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 restart ! ocean restart USE sbcrnf ! River runoff USE sbcmod ! ln_rnf USE iom USE lbclnk ! ocean lateral boundary conditions (or mpp link) USE wrk_nemo ! Memory Allocation USE timing ! Timing 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. !! !! 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 (Fwe=0), thus only Fwi remains: !! sa = sa + emp * sn / e3t for k=1 !! where emp, the surface freshwater budget (evaporation minus !! precipitation minus runoff) given in kg/m2/s is divided !! by 1035 kg/m3 (density of ocena 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 REAL(wp) :: zfact, z1_e3t, zsrau, zdep 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 zsrau = 1. / rau0 ! initialization 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 DO jj = 1, jpj DO ji = 1, jpi ! temperature : heat flux + cooling/heating effet of EMP flux sbc_tsc(ji,jj,jp_tem) = ro0cpr * qns(ji,jj) - zsrau * emp(ji,jj) * tsn(ji,jj,1,jp_tem) ! concent./dilut. effect due to sea-ice melt/formation and (possibly) SSS restoration sbc_tsc(ji,jj,jp_sal) = ( emps(ji,jj) - emp(ji,jj) ) * zsrau * tsn(ji,jj,1,jp_sal) END DO END DO ELSE ! Constant Volume case DO jj = 2, jpj DO ji = fs_2, fs_jpim1 ! vector opt. ! temperature : heat flux sbc_tsc(ji,jj,jp_tem) = ro0cpr * qns(ji,jj) ! salinity : salt flux + concent./dilut. effect (both in emps) sbc_tsc(ji,jj,jp_sal) = zsrau * emps(ji,jj) * tsn(ji,jj,1,jp_sal) END DO END DO 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 ! !---------------------------------------- ! River Runoff effects !---------------------------------------- ! zfact = 0.5e0 ! Effect on (t,s) due to river runoff (dilution effect automatically applied via vertical tracer advection) IF( ln_rnf ) THEN DO jj = 2, jpj DO ji = fs_2, fs_jpim1 zdep = 1. / h_rnf(ji,jj) zdep = zfact * zdep IF ( rnf(ji,jj) /= 0._wp ) THEN 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 !!gm It should be useless CALL lbc_lnk( tsa(:,:,:,jp_tem), 'T', 1. ) ; CALL lbc_lnk( tsa(:,:,:,jp_sal), 'T', 1. ) 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