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! C-grid ice dynamics : U & V-points (same as ocean)
DO_2D( nn_hls, nn_hls, nn_hls, nn_hls )
wndm_ice(ji,jj) = SQRT( pwndi(ji,jj) * pwndi(ji,jj) + pwndj(ji,jj) * pwndj(ji,jj) )
END_2D
!
! Make ice-atm. drag dependent on ice concentration
SELECT CASE( nblk_ice )
CASE( np_ice_cst )
! Constant bulk transfer coefficients over sea-ice:
Cd_ice(:,:) = rn_Cd_i
Ch_ice(:,:) = rn_Ch_i
Ce_ice(:,:) = rn_Ce_i
! no height adjustment, keeping zt values:
theta_zu_i(:,:) = ptair(:,:)
q_zu_i(:,:) = pqair(:,:)
CASE( np_ice_an05 ) ! calculate new drag from Lupkes(2015) equations
ztmp(:,:) = q_sat( ptsui(:,:), pslp(:,:), l_ice=.TRUE. ) ! temporary array for SSQ
CALL turb_ice_an05( rn_zqt, rn_zu, ptsui, ptair, ztmp, pqair, wndm_ice, &
& Cd_ice, Ch_ice, Ce_ice, theta_zu_i, q_zu_i )
!!
CASE( np_ice_lu12 )
ztmp(:,:) = q_sat( ptsui(:,:), pslp(:,:), l_ice=.TRUE. ) ! temporary array for SSQ
CALL turb_ice_lu12( rn_zqt, rn_zu, ptsui, ptair, ztmp, pqair, wndm_ice, fr_i, &
& Cd_ice, Ch_ice, Ce_ice, theta_zu_i, q_zu_i )
!!
CASE( np_ice_lg15 ) ! calculate new drag from Lupkes(2015) equations
ztmp(:,:) = q_sat( ptsui(:,:), pslp(:,:), l_ice=.TRUE. ) ! temporary array for SSQ
CALL turb_ice_lg15( rn_zqt, rn_zu, ptsui, ptair, ztmp, pqair, wndm_ice, fr_i, &
& Cd_ice, Ch_ice, Ce_ice, theta_zu_i, q_zu_i )
!!
END SELECT
IF( iom_use('Cd_ice').OR.iom_use('Ce_ice').OR.iom_use('Ch_ice').OR.iom_use('taum_ice').OR.iom_use('utau_ice').OR.iom_use('vtau_ice') ) &
& ztmp(:,:) = ( 1._wp - MAX(0._wp, SIGN( 1._wp, 1.E-6_wp - fr_i )) )*tmask(:,:,1) ! mask for presence of ice !
IF( iom_use('Cd_ice') ) CALL iom_put("Cd_ice", Cd_ice*ztmp)
IF( iom_use('Ce_ice') ) CALL iom_put("Ce_ice", Ce_ice*ztmp)
IF( iom_use('Ch_ice') ) CALL iom_put("Ch_ice", Ch_ice*ztmp)
IF( ln_blk ) THEN
! ---------------------------------------------------- !
! Wind stress relative to nonmoving ice ( U10m ) !
! ---------------------------------------------------- !
! supress moving ice in wind stress computation as we don't know how to do it properly...
DO_2D( 0, 1, 0, 1 ) ! at T point
zztmp1 = rhoa(ji,jj) * Cd_ice(ji,jj) * wndm_ice(ji,jj)
putaui(ji,jj) = zztmp1 * pwndi(ji,jj)
pvtaui(ji,jj) = zztmp1 * pwndj(ji,jj)
END_2D
!#LB: saving the module, and x-y components, of the ai wind-stress at T-points: NOT weighted by the ice concentration !!!
IF(iom_use('taum_ice')) CALL iom_put('taum_ice', SQRT( putaui*putaui + pvtaui*pvtaui )*ztmp )
!#LB: These 2 lines below mostly here for 'STATION_ASF' test-case, otherwize "utau_oi" (U-grid) and vtau_oi" (V-grid) does the job in: [ICE/icedyn_rhg_evp.F90])
IF(iom_use('utau_ice')) CALL iom_put("utau_ice", putaui*ztmp) ! utau at T-points!
