| 1 | MODULE albedo |
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| 2 | !!====================================================================== |
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| 3 | !! *** MODULE albedo *** |
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| 4 | !! Ocean forcing: bulk thermohaline forcing of the ocean (or ice) |
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| 5 | !!===================================================================== |
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| 6 | !! History : 8.0 ! 2001-04 (LIM 1.0) |
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| 7 | !! NEMO 1.0 ! 2003-07 (C. Ethe, G. Madec) Optimization (old name:shine) |
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| 8 | !! - ! 2004-11 (C. Talandier) add albedo_init |
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| 9 | !! - ! 2001-06 (M. Vancoppenolle) LIM 3.0 |
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| 10 | !! - ! 2006-08 (G. Madec) cleaning for surface module |
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| 11 | !!---------------------------------------------------------------------- |
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| 12 | |
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| 13 | !!---------------------------------------------------------------------- |
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| 14 | !! albedo_ice : albedo for ice (clear and overcast skies) |
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| 15 | !! albedo_oce : albedo for ocean (clear and overcast skies) |
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| 16 | !! albedo_init : initialisation of albedo computation |
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| 17 | !!---------------------------------------------------------------------- |
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| 18 | USE phycst ! physical constants |
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| 19 | USE in_out_manager ! I/O manager |
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| 20 | USE lib_mpp ! MPP library |
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| 21 | |
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| 22 | IMPLICIT NONE |
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| 23 | PRIVATE |
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| 24 | |
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| 25 | PUBLIC albedo_ice ! routine called sbcice_lim.F90 |
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| 26 | PUBLIC albedo_oce ! routine called by ??? |
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| 27 | |
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| 28 | INTEGER :: albd_init = 0 !: control flag for initialization |
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| 29 | REAL(wp) :: zzero = 0.e0 ! constant values |
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| 30 | REAL(wp) :: zone = 1.e0 ! " " |
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| 31 | |
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| 32 | REAL(wp) :: c1 = 0.05 ! constants values |
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| 33 | REAL(wp) :: c2 = 0.10 ! " " |
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| 34 | REAL(wp) :: rmue = 0.40 ! cosine of local solar altitude |
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| 35 | |
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| 36 | ! !!* namelist namsbc_alb |
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| 37 | REAL(wp) :: rn_cloud = 0.06 ! cloudiness effect on snow or ice albedo (Grenfell & Perovich, 1984) |
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| 38 | #if defined key_lim3 |
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| 39 | REAL(wp) :: rn_albice = 0.53 ! albedo of melting ice in the arctic and antarctic (Shine & Hendersson-Sellers) |
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| 40 | #else |
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| 41 | REAL(wp) :: rn_albice = 0.50 ! albedo of melting ice in the arctic and antarctic (Shine & Hendersson-Sellers) |
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| 42 | #endif |
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| 43 | REAL(wp) :: rn_alphd = 0.80 ! coefficients for linear interpolation used to compute |
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| 44 | REAL(wp) :: rn_alphdi = 0.72 ! albedo between two extremes values (Pyane, 1972) |
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| 45 | REAL(wp) :: rn_alphc = 0.65 ! |
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| 46 | |
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| 47 | !!---------------------------------------------------------------------- |
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| 48 | !! NEMO/OPA 3.3 , NEMO Consortium (2010) |
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| 49 | !! $Id$ |
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| 50 | !! Software governed by the CeCILL licence (NEMOGCM/NEMO_CeCILL.txt) |
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| 51 | !!---------------------------------------------------------------------- |
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| 52 | CONTAINS |
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| 53 | |
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| 54 | SUBROUTINE albedo_ice( pt_ice, ph_ice, ph_snw, pa_ice_cs, pa_ice_os ) |
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| 55 | !!---------------------------------------------------------------------- |
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| 56 | !! *** ROUTINE albedo_ice *** |
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| 57 | !! |
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| 58 | !! ** Purpose : Computation of the albedo of the snow/ice system |
