!||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| module ice !BOP ! !MODULE: ice ! ! !DESCRIPTION: ! This module currently contains routines for computing ice ! formation and the heat flux associated with ice formation. ! This heat flux is sent to the ice model via the flux coupler. ! In the future, this module could contain the driver for a ! subroutinized ice model. ! ! !REVISION HISTORY: ! SVN:$Id: ice.F90 17759 2009-08-12 20:20:36Z njn01 $ ! !USES: use POP_KindsMod use POP_IOUnitsMod use kinds_mod, only: int_kind, log_kind, char_len, r8 use blocks, only: nx_block, ny_block, block use domain_size use constants, only: cp_sw, latent_heat_fusion, delim_fmt, blank_fmt, & sea_ice_salinity, ppt_to_salt, ocn_ref_salinity, c0, p5, hflux_factor,& grav, eps2, ndelim_fmt use broadcast, only: broadcast_scalar use communicate, only: my_task, master_task use io_types, only: nml_in, nml_filename, stdout use time_management, only: freq_opt_never, freq_opt_nyear, freq_opt_nday, & freq_opt_nhour, freq_opt_nsecond, freq_opt_nstep, init_time_flag, & max_blocks_clinic, km, nt, avg_ts, back_to_back, dtt, check_time_flag,& partial_bottom_cells, KMT, DZT, DZ, freq_opt_nmonth, dt, tmix_matsuno,& tmix_iopt, ice_ts, access_time_flag use exit_mod, only: sigAbort, exit_pop, flushm use prognostic use passive_tracers, only: tracer_ref_val use grid, only: sfc_layer_varthick, sfc_layer_type implicit none private save ! !PUBLIC MEMBER FUNCTIONS: public :: init_ice, & increment_tlast_ice,& ice_formation, & tfreez, & ice_flx_to_coupler, & tmelt ! !PUBLIC DATA MEMBERS: logical (log_kind), public :: & liceform ! flag to turn on/off ice formation logical (log_kind), public :: & lactive_ice ! T ==> ocn is coupled to an active ice model ! F ==> ocn is coupled to a dummy ice model integer (int_kind), public :: & ice_cpl_flag ! time flag id for coupled timestep real (r8), public :: & tlast_ice, &! time since last ice flux computed time_weight, & salice ! sea ice salinity in msu real (r8), dimension(:,:,:), allocatable, public :: & AQICE, &! sum of accumulated ice heat flux since tlast QFLUX, &! internal ocn heat flux due to ice formation QICE ! tot column cooling from ice form (in C*cm) real (r8), dimension(nx_block,ny_block,max_blocks_clinic), public :: & FW_FREEZE ! water flux at T points due to frazil ice formation real (r8), public :: & cp_over_lhfusion ! cp_sw/latent_heat_fusion !EOP !BOC !----------------------------------------------------------------------- ! ! module variables ! !----------------------------------------------------------------------- integer (int_kind) :: & ice_flag, &! time flag id for ice formation kmxice ! lowest level from which to integrate ! ice formation real (r8) :: & salref ! ocean ref salinity in msu !EOC !*********************************************************************** contains !*********************************************************************** !BOP ! !IROUTINE: ! !INTERFACE: subroutine init_ice ! !DESCRIPTION: ! This routine initializes ice variables. It must be called ! before initializing restarts because this module add the accumulated ! ice heat flux to the restart file. ! ! !REVISION HISTORY: ! same as module !EOP !BOC !----------------------------------------------------------------------- ! ! local variables ! !----------------------------------------------------------------------- integer (int_kind) :: & nml_error ! namelist i/o error flag character (char_len) :: & ice_freq_opt ! option for frequency of computing ice integer (int_kind) :: & ice_freq_iopt, &! int option for freq units ice_freq ! freq for computing ice in above units namelist /ice_nml/ kmxice, ice_freq_opt, ice_freq, lactive_ice !----------------------------------------------------------------------- ! ! read input namelists ! !