- Timestamp:
- 2016-02-24T08:56:48+01:00 (8 years ago)
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branches/2016/dev_r6325_SIMPLIF_1/NEMOGCM/NEMO/OPA_SRC/SBC/albedo.F90
r4624 r6347 8 8 !! - ! 2004-11 (C. Talandier) add albedo_init 9 9 !! - ! 2001-06 (M. Vancoppenolle) LIM 3.0 10 !! - ! 2006-08 (G. Madec) cleaning for surface module 10 !! 3.2 ! 2006-08 (G. Madec) cleaning for surface module 11 !! 3.6 ! 2016-01 (C. Rousset) new parameterization for sea ice albedo 11 12 !!---------------------------------------------------------------------- 12 13 … … 17 18 !!---------------------------------------------------------------------- 18 19 USE phycst ! physical constants 20 ! 19 21 USE in_out_manager ! I/O manager 20 22 USE lib_mpp ! MPP library … … 25 27 PRIVATE 26 28 27 PUBLIC albedo_ice ! routinecalled sbcice_lim.F9028 PUBLIC albedo_oce ! routine called by ???29 30 INTEGER :: albd_init = 0 !:control flag for initialization31 REAL(wp) :: zzero = 0.e0 ! constant values32 REAL(wp) :: zone = 1.e0 ! " "33 34 REAL(wp) :: c1 = 0.05 ! constants values35 REAL(wp) :: c2 = 0.10 !" "36 REAL(wp) :: r mue = 0.40 ! cosine of local solar altitude37 29 PUBLIC albedo_ice ! called sbcice_lim.F90 30 PUBLIC albedo_oce ! called by sbccpl.F90 31 32 INTEGER :: albd_init = 0 ! control flag for initialization 33 34 REAL(wp) :: rmue = 0.400_wp ! cosine of local solar altitude 35 REAL(wp) :: ralb_oce = 0.066_wp ! ocean or lead albedo (Pegau and Paulson, Ann. Glac. 2001) 36 REAL(wp) :: c1 = 0.050_wp ! snow thickness (only for nn_ice_alb=0) 37 REAL(wp) :: c2 = 0.100_wp ! " " 38 REAL(wp) :: rcloud = 0.060_wp ! cloud effect on albedo (only-for nn_ice_alb=0) 39 38 40 ! !!* namelist namsbc_alb 39 REAL(wp) :: rn_cloud ! cloudiness effect on snow or ice albedo (Grenfell & Perovich, 1984) 40 #if defined key_lim3 41 REAL(wp) :: rn_albice ! albedo of melting ice in the arctic and antarctic (Shine & Hendersson-Sellers) 42 #else 43 REAL(wp) :: rn_albice ! albedo of melting ice in the arctic and antarctic (Shine & Hendersson-Sellers) 44 #endif 45 REAL(wp) :: rn_alphd ! coefficients for linear interpolation used to compute 46 REAL(wp) :: rn_alphdi ! albedo between two extremes values (Pyane, 1972) 47 REAL(wp) :: rn_alphc ! 41 INTEGER :: nn_ice_alb ! type of albedo parameterization 42 REAL(wp) :: rn_albice ! albedo of bare puddled ice 48 43 49 44 !!---------------------------------------------------------------------- … … 59 54 !! 60 55 !! ** Purpose : Computation of the albedo of the snow/ice system 61 !! as well as the ocean one62 56 !! 63 !! ** Method : - Computation of the albedo of snow or ice (choose the 64 !! rignt one by a large number of tests 65 !! - Computation of the albedo of the ocean 66 !! 67 !! References : Shine and Hendersson-Sellers 1985, JGR, 90(D1), 2243-2250. 57 !! ** Method : Two schemes are available (from namelist parameter nn_ice_alb) 58 !! 0: the scheme is that of Shine & Henderson-Sellers (JGR 1985) for clear-skies 59 !! 1: the scheme is "home made" (for cloudy skies) and based on Brandt et al. (J. Climate 2005) 60 !! and Grenfell & Perovich (JGR 2004) 61 !! Description of scheme 1: 62 !! 