MODULE trasbc !!============================================================================== !! *** MODULE trasbc *** !! Ocean active tracers: surface boundary condition !!============================================================================== !! History : OPA ! 1998-10 (G. Madec, G. Roullet, M. Imbard) Original code !! 8.2 ! 2001-02 (D. Ludicone) sea ice and free surface !! NEMO 1.0 ! 2002-06 (G. Madec) F90: Free form and module !! 3.3 ! 2010-04 (M. Leclair, G. Madec) Forcing averaged over 2 time steps !! - ! 2010-09 (C. Ethe, G. Madec) Merge TRA-TRC !!---------------------------------------------------------------------- !!---------------------------------------------------------------------- !! tra_sbc : update the tracer trend at ocean surface !!---------------------------------------------------------------------- USE oce ! ocean dynamics and active tracers USE sbc_oce ! surface boundary condition: ocean USE dom_oce ! ocean space domain variables USE phycst ! physical constant USE traqsr ! solar radiation penetration USE trdmod_oce ! ocean trends USE trdtra ! ocean trends USE in_out_manager ! I/O manager USE prtctl ! Print control USE sbcrnf ! River runoff USE sbcisf ! Ice shelf USE sbcmod ! ln_rnf USE iom USE lbclnk ! ocean lateral boundary conditions (or mpp link) USE wrk_nemo ! Memory Allocation USE timing ! Timing USE eosbn2 IMPLICIT NONE PRIVATE PUBLIC tra_sbc ! routine called by step.F90 !! * Substitutions # include "domzgr_substitute.h90" # include "vectopt_loop_substitute.h90" !!---------------------------------------------------------------------- !! NEMO/OPA 3.3 , NEMO Consortium (2010) !! $Id$ !! Software governed by the CeCILL licence (NEMOGCM/NEMO_CeCILL.txt) !!---------------------------------------------------------------------- CONTAINS SUBROUTINE tra_sbc ( kt ) !!---------------------------------------------------------------------- !! *** ROUTINE tra_sbc *** !! !! ** Purpose : Compute the tracer surface boundary condition trend of !! (flux through the interface, concentration/dilution effect) !! and add it to the general trend of tracer equations. !! !! ** Method : !! Following Roullet and Madec (2000), the air-sea flux can be divided !! into three effects: (1) Fext, external forcing; !! (2) Fwi, concentration/dilution effect due to water exchanged !! at the surface by evaporation, precipitations and runoff (E-P-R); !! (3) Fwe, tracer carried with the water that is exchanged. !! - salinity : salt flux only due to freezing/melting !! sa = sa + sfx / rau0 / e3t for k=1 !! !! Fext, flux through the air-sea interface for temperature and salt: !! - temperature : heat flux q (w/m2). If penetrative solar !! radiation q is only the non solar part of the heat flux, the !! solar part is added in traqsr.F routine. !! ta = ta + q /(rau0 rcp e3t) for k=1 !! - salinity : no salt flux !! !! The formulation for Fwb and Fwi vary according to the free !! surface formulation (linear or variable volume). !! * Linear free surface !! The surface freshwater flux modifies the ocean volume !! and thus the concentration