| 1 | MODULE albedo |
|---|
| 2 | !!====================================================================== |
|---|
| 3 | !! *** MODULE albedo *** |
|---|
| 4 | !! Ocean forcing: bulk thermohaline forcing of the ocean (or ice) |
|---|
| 5 | !!===================================================================== |
|---|
| 6 | !! History : 8.0 ! 2001-04 (LIM 1.0) |
|---|
| 7 | !! NEMO 1.0 ! 2003-07 (C. Ethe, G. Madec) Optimization (old name:shine) |
|---|
| 8 | !! - ! 2004-11 (C. Talandier) add albedo_init |
|---|
| 9 | !! - ! 2001-06 (M. Vancoppenolle) LIM 3.0 |
|---|
| 10 | !! - ! 2006-08 (G. Madec) cleaning for surface module |
|---|
| 11 | !! 3.6 ! 2016-01 (C. Rousset) new parameterization for sea ice albedo |
|---|
| 12 | !!---------------------------------------------------------------------- |
|---|
| 13 | |
|---|
| 14 | !!---------------------------------------------------------------------- |
|---|
| 15 | !! albedo_ice : albedo for ice (clear and overcast skies) |
|---|
| 16 | !! albedo_oce : albedo for ocean (clear and overcast skies) |
|---|
| 17 | !! albedo_init : initialisation of albedo computation |
|---|
| 18 | !!---------------------------------------------------------------------- |
|---|
| 19 | USE phycst ! physical constants |
|---|
| 20 | USE in_out_manager ! I/O manager |
|---|
| 21 | USE lib_mpp ! MPP library |
|---|
| 22 | USE wrk_nemo ! work arrays |
|---|
| 23 | USE lib_fortran ! Fortran utilities (allows no signed zero when 'key_nosignedzero' defined) |
|---|
| 24 | |
|---|
| 25 | USE yomhook, ONLY: lhook, dr_hook |
|---|
| 26 | USE parkind1, ONLY: jprb, jpim |
|---|
| 27 | |
|---|
| 28 | IMPLICIT NONE |
|---|
| 29 | PRIVATE |
|---|
| 30 | |
|---|
| 31 | PUBLIC albedo_ice ! routine called sbcice_lim.F90 |
|---|
| 32 | PUBLIC albedo_oce ! routine called by ??? |
|---|
| 33 | |
|---|
| 34 | INTEGER :: albd_init = 0 !: control flag for initialization |
|---|
| 35 | |
|---|
| 36 | REAL(wp) :: rmue = 0.40 ! cosine of local solar altitude |
|---|
| 37 | REAL(wp) :: ralb_oce = 0.066 ! ocean or lead albedo (Pegau and Paulson, Ann. Glac. 2001) |
|---|
| 38 | REAL(wp) :: c1 = 0.05 ! snow thickness (only for nn_ice_alb=0) |
|---|
| 39 | REAL(wp) :: c2 = 0.10 ! " " |
|---|
| 40 | REAL(wp) :: rcloud = 0.06 ! cloud effect on albedo (only-for nn_ice_alb=0) |
|---|
| 41 | |
|---|
| 42 | ! !!* namelist namsbc_alb |
|---|
| 43 | INTEGER :: nn_ice_alb |
|---|
| 44 | REAL(wp) :: rn_albice |
|---|
| 45 | |
|---|
| 46 | !!---------------------------------------------------------------------- |
|---|
| 47 | !! NEMO/OPA 3.3 , NEMO Consortium (2010) |
|---|
| 48 | !! $Id$ |
|---|
| 49 | !! Software governed by the CeCILL licence (NEMOGCM/NEMO_CeCILL.txt) |
|---|
| 50 | !!---------------------------------------------------------------------- |
|---|
| 51 | CONTAINS |