1) Albedo dependency on ice thickness follows the findings from Brandt et al (2005) 63 !! which are an update of Allison et al. (JGR 1993) ; Brandt et al. 1999 64 !! 0-5cm : linear function of ice thickness 65 !! 5-150cm: log function of ice thickness 66 !! > 150cm: constant 67 !! 2) Albedo dependency on snow thickness follows the findings from Grenfell & Perovich (2004) 68 !! i.e. it increases as -EXP(-snw_thick/0.02) during freezing and -EXP(-snw_thick/0.03) during melting 69 !! 3) Albedo dependency on clouds is speculated from measurements of Grenfell and Perovich (2004) 70 !! i.e. cloudy-clear albedo depend on cloudy albedo following a 2d order polynomial law 71 !! 4) The needed 4 parameters are: dry and melting snow, freezing ice and bare puddled ice 72 !! 73 !! ** Note : The parameterization from Shine & Henderson-Sellers presents several misconstructions: 74 !! 1) ice albedo when ice thick. tends to 0 is different than ocean albedo 75 !! 2) for small ice thick. covered with some snow (<3cm?), albedo is larger 76 !! under melting conditions than under freezing conditions 77 !! 3) the evolution of ice albedo as a function of ice thickness shows 78 !! 3 sharp inflexion points (at 5cm, 100cm and 150cm) that look highly unrealistic 79 !! 80 !! References : Shine & Henderson-Sellers 1985, JGR, 90(D1), 2243-2250. 81 !! Brandt et al. 2005, J. Climate, vol 18 82 !! Grenfell & Perovich 2004, JGR, vol 109 68 83 !!---------------------------------------------------------------------- 69 84 REAL(wp), INTENT(in ), DIMENSION(:,:,:) :: pt_ice ! ice surface temperature (Kelvin) … … 73 88 REAL(wp), INTENT( out), DIMENSION(:,:,:) :: pa_ice_os ! albedo of ice under overcast sky 74 89 !! 75 INTEGER :: ji, jj, jl ! dummy loop indices 76 INTEGER :: ijpl ! number of ice categories (3rd dim of ice input arrays) 77 REAL(wp) :: zalbpsnm ! albedo of ice under clear sky when snow is melting 78 REAL(wp) :: zalbpsnf ! albedo of ice under clear sky when snow is freezing 79 REAL(wp) :: zalbpsn ! albedo of snow/ice system when ice is coverd by snow 80 REAL(wp) :: zalbpic ! albedo of snow/ice system when ice is free of snow 81 REAL(wp) :: zithsn ! = 1 for hsn >= 0 ( ice is cov. by snow ) ; = 0 otherwise (ice is free of snow) 82 REAL(wp) :: zitmlsn ! = 1 freezinz snow (pt_ice >=rt0_snow) ; = 0 melting snow (pt_ice<rt0_snow) 83 REAL(wp) :: zihsc1 ! = 1 hsn <= c1 ; = 0 hsn > c1 84 REAL(wp) :: zihsc2 ! = 1 hsn >= c2 ; = 0 hsn < c2 85 !! 86 REAL(wp), POINTER, DIMENSION(:,:,:) :: zalbfz ! = rn_alphdi for freezing ice ; = rn_albice for melting ice 87 REAL(wp), POINTER, DIMENSION(:,:,:) :: zficeth ! function of ice thickness 90 INTEGER :: ji, jj, jl ! dummy loop indices 91 INTEGER :: ijpl ! number of ice categories (3rd dim of ice input arrays) 92 REAL(wp) :: ralb_im, ralb_sf, ralb_sm, ralb_if 93 REAL(wp) :: zswitch, z1_c1, z1_c2 94 REAL(wp) :: zalb_sm, zalb_sf, zalb_st ! albedo of snow melting, freezing, total 95 REAL(wp), POINTER, DIMENSION(:,:,:) :: zalb, zalb_it ! intermediate variable & albedo of ice (snow free) 88 96 !!