of a tracer and the temperature. !! First order of the effect of surface freshwater exchange !! for salinity, it can be neglected on temperature (especially !! as the temperature of precipitations and runoffs is usually !! unknown). !! - temperature : we assume that the temperature of both !! precipitations and runoffs is equal to the SST, thus there !! is no additional flux since in this case, the concentration !! dilution effect is balanced by the net heat flux associated !! to the freshwater exchange (Fwe+Fwi=0): !! (Tp P - Te E) + SST (P-E) = 0 when Tp=Te=SST !! - salinity : evaporation, precipitation and runoff !! water has a zero salinity but there is a salt flux due to !! freezing/melting, thus: !! sa = sa + emp * sn / rau0 / e3t for k=1 !! + sfx / rau0 / e3t !! where emp, the surface freshwater budget (evaporation minus !! precipitation minus runoff) given in kg/m2/s is divided !! by rau0 = 1020 kg/m3 (density of sea water) to obtain m/s. !! Note: even though Fwe does not appear explicitly for !! temperature in this routine, the heat carried by the water !! exchanged through the surface is part of the total heat flux !! forcing and must be taken into account in the global heat !! balance). !! * nonlinear free surface (variable volume, lk_vvl) !! contrary to the linear free surface case, Fwi is properly !! taken into account by using the true layer thicknesses to !! calculate tracer content and advection. There is no need to !! deal with it in this routine. !! - temperature: Fwe=SST (P-E+R) is added to Fext. !! - salinity: Fwe = 0, there is no surface flux of salt. !! !! ** Action : - Update the 1st level of (ta,sa) with the trend associated !! with the tracer surface boundary condition !! - save the trend it in ttrd ('key_trdtra') !!---------------------------------------------------------------------- INTEGER, INTENT(in) :: kt ! ocean time-step index !! INTEGER :: ji, jj, jk, jn ! dummy loop indices INTEGER :: ikt, ikb INTEGER :: nk_isf REAL(wp) :: zfact, z1_e3t, zdep REAL(wp) :: zalpha, zhk REAL(wp) :: zt_frz, zpress REAL(wp), POINTER, DIMENSION(:,:,:) :: ztrdt, ztrds !!---------------------------------------------------------------------- ! IF( nn_timing == 1 ) CALL timing_start('tra_sbc') ! IF( kt == nit000 ) THEN IF(lwp) WRITE(numout,*) IF(lwp) WRITE(numout,*) 'tra_sbc : TRAcer Surface Boundary Condition' IF(lwp) WRITE(numout,*) '~~~~~~~ ' ENDIF IF( l_trdtra ) THEN !* Save ta and sa trends CALL wrk_alloc( jpi, jpj, jpk, ztrdt, ztrds ) ztrdt(:,:,:) = tsa(:,:,:,jp_tem) ztrds(:,:,:) = tsa(:,:,:,jp_sal) ENDIF !!gm IF( .NOT.ln_traqsr ) qsr(:,:) = 0.e0 ! no solar radiation penetration IF( .NOT.ln_traqsr ) THEN ! no solar radiation penetration qns(:,:) = qns(:,:) + qsr(:,:) ! total heat flux in qns qsr(:,:) = 0.e0 ! qsr set to zero ENDIF !---------------------------------------- ! EMP, EMPS and QNS effects !