IF(iom_use('vtau_ice')) CALL iom_put("vtau_ice", pvtaui*ztmp) ! vtau at T-points!
!
DO_2D( 0, 0, 0, 0 ) ! U & V-points (same as ocean).
!#LB: QUESTION?? so SI3 expects wind stress vector to be provided at U & V points? Not at T-points ?
! take care of the land-sea mask to avoid "pollution" of coastal stress. p[uv]taui used in frazil and rheology
zztmp1 = 0.5_wp * ( 2. - umask(ji,jj,1) ) * MAX( tmask(ji,jj,1),tmask(ji+1,jj ,1) )
zztmp2 = 0.5_wp * ( 2. - vmask(ji,jj,1) ) * MAX( tmask(ji,jj,1),tmask(ji ,jj+1,1) )
putaui(ji,jj) = zztmp1 * ( putaui(ji,jj) + putaui(ji+1,jj ) )
pvtaui(ji,jj) = zztmp2 * ( pvtaui(ji,jj) + pvtaui(ji ,jj+1) )
END_2D
CALL lbc_lnk( 'sbcblk', putaui, 'U', -1._wp, pvtaui, 'V', -1._wp )
!
IF(sn_cfctl%l_prtctl) CALL prt_ctl( tab2d_1=putaui , clinfo1=' blk_ice: putaui : ' &
& , tab2d_2=pvtaui , clinfo2=' pvtaui : ' )
ELSE ! ln_abl
DO_2D( nn_hls, nn_hls, nn_hls, nn_hls )
pcd_dui(ji,jj) = wndm_ice(ji,jj) * Cd_ice(ji,jj)
pseni (ji,jj) = wndm_ice(ji,jj) * Ch_ice(ji,jj)
pevpi (ji,jj) = wndm_ice(ji,jj) * Ce_ice(ji,jj)
END_2D
!#LB:
pssqi(:,:) = q_sat( ptsui(:,:), pslp(:,:), l_ice=.TRUE. ) ; ! more accurate way to obtain ssq !
!#LB.
ENDIF !IF( ln_blk )
!
IF(sn_cfctl%l_prtctl) CALL prt_ctl(tab2d_1=wndm_ice , clinfo1=' blk_ice: wndm_ice : ')
!
END SUBROUTINE blk_ice_1
SUBROUTINE blk_ice_2( ptsu, phs, phi, palb, ptair, pqair, pslp, pdqlw, pprec, psnow )
!!---------------------------------------------------------------------
!! *** ROUTINE blk_ice_2 ***
!!
!! ** Purpose : provide the heat and mass fluxes at air-ice interface
!!
!! ** Method : compute heat and freshwater exchanged
!! between atmosphere and sea-ice using bulk formulation
!! formulea, ice variables and read atmmospheric fields.
!!
!! caution : the net upward water flux has with mm/day unit
!!---------------------------------------------------------------------
REAL(wp), DIMENSION(:,:,:), INTENT(in) :: ptsu ! sea ice surface temperature [K]
REAL(wp), DIMENSION(:,:,:), INTENT(in) :: phs ! snow thickness
REAL(wp), DIMENSION(:,:,:), INTENT(in) :: phi ! ice thickness
REAL(wp), DIMENSION(:,:,:), INTENT(in) :: palb ! ice albedo (all skies)
REAL(wp), DIMENSION(:,: ), INTENT(in) :: ptair ! potential temperature of air #LB: okay ???
REAL(wp), DIMENSION(:,: ), INTENT(in) :: pqair ! specific humidity of air
REAL(wp), DIMENSION(:,: ), INTENT(in) :: pslp
REAL(wp), DIMENSION(:,: ), INTENT(in) :: pdqlw
REAL(wp), DIMENSION(:,: ), INTENT(in) :: pprec
REAL(wp), DIMENSION(:,: ), INTENT(in) :: psnow
!!