|---|
| 52 | |
|---|
| 53 | SUBROUTINE albedo_ice( pt_ice, ph_ice, ph_snw, pa_ice_cs, pa_ice_os ) |
|---|
| 54 | !!---------------------------------------------------------------------- |
|---|
| 55 | !! *** ROUTINE albedo_ice *** |
|---|
| 56 | !! |
|---|
| 57 | !! ** Purpose : Computation of the albedo of the snow/ice system |
|---|
| 58 | !! |
|---|
| 59 | !! ** Method : Two schemes are available (from namelist parameter nn_ice_alb) |
|---|
| 60 | !! 0: the scheme is that of Shine & Henderson-Sellers (JGR 1985) for clear-skies |
|---|
| 61 | !! 1: the scheme is "home made" (for cloudy skies) and based on Brandt et al. (J. Climate 2005) |
|---|
| 62 | !! and Grenfell & Perovich (JGR 2004) |
|---|
| 63 | !! Description of scheme 1: |
|---|
| 64 | !! 1) Albedo dependency on ice thickness follows the findings from Brandt et al (2005) |
|---|
| 65 | !! which are an update of Allison et al. (JGR 1993) ; Brandt et al. 1999 |
|---|
| 66 | !! 0-5cm : linear function of ice thickness |
|---|
| 67 | !! 5-150cm: log function of ice thickness |
|---|
| 68 | !! > 150cm: constant |
|---|
| 69 | !! 2) Albedo dependency on snow thickness follows the findings from Grenfell & Perovich (2004) |
|---|
| 70 | !! i.e. it increases as -EXP(-snw_thick/0.02) during freezing and -EXP(-snw_thick/0.03) during melting |
|---|
| 71 | !! 3) Albedo dependency on clouds is speculated from measurements of Grenfell and Perovich (2004) |
|---|
| 72 | !! i.e. cloudy-clear albedo depend on cloudy albedo following a 2d order polynomial law |
|---|
| 73 | !! 4) The needed 4 parameters are: dry and melting snow, freezing ice and bare puddled ice |
|---|
| 74 | !! |
|---|
| 75 | !! ** Note : The parameterization from Shine & Henderson-Sellers presents several misconstructions: |
|---|
| 76 | !! 1) ice albedo when ice thick. tends to 0 is different than ocean albedo |
|---|
| 77 | !! 2) for small ice thick. covered with some snow (<3cm?), albedo is larger |
|---|
| 78 | !! under melting conditions than under freezing conditions |
|---|
| 79 | !! 3) the evolution of ice albedo as a function of ice thickness shows |
|---|
| 80 | !! 3 sharp inflexion points (at 5cm, 100cm and 150cm) that look highly unrealistic |
|---|
| 81 | !! |
|---|
| 82 | !! References : Shine & Henderson-Sellers 1985, JGR, 90(D1), 2243-2250. |
|---|
| 83 | !! Brandt et al. 2005, J. Climate, vol 18 |
|---|
| 84 | !! Grenfell & Perovich 2004, JGR, vol 109 |
|---|
| 85 | !!---------------------------------------------------------------------- |
|---|
| 86 | REAL(wp), INTENT(in ), DIMENSION(:,:,:) :: pt_ice ! ice surface temperature (Kelvin) |
|---|
| 87 | REAL(wp), INTENT(in ), DIMENSION(:,:,:) :: ph_ice ! sea-ice thickness |
|---|
| 88 | REAL(wp), INTENT(in ), DIMENSION(:,:,:) :: ph_snw ! snow thickness |
|---|