----------------------------------------------------------------------- cp_over_lhfusion = rho_sw*cp_sw/(latent_heat_fusion*rho_fw) kmxice = 1 ice_freq_opt = 'never' ice_freq = 100000 lactive_ice = .false. if (my_task == master_task) then open (nml_in, file=nml_filename, status='old',iostat=nml_error) if (nml_error /= 0) then nml_error = -1 else nml_error = 1 endif do while (nml_error > 0) read(nml_in, nml=ice_nml,iostat=nml_error) end do if (nml_error == 0) close(nml_in) endif call broadcast_scalar(nml_error, master_task) if (nml_error /= 0) then call exit_POP(sigAbort,'ERROR reading ice_nml') endif if (my_task == master_task) then write(stdout,blank_fmt) write(stdout,ndelim_fmt) write(stdout,blank_fmt) write(stdout,*) 'Ice:' write(stdout,blank_fmt) write(stdout,*) ' ice_nml namelist settings:' write(stdout,blank_fmt) write(stdout,ice_nml) write(stdout,delim_fmt) !*** !*** define salice and salref in msu !*** salice = sea_ice_salinity*ppt_to_salt salref = ocn_ref_salinity*ppt_to_salt liceform = .true. select case (ice_freq_opt) case ('never') write(stdout,'(a22)') 'Ice formation disabled' liceform = .false. ice_freq_iopt = freq_opt_never case ('coupled') write(stdout,'(a44)') & 'Ice formation computed on coupler time steps' ice_freq_iopt = freq_opt_never ! check coupler flag instead case ('nyear') write(stdout,'(a29,i4,a9)') 'Ice formation computed every ', & ice_freq,' years. ' ice_freq_iopt = freq_opt_nyear case ('nmonth') write(stdout,'(a29,i4,a9)') 'Ice formation computed every ', & ice_freq,' months. ' ice_freq_iopt = freq_opt_nmonth case ('nday') write(stdout,'(a29,i4,a9)') 'Ice formation computed every ', & ice_freq,' days. ' ice_freq_iopt = freq_opt_nday case ('nhour') write(stdout,'(a29,i4,a9)') 'Ice formation computed every ', & ice_freq,' hours. ' ice_freq_iopt = freq_opt_nhour case ('nsecond') write(stdout,'(a29,i4,a9)') 'Ice formation computed every ', & ice_freq,' seconds.' ice_freq_iopt = freq_opt_nsecond case ('nstep') write(stdout,'(a29,i4,a9)') 'Ice formation computed every ', & ice_freq,' steps. ' ice_freq_iopt = freq_opt_nstep case default ice_freq_iopt = -1000 end select if (liceform) then write(stdout,'(a20,1pe10.3)') 'Ice salinity(ppt) = ', & sea_ice_salinity write(stdout,'(a30,i3,a13)') 'Ice formation computed in top ', & kmxice, ' levels only.' endif call POP_IOUnitsFlush(POP_stdout) ; call POP_IOUnitsFlush(stdout) endif call broadcast_scalar(ice_freq_iopt, master_task) call broadcast_scalar(lactive_ice, master_task) if (ice_freq_iopt == -1000) then call exit_POP(sigAbort,'unknown restart frequency option') endif call broadcast_scalar(liceform, master_task) !----------------------------------------------------------------------- ! ! if ice turned on, broadcast remaining vars and allocate memory ! !----------------------------------------------------------------------- if (liceform) then call broadcast_scalar(ice_freq, master_task) call broadcast_scalar(kmxice, master_task) call broadcast_scalar(salice, master_task) call broadcast_scalar(salref, master_task) !*** !*** set up ice time flag and get coupled_ts id for local use !*** call init_time_flag('ice',ice_flag, default=.false., & owner = 'init_ice', & freq_opt = ice_freq_iopt, & freq = ice_freq) call access_time_flag('coupled_ts', ice_cpl_flag) !*** !*** must keep track of time since last ice flux computed !*** tlast_ice = c0 !*** !*** allocate and initialize ice flux arrays !*** allocate( QICE(nx_block,ny_block,max_blocks_clinic), & AQICE(nx_block,ny_block,max_blocks_clinic), & QFLUX(nx_block,ny_block,max_blocks_clinic)) QICE = c0 AQICE = c0 QFLUX = c0 endif FW_FREEZE = c0 !----------------------------------------------------------------------- !EOC call flushm (stdout) end subroutine init_ice !*********************************************************************** !BOP ! !IROUTINE: ! !INTERFACE: subroutine increment_tlast_ice ! !DESCRIPTION: ! This subroutine increments tlast_ice in a nonthreaded region. ! !REVISION HISTORY: ! same as module !EOP !BOC !