INTEGER :: ji, jj, jl ! dummy loop indices
REAL(wp) :: zst, zst3, zsq ! local variable
REAL(wp) :: zcoef_dqlw, zcoef_dqla ! - -
REAL(wp) :: zztmp, zzblk, zztmp1, z1_rLsub ! - -
REAL(wp), DIMENSION(jpi,jpj,jpl) :: z_qlw ! long wave heat flux over ice
REAL(wp), DIMENSION(jpi,jpj,jpl) :: z_qsb ! sensible heat flux over ice
REAL(wp), DIMENSION(jpi,jpj,jpl) :: z_dqlw ! long wave heat sensitivity over ice
REAL(wp), DIMENSION(jpi,jpj,jpl) :: z_dqsb ! sensible heat sensitivity over ice
REAL(wp), DIMENSION(jpi,jpj) :: zevap, zsnw ! evaporation and snw distribution after wind blowing (SI3)
REAL(wp), DIMENSION(jpi,jpj) :: ztri
REAL(wp), DIMENSION(jpi,jpj) :: zcptrain, zcptsnw, zcptn ! Heat content per unit mass (J/kg)
!!---------------------------------------------------------------------
!
zcoef_dqlw = 4._wp * emiss_i * stefan ! local scalars
!
zztmp = 1. / ( 1. - albo )
dqla_ice(:,:,:) = 0._wp
! Heat content per unit mass (J/kg)
zcptrain(:,:) = ( ptair - rt0 ) * rcp * tmask(:,:,1)
zcptsnw (:,:) = ( MIN( ptair, rt0 ) - rt0 ) * rcpi * tmask(:,:,1)
zcptn (:,:) = sst_m * rcp * tmask(:,:,1)
!
! ! ========================== !
DO jl = 1, jpl ! Loop over ice categories !
! ! ========================== !
DO_2D( nn_hls, nn_hls, nn_hls, nn_hls )
zst = ptsu(ji,jj,jl) ! surface temperature of sea-ice [K]
zsq = q_sat( zst, pslp(ji,jj), l_ice=.TRUE. ) ! surface saturation specific humidity when ice present
! ----------------------------!
! I Radiative FLUXES !
! ----------------------------!
! Short Wave (sw)
qsr_ice(ji,jj,jl) = zztmp * ( 1. - palb(ji,jj,jl) ) * qsr(ji,jj)
! Long Wave (lw)
zst3 = zst * zst * zst
z_qlw(ji,jj,jl) = emiss_i * ( pdqlw(ji,jj) - stefan * zst * zst3 ) * tmask(ji,jj,1)
! lw sensitivity
z_dqlw(ji,jj,jl) = zcoef_dqlw * zst3
! ----------------------------!
! II Turbulent FLUXES !
! ----------------------------!
! ... turbulent heat fluxes with Ch_ice recalculated in blk_ice_1
! Common term in bulk F. equations...
zzblk = rhoa(ji,jj) * wndm_ice(ji,jj)
! Sensible Heat
zztmp1 = zzblk * rCp_air * Ch_ice(ji,jj)
z_qsb (ji,jj,jl) = zztmp1 * (zst - theta_zu_i(ji,jj))
z_dqsb(ji,jj,jl) = zztmp1 ! ==> Qsens sensitivity (Dqsb_ice/Dtn_ice)
! Latent Heat
zztmp1 = zzblk * rLsub * Ce_ice(ji,jj)
qla_ice(ji,jj,jl) = MAX( zztmp1 * (zsq - q_zu_i(ji,jj)) , 0._wp ) ! #LB: only sublimation (and not condensation) ???
IF(qla_ice(ji,jj,jl)>0._wp) dqla_ice(ji,jj,jl) = zztmp1*dq_sat_dt_ice(zst, pslp(ji,jj)) ! ==> Qlat sensitivity (dQlat/dT)
! !#LB: dq_sat_dt_ice() in "sbc_phy.F90"
!#LB: without this unjustified "condensation sensure":
!qla_ice( ji,jj,jl) = zztmp1 * (zsq - q_zu_i(ji,jj))
!dqla_ice(ji,jj,jl) = zztmp1 * dq_sat_dt_ice(zst, pslp(ji,jj)) ! ==> Qlat sensitivity (dQlat/dT)
! ----------------------------!
