source: NEMO/branches/2020/dev_r12563_ASINTER-06_ABL_improvement/src/ICE/icealb.F90 @ 12808

Last change on this file since 12808 was 12377, checked in by acc, 10 months ago

The big one. Merging all 2019 developments from the option 1 branch back onto the trunk.

This changeset reproduces 2019/dev_r11943_MERGE_2019 on the trunk using a 2-URL merge
onto a working copy of the trunk. I.e.:

svn merge —ignore-ancestry \

svn+ssh://acc@forge.ipsl.jussieu.fr/ipsl/forge/projets/nemo/svn/NEMO/trunk \
svn+ssh://acc@forge.ipsl.jussieu.fr/ipsl/forge/projets/nemo/svn/NEMO/branches/2019/dev_r11943_MERGE_2019 ./

The —ignore-ancestry flag avoids problems that may otherwise arise from the fact that
the merge history been trunk and branch may have been applied in a different order but
care has been taken before this step to ensure that all applicable fixes and updates
are present in the merge branch.

The trunk state just before this step has been branched to releases/release-4.0-HEAD
and that branch has been immediately tagged as releases/release-4.0.2. Any fixes
or additions in response to tickets on 4.0, 4.0.1 or 4.0.2 should be done on
releases/release-4.0-HEAD. From now on future 'point' releases (e.g. 4.0.2) will
remain unchanged with periodic releases as needs demand. Note release-4.0-HEAD is a
transitional naming convention. Future full releases, say 4.2, will have a release-4.2
branch which fulfills this role and the first point release (e.g. 4.2.0) will be made
immediately following the release branch creation.

2020 developments can be started from any trunk revision later than this one.