--------------------------------------------------------------------- 97 98 ijpl = SIZE( pt_ice, 3 ) ! number of ice categories 89 99 90 ijpl = SIZE( pt_ice, 3 ) ! number of ice categories 91 92 CALL wrk_alloc( jpi,jpj,ijpl, zalbfz, zficeth ) 100 CALL wrk_alloc( jpi,jpj,ijpl, zalb, zalb_it ) 93 101 94 102 IF( albd_init == 0 ) CALL albedo_init ! initialization 95 103 96 !---------------------------97 ! Computation of zficeth98 !---------------------------99 ! ice free of snow and melts100 WHERE ( ph_snw == 0._wp .AND. pt_ice >= rt0_ice ) ; zalbfz(:,:,:) = rn_albice101 ELSE WHERE ; zalbfz(:,:,:) = rn_alphdi102 END WHERE103 104 WHERE ( 1.5 < ph_ice ) ; zficeth = zalbfz105 ELSE WHERE( 1.0 < ph_ice .AND. ph_ice <= 1.5 ) ; zficeth = 0.472 + 2.0 * ( zalbfz - 0.472 ) * ( ph_ice - 1.0 )106 ELSE WHERE( 0.05 < ph_ice .AND. ph_ice <= 1.0 ) ; zficeth = 0.2467 + 0.7049 * ph_ice &107 & - 0.8608 * ph_ice * ph_ice &108 & + 0.3812 * ph_ice * ph_ice * ph_ice109 ELSE WHERE ; zficeth = 0.1 + 3.6 * ph_ice110 END WHERE111 112 !!gm old code113 ! DO jl = 1, ijpl114 ! DO jj = 1, jpj115 ! DO ji = 1, jpi116 ! IF( ph_ice(ji,jj,jl) > 1.5 ) THEN117 ! zficeth(ji,jj,jl) = zalbfz(ji,jj,jl)118 ! ELSEIF( ph_ice(ji,jj,jl) > 1.0 .AND. ph_ice(ji,jj,jl) <= 1.5 ) THEN119 ! zficeth(ji,jj,jl) = 0.472 + 2.0 * ( zalbfz(ji,jj,jl) - 0.472 ) * ( ph_ice(ji,jj,jl) - 1.0 )120 ! ELSEIF( ph_ice(ji,jj,jl) > 0.05 .AND. ph_ice(ji,jj,jl) <= 1.0 ) THEN121 ! zficeth(ji,jj,jl) = 0.2467 + 0.7049 * ph_ice(ji,jj,jl) &122 ! & - 0.8608 * ph_ice(ji,jj,jl) * ph_ice(ji,jj,jl) &123 ! & + 0.3812 * ph_ice(ji,jj,jl) * ph_ice(ji,jj,jl) * ph_ice (ji,jj,jl)124 ! ELSE125 ! zficeth(ji,jj,jl) = 0.1 + 3.6 * ph_ice(ji,jj,jl)126 ! ENDIF127 ! END DO128 ! END DO129 ! END DO130 !!gm end old code131 104 132 !----------------------------------------------- 133 ! Computation of the snow/ice albedo system 134 !-------------------------- --------------------- 105 SELECT CASE ( nn_ice_alb ) ! Select the albedo parameterization 106 ! 107 ! !------------------------------------------ 108 CASE( 0 ) ! Shine and Henderson-Sellers (1985) 109 ! !------------------------------------------ 110 ! 111 ralb_sf = 0.80 ! dry snow 112 ralb_sm = 0.65 ! melting snow 113 ralb_if = 0.72 ! bare frozen ice 114 ralb_im = rn_albice ! bare puddled ice 115 ! 116 ! Computation of ice albedo (free of snow) 117 WHERE ( ph_snw == 0._wp .AND. pt_ice >= rt0_ice ) ; zalb(:,:,:) = ralb_im 118 ELSE WHERE ; zalb(:,:,:) = ralb_if 119 END WHERE 135 120 136 ! Albedo of snow-ice for clear sky. 137 !----------------------------------------------- 138 DO jl = 1, ijpl 139 DO jj = 1, jpj 140 DO ji = 1, jpi 141 ! Case of ice covered by snow. 142 ! ! freezing snow 143 zihsc1 = 1.0 - MAX( zzero , SIGN( zone , - ( ph_snw(ji,jj,jl) - c1 ) ) ) 144 zalbpsnf = ( 1.0 - zihsc1 ) * ( zficeth(ji,jj,jl) & 145 & + ph_snw(ji,jj,jl) * ( rn_alphd - zficeth(ji,jj,jl) ) / c1 ) & 146 & + zihsc1 * rn_alphd 147 ! ! melting snow 148 zihsc2 = MAX( zzero , SIGN( zone , ph_snw(ji,jj,jl) - c2 ) ) 149 zalbpsnm = ( 1.0 - zihsc2 ) * ( rn_albice + ph_snw(ji,jj,jl) * ( rn_alphc - rn_albice ) / c2 ) & 150 & + zihsc2 * rn_alphc 151 ! 