! III Total FLUXES !
! ----------------------------!
! Downward Non Solar flux
qns_ice (ji,jj,jl) = z_qlw (ji,jj,jl) - z_qsb (ji,jj,jl) - qla_ice (ji,jj,jl)
! Total non solar heat flux sensitivity for ice
dqns_ice(ji,jj,jl) = - ( z_dqlw(ji,jj,jl) + z_dqsb(ji,jj,jl) + dqla_ice(ji,jj,jl) ) !#LB: correct signs ????
END_2D
!
END DO
!
tprecip(:,:) = pprec(:,:) * rn_pfac * tmask(:,:,1) ! total precipitation [kg/m2/s]
sprecip(:,:) = psnow(:,:) * rn_pfac * tmask(:,:,1) ! solid precipitation [kg/m2/s]
CALL iom_put( 'snowpre', sprecip ) ! Snow precipitation
CALL iom_put( 'precip' , tprecip ) ! Total precipitation
! --- evaporation --- !
z1_rLsub = 1._wp / rLsub
evap_ice (:,:,:) = rn_efac * qla_ice (:,:,:) * z1_rLsub ! sublimation
devap_ice(:,:,:) = rn_efac * dqla_ice(:,:,:) * z1_rLsub ! d(sublimation)/dT
zevap (:,:) = emp(:,:) + tprecip(:,:) ! evaporation over ocean !LB: removed rn_efac here, correct???
! --- evaporation minus precipitation --- !
zsnw(:,:) = 0._wp
CALL ice_var_snwblow( (1.-at_i_b(:,:)), zsnw ) ! snow distribution over ice after wind blowing
emp_oce(:,:) = ( 1._wp - at_i_b(:,:) ) * zevap(:,:) - ( tprecip(:,:) - sprecip(:,:) ) - sprecip(:,:) * (1._wp - zsnw )
emp_ice(:,:) = SUM( a_i_b(:,:,:) * evap_ice(:,:,:), dim=3 ) - sprecip(:,:) * zsnw
emp_tot(:,:) = emp_oce(:,:) + emp_ice(:,:)
! --- heat flux associated with emp --- !
qemp_oce(:,:) = - ( 1._wp - at_i_b(:,:) ) * zevap(:,:) * zcptn(:,:) & ! evap at sst
& + ( tprecip(:,:) - sprecip(:,:) ) * zcptrain(:,:) & ! liquid precip at Tair
& + sprecip(:,:) * ( 1._wp - zsnw ) * ( zcptsnw (:,:) - rLfus ) ! solid precip at min(Tair,Tsnow)
qemp_ice(:,:) = sprecip(:,:) * zsnw * ( zcptsnw (:,:) - rLfus ) ! solid precip (only)
! --- total solar and non solar fluxes --- !
qns_tot(:,:) = ( 1._wp - at_i_b(:,:) ) * qns_oce(:,:) + SUM( a_i_b(:,:,:) * qns_ice(:,:,:), dim=3 ) &
& + qemp_ice(:,:) + qemp_oce(:,:)
qsr_tot(:,:) = ( 1._wp - at_i_b(:,:) ) * qsr_oce(:,:) + SUM( a_i_b(:,:,:) * qsr_ice(:,:,:), dim=3 )
! --- heat content of precip over ice in J/m3 (to be used in 1D-thermo) --- !
qprec_ice(:,:) = rhos * ( zcptsnw(:,:) - rLfus )
! --- heat content of evap over ice in W/m2 (to be used in 1D-thermo) ---
DO jl = 1, jpl
qevap_ice(:,:,jl) = 0._wp ! should be -evap_ice(:,:,jl)*( ( Tice - rt0 ) * rcpi * tmask(:,:,1) )
! ! But we do not have Tice => consider it at 0degC => evap=0
END DO
! --- shortwave radiation transmitted thru the surface scattering layer (W/m2) --- !