---------------------------------------- ! Set before sbc tracer content fields ! ************************************ IF( kt == nit000 ) THEN ! Set the forcing field at nit000 - 1 ! ! ----------------------------------- IF( ln_rstart .AND. & ! Restart: read in restart file & iom_varid( numror, 'sbc_hc_b', ldstop = .FALSE. ) > 0 ) THEN IF(lwp) WRITE(numout,*) ' nit000-1 surface tracer content forcing fields red in the restart file' zfact = 0.5e0 CALL iom_get( numror, jpdom_autoglo, 'sbc_hc_b', sbc_tsc_b(:,:,jp_tem) ) ! before heat content sbc trend CALL iom_get( numror, jpdom_autoglo, 'sbc_sc_b', sbc_tsc_b(:,:,jp_sal) ) ! before salt content sbc trend ELSE ! No restart or restart not found: Euler forward time stepping zfact = 1.e0 sbc_tsc_b(:,:,:) = 0.e0 ENDIF ELSE ! Swap of forcing fields ! ! ---------------------- zfact = 0.5e0 sbc_tsc_b(:,:,:) = sbc_tsc(:,:,:) ENDIF ! Compute now sbc tracer content fields ! ************************************* ! Concentration dilution effect on (t,s) due to ! evaporation, precipitation and qns, but not river runoff IF( lk_vvl ) THEN ! Variable Volume case ==>> heat content of mass flux is in qns DO jj = 1, jpj DO ji = 1, jpi sbc_tsc(ji,jj,jp_tem) = r1_rau0_rcp * qns(ji,jj) ! non solar heat flux sbc_tsc(ji,jj,jp_sal) = r1_rau0 * sfx(ji,jj) ! salt flux due to freezing/melting END DO END DO ELSE ! Constant Volume case ==>> Concentration dilution effect DO jj = 2, jpj DO ji = fs_2, fs_jpim1 ! vector opt. ! temperature : heat flux sbc_tsc(ji,jj,jp_tem) = r1_rau0_rcp * qns(ji,jj) & ! non solar heat flux & + r1_rau0 * emp(ji,jj) * tsn(ji,jj,1,jp_tem) ! concent./dilut. effect ! salinity : salt flux + concent./dilut. effect (both in sfx) sbc_tsc(ji,jj,jp_sal) = r1_rau0 * ( sfx(ji,jj) & ! salt flux (freezing/melting) & + emp(ji,jj) * tsn(ji,jj,1,jp_sal) ) ! concent./dilut. effect END DO END DO CALL iom_put( "emp_x_sst", emp (:,:) * tsn(:,:,1,jp_tem) ) ! c/d term on sst CALL iom_put( "emp_x_sss", emp (:,:) * tsn(:,:,1,jp_sal) ) ! c/d term on sss ENDIF ! Concentration dilution effect on (t,s) due to evapouration, precipitation and qns, but not river runoff DO jn = 1, jpts DO jj = 2, jpj DO ji = fs_2, fs_jpim1 ! vector opt. z1_e3t = zfact / fse3t(ji,jj,1) tsa(ji,jj,1,jn) = tsa(ji,jj,1,jn) + ( sbc_tsc_b(ji,jj,jn) + sbc_tsc(ji,jj,jn) ) * z1_e3t END DO END DO END DO ! Write in the ocean restart file ! ******************************* IF( lrst_oce ) THEN IF(lwp) WRITE(numout,*) IF(lwp) WRITE(numout,*) 'sbc : ocean surface tracer content forcing fields written in ocean restart file ', & & 'at it= ', kt,' date= ', ndastp IF(lwp) WRITE(numout,*) '~~~~' CALL iom_rstput( kt, nitrst, numrow, 'sbc_hc_b', sbc_tsc(:,:,jp_tem) ) CALL iom_rstput( kt, nitrst, numrow, 'sbc_sc_b', sbc_tsc(:,:,jp_sal) ) ENDIF ! ! !---------------------------------------- ! Ice Shelf effects (ISF) ! tbl treated as in Losh (2008) JGR !