----------------------------------------------------------------------- ! ! increment time since last evaluation ! !----------------------------------------------------------------------- if (avg_ts .or. back_to_back) then time_weight = p5 else time_weight = c1 endif tlast_ice = tlast_ice + dtt*time_weight !----------------------------------------------------------------------- !EOC end subroutine increment_tlast_ice !*********************************************************************** !BOP ! !IROUTINE: ! !INTERFACE: subroutine ice_formation(TNEW, SHF_IN, iblock,this_block,lfw_as_salt_flx) ! !DESCRIPTION: ! This subroutine computes ocean heat flux to the sea-ice. it forms ! the necessary ice in the ocean and adjusts the potential ! temperature and salinity fields accordingly. the logic of this ! subroutine is based on William Large''s 1-d model and is based ! on a version from the NCOM model written by Gokhan Danabasoglu. ! !REVISION HISTORY: ! same as module ! !INPUT/OUTPUT PARAMETERS: real (r8), dimension(nx_block,ny_block,km,nt), intent(inout) :: & TNEW ! tracers at new time level ! !INPUT PARAMETERS: real (r8), dimension(nx_block,ny_block), intent(in) :: & SHF_IN ! surface heat flux integer (int_kind), intent(in) :: & iblock ! block information for current block type (block), intent(in) :: & this_block ! block information for current block logical (log_kind), intent(in) :: & lfw_as_salt_flx !EOP !BOC !----------------------------------------------------------------------- ! ! local variables ! !----------------------------------------------------------------------- integer (int_kind) :: & k, &! vertical level index bid, &! local block index n ! tracer index real (r8), dimension(nx_block,ny_block) :: & POTICE, & ! potential amt of ice formation WORK1, & ! work array TFRZ ! freezing temp of water real (r8) :: & ref_val ! tracer reference value !----------------------------------------------------------------------- ! ! presently, the check_time_flag does not produce the same results ! as ice_ts. for now, ice_ts will be set in time_management and ! used here !----------------------------------------------------------------------- !=====if (check_time_flag(ice_flag) .or. !====& check_time_flag(ice_cpl_flag)) then !======================== if ( ice_ts ) then !======================== bid = this_block%local_id !----------------------------------------------------------------------- ! ! initialize flux to zero ! !----------------------------------------------------------------------- QICE(:,:,bid) = c0 POTICE = c0 !----------------------------------------------------------------------- ! ! compute frazil ice formation for sub-surface layers. if ice ! forms in lower layers but layers above are warm - the heat is ! used to melt the ice. the ice formation occurs at salinity, Si. ! this volume is replaced with an equal volume at the salinity of ! the layer above. the total ice heat flux is accumulated. ! ! WARNING: unless a monotone advection scheme is in place, ! advective errors could lead to temps that are far below freezing ! in some locations and this scheme will form lots of ice. ! ice formation should be limited to the top layer (kmxice=1) ! if the advection scheme is not monotone. ! !----------------------------------------------------------------------- do k=kmxice,2,-1 !*** !*** potice is the potential amount of ice formation !*** (potice>0) or melting (potice<0) in layer k !*** call tfreez(TFRZ,TNEW(:,:,k,2)) if (partial_bottom_cells) then where (k <= KMT(:,:,bid)) & POTICE = (TFRZ - TNEW(:,:,k,1))*DZT(:,:,k,bid) else where (k <= KMT(:,:,bid)) & POTICE = (TFRZ - TNEW(:,:,k,1))*dz(k) endif !*** !*** if potice < 0, use the heat to melt any ice !*** from lower layers !*** if potice > 0, keep on freezing (QICE < 0) !*** POTICE = max(POTICE,QICE(:,:,bid)) !*** !