IF( nn_qtrice == 0 ) THEN
! formulation derived from Grenfell and Maykut (1977), where transmission rate
! 1) depends on cloudiness
! 2) is 0 when there is any snow
! 3) tends to 1 for thin ice
ztri(:,:) = 0.18 * ( 1.0 - cloud_fra(:,:) ) + 0.35 * cloud_fra(:,:) ! surface transmission when hi>10cm
DO jl = 1, jpl
WHERE ( phs(:,:,jl) <= 0._wp .AND. phi(:,:,jl) < 0.1_wp ) ! linear decrease from hi=0 to 10cm
qtr_ice_top(:,:,jl) = qsr_ice(:,:,jl) * ( ztri(:,:) + ( 1._wp - ztri(:,:) ) * ( 1._wp - phi(:,:,jl) * 10._wp ) )
ELSEWHERE( phs(:,:,jl) <= 0._wp .AND. phi(:,:,jl) >= 0.1_wp ) ! constant (ztri) when hi>10cm
qtr_ice_top(:,:,jl) = qsr_ice(:,:,jl) * ztri(:,:)
ELSEWHERE ! zero when hs>0
qtr_ice_top(:,:,jl) = 0._wp
END WHERE
ENDDO
ELSEIF( nn_qtrice == 1 ) THEN
! formulation is derived from the thesis of M. Lebrun (2019).
! It represents the best fit using several sets of observations
! It comes with snow conductivities adapted to freezing/melting conditions (see icethd_zdf_bl99.F90)
qtr_ice_top(:,:,:) = 0.3_wp * qsr_ice(:,:,:)
ENDIF
!
IF( iom_use('evap_ao_cea') .OR. iom_use('hflx_evap_cea') ) THEN
CALL iom_put( 'evap_ao_cea' , zevap(:,:) * ( 1._wp - at_i_b(:,:) ) * tmask(:,:,1) ) ! ice-free oce evap (cell average)
CALL iom_put( 'hflx_evap_cea', zevap(:,:) * ( 1._wp - at_i_b(:,:) ) * tmask(:,:,1) * zcptn(:,:) ) ! heat flux from evap (cell average)
ENDIF
IF( iom_use('rain') .OR. iom_use('rain_ao_cea') .OR. iom_use('hflx_rain_cea') ) THEN
CALL iom_put( 'rain' , tprecip(:,:) - sprecip(:,:) ) ! liquid precipitation
CALL iom_put( 'rain_ao_cea' , ( tprecip(:,:) - sprecip(:,:) ) * ( 1._wp - at_i_b(:,:) ) ) ! liquid precipitation over ocean (cell average)
CALL iom_put( 'hflx_rain_cea', ( tprecip(:,:) - sprecip(:,:) ) * zcptrain(:,:) ) ! heat flux from rain (cell average)
ENDIF
IF( iom_use('snow_ao_cea') .OR. iom_use('snow_ai_cea') .OR. &
& iom_use('hflx_snow_cea') .OR. iom_use('hflx_snow_ao_cea') .OR. iom_use('hflx_snow_ai_cea') ) THEN
CALL iom_put( 'snow_ao_cea' , sprecip(:,:) * ( 1._wp - zsnw(:,:) ) ) ! Snow over ice-free ocean (cell average)
CALL iom_put( 'snow_ai_cea' , sprecip(:,:) * zsnw(:,:) ) ! Snow over sea-ice (cell average)
CALL iom_put( 'hflx_snow_cea' , sprecip(:,:) * ( zcptsnw(:,:) - rLfus ) ) ! heat flux from snow (cell average)
CALL iom_put( 'hflx_snow_ao_cea', sprecip(:,:) * ( zcptsnw(:,:) - rLfus ) * ( 1._wp - zsnw(:,:) ) ) ! heat flux from snow (over ocean)
CALL iom_put( 'hflx_snow_ai_cea', sprecip(:,:) * ( zcptsnw(:,:) - rLfus ) * zsnw(:,:) ) ! heat flux from snow (over ice)
ENDIF
IF( iom_use('hflx_prec_cea') ) THEN ! heat flux from precip (cell average)
CALL iom_put('hflx_prec_cea' , sprecip(:,:) * ( zcptsnw (:,:) - rLfus ) &
& + ( tprecip(:,:) - sprecip(:,:) ) * zcptrain(:,:) )
ENDIF
IF( iom_use('subl_ai_cea') .OR. iom_use('hflx_subl_cea') ) THEN
CALL iom_put( 'subl_ai_cea' , SUM( a_i_b(:,:,:) * evap_ice(:,:,:), dim=3 ) * tmask(:,:,1) ) ! Sublimation over sea-ice (cell average)
CALL iom_put( 'hflx_subl_cea', SUM( a_i_b(:,:,:) * qevap_ice(:,:,:), dim=3 ) * tmask(:,:,1) ) ! Heat flux from sublimation (cell average)
ENDIF
!