| 89 | REAL(wp), INTENT( out), DIMENSION(:,:,:) :: pa_ice_cs ! albedo of ice under clear sky |
|---|
| 90 | REAL(wp), INTENT( out), DIMENSION(:,:,:) :: pa_ice_os ! albedo of ice under overcast sky |
|---|
| 91 | !! |
|---|
| 92 | INTEGER :: ji, jj, jl ! dummy loop indices |
|---|
| 93 | INTEGER :: ijpl ! number of ice categories (3rd dim of ice input arrays) |
|---|
| 94 | REAL(wp) :: ralb_im, ralb_sf, ralb_sm, ralb_if |
|---|
| 95 | REAL(wp) :: zswitch, z1_c1, z1_c2 |
|---|
| 96 | REAL(wp) :: zalb_sm, zalb_sf, zalb_st ! albedo of snow melting, freezing, total |
|---|
| 97 | REAL(wp), POINTER, DIMENSION(:,:,:) :: zalb, zalb_it ! intermediate variable & albedo of ice (snow free) |
|---|
| 98 | INTEGER(KIND=jpim), PARAMETER :: zhook_in = 0 |
|---|
| 99 | INTEGER(KIND=jpim), PARAMETER :: zhook_out = 1 |
|---|
| 100 | REAL(KIND=jprb) :: zhook_handle |
|---|
| 101 | |
|---|
| 102 | CHARACTER(LEN=*), PARAMETER :: RoutineName='ALBEDO_ICE' |
|---|
| 103 | |
|---|
| 104 | IF (lhook) CALL dr_hook(RoutineName,zhook_in,zhook_handle) |
|---|
| 105 | |
|---|
| 106 | !!--------------------------------------------------------------------- |
|---|
| 107 | |
|---|
| 108 | ijpl = SIZE( pt_ice, 3 ) ! number of ice categories |
|---|
| 109 | |
|---|
| 110 | CALL wrk_alloc( jpi,jpj,ijpl, zalb, zalb_it ) |
|---|
| 111 | |
|---|
| 112 | IF( albd_init == 0 ) CALL albedo_init ! initialization |
|---|
| 113 | |
|---|
| 114 | |
|---|
| 115 | SELECT CASE ( nn_ice_alb ) |
|---|
| 116 | |
|---|
| 117 | !------------------------------------------ |
|---|
| 118 | ! Shine and Henderson-Sellers (1985) |
|---|
| 119 | !------------------------------------------ |
|---|
| 120 | CASE( 0 ) |
|---|
| 121 | |
|---|
| 122 | ralb_sf = 0.80 ! dry snow |
|---|
| 123 | ralb_sm = 0.65 ! melting snow |
|---|
| 124 | ralb_if = 0.72 ! bare frozen ice |
|---|
| 125 | ralb_im = rn_albice ! bare puddled ice |
|---|
| 126 | |
|---|
| 127 | ! Computation of ice albedo (free of snow) |
|---|
| 128 | WHERE ( ph_snw == 0._wp .AND. pt_ice >= rt0_ice ) ; zalb(:,:,:) = ralb_im |
|---|
| 129 | ELSE WHERE ; zalb(:,:,:) = ralb_if |
|---|
| 130 | END WHERE |
|---|
| 131 | |
|---|
| 132 | WHERE ( 1.5 < ph_ice ) ; zalb_it = zalb |
|---|
| 133 | ELSE WHERE( 1.0 < ph_ice .AND. ph_ice <= 1.5 ) ; zalb_it = 0.472 + 2.0 * ( zalb - 0.472 ) * ( ph_ice - 1.0 ) |
|---|
| 134 | ELSE WHERE( 0.05 < ph_ice .AND. ph_ice <= 1.0 ) ; zalb_it = 0.2467 + 0.7049 * ph_ice & |
|---|
| 135 | & - 0.8608 * ph_ice * ph_ice & |
|---|
| 136 | & + 0.3812 * ph_ice * ph_ice * ph_ice |
|---|
| 137 | ELSE WHERE ; zalb_it = 0.1 + 3.6 * ph_ice |
|---|
| 138 | END WHERE |
|---|
| 139 | |
|---|
| 140 | DO jl = 1, ijpl |
|---|
| 141 | DO jj = 1, jpj |
|---|
| 142 | DO ji = 1, jpi |
|---|
| 143 | ! freezing snow |
|---|
| 144 | ! no effect of underlying ice layer IF snow thickness > c1. Albedo does not depend on snow thick if > c2 |