  • Property svn:keywords set to Id
File size: 12.2 KB
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1MODULE icealb
2   !!======================================================================
3   !!                       ***  MODULE  icealb  ***
4   !! Atmospheric forcing:  Albedo over sea ice
5   !!=====================================================================
6   !! History :  4.0  !  2017-07  (C. Rousset)       Split ice and ocean albedos
7   !!            4.0  !  2018     (many people)      SI3 [aka Sea Ice cube]
8   !!----------------------------------------------------------------------
9#if defined key_si3
10   !!----------------------------------------------------------------------
11   !!   'key_si3'                                       SI3 sea-ice model
12   !!----------------------------------------------------------------------
13   !!   ice_alb        : albedo for ice (clear and overcast skies)
14   !!   ice_alb_init   : initialisation of albedo computation
15   !!----------------------------------------------------------------------
16   USE ice, ONLY: jpl ! sea-ice: number of categories
17   USE phycst         ! physical constants
18   USE dom_oce        ! domain: ocean
19   !
20   USE in_out_manager ! I/O manager
21   USE lib_mpp        ! MPP library
22   USE lib_fortran    ! Fortran utilities (allows no signed zero when 'key_nosignedzero' defined) 
23   USE timing         ! Timing
24
25   IMPLICIT NONE
26   PRIVATE
27
28   PUBLIC   ice_alb_init   ! called in icestp
29   PUBLIC   ice_alb        ! called in icesbc.F90 and iceupdate.F90
30
31   REAL(wp), PUBLIC, PARAMETER ::   rn_alb_oce = 0.066   !: ocean or lead albedo (Pegau and Paulson, Ann. Glac. 2001)
32   !
33   !                             !!* albedo namelist (namalb)
34   REAL(wp) ::   rn_alb_sdry      ! dry snow albedo
35   REAL(wp) ::   rn_alb_smlt      ! melting snow albedo
36   REAL(wp) ::   rn_alb_idry      ! dry ice albedo
37   REAL(wp) ::   rn_alb_imlt      ! bare puddled ice albedo
38   REAL(wp) ::   rn_alb_dpnd      ! ponded ice albedo
39
40   !! * Substitutions
41#  include "do_loop_substitute.h90"
42   !!----------------------------------------------------------------------
43   !! NEMO/ICE 4.0 , NEMO Consortium (2018)
44   !! $Id$
45   !! Software governed by the CeCILL license (see ./LICENSE)
46   !!----------------------------------------------------------------------
47CONTAINS
48
49   SUBROUTINE ice_alb( pt_su, ph_ice, ph_snw, ld_pnd_alb, pafrac_pnd, ph_pnd, palb_cs, palb_os )
50      !!----------------------------------------------------------------------
51      !!               ***  ROUTINE ice_alb  ***
52      !!         
53      !! ** Purpose :   Computation of the albedo of the snow/ice system
54      !!       
55      !! ** Method  :   The scheme is "home made" (for cloudy skies) and based on Brandt et al. (J. Climate 2005)
56      !!                                                                      and Grenfell & Perovich (JGR 2004)
57      !!                  1) Albedo dependency on ice thickness follows the findings from Brandt et al (2005)
58      !!                     which are an update of Allison et al. (JGR 1993) ; Brandt et al. 1999
59      !!                     0-5cm  : linear function of ice thickness
60      !!                     5-150cm: log    function of ice thickness
61      !!                     > 150cm: constant
62      !!                  2) Albedo dependency on snow thickness follows the findings from Grenfell & Perovich (2004)
63      !!                     i.e. it increases as -EXP(-snw_thick/0.02) during freezing and -EXP(-snw_thick/0.03) during melting
64      !!                  3) Albedo dependency on clouds is speculated from measurements of Grenfell and Perovich (2004)
65      !!                     i.e. cloudy-clear albedo depend on cloudy albedo following a 2d order polynomial law
66      !!                  4) The needed 4 parameters are: dry and melting snow, freezing ice and bare puddled ice
67      !!
68      !!                     compilation of values from literature (reference overcast sky values)
69      !!                        rn_alb_sdry = 0.85      ! dry snow
70      !!                        rn_alb_smlt = 0.75      ! melting snow
71      !!                        rn_alb_idry = 0.60      ! bare frozen ice
72      !!                        rn_alb_imlt = 0.50      ! bare puddled ice albedo