IF(sn_cfctl%l_prtctl) THEN
CALL prt_ctl(tab3d_1=qla_ice , clinfo1=' blk_ice: qla_ice : ', tab3d_2=z_qsb , clinfo2=' z_qsb : ', kdim=jpl)
CALL prt_ctl(tab3d_1=z_qlw , clinfo1=' blk_ice: z_qlw : ', tab3d_2=dqla_ice, clinfo2=' dqla_ice : ', kdim=jpl)
CALL prt_ctl(tab3d_1=z_dqsb , clinfo1=' blk_ice: z_dqsb : ', tab3d_2=z_dqlw , clinfo2=' z_dqlw : ', kdim=jpl)
CALL prt_ctl(tab3d_1=dqns_ice, clinfo1=' blk_ice: dqns_ice : ', tab3d_2=qsr_ice , clinfo2=' qsr_ice : ', kdim=jpl)
CALL prt_ctl(tab3d_1=ptsu , clinfo1=' blk_ice: ptsu : ', tab3d_2=qns_ice , clinfo2=' qns_ice : ', kdim=jpl)
CALL prt_ctl(tab2d_1=tprecip , clinfo1=' blk_ice: tprecip : ', tab2d_2=sprecip , clinfo2=' sprecip : ')
ENDIF
!#LB:
! air-ice heat flux components that are not written from ice_stp()@icestp.F90:
IF( iom_use('qla_ice') ) CALL iom_put( 'qla_ice', SUM( - qla_ice * a_i_b, dim=3 ) ) !#LB: sign consistent with what's done for ocean
IF( iom_use('qsb_ice') ) CALL iom_put( 'qsb_ice', SUM( - z_qsb * a_i_b, dim=3 ) ) !#LB: ==> negative => loss of heat for sea-ice
IF( iom_use('qlw_ice') ) CALL iom_put( 'qlw_ice', SUM( z_qlw * a_i_b, dim=3 ) )
!#LB.
END SUBROUTINE blk_ice_2
SUBROUTINE blk_ice_qcn( ld_virtual_itd, ptsu, ptb, phs, phi )
!!---------------------------------------------------------------------
!! *** ROUTINE blk_ice_qcn ***
!!
!! ** Purpose : Compute surface temperature and snow/ice conduction flux
!! to force sea ice / snow thermodynamics
!! in the case conduction flux is emulated
!!
!! ** Method : compute surface energy balance assuming neglecting heat storage
!! following the 0-layer Semtner (1976) approach
!!
!! ** Outputs : - ptsu : sea-ice / snow surface temperature (K)
!! - qcn_ice : surface inner conduction flux (W/m2)
!!
!!---------------------------------------------------------------------
LOGICAL , INTENT(in ) :: ld_virtual_itd ! single-category option
REAL(wp), DIMENSION(:,:,:), INTENT(inout) :: ptsu ! sea ice / snow surface temperature
REAL(wp), DIMENSION(:,:) , INTENT(in ) :: ptb ! sea ice base temperature
REAL(wp), DIMENSION(:,:,:), INTENT(in ) :: phs ! snow thickness
REAL(wp), DIMENSION(:,:,:), INTENT(in ) :: phi ! sea ice thickness
!
INTEGER , PARAMETER :: nit = 10 ! number of iterations
REAL(wp), PARAMETER :: zepsilon = 0.1_wp ! characteristic thickness for enhanced conduction
!
