MODULE albedo !!====================================================================== !! *** MODULE albedo *** !! Ocean forcing: bulk thermohaline forcing of the ocean (or ice) !!===================================================================== !! History : 8.0 ! 01-04 (LIM 1.0) !! 8.5 ! 03-07 (C. Ethe, G. Madec) Optimization (old name:shine) !! 9.0 ! 04-11 (C. Talandier) add albedo_init !! - ! 01-06 (M. Vancoppenolle) LIM 3.0 !! - ! 06-08 (G. Madec) cleaning for surface module !!---------------------------------------------------------------------- !! albedo_ice : albedo for ice (clear and overcast skies) !! albedo_oce : albedo for ocean (clear and overcast skies) !! albedo_init : initialisation of albedo computation !!---------------------------------------------------------------------- USE phycst ! physical constants USE in_out_manager ! I/O manager IMPLICIT NONE PRIVATE PUBLIC albedo_ice ! routine called sbcice_lim.F90 PUBLIC albedo_oce ! routine called by ??? INTEGER :: albd_init = 0 !: control flag for initialization REAL(wp) :: zzero = 0.e0 ! constant values REAL(wp) :: zone = 1.e0 ! " " REAL(wp) :: c1 = 0.05 ! constants values REAL(wp) :: c2 = 0.10 ! " " REAL(wp) :: rmue = 0.40 ! cosine of local solar altitude !!* namelist namalb REAL(wp) :: & cgren = 0.06 , & ! cloudiness effect on snow or ice albedo (Grenfell & Perovich, 1984) #if defined key_lim3 albice = 0.53 , & ! albedo of melting ice in the arctic and antarctic (Shine & Hendersson-Sellers) #else albice = 0.50 , & ! albedo of melting ice in the arctic and antarctic (Shine & Hendersson-Sellers) #endif alphd = 0.80 , & ! coefficients for linear interpolation used to compute alphdi = 0.72 , & ! albedo between two extremes values (Pyane, 1972) alphc = 0.65 !!---------------------------------------------------------------------- !! OPA 9.0 , LOCEAN-IPSL (2006) !! $Id$ !! Software governed by the CeCILL licence (modipsl/doc/NEMO_CeCILL.txt) !!---------------------------------------------------------------------- CONTAINS SUBROUTINE albedo_ice( pt_ice, ph_ice, ph_snw, pa_ice_cs, pa_ice_os ) !!---------------------------------------------------------------------- !! *** ROUTINE albedo_ice *** !! !! ** Purpose : Computation of the albedo of the snow/ice system !! as well as the ocean one !! !! ** Method : - Computation of the albedo of snow or ice (choose the !! rignt one by a large number of tests !! - Computation of the albedo of the ocean !! !! References : Shine and Hendersson-Sellers 1985, JGR, 90(D1), 2243-2250. !!---------------------------------------------------------------------- REAL(wp), INTENT(in ), DIMENSION(:,:,:) :: pt_ice ! ice surface temperature REAL(wp), INTENT(in ), DIMENSION(:,:,:) :: ph_ice ! sea-ice thickness REAL(wp), INTENT(in ), DIMENSION(:,:,:) :: ph_snw ! snow thickness REAL(wp), INTENT( out), DIMENSION(:,:,:) :: pa_ice_cs ! albedo of ice under clear sky REAL(wp), INTENT( out), DIMENSION(:,:,:) :: pa_ice_os ! albedo of ice under overcast sky !! INTEGER :: ji, jj, jl ! dummy loop indices INTEGER :: ijpl ! number of ice categories (3rd dim of ice input arrays) REAL(wp) :: zalbpsnm ! albedo of ice under clear sky when snow is melting REAL(wp) :: zalbpsnf ! albedo of ice under clear sky when snow is freezing REAL(wp) :: zalbpsn ! albedo of snow/ice system when ice is coverd by snow REAL(wp) :: zalbpic ! albedo of snow/ice system when ice is free of snow REAL(wp) :: zithsn ! = 1 for hsn >= 0 ( ice is cov. by snow ) ; = 0 otherwise (ice is free of snow) REAL(wp) :: zitmlsn ! = 1 freezinz snow (pt_ice >=rt0_snow) ; = 0 melting snow (pt_ice c1 REAL(wp) :: zihsc2 ! = 1 hsn >= c2 ; = 0 hsn < c2 !! LOGICAL , DIMENSION(jpi,jpj,SIZE(pt_ice,3)) :: llmask REAL(wp), DIMENSION(jpi,jpj,SIZE(pt_ice,3)) :: zalbfz ! = alphdi for freezing ice ; = albice for melting ice REAL(wp), DIMENSION(jpi,jpj,SIZE(pt_ice,3)) :: zficeth ! function of ice thickness !!--------------------------------------------------------------------- ijpl = SIZE( pt_ice, 3 ) ! number of ice categories IF( albd_init == 0 ) CALL albedo_init ! initialization !--------------------------- ! Computation of zficeth !