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| 59 | !! as well as the ocean one |
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| 60 | !! |
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| 61 | !! ** Method : - Computation of the albedo of snow or ice (choose the |
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| 62 | !! rignt one by a large number of tests |
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| 63 | !! - Computation of the albedo of the ocean |
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| 64 | !! |
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| 65 | !! References : Shine and Hendersson-Sellers 1985, JGR, 90(D1), 2243-2250. |
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| 66 | !!---------------------------------------------------------------------- |
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| 67 | USE wrk_nemo, ONLY: wrk_in_use, wrk_not_released |
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| 68 | USE wrk_nemo, ONLY: wrk_3d_6 , wrk_3d_7 ! 3D workspace |
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| 69 | !! |
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| 70 | REAL(wp), INTENT(in ), DIMENSION(:,:,:) :: pt_ice ! ice surface temperature (Kelvin) |
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| 71 | REAL(wp), INTENT(in ), DIMENSION(:,:,:) :: ph_ice ! sea-ice thickness |
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| 72 | REAL(wp), INTENT(in ), DIMENSION(:,:,:) :: ph_snw ! snow thickness |
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| 73 | REAL(wp), INTENT( out), DIMENSION(:,:,:) :: pa_ice_cs ! albedo of ice under clear sky |
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| 74 | REAL(wp), INTENT( out), DIMENSION(:,:,:) :: pa_ice_os ! albedo of ice under overcast sky |
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| 75 | !! |
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| 76 | INTEGER :: ji, jj, jl ! dummy loop indices |
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| 77 | INTEGER :: ijpl ! number of ice categories (3rd dim of ice input arrays) |
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| 78 | REAL(wp) :: zalbpsnm ! albedo of ice under clear sky when snow is melting |
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| 79 | REAL(wp) :: zalbpsnf ! albedo of ice under clear sky when snow is freezing |
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| 80 | REAL(wp) :: zalbpsn ! albedo of snow/ice system when ice is coverd by snow |
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| 81 | REAL(wp) :: zalbpic ! albedo of snow/ice system when ice is free of snow |
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| 82 | REAL(wp) :: zithsn ! = 1 for hsn >= 0 ( ice is cov. by snow ) ; = 0 otherwise (ice is free of snow) |
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| 83 | REAL(wp) :: zitmlsn ! = 1 freezinz snow (pt_ice >=rt0_snow) ; = 0 melting snow (pt_ice<rt0_snow) |
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| 84 | REAL(wp) :: zihsc1 ! = 1 hsn <= c1 ; = 0 hsn > c1 |
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| 85 | REAL(wp) :: zihsc2 ! = 1 hsn >= c2 ; = 0 hsn < c2 |
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| 86 | !! |
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| 87 | REAL(wp), POINTER, DIMENSION(:,:,:) :: zalbfz ! = rn_alphdi for freezing ice ; = rn_albice for melting ice |
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| 88 | REAL(wp), POINTER, DIMENSION(:,:,:) :: zficeth ! function of ice thickness |
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| 89 | !!--------------------------------------------------------------------- |
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| 90 | |
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| 91 | ijpl = SIZE( pt_ice, 3 ) ! number of ice categories |
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| 92 | |
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| 93 | IF( wrk_in_use(3, 6,7) ) THEN |
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| 94 | CALL ctl_stop('albedo_ice: requested workspace arrays are unavailable') ; RETURN |
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| 95 | ENDIF |
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| 96 | ! Associate pointers with sub-arrays of workspace arrays |
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| 97 | zalbfz => wrk_3d_6(:,:,1:ijpl) |
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| 98 | zficeth => wrk_3d_7(:,:,1:ijpl) |
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| 99 | |
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| 100 | IF( albd_init == 0 ) CALL albedo_init ! initialization |
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| 101 | |
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| 102 | !--------------------------- |
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| 103 | ! Computation of zficeth |
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| 104 | !--------------------------- |
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| 105 | ! ice free of snow and melts |
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| 106 | WHERE ( ph_snw == 0._wp .AND. pt_ice >= rt0_ice ) ; zalbfz(:,:,:) = rn_albice |
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| 107 | ELSE WHERE ; zalbfz(:,:,:) = rn_alphdi |
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| 108 | END WHERE |
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| 109 | |
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| 110 | WHERE ( 1.5 < ph_ice ) ; zficeth = zalbfz |
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| 111 | ELSE WHERE( 1.0 < ph_ice .AND. ph_ice <= 1.5 ) ; zficeth = 0.472 + 2.0 * ( zalbfz - 0.472 ) * ( ph_ice - 1.0 ) |