*** adjust tracer values based on freeze/melt !*** if (partial_bottom_cells) then TNEW(:,:,k,1) = TNEW(:,:,k,1) + POTICE/DZT(:,:,k,bid) else TNEW(:,:,k,1) = TNEW(:,:,k,1) + POTICE/dz(k) endif if (sfc_layer_type == sfc_layer_varthick .and. .not. lfw_as_salt_flx) then if (partial_bottom_cells) then TNEW(:,:,k,2) = ( TNEW(:,:,k,2) & * (DZT(:,:,k,bid) + cp_over_lhfusion * QICE(:,:,bid)) & + cp_over_lhfusion * (TNEW(:,:,k-1,2) & * (POTICE - QICE(:,:,bid)) - salice * POTICE) )/DZT(:,:,k,bid) else TNEW(:,:,k,2) = ( TNEW(:,:,k,2) & * (dz(k) + cp_over_lhfusion * QICE(:,:,bid)) & + cp_over_lhfusion * (TNEW(:,:,k-1,2) & * (POTICE - QICE(:,:,bid)) - salice * POTICE) )/dz(k) endif else do n=2,nt ref_val = salref - salice if (n > 2) & ref_val = ref_val * (tracer_ref_val(n) / salref) if (ref_val /= c0) then if (partial_bottom_cells) then TNEW(:,:,k,n) = TNEW(:,:,k,n) & + ref_val*POTICE*cp_over_lhfusion/DZT(:,:,k,bid) else TNEW(:,:,k,n) = TNEW(:,:,k,n) & + ref_val*POTICE*cp_over_lhfusion/dz(k) endif endif end do endif !*** accumulate freezing potential QICE(:,:,bid) = QICE(:,:,bid) - POTICE enddo ! k loop !----------------------------------------------------------------------- ! ! now repeat the above algorithm for the surface layer. when fresh ! water flux formulation is used, the surface layer does not get ! any salt from other layers. instead, its volume changes. ! !----------------------------------------------------------------------- k = 1 call tfreez(TFRZ,TNEW(:,:,k,2)) if (partial_bottom_cells) then WORK1 = DZT(:,:,k,bid) else WORK1 = dz(k) endif if (sfc_layer_type == sfc_layer_varthick) & WORK1 = WORK1 + PSURF(:,:,newtime,bid)/grav + eps2 where ( k <= KMT(:,:,bid) ) POTICE = (TFRZ - TNEW(:,:,k,1))*WORK1 endwhere POTICE = max(POTICE, QICE(:,:,bid)) TNEW(:,:,k,1) = TNEW(:,:,k,1) + POTICE/WORK1 if (sfc_layer_type == sfc_layer_varthick .and. .not. lfw_as_salt_flx) then TNEW(:,:,k,2) = & (TNEW(:,:,k,2)*(WORK1 + cp_over_lhfusion*QICE(:,:,bid)) - & salice*QICE(:,:,bid)*cp_over_lhfusion )/WORK1 else do n=2,nt ref_val = salref - salice if (n > 2) ref_val = ref_val * (tracer_ref_val(n) / salref) if (ref_val /= c0) & TNEW(:,:,k,n) = TNEW(:,:,k,n) & + ref_val * POTICE * cp_over_lhfusion / WORK1 end do endif QICE(:,:,bid) = QICE(:,:,bid) - POTICE !----------------------------------------------------------------------- ! ! let any residual heat in the upper layer melt previously formed ice ! !----------------------------------------------------------------------- AQICE(:,:,bid) = AQICE(:,:,bid) + time_weight*QICE(:,:,bid) !----------------------------------------------------------------------- ! ! recalculate freezing potential based on adjusted T. ! only interested in melt potential now (POTICE < 0) - use this ! melt to offset any accumulated freezing (AQICE < 0) and ! adjust T and S to reflect this melting. when freshwater flux ! formulation, compute the associated freshwater flux instead of ! adjusting S. ! !----------------------------------------------------------------------- call tfreez(TFRZ,TNEW(:,:,k,2)) where (k <= KMT(:,:,bid)) POTICE = (TFRZ - TNEW(:,:,k,1)) * WORK1 endwhere POTICE = max(POTICE, AQICE(:,:,bid)) TNEW(:,:,k,1) = TNEW(:,:,k,1) + POTICE/WORK1 if ( sfc_layer_type == sfc_layer_varthick .and. .not. lfw_as_salt_flx ) then FW_FREEZE(:,:,bid) = time_weight * min(POTICE(:,:),QICE(:,:,bid)) & * cp_over_lhfusion / dt(k) else do n=2,nt ref_val = salref - salice if (n > 2) ref_val = ref_val * (tracer_ref_val(n)/salref) if (ref_val /= c0) & TNEW(:,:,k,n) = TNEW(:,:,k,n) & + ref_val*POTICE*cp_over_lhfusion/WORK1 end do endif AQICE(:,:,bid) = AQICE(:,:,bid) - time_weight*POTICE endif ! time to do ice !----------------------------------------------------------------------- !EOC end subroutine ice_formation !*********************************************************************** subroutine ice_flx_to_coupler(TCUR,bid) !