|---|
| 145 | ! ! freezing snow |
|---|
| 146 | zswitch = 1._wp - MAX( 0._wp , SIGN( 1._wp , - ( ph_snw(ji,jj,jl) - c1 ) ) ) |
|---|
| 147 | zalb_sf = ( 1._wp - zswitch ) * ( zalb_it(ji,jj,jl) & |
|---|
| 148 | & + ph_snw(ji,jj,jl) * ( ralb_sf - zalb_it(ji,jj,jl) ) / c1 ) & |
|---|
| 149 | & + zswitch * ralb_sf |
|---|
| 150 | |
|---|
| 151 | ! melting snow |
|---|
| 152 | ! no effect of underlying ice layer. Albedo does not depend on snow thick IF > c2 |
|---|
| 153 | zswitch = MAX( 0._wp , SIGN( 1._wp , ph_snw(ji,jj,jl) - c2 ) ) |
|---|
| 154 | zalb_sm = ( 1._wp - zswitch ) * ( ralb_im + ph_snw(ji,jj,jl) * ( ralb_sm - ralb_im ) / c2 ) & |
|---|
| 155 | & + zswitch * ralb_sm |
|---|
| 156 | ! |
|---|
| 157 | ! snow albedo |
|---|
| 158 | zswitch = MAX( 0._wp , SIGN( 1._wp , pt_ice(ji,jj,jl) - rt0_snow ) ) |
|---|
| 159 | zalb_st = zswitch * zalb_sm + ( 1._wp - zswitch ) * zalb_sf |
|---|
| 160 | |
|---|
| 161 | ! Ice/snow albedo |
|---|
| 162 | zswitch = 1._wp - MAX( 0._wp , SIGN( 1._wp , - ph_snw(ji,jj,jl) ) ) |
|---|
| 163 | pa_ice_cs(ji,jj,jl) = zswitch * zalb_st + ( 1._wp - zswitch ) * zalb_it(ji,jj,jl) |
|---|
| 164 | ! |
|---|
| 165 | END DO |
|---|
| 166 | END DO |
|---|
| 167 | END DO |
|---|
| 168 | |
|---|
| 169 | pa_ice_os(:,:,:) = pa_ice_cs(:,:,:) + rcloud ! Oberhuber correction for overcast sky |
|---|
| 170 | |
|---|
| 171 | !------------------------------------------ |
|---|
| 172 | ! New parameterization (2016) |
|---|
| 173 | !------------------------------------------ |
|---|
| 174 | CASE( 1 ) |
|---|
| 175 | |
|---|
| 176 | ralb_im = rn_albice ! bare puddled ice |
|---|
| 177 | ! compilation of values from literature |
|---|
| 178 | ralb_sf = 0.85 ! dry snow |
|---|
| 179 | ralb_sm = 0.75 ! melting snow |
|---|
| 180 | ralb_if = 0.60 ! bare frozen ice |
|---|
| 181 | ! Perovich et al 2002 (Sheba) => the only dataset for which all types of ice/snow were retrieved |
|---|
| 182 | ! ralb_sf = 0.85 ! dry snow |
|---|
| 183 | ! ralb_sm = 0.72 ! melting snow |
|---|
| 184 | ! ralb_if = 0.65 ! bare frozen ice |
|---|
| 185 | ! Brandt et al 2005 (East Antarctica) |
|---|
| 186 | ! ralb_sf = 0.87 ! dry snow |
|---|
| 187 | ! ralb_sm = 0.82 ! melting snow |
|---|
| 188 | ! ralb_if = 0.54 ! bare frozen ice |
|---|
| 189 | ! |
|---|
| 190 | ! Computation of ice albedo (free of snow) |
|---|
| 191 | z1_c1 = 1. / ( LOG(1.5) - LOG(0.05) ) |
|---|
| 192 | z1_c2 = 1. / 0.05 |
|---|
| 193 | WHERE ( ph_snw == 0._wp .AND. pt_ice >= rt0_ice ) ; zalb = ralb_im |
|---|
| 194 | ELSE WHERE ; zalb = ralb_if |
|---|
| 195 | END WHERE |
|---|
| 196 | |
|---|
| 197 | WHERE ( 1.5 < ph_ice ) ; zalb_it = zalb |
|---|
| 198 | ELSE WHERE( 0.05 < ph_ice .AND. ph_ice <= 1.5 ) ; zalb_it = zalb + ( 0.18 - zalb ) * z1_c1 * & |