152 zitmlsn = MAX( zzero , SIGN( zone , pt_ice(ji,jj,jl) - rt0_snow ) ) 153 zalbpsn = zitmlsn * zalbpsnm + ( 1.0 - zitmlsn ) * zalbpsnf 154 155 ! Case of ice free of snow. 156 zalbpic = zficeth(ji,jj,jl) 157 158 ! albedo of the system 159 zithsn = 1.0 - MAX( zzero , SIGN( zone , - ph_snw(ji,jj,jl) ) ) 160 pa_ice_cs(ji,jj,jl) = zithsn * zalbpsn + ( 1.0 - zithsn ) * zalbpic 121 WHERE ( 1.5 < ph_ice ) ; zalb_it = zalb 122 ELSE WHERE( 1.0 < ph_ice .AND. ph_ice <= 1.5 ) ; zalb_it = 0.472 + 2.0 * ( zalb - 0.472 ) * ( ph_ice - 1.0 ) 123 ELSE WHERE( 0.05 < ph_ice .AND. ph_ice <= 1.0 ) ; zalb_it = 0.2467 + 0.7049 * ph_ice & 124 & - 0.8608 * ph_ice * ph_ice & 125 & + 0.3812 * ph_ice * ph_ice * ph_ice 126 ELSE WHERE ; zalb_it = 0.1 + 3.6 * ph_ice 127 END WHERE 128 ! 129 DO jl = 1, ijpl 130 DO jj = 1, jpj 131 DO ji = 1, jpi 132 ! freezing snow 133 ! no effect of underlying ice layer IF snow thickness > c1. Albedo does not depend on snow thick if > c2 134 ! ! freezing snow 135 zswitch = 1._wp - MAX( 0._wp , SIGN( 1._wp , - ( ph_snw(ji,jj,jl) - c1 ) ) ) 136 zalb_sf = ( 1._wp - zswitch ) * ( zalb_it(ji,jj,jl) & 137 & + ph_snw(ji,jj,jl) * ( ralb_sf - zalb_it(ji,jj,jl) ) / c1 ) & 138 & + zswitch * ralb_sf 139 ! 140 ! melting snow 141 ! no effect of underlying ice layer. Albedo does not depend on snow thick IF > c2 142 zswitch = MAX( 0._wp , SIGN( 1._wp , ph_snw(ji,jj,jl) - c2 ) ) 143 zalb_sm = ( 1._wp - zswitch ) * ( ralb_im + ph_snw(ji,jj,jl) * ( ralb_sm - ralb_im ) / c2 ) & 144 & + zswitch * ralb_sm 145 ! 146 ! snow albedo 147 zswitch = MAX( 0._wp , SIGN( 1._wp , pt_ice(ji,jj,jl) - rt0_snow ) ) 148 zalb_st = zswitch * zalb_sm + ( 1._wp - zswitch ) * zalb_sf 149 ! 150 ! Ice/snow albedo 151 zswitch = 1._wp - MAX( 0._wp , SIGN( 1._wp , - ph_snw(ji,jj,jl) ) ) 152 pa_ice_cs(ji,jj,jl) = zswitch * zalb_st + ( 1._wp - zswitch ) * zalb_it(ji,jj,jl) 153 ! 154 END DO 161 155 END DO 162 156 END DO 163 END DO 164 165 ! Albedo of snow-ice for overcast sky. 166 !---------------------------------------------- 167 pa_ice_os(:,:,:) = pa_ice_cs(:,:,:) + rn_cloud ! Oberhuber correction 168 ! 169 CALL wrk_dealloc( jpi,jpj,ijpl, zalbfz, zficeth ) 157 ! 158 pa_ice_os(:,:,:) = pa_ice_cs(:,:,:) + rcloud ! Oberhuber correction for overcast sky 159 ! 160 ! !------------------------------------------ 161 CASE( 1 ) ! New parameterization (2016) 162 ! !------------------------------------------ 163 ! 164 ralb_im = rn_albice ! bare puddled ice 165 ! compilation of values from literature 166 ralb_sf = 0.85 ! dry snow 167 ralb_sm = 0.75 ! melting snow 168 ralb_if = 0.60 ! bare frozen ice 169 ! Perovich et al 2002 (Sheba) => the only dataset for which all types of ice/snow were retrieved 170 ! ralb_sf = 0.85 ! dry snow 171 ! ralb_sm = 0.72 ! melting snow 172 ! ralb_if = 0.65 ! bare frozen ice 173 ! Brandt et al 2005 (East Antarctica) 174 ! ralb_sf = 0.87 ! dry snow 175 ! ralb_sm = 0.82 ! melting snow 176 ! ralb_if = 0.54 ! bare frozen ice 177 ! 178 ! Computation of ice albedo (free of snow) 179 z1_c1 = 1._wp / ( LOG(1.5_wp) - LOG(0.05_wp) ) 180 z1_c2 = 1._wp / 0.05_wp 181 WHERE ( ph_snw == 0._wp .AND. pt_ice >= rt0_ice ) ; zalb = ralb_im 182 ELSE WHERE ; zalb = ralb_if 183 END WHERE 184 ! 185 WHERE ( 1.5 < ph_ice ) ; zalb_it = zalb 186 ELSE WHERE( 0.05 < ph_ice .AND. ph_ice <= 1.5 ) ; zalb_it = zalb + ( 0.18_wp - zalb ) * z1_c1 * & 187 & ( LOG(1.5_wp) - LOG(ph_ice) ) 188 ELSE WHERE ; zalb_it = ralb_oce + ( 0.18_wp - ralb_oce ) * z1_c2 * ph_ice 189 END WHERE 190 ! 