----------------------------------------------------------------------- ! ! This subroutine sets up the ice formation / melting potential ! heat fluxes to be sent to the coupler. ice formation heat flux ! is accumulated for time averaging. ! !----------------------------------------------------------------------- real (r8), dimension(nx_block,ny_block,km,nt), intent(in) :: & TCUR ! tracers at new time level integer (int_kind), intent(in) :: & bid ! local block index !----------------------------------------------------------------------- ! ! local variables ! !----------------------------------------------------------------------- integer (int_kind) :: & k ! vertical level index real (r8), dimension(nx_block,ny_block) :: & WORK1, WORK2 ! work arrays real (r8), dimension(nx_block,ny_block) :: & TFRZ ! freezing temp of water !----------------------------------------------------------------------- ! ! compute the first layer thickness ! !----------------------------------------------------------------------- k = 1 call tfreez(TFRZ,TCUR(:,:,k,2)) if (partial_bottom_cells) then WORK1 = DZT(:,:,k,bid) else WORK1 = dz(k) endif if ( sfc_layer_type == sfc_layer_varthick ) & WORK1 = WORK1 + PSURF(:,:,curtime,bid)/grav + eps2 !----------------------------------------------------------------------- ! ! first compute the melt potential ! !----------------------------------------------------------------------- WORK2 = c0 where ( k <= KMT(:,:,bid) ) WORK2 = (TFRZ - TCUR(:,:,k,1)) * WORK1 endwhere !----------------------------------------------------------------------- ! ! adjust ice formation amount when mixing step is tavg ! !----------------------------------------------------------------------- if ( tmix_iopt /= tmix_matsuno ) then AQICE(:,:,bid) = p5 * AQICE(:,:,bid) endif !----------------------------------------------------------------------- ! ! merge the ice formation and melt potential fluxes and compute ! !----------------------------------------------------------------------- where ( AQICE(:,:,bid) < c0 ) QICE(:,:,bid) = -AQICE(:,:,bid) elsewhere QICE(:,:,bid) = WORK2 endwhere if (tlast_ice == c0) then QFLUX(:,:,bid) = c0 else QFLUX(:,:,bid) = QICE(:,:,bid)/tlast_ice/hflux_factor endif end subroutine ice_flx_to_coupler !*********************************************************************** !BOP ! !IROUTINE: ! !INTERFACE: subroutine tfreez(TFRZ,SALT) ! !DESCRIPTION: ! This function computes the freezing point of salt water. ! ! !REVISION HISTORY: ! same as module ! !INPUT PARAMETERS: real (r8), dimension(nx_block,ny_block), intent(in) :: & SALT ! salinity in model units (g/g) ! !OUTPUT PARAMETERS: real (r8), dimension(nx_block,ny_block), intent(out) :: & TFRZ ! freezing temperature of water in deg C !EOP !BOC !----------------------------------------------------------------------- ! ! use only the first salinity term in the expansion ! !----------------------------------------------------------------------- !TFRZ = -0.0544_r8*SALT*salt_to_ppt TFRZ = -1.8_r8 !----------------------------------------------------------------------- !EOC end subroutine tfreez !BOP ! !IROUTINE: ! !INTERFACE: subroutine tmelt (TMLT,SALT) ! !DESCRIPTION: ! This subroutine sets the melting point temperature of ice. ! For now, TMLT is a separate routine than TFRZ. ! ! !REVISION HISTORY: ! same as module ! !INPUT PARAMETERS: real (r8), dimension(nx_block,ny_block), intent(in) :: & SALT ! salinity in model units (g/g) ! !OUTPUT PARAMETERS: real (r8), dimension(nx_block,ny_block) :: & TMLT ! melting temperature in deg C !EOP !BOC if ( lactive_ice ) then TMLT = c0 else call tfreez(TMLT,SALT) endif !----------------------------------------------------------------------- !EOC end subroutine tmelt !*********************************************************************** end module ice !|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||