Changeset 12854 for NEMO/branches/2020/r4.0-HEAD_r12713_clem_dan_fixcpl/src/ICE/icealb.F90

Timestamp:

2020-05-01T19:06:23+02:00 (4 years ago)

Author:

clem

Message:

1st implementation of snow fraction (impact on albedo). Light transmission is still not ok since we need a non-zero penetration of solar flux when snow thickness is > 0

File:

• NEMO/branches/2020/r4.0-HEAD_r12713_clem_dan_fixcpl/src/ICE/icealb.F90 (modified) (5 diffs)

NEMO/branches/2020/r4.0-HEAD_r12713_clem_dan_fixcpl/src/ICE/icealb.F90

@@ -14 +14 @@
    !!   ice_alb_init   : initialisation of albedo computation
    !!----------------------------------------------------------------------
-   USE ice, ONLY: jpl ! sea-ice: number of categories
    USE phycst         ! physical constants
    USE dom_oce        ! domain: ocean
+   USE ice, ONLY: jpl ! sea-ice: number of categories
+   USE icevar         ! sea-ice: operations
    !
    USE in_out_manager ! I/O manager
@@ -100 +101 @@
       REAL(wp), INTENT(  out), DIMENSION(:,:,:) ::   palb_ice     !  albedo of ice
       !
+      REAL(wp), DIMENSION(jpi,jpj,jpl) :: za_s_fra   ! ice fraction covered by snow
       INTEGER  ::   ji, jj, jl                ! dummy loop indices
       REAL(wp) ::   z1_c1, z1_c2,z1_c3, z1_c4 ! local scalar
@@ -107 +109 @@
       REAL(wp) ::   zalb_snw, zafrac_snw      ! snow-covered sea ice albedo & relative snow fraction
       REAL(wp) ::   zalb_cs, zalb_os          ! albedo of ice under clear/overcast sky
-      REAL(wp) ::   zhs_min = 0.1_wp          ! minimum snow thickness to fully shade melt ponds and ice 
-      REAL(wp) ::   z1_hsmin
       !!---------------------------------------------------------------------
       !
@@ -119 +119 @@
       z1_c4 = 1. / 0.03
       !
+      CALL ice_var_snwfra( ph_snw, za_s_fra )   ! calculate ice fraction covered by snow
+      !
       DO jl = 1, jpl
          DO jj = 1, jpj
@@ -126 +128 @@
                !--- Specific snow, ice and pond fractions ---!
                !---------------------------------------------!               
-               IF( ph_snw(ji,jj,jl) < zhs_min ) THEN   !--- thin snow partially shades melt ponds and ice
-                  IF( ld_pnd_alb ) THEN   ;   zafrac_pnd = pafrac_pnd(ji,jj,jl)
-                  ELSE                    ;   zafrac_pnd = 0._wp   ;   ENDIF
-                  zafrac_snw = MAX( 0._wp, ( ph_snw(ji,jj,jl) * z1_hsmin ) * ( 1._wp - zafrac_pnd ) ) ! max for roundoff errors
-                  zafrac_ice = MAX( 0._wp, 1._wp - zafrac_pnd - zafrac_snw )                          ! max for roundoff errors
+               zafrac_snw = za_s_fra(ji,jj,jl)
+               IF( ld_pnd_alb ) THEN
+                  zafrac_pnd = MIN( pafrