fall was uniform, a fraction (1-at_i) would fall into leads
	664	!! but because of the winds, more snow falls on leads than on sea ice
	665	!! and a greater fraction (1-at_i)^beta of the total mass of snow
	666	!! (beta < 1) falls in leads.
	667	!! In reality, beta depends on wind speed,
	668	!! and should decrease with increasing wind speed but here, it is
	669	!! considered as a constant. an average value is 0.66
[8586]	670	!!--------------------------------------------------------------------------
	671	!!gm I think it can be usefull to set this as a FUNCTION, not a SUBROUTINE....
	672	SUBROUTINE ice_thd_snwblow_2d( pin, pout )
	673	REAL(wp), DIMENSION(:,:), INTENT(in ) :: pin ! previous fraction lead ( 1. - a_i_b )
	674	REAL(wp), DIMENSION(:,:), INTENT(inout) :: pout
	675	pout = ( 1._wp - ( pin )**rn_blow_s )
	676	END SUBROUTINE ice_thd_snwblow_2d
	677
	678	SUBROUTINE ice_thd_snwblow_1d( pin, pout )
	679	REAL(wp), DIMENSION(:), INTENT(in ) :: pin
	680	REAL(wp), DIMENSION(:), INTENT(inout) :: pout
	681	pout = ( 1._wp - ( pin )**rn_blow_s )
	682	END SUBROUTINE ice_thd_snwblow_1d
	683
	684	#else
	685	!!----------------------------------------------------------------------
[9570]	686	!! Default option NO SI3 sea-ice model
[8586]	687	!!----------------------------------------------------------------------
	688	#endif
	689
	690	!!======================================================================
	691	END MODULE icethd_dh

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source: NEMO/branches/UKMO/NEMO_4.0_GO8_coupled_iodef/src/ICE/icethd_dh.F90 @ 11954

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