INTEGER :: ji, jj, jl ! dummy loop indices
INTEGER :: iter ! local integer
REAL(wp) :: zfac, zfac2, zfac3 ! local scalars
REAL(wp) :: zkeff_h, ztsu, ztsu0 !
REAL(wp) :: zqc, zqnet !
REAL(wp) :: zhe, zqa0 !
REAL(wp), DIMENSION(jpi,jpj,jpl) :: zgfac ! enhanced conduction factor
!!---------------------------------------------------------------------
! -------------------------------------!
! I Enhanced conduction factor !
! -------------------------------------!
! Emulates the enhancement of conduction by unresolved thin ice (ld_virtual_itd = T)
! Fichefet and Morales Maqueda, JGR 1997
!
zgfac(:,:,:) = 1._wp
IF( ld_virtual_itd ) THEN
!
zfac = 1._wp / ( rn_cnd_s + rcnd_i )
zfac2 = EXP(1._wp) * 0.5_wp * zepsilon
zfac3 = 2._wp / zepsilon
!
DO jl = 1, jpl
DO_2D( nn_hls, nn_hls, nn_hls, nn_hls )
zhe = ( rn_cnd_s * phi(ji,jj,jl) + rcnd_i * phs(ji,jj,jl) ) * zfac ! Effective thickness
IF( zhe >= zfac2 ) zgfac(ji,jj,jl) = MIN( 2._wp, 0.5_wp * ( 1._wp + LOG( zhe * zfac3 ) ) ) ! Enhanced conduction factor
END_2D
END DO
!
ENDIF
! -------------------------------------------------------------!
! II Surface temperature and conduction flux !
! -------------------------------------------------------------!
!
zfac = rcnd_i * rn_cnd_s
!
DO jl = 1, jpl
DO_2D( nn_hls, nn_hls, nn_hls, nn_hls )
!
zkeff_h = zfac * zgfac(ji,jj,jl) / & ! Effective conductivity of the snow-ice system divided by thickness
& ( rcnd_i * phs(ji,jj,jl) + rn_cnd_s * MAX( 0.01, phi(ji,jj,jl) ) )
ztsu = ptsu(ji,jj,jl) ! Store current iteration temperature
ztsu0 = ptsu(ji,jj,jl) ! Store initial surface temperature
zqa0 = qsr_ice(ji,jj,jl) - qtr_ice_top(ji,jj,jl) + qns_ice(ji,jj,jl) ! Net initial atmospheric heat flux
!
DO iter = 1, nit ! --- Iterative loop
zqc = zkeff_h * ( ztsu - ptb(ji,jj) ) ! Conduction heat flux through snow-ice system (>0 downwards)
zqnet = zqa0 + dqns_ice(ji,jj,jl) * ( ztsu - ptsu(ji,jj,jl) ) - zqc ! Surface energy budget
ztsu = ztsu - zqnet / ( dqns_ice(ji,jj,jl) - zkeff_h ) ! Temperature update
END DO
!
ptsu (ji,jj,jl) = MIN( rt0, ztsu )
qcn_ice(ji,jj,jl) = zkeff_h * ( ptsu(ji,jj,jl) - ptb(ji,jj) )
qns_ice(ji,jj,jl) = qns_ice(ji,jj,jl) + dqns_ice(ji,jj,jl) * ( ptsu(ji,jj,jl) - ztsu0 )
qml_ice(ji,jj,jl) = ( qsr_ice(ji,jj,jl) - qtr_ice_top(ji,jj,jl) + qns_ice(ji,jj,jl) - qcn_ice(ji,jj,jl) ) &
& * MAX( 0._wp , SIGN( 1._wp, ptsu(ji,jj,jl) - rt0 ) )
! --- Diagnose the heat loss due to changing non-solar flux (as in icethd_zdf_bl99) --- !
hfx_err_dif(ji,jj) = hfx_err_dif(ji,jj) - ( dqns_ice(ji,jj,jl) * ( ptsu(ji,jj,jl) - ztsu0 ) ) * a_i_b(ji,jj,jl)
END_2D
!
END DO
!
END SUBROUTINE blk_ice_qcn
#endif
!!======================================================================
END MODULE sbcblk