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| 112 | ELSE WHERE( 0.05 < ph_ice .AND. ph_ice <= 1.0 ) ; zficeth = 0.2467 + 0.7049 * ph_ice & |
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| 113 | & - 0.8608 * ph_ice * ph_ice & |
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| 114 | & + 0.3812 * ph_ice * ph_ice * ph_ice |
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| 115 | ELSE WHERE ; zficeth = 0.1 + 3.6 * ph_ice |
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| 116 | END WHERE |
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| 117 | |
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| 118 | !!gm old code |
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| 119 | ! DO jl = 1, ijpl |
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| 120 | ! DO jj = 1, jpj |
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| 121 | ! DO ji = 1, jpi |
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| 122 | ! IF( ph_ice(ji,jj,jl) > 1.5 ) THEN |
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| 123 | ! zficeth(ji,jj,jl) = zalbfz(ji,jj,jl) |
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| 124 | ! ELSEIF( ph_ice(ji,jj,jl) > 1.0 .AND. ph_ice(ji,jj,jl) <= 1.5 ) THEN |
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| 125 | ! zficeth(ji,jj,jl) = 0.472 + 2.0 * ( zalbfz(ji,jj,jl) - 0.472 ) * ( ph_ice(ji,jj,jl) - 1.0 ) |
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| 126 | ! ELSEIF( ph_ice(ji,jj,jl) > 0.05 .AND. ph_ice(ji,jj,jl) <= 1.0 ) THEN |
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| 127 | ! zficeth(ji,jj,jl) = 0.2467 + 0.7049 * ph_ice(ji,jj,jl) & |
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| 128 | ! & - 0.8608 * ph_ice(ji,jj,jl) * ph_ice(ji,jj,jl) & |
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| 129 | ! & + 0.3812 * ph_ice(ji,jj,jl) * ph_ice(ji,jj,jl) * ph_ice (ji,jj,jl) |
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| 130 | ! ELSE |
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| 131 | ! zficeth(ji,jj,jl) = 0.1 + 3.6 * ph_ice(ji,jj,jl) |
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| 132 | ! ENDIF |
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| 133 | ! END DO |
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| 134 | ! END DO |
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| 135 | ! END DO |
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| 136 | !!gm end old code |
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| 137 | |
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| 138 | !----------------------------------------------- |
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| 139 | ! Computation of the snow/ice albedo system |
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| 140 | !-------------------------- --------------------- |
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| 141 | |
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| 142 | ! Albedo of snow-ice for clear sky. |
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| 143 | !----------------------------------------------- |
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| 144 | DO jl = 1, ijpl |
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| 145 | DO jj = 1, jpj |
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| 146 | DO ji = 1, jpi |
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| 147 | ! Case of ice covered by snow. |
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| 148 | ! ! freezing snow |
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| 149 | zihsc1 = 1.0 - MAX( zzero , SIGN( zone , - ( ph_snw(ji,jj,jl) - c1 ) ) ) |
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| 150 | zalbpsnf = ( 1.0 - zihsc1 ) * ( zficeth(ji,jj,jl) & |
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| 151 | & + ph_snw(ji,jj,jl) * ( rn_alphd - zficeth(ji,jj,jl) ) / c1 ) & |
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| 152 | & + zihsc1 * rn_alphd |
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| 153 | ! ! melting snow |
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| 154 | zihsc2 = MAX( zzero , SIGN( zone , ph_snw(ji,jj,jl) - c2 ) ) |
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| 155 | zalbpsnm = ( 1.0 - zihsc2 ) * ( rn_albice + ph_snw(ji,jj,jl) * ( rn_alphc - rn_albice ) / c2 ) & |
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| 156 | & + zihsc2 * rn_alphc |
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| 157 | ! |
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| 158 | zitmlsn = MAX( zzero , SIGN( zone , pt_ice(ji,jj,jl) - rt0_snow ) ) |
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| 159 | zalbpsn = zitmlsn * zalbpsnm + ( 1.0 - zitmlsn ) * zalbpsnf |
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| 160 | |
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| 161 | ! Case of ice free of snow. |
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| 162 | zalbpic = zficeth(ji,jj,jl) |
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| 163 | |
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| 164 | ! albedo of the system |
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| 165 | zithsn = 1.0 - MAX( zzero , SIGN( zone , - ph_snw(ji,jj,jl) ) ) |
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| 166 | pa_ice_cs(ji,jj,jl) = zithsn * zalbpsn + ( 1.0 - zithsn ) * zalbpic |
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| 167 | END DO |
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| 168 | END DO |
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| 169 | END DO |
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| 170 | |
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| 171 | ! Albedo of snow-ice for overcast sky. |
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| 172 | !---------------------------------------------- |