73      !!                        rn_alb_dpnd = 0.36      ! ponded-ice overcast albedo (Lecomte et al, 2015)
74      !!                                                ! early melt pnds 0.27, late melt ponds 0.14 Grenfell & Perovich
75      !!                     Perovich et al 2002 (Sheba) => the only dataset for which all types of ice/snow were retrieved
76      !!                        rn_alb_sdry = 0.85      ! dry snow
77      !!                        rn_alb_smlt = 0.72      ! melting snow
78      !!                        rn_alb_idry = 0.65      ! bare frozen ice
79      !!                     Brandt et al 2005 (East Antarctica)
80      !!                        rn_alb_sdry = 0.87      ! dry snow
81      !!                        rn_alb_smlt = 0.82      ! melting snow
82      !!                        rn_alb_idry = 0.54      ! bare frozen ice
83      !!
84      !! ** Note    :   The old parameterization from Shine & Henderson-Sellers (not here anymore) presented several misconstructions
85      !!                  1) ice albedo when ice thick. tends to 0 is different than ocean albedo
86      !!                  2) for small ice thick. covered with some snow (<3cm?), albedo is larger
87      !!                     under melting conditions than under freezing conditions
88      !!                  3) the evolution of ice albedo as a function of ice thickness shows 
89      !!                     3 sharp inflexion points (at 5cm, 100cm and 150cm) that look highly unrealistic
90      !!
91      !! References :   Shine & Henderson-Sellers 1985, JGR, 90(D1), 2243-2250.
92      !!                Brandt et al. 2005, J. Climate, vol 18
93      !!                Grenfell & Perovich 2004, JGR, vol 109
94      !!----------------------------------------------------------------------
95      REAL(wp), INTENT(in   ), DIMENSION(:,:,:) ::   pt_su        !  ice surface temperature (Kelvin)
96      REAL(wp), INTENT(in   ), DIMENSION(:,:,:) ::   ph_ice       !  sea-ice thickness
97      REAL(wp), INTENT(in   ), DIMENSION(:,:,:) ::   ph_snw       !  snow depth
98      LOGICAL , INTENT(in   )                   ::   ld_pnd_alb   !  effect of melt ponds on albedo
99      REAL(wp), INTENT(in   ), DIMENSION(:,:,:) ::   pafrac_pnd   !  melt pond relative fraction (per unit ice area)
100      REAL(wp), INTENT(in   ), DIMENSION(:,:,:) ::   ph_pnd       !  melt pond depth
101      REAL(wp), INTENT(  out), DIMENSION(:,:,:) ::   palb_cs      !  albedo of ice under clear    sky
102      REAL(wp), INTENT(  out), DIMENSION(:,:,:) ::   palb_os      !  albedo of ice under overcast sky
103      !
104      INTEGER  ::   ji, jj, jl                ! dummy loop indices
105      REAL(wp) ::   z1_c1, z1_c2,z1_c3, z1_c4 ! local scalar
106      REAL(wp) ::   z1_href_pnd               ! inverse of the characteristic length scale (Lecomte et al. 2015)
107      REAL(wp) ::   zalb_pnd, zafrac_pnd      ! ponded sea ice albedo & relative pound fraction
108      REAL(wp) ::   zalb_ice, zafrac_ice      ! bare sea ice albedo & relative ice fraction
109      REAL(wp) ::   zalb_snw, zafrac_snw      ! snow-covered sea ice albedo & relative snow fraction
110      !!---------------------------------------------------------------------
111      !
112      IF( ln_timing )   CALL timing_start('icealb')
113      !
114      z1_href_pnd = 1. / 0.05
115      z1_c1 = 1. / ( LOG(1.5) - LOG(0.05) ) 
116      z1_c2 = 1. / 0.05
117      z1_c3 = 1. / 0.02
118      z1_c4 = 1. / 0.03
119      !
120      DO jl = 1, jpl
121         DO_2D_11_11
122            !                       !--- Specific snow, ice and pond fractions (for now, we prevent melt ponds and snow at the same time)
123            IF( ph_snw(ji,jj,jl) == 0._wp ) THEN
124               zafrac_snw = 0._wp
125               IF( ld_pnd_alb ) THEN
126                  zafrac_pnd = pafrac_pnd(ji,jj,jl)
127               ELSE
128                  zafrac_pnd = 0._wp
129               ENDIF
130               zafrac_ice = 1._wp - zafrac_pnd
131            ELSE
132               zafrac_snw = 1._wp      ! Snow fully "shades" melt ponds and ice
133               zafrac_pnd = 0._wp
134               zafrac_ice = 0._wp
135            ENDIF
136            !
137            !                       !--- Bare ice albedo (for hi > 150cm)
138            IF( ld_pnd_alb ) THEN
139               zalb_ice = rn_alb_idry