191 z1_c1 = 1._wp / 0.02_wp 192 z1_c2 = 1._wp / 0.03_wp 193 ! Computation of the snow/ice albedo 194 DO jl = 1, ijpl 195 DO jj = 1, jpj 196 DO ji = 1, jpi 197 zalb_sf = ralb_sf - ( ralb_sf - zalb_it(ji,jj,jl)) * EXP( - ph_snw(ji,jj,jl) * z1_c1 ); 198 zalb_sm = ralb_sm - ( ralb_sm - zalb_it(ji,jj,jl)) * EXP( - ph_snw(ji,jj,jl) * z1_c2 ); 199 ! 200 ! snow albedo 201 zswitch = MAX( 0._wp , SIGN( 1._wp , pt_ice(ji,jj,jl) - rt0_snow ) ) 202 zalb_st = zswitch * zalb_sm + ( 1._wp - zswitch ) * zalb_sf 203 ! 204 ! Ice/snow albedo 205 zswitch = MAX( 0._wp , SIGN( 1._wp , - ph_snw(ji,jj,jl) ) ) 206 pa_ice_os(ji,jj,jl) = zswitch * zalb_it(ji,jj,jl) + ( 1._wp - zswitch ) * zalb_st 207 208 END DO 209 END DO 210 END DO 211 ! Effect of the clouds (2d order polynomial) 212 pa_ice_cs = pa_ice_os - ( - 0.1010_wp * pa_ice_os * pa_ice_os + 0.1933_wp * pa_ice_os - 0.0148_wp ) 213 !!gm better coding ? 214 ! pa_ice_cs = 0.1010_wp * pa_ice_os + 0.8067_wp ) * pa_ice_os + 0.0148_wp 215 ! and even better: merge this implicit do loop with the previous one 216 !!gm end 217 END SELECT 218 ! 219 CALL wrk_dealloc( jpi,jpj,ijpl, zalb, zalb_it ) 170 220 ! 171 221 END SUBROUTINE albedo_ice … … 181 231 REAL(wp), DIMENSION(:,:), INTENT(out) :: pa_oce_cs ! albedo of ocean under clear sky 182 232 !! 183 REAL(wp) :: zcoef ! local scalar184 !!---------------------------------------------------------------------- 185 ! 186 zcoef = 0.05 / ( 1.1 * rmue**1.4 + 0.15 ) ! Parameterization of Briegled and Ramanathan, 1982187 pa_oce_cs(:,:) = zcoef 188 pa_oce_os(:,:) = 0.06! Parameterization of Kondratyev, 1969 and Payne, 1972233 REAL(wp) :: zcoef 234 !!---------------------------------------------------------------------- 235 ! 236 zcoef = 0.05 / ( 1.1 * rmue**1.4 + 0.15 ) ! Parameterization of Briegled and Ramanathan, 1982 237 pa_oce_cs(:,:) = zcoef 238 pa_oce_os(:,:) = 0.06 ! Parameterization of Kondratyev, 1969 and Payne, 1972 189 239 ! 190 240 END SUBROUTINE albedo_oce … … 200 250 !!---------------------------------------------------------------------- 201 251 INTEGER :: ios ! Local integer output status for namelist read 202 NAMELIST/namsbc_alb/ rn_cloud, rn_albice, rn_alphd, rn_alphdi, rn_alphc252 NAMELIST/namsbc_alb/ nn_ice_alb, rn_albice 203 253 !!---------------------------------------------------------------------- 204 254 ! … … 219 269 WRITE(numout,*) '~~~~~~~' 220 270 WRITE(numout,*) ' Namelist namsbc_alb : albedo ' 221 WRITE(numout,*) ' correction for snow and ice albedo rn_cloud = ', rn_cloud 222 WRITE(numout,*) ' albedo of melting ice in the arctic and antarctic rn_albice = ', rn_albice 223 WRITE(numout,*) ' coefficients for linear rn_alphd = ', rn_alphd 224 WRITE(numout,*) ' interpolation used to compute albedo rn_alphdi = ', rn_alphdi 225 WRITE(numout,*) ' between two extremes values (Pyane, 1972) rn_alphc = ', rn_alphc 271 WRITE(numout,*) ' choose the albedo parameterization nn_ice_alb = ', nn_ice_alb 272 WRITE(numout,*) ' albedo of bare puddled ice rn_albice = ', rn_albice 226 273 ENDIF 227 274 !
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