--------------------------- llmask = ( ph_snw == 0.e0 ) .AND. ( pt_ice >= rt0_ice ) ! ice free of snow and melts WHERE( llmask ) zalbfz = albice ELSEWHERE zalbfz = alphdi END WHERE DO jl = 1, ijpl DO jj = 1, jpj DO ji = 1, jpi IF( ph_ice(ji,jj,jl) > 1.5 ) THEN zficeth(ji,jj,jl) = zalbfz(ji,jj,jl) ELSEIF( ph_ice(ji,jj,jl) > 1.0 .AND. ph_ice(ji,jj,jl) <= 1.5 ) THEN zficeth(ji,jj,jl) = 0.472 + 2.0 * ( zalbfz(ji,jj,jl) - 0.472 ) * ( ph_ice(ji,jj,jl) - 1.0 ) ELSEIF( ph_ice(ji,jj,jl) > 0.05 .AND. ph_ice(ji,jj,jl) <= 1.0 ) THEN zficeth(ji,jj,jl) = 0.2467 + 0.7049 * ph_ice(ji,jj,jl) & & - 0.8608 * ph_ice(ji,jj,jl) * ph_ice(ji,jj,jl) & & + 0.3812 * ph_ice(ji,jj,jl) * ph_ice(ji,jj,jl) * ph_ice (ji,jj,jl) ELSE zficeth(ji,jj,jl) = 0.1 + 3.6 * ph_ice(ji,jj,jl) ENDIF END DO END DO END DO !----------------------------------------------- ! Computation of the snow/ice albedo system !-------------------------- --------------------- ! Albedo of snow-ice for clear sky. !----------------------------------------------- DO jl = 1, ijpl DO jj = 1, jpj DO ji = 1, jpi ! Case of ice covered by snow. ! ! freezing snow zihsc1 = 1.0 - MAX( zzero , SIGN( zone , - ( ph_snw(ji,jj,jl) - c1 ) ) ) zalbpsnf = ( 1.0 - zihsc1 ) * ( zficeth(ji,jj,jl) & & + ph_snw(ji,jj,jl) * ( alphd - zficeth(ji,jj,jl) ) / c1 ) & & + zihsc1 * alphd ! ! melting snow zihsc2 = MAX( zzero , SIGN( zone , ph_snw(ji,jj,jl) - c2 ) ) zalbpsnm = ( 1.0 - zihsc2 ) * ( albice + ph_snw(ji,jj,jl) * ( alphc - albice ) / c2 ) & & + zihsc2 * alphc ! zitmlsn = MAX( zzero , SIGN( zone , pt_ice(ji,jj,jl) - rt0_snow ) ) zalbpsn = zitmlsn * zalbpsnm + ( 1.0 - zitmlsn ) * zalbpsnf ! Case of ice free of snow. zalbpic = zficeth(ji,jj,jl) ! albedo of the system zithsn = 1.0 - MAX( zzero , SIGN( zone , - ph_snw(ji,jj,jl) ) ) pa_ice_cs(ji,jj,jl) = zithsn * zalbpsn + ( 1.0 - zithsn ) * zalbpic END DO END DO END DO ! Albedo of snow-ice for overcast sky. !---------------------------------------------- pa_ice_os(:,:,:) = pa_ice_cs(:,:,:) + cgren ! Oberhuber correction ! END SUBROUTINE albedo_ice SUBROUTINE albedo_oce( pa_oce_os , pa_oce_cs ) !!---------------------------------------------------------------------- !! *** ROUTINE albedo_oce *** !! !! ** Purpose : Computation of the albedo of the ocean !! !! ** Method : .... !!---------------------------------------------------------------------- REAL(wp), DIMENSION(jpi,jpj), INTENT(out) :: pa_oce_os ! albedo of ocean under overcast sky REAL(wp), DIMENSION(jpi,jpj), INTENT(out) :: pa_oce_cs ! albedo of ocean under clear sky !! REAL(wp) :: zcoef ! temporary scalar !!---------------------------------------------------------------------- ! zcoef = 0.05 / ( 1.1 * rmue**1.4 + 0.15 ) ! Parameterization of Briegled and Ramanathan, 1982 pa_oce_cs(:,:) = zcoef pa_oce_os(:,:) = 0.06 ! Parameterization of Kondratyev, 1969 and Payne, 1972 ! END SUBROUTINE albedo_oce SUBROUTINE albedo_init !!---------------------------------------------------------------------- !! *** ROUTINE albedo_init *** !! !! ** Purpose : initializations for the albedo parameters !! !! ** Method : Read the namelist namalb !!---------------------------------------------------------------------- NAMELIST/namalb/ cgren, albice, alphd, alphdi, alphc !!---------------------------------------------------------------------- ! set the initialization flag to 1 albd_init = 1 ! indicate that the initialization has been done ! Read Namelist namalb : albedo parameters REWIND( numnam ) READ ( numnam, namalb ) IF(lwp) THEN ! Control print WRITE(numout,*) WRITE(numout,*) 'albedo_init : set albedo parameters from namelist namalb' WRITE(numout,*) '~~~~~~~~~~~' WRITE(numout,*) ' correction for snow and ice albedo cgren = ', cgren WRITE(numout,*) ' albedo of melting ice in the arctic and antarctic albice = ', albice WRITE(numout,*) ' coefficients for linear alphd = ', alphd WRITE(numout,*) ' interpolation used to compute albedo alphdi = ', alphdi WRITE(numout,*) ' between two extremes values (Pyane, 1972) alphc = ', alphc ENDIF ! END SUBROUTINE albedo_init !!====================================================================== END MODULE albedo