|---|
| 199 | & ( LOG(1.5) - LOG(ph_ice) ) |
|---|
| 200 | ELSE WHERE ; zalb_it = ralb_oce + ( 0.18 - ralb_oce ) * z1_c2 * ph_ice |
|---|
| 201 | END WHERE |
|---|
| 202 | |
|---|
| 203 | z1_c1 = 1. / 0.02 |
|---|
| 204 | z1_c2 = 1. / 0.03 |
|---|
| 205 | ! Computation of the snow/ice albedo |
|---|
| 206 | DO jl = 1, ijpl |
|---|
| 207 | DO jj = 1, jpj |
|---|
| 208 | DO ji = 1, jpi |
|---|
| 209 | zalb_sf = ralb_sf - ( ralb_sf - zalb_it(ji,jj,jl)) * EXP( - ph_snw(ji,jj,jl) * z1_c1 ); |
|---|
| 210 | zalb_sm = ralb_sm - ( ralb_sm - zalb_it(ji,jj,jl)) * EXP( - ph_snw(ji,jj,jl) * z1_c2 ); |
|---|
| 211 | |
|---|
| 212 | ! snow albedo |
|---|
| 213 | zswitch = MAX( 0._wp , SIGN( 1._wp , pt_ice(ji,jj,jl) - rt0_snow ) ) |
|---|
| 214 | zalb_st = zswitch * zalb_sm + ( 1._wp - zswitch ) * zalb_sf |
|---|
| 215 | |
|---|
| 216 | ! Ice/snow albedo |
|---|
| 217 | zswitch = MAX( 0._wp , SIGN( 1._wp , - ph_snw(ji,jj,jl) ) ) |
|---|
| 218 | pa_ice_os(ji,jj,jl) = ( 1._wp - zswitch ) * zalb_st + zswitch * zalb_it(ji,jj,jl) |
|---|
| 219 | |
|---|
| 220 | END DO |
|---|
| 221 | END DO |
|---|
| 222 | END DO |
|---|
| 223 | ! Effect of the clouds (2d order polynomial) |
|---|
| 224 | pa_ice_cs = pa_ice_os - ( - 0.1010 * pa_ice_os * pa_ice_os + 0.1933 * pa_ice_os - 0.0148 ); |
|---|
| 225 | |
|---|
| 226 | END SELECT |
|---|
| 227 | |
|---|
| 228 | CALL wrk_dealloc( jpi,jpj,ijpl, zalb, zalb_it ) |
|---|
| 229 | ! |
|---|
| 230 | IF (lhook) CALL dr_hook(RoutineName,zhook_out,zhook_handle) |
|---|
| 231 | END SUBROUTINE albedo_ice |
|---|
| 232 | |
|---|
| 233 | |
|---|
| 234 | SUBROUTINE albedo_oce( pa_oce_os , pa_oce_cs ) |
|---|
| 235 | !!---------------------------------------------------------------------- |
|---|
| 236 | !! *** ROUTINE albedo_oce *** |
|---|
| 237 | !! |
|---|
| 238 | !! ** Purpose : Computation of the albedo of the ocean |
|---|
| 239 | !!---------------------------------------------------------------------- |
|---|
| 240 | REAL(wp), DIMENSION(:,:), INTENT(out) :: pa_oce_os ! albedo of ocean under overcast sky |
|---|
| 241 | REAL(wp), DIMENSION(:,:), INTENT(out) :: pa_oce_cs ! albedo of ocean under clear sky |
|---|
| 242 | !! |
|---|
| 243 | REAL(wp) :: zcoef |
|---|
| 244 | INTEGER(KIND=jpim), PARAMETER :: zhook_in = 0 |
|---|
| 245 | INTEGER(KIND=jpim), PARAMETER :: zhook_out = 1 |
|---|
| 246 | REAL(KIND=jprb) :: zhook_handle |
|---|
| 247 | |
|---|
| 248 | CHARACTER(LEN=*), PARAMETER :: RoutineName='ALBEDO_OCE' |
|---|
| 249 | |
|---|
| 250 | IF (lhook) CALL dr_hook(RoutineName,zhook_in,zhook_handle) |
|---|
| 251 | |
|---|
| 252 | !!---------------------------------------------------------------------- |
|---|
| 253 | ! |
|---|
| 254 | zcoef = 0.05 / ( 1.1 * rmue**1.4 + 0.15 ) ! Parameterization of Briegled and Ramanathan, 1982 |
|---|