140            ELSE
141               IF( ph_snw(ji,jj,jl) == 0._wp .AND. pt_su(ji,jj,jl) >= rt0 ) THEN  ;   zalb_ice = rn_alb_imlt
142               ELSE                                                               ;   zalb_ice = rn_alb_idry   ;   ENDIF
143            ENDIF
144            !                       !--- Bare ice albedo (for hi < 150cm)
145            IF( 0.05 < ph_ice(ji,jj,jl) .AND. ph_ice(ji,jj,jl) <= 1.5 ) THEN      ! 5cm < hi < 150cm
146               zalb_ice = zalb_ice    + ( 0.18 - zalb_ice   ) * z1_c1 * ( LOG(1.5) - LOG(ph_ice(ji,jj,jl)) )
147            ELSEIF( ph_ice(ji,jj,jl) <= 0.05 ) THEN                               ! 0cm < hi < 5cm
148               zalb_ice = rn_alb_oce  + ( 0.18 - rn_alb_oce ) * z1_c2 * ph_ice(ji,jj,jl)
149            ENDIF
150            !
151            !                       !--- Snow-covered ice albedo (freezing, melting cases)
152            IF( pt_su(ji,jj,jl) < rt0 ) THEN
153               zalb_snw = rn_alb_sdry - ( rn_alb_sdry - zalb_ice ) * EXP( - ph_snw(ji,jj,jl) * z1_c3 )
154            ELSE
155               zalb_snw = rn_alb_smlt - ( rn_alb_smlt - zalb_ice ) * EXP( - ph_snw(ji,jj,jl) * z1_c4 )
156            ENDIF
157            !                       !--- Ponded ice albedo
158            IF( ld_pnd_alb ) THEN
159               zalb_pnd = rn_alb_dpnd - ( rn_alb_dpnd - zalb_ice ) * EXP( - ph_pnd(ji,jj,jl) * z1_href_pnd ) 
160            ELSE
161               zalb_pnd = rn_alb_dpnd
162            ENDIF
163            !                       !--- Surface albedo is weighted mean of snow, ponds and bare ice contributions
164            palb_os(ji,jj,jl) = ( zafrac_snw * zalb_snw + zafrac_pnd * zalb_pnd + zafrac_ice * zalb_ice ) * tmask(ji,jj,1)
165            !
166            palb_cs(ji,jj,jl) = palb_os(ji,jj,jl)  &
167               &                - ( - 0.1010 * palb_os(ji,jj,jl) * palb_os(ji,jj,jl)  &
168               &                    + 0.1933 * palb_os(ji,jj,jl) - 0.0148 ) * tmask(ji,jj,1)
169            !
170         END_2D
171      END DO
172      !
173      !
174      IF( ln_timing )   CALL timing_stop('icealb')
175      !
176   END SUBROUTINE ice_alb
177
178
179   SUBROUTINE ice_alb_init
180      !!----------------------------------------------------------------------
181      !!                 ***  ROUTINE alb_init  ***
182      !!
183      !! ** Purpose :   initializations for the albedo parameters
184      !!
185      !! ** Method  :   Read the namelist namalb
186      !!----------------------------------------------------------------------
187      INTEGER ::   ios   ! Local integer output status for namelist read
188      !!
189      NAMELIST/namalb/ rn_alb_sdry, rn_alb_smlt, rn_alb_idry, rn_alb_imlt, rn_alb_dpnd
190      !!----------------------------------------------------------------------
191      !
192      READ  ( numnam_ice_ref, namalb, IOSTAT = ios, ERR = 901)
193901   IF( ios /= 0 )   CALL ctl_nam ( ios , 'namalb in reference namelist' )
194      READ  ( numnam_ice_cfg, namalb, IOSTAT = ios, ERR = 902 )
195902   IF( ios >  0 )   CALL ctl_nam ( ios , 'namalb in configuration namelist' )
196      IF(lwm) WRITE( numoni, namalb )
197      !
198      IF(lwp) THEN                      ! Control print
199         WRITE(numout,*)
200         WRITE(numout,*) 'ice_alb_init: set albedo parameters'
201         WRITE(numout,*) '~~~~~~~~~~~~'
202         WRITE(numout,*) '   Namelist namalb:'
203         WRITE(numout,*) '      albedo of dry snow                   rn_alb_sdry = ', rn_alb_sdry
204         WRITE(numout,*) '      albedo of melting snow               rn_alb_smlt = ', rn_alb_smlt
205         WRITE(numout,*) '      albedo of dry ice                    rn_alb_idry = ', rn_alb_idry
206         WRITE(numout,*) '      albedo of bare puddled ice           rn_alb_imlt = ', rn_alb_imlt
207         WRITE(numout,*) '      albedo of ponded ice                 rn_alb_dpnd = ', rn_alb_dpnd
208      ENDIF
209      !
210   END SUBROUTINE ice_alb_init
211
212#else
213   !!----------------------------------------------------------------------
214   !!   Default option           Dummy module         NO SI3 sea-ice model
215   !!----------------------------------------------------------------------
216#endif
217
218   !!======================================================================
219END MODULE icealb
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