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| 173 | pa_ice_os(:,:,:) = pa_ice_cs(:,:,:) + rn_cloud ! Oberhuber correction |
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| 174 | ! |
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| 175 | IF( wrk_not_released(3, 6,7) ) CALL ctl_stop('albedo_ice: failed to release workspace arrays') |
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| 176 | ! |
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| 177 | END SUBROUTINE albedo_ice |
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| 178 | |
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| 179 | |
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| 180 | SUBROUTINE albedo_oce( pa_oce_os , pa_oce_cs ) |
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| 181 | !!---------------------------------------------------------------------- |
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| 182 | !! *** ROUTINE albedo_oce *** |
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| 183 | !! |
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| 184 | !! ** Purpose : Computation of the albedo of the ocean |
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| 185 | !!---------------------------------------------------------------------- |
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| 186 | REAL(wp), DIMENSION(:,:), INTENT(out) :: pa_oce_os ! albedo of ocean under overcast sky |
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| 187 | REAL(wp), DIMENSION(:,:), INTENT(out) :: pa_oce_cs ! albedo of ocean under clear sky |
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| 188 | !! |
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| 189 | REAL(wp) :: zcoef ! local scalar |
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| 190 | !!---------------------------------------------------------------------- |
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| 191 | ! |
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| 192 | zcoef = 0.05 / ( 1.1 * rmue**1.4 + 0.15 ) ! Parameterization of Briegled and Ramanathan, 1982 |
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| 193 | pa_oce_cs(:,:) = zcoef |
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| 194 | pa_oce_os(:,:) = 0.06 ! Parameterization of Kondratyev, 1969 and Payne, 1972 |
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| 195 | ! |
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| 196 | END SUBROUTINE albedo_oce |
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| 197 | |
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| 198 | |
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| 199 | SUBROUTINE albedo_init |
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| 200 | !!---------------------------------------------------------------------- |
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| 201 | !! *** ROUTINE albedo_init *** |
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| 202 | !! |
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| 203 | !! ** Purpose : initializations for the albedo parameters |
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| 204 | !! |
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| 205 | !! ** Method : Read the namelist namsbc_alb |
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| 206 | !!---------------------------------------------------------------------- |
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| 207 | NAMELIST/namsbc_alb/ rn_cloud, rn_albice, rn_alphd, rn_alphdi, rn_alphc |
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| 208 | !!---------------------------------------------------------------------- |
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| 209 | ! |
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| 210 | albd_init = 1 ! indicate that the initialization has been done |
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| 211 | ! |
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| 212 | REWIND( numnam ) ! Read Namelist namsbc_alb : albedo parameters |
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| 213 | READ ( numnam, namsbc_alb ) |
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| 214 | ! |
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| 215 | IF(lwp) THEN ! Control print |
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| 216 | WRITE(numout,*) |
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| 217 | WRITE(numout,*) 'albedo : set albedo parameters' |
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| 218 | WRITE(numout,*) '~~~~~~~' |
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| 219 | WRITE(numout,*) ' Namelist namsbc_alb : albedo ' |
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| 220 | WRITE(numout,*) ' correction for snow and ice albedo rn_cloud = ', rn_cloud |
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| 221 | WRITE(numout,*) ' albedo of melting ice in the arctic and antarctic rn_albice = ', rn_albice |
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| 222 | WRITE(numout,*) ' coefficients for linear rn_alphd = ', rn_alphd |
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| 223 | WRITE(numout,*) ' interpolation used to compute albedo rn_alphdi = ', rn_alphdi |
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| 224 | WRITE(numout,*) ' between two extremes values (Pyane, 1972) rn_alphc = ', rn_alphc |
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| 225 | ENDIF |
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| 226 | ! |
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| 227 | END SUBROUTINE albedo_init |
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| 228 | |
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| 229 | !!====================================================================== |
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| 230 | END MODULE albedo |
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