| 255 | pa_oce_cs(:,:) = zcoef |
|---|
| 256 | pa_oce_os(:,:) = 0.06 ! Parameterization of Kondratyev, 1969 and Payne, 1972 |
|---|
| 257 | ! |
|---|
| 258 | IF (lhook) CALL dr_hook(RoutineName,zhook_out,zhook_handle) |
|---|
| 259 | END SUBROUTINE albedo_oce |
|---|
| 260 | |
|---|
| 261 | |
|---|
| 262 | SUBROUTINE albedo_init |
|---|
| 263 | !!---------------------------------------------------------------------- |
|---|
| 264 | !! *** ROUTINE albedo_init *** |
|---|
| 265 | !! |
|---|
| 266 | !! ** Purpose : initializations for the albedo parameters |
|---|
| 267 | !! |
|---|
| 268 | !! ** Method : Read the namelist namsbc_alb |
|---|
| 269 | !!---------------------------------------------------------------------- |
|---|
| 270 | INTEGER :: ios ! Local integer output status for namelist read |
|---|
| 271 | NAMELIST/namsbc_alb/ nn_ice_alb, rn_albice |
|---|
| 272 | INTEGER(KIND=jpim), PARAMETER :: zhook_in = 0 |
|---|
| 273 | INTEGER(KIND=jpim), PARAMETER :: zhook_out = 1 |
|---|
| 274 | REAL(KIND=jprb) :: zhook_handle |
|---|
| 275 | |
|---|
| 276 | CHARACTER(LEN=*), PARAMETER :: RoutineName='ALBEDO_INIT' |
|---|
| 277 | |
|---|
| 278 | IF (lhook) CALL dr_hook(RoutineName,zhook_in,zhook_handle) |
|---|
| 279 | |
|---|
| 280 | !!---------------------------------------------------------------------- |
|---|
| 281 | ! |
|---|
| 282 | albd_init = 1 ! indicate that the initialization has been done |
|---|
| 283 | ! |
|---|
| 284 | REWIND( numnam_ref ) ! Namelist namsbc_alb in reference namelist : Albedo parameters |
|---|
| 285 | READ ( numnam_ref, namsbc_alb, IOSTAT = ios, ERR = 901) |
|---|
| 286 | 901 IF( ios /= 0 ) CALL ctl_nam ( ios , 'namsbc_alb in reference namelist', lwp ) |
|---|
| 287 | |
|---|
| 288 | REWIND( numnam_cfg ) ! Namelist namsbc_alb in configuration namelist : Albedo parameters |
|---|
| 289 | READ ( numnam_cfg, namsbc_alb, IOSTAT = ios, ERR = 902 ) |
|---|
| 290 | 902 IF( ios /= 0 ) CALL ctl_nam ( ios , 'namsbc_alb in configuration namelist', lwp ) |
|---|
| 291 | IF(lwm) WRITE ( numond, namsbc_alb ) |
|---|
| 292 | ! |
|---|
| 293 | IF(lwp) THEN ! Control print |
|---|
| 294 | WRITE(numout,*) |
|---|
| 295 | WRITE(numout,*) 'albedo : set albedo parameters' |
|---|
| 296 | WRITE(numout,*) '~~~~~~~' |
|---|
| 297 | WRITE(numout,*) ' Namelist namsbc_alb : albedo ' |
|---|
| 298 | WRITE(numout,*) ' choose the albedo parameterization nn_ice_alb = ', nn_ice_alb |
|---|
| 299 | WRITE(numout,*) ' albedo of bare puddled ice rn_albice = ', rn_albice |
|---|
| 300 | ENDIF |
|---|
| 301 | ! |
|---|
| 302 | IF (lhook) CALL dr_hook(RoutineName,zhook_out,zhook_handle) |
|---|
| 303 | END SUBROUTINE albedo_init |
|---|
| 304 | |
|---|
| 305 | !!====================================================================== |
|---|
| 306 | END MODULE albedo |
|---|