---------------------------------------- ! IF (nn_isf .GT. 0) THEN zfact = 0.5e0 DO jj = 2, jpj DO ji = fs_2, fs_jpim1 ikt = misfkt(ji,jj) ikb = misfkb(ji,jj) ! level fully include in the ice shelf boundary layer ! if isfdiv, we have to remove heat flux due to inflow at 0oC (as in rnf when you add rnf at sst) ! sign - because fwf sign of evapo (rnf sign of precip) DO jk = ikt, ikb - 1 ! compute tfreez for the temperature correction (we add water at freezing temperature) zpress = grav*rau0*fsdept(ji,jj,jk)*1.e-04 zt_frz = -1.9 !tfreez1D( tsn(ji,jj,jk,jp_sal), zpress ) ! compute trend tsa(ji,jj,jk,jp_tem) = tsa(ji,jj,jk,jp_tem) & & + zfact * (risf_tsc_b(ji,jj,jp_tem) + risf_tsc(ji,jj,jp_tem) & & - rdivisf * (fwfisf(ji,jj) + fwfisf_b(ji,jj)) * zt_frz * r1_rau0) & & * r1_hisf_tbl(ji,jj) tsa(ji,jj,jk,jp_sal) = tsa(ji,jj,jk,jp_sal) & & + zfact * (risf_tsc_b(ji,jj,jp_sal) + risf_tsc(ji,jj,jp_sal)) * r1_hisf_tbl(ji,jj) END DO ! level partially include in ice shelf boundary layer zhk = SUM( fse3t(ji, jj, ikt:ikb - 1)) * r1_hisf_tbl(ji,jj) ! proportion of tbl cover by cell from ikt to ikb - 1 zalpha = rhisf_tbl(ji,jj) * ( 1._wp - zhk ) / fse3t(ji,jj,ikb) ! proportion of bottom cell influenced by boundary layer ! compute tfreez for the temperature correction (we add water at freezing temperature) zpress = grav*rau0*fsdept(ji,jj,ikb)*1.e-04 zt_frz = -1.9 !tfreez1D( tsn(ji,jj,ikb,jp_sal), zpress ) ! compute trend tsa(ji,jj,ikb,jp_tem) = tsa(ji,jj,ikb,jp_tem) & & + zfact * (risf_tsc_b(ji,jj,jp_tem) + risf_tsc(ji,jj,jp_tem) & & - rdivisf * (fwfisf(ji,jj) + fwfisf_b(ji,jj)) * zt_frz * r1_rau0) & & * r1_hisf_tbl(ji,jj) * zalpha tsa(ji,jj,ikb,jp_sal) = tsa(ji,jj,ikb,jp_sal) & & + zfact * (risf_tsc_b(ji,jj,jp_sal) + risf_tsc(ji,jj,jp_sal)) * r1_hisf_tbl(ji,jj) * zalpha END DO END DO IF( lrst_oce ) THEN IF(lwp) WRITE(numout,*) IF(lwp) WRITE(numout,*) 'sbc : isf surface tracer content forcing fields written in ocean restart file ', & & 'at it= ', kt,' date= ', ndastp IF(lwp) WRITE(numout,*) '~~~~' CALL iom_rstput( kt, nitrst, numrow, 'fwf_isf_b', fwfisf(:,:) ) CALL iom_rstput( kt, nitrst, numrow, 'isf_hc_b' , risf_tsc(:,:,jp_tem) ) CALL iom_rstput( kt, nitrst, numrow, 'isf_sc_b' , risf_tsc(:,:,jp_sal) ) ENDIF END IF ! !---------------------------------------- ! River Runoff effects !---------------------------------------- ! IF( ln_rnf ) THEN ! input of heat and salt due to river runoff zfact = 0.5_wp DO jj = 2, jpj DO ji = fs_2, fs_jpim1 IF( rnf(ji,jj) /= 0._wp ) THEN zdep = zfact / h_rnf(ji,jj) DO jk = 1, nk_rnf(ji,jj) tsa(ji,jj,jk,jp_tem) = tsa(ji,jj,jk,jp_tem) & & + ( rnf_tsc_b(ji,jj,jp_tem) + rnf_tsc(ji,jj,jp_tem) ) * zdep IF( ln_rnf_sal ) tsa(ji,jj,jk,jp_sal) = tsa(ji,jj,jk,jp_sal) & & + ( rnf_tsc_b(ji,jj,jp_sal) + rnf_tsc(ji,jj,jp_sal) ) * zdep END DO ENDIF END DO END DO ENDIF IF( l_trdtra ) THEN ! save the horizontal diffusive trends for further diagnostics ztrdt(:,:,:) = tsa(:,:,:,jp_tem) - ztrdt(:,:,:) ztrds(:,:,:) = tsa(:,:,:,jp_sal) - ztrds(:,:,:) CALL trd_tra( kt, 'TRA', jp_tem, jptra_trd_nsr, ztrdt ) CALL trd_tra( kt, 'TRA', jp_sal, jptra_trd_nsr, ztrds ) CALL wrk_dealloc( jpi, jpj, jpk, ztrdt, ztrds ) ENDIF ! IF(ln_ctl) CALL prt_ctl( tab3d_1=tsa(:,:,:,jp_tem), clinfo1=' sbc - Ta: ', mask1=tmask, & & tab3d_2=tsa(:,:,:,jp_sal), clinfo2= ' Sa: ', mask2=tmask, clinfo3='tra' ) ! IF( nn_timing == 1 ) CALL timing_stop('tra_sbc') ! END SUBROUTINE tra_sbc !!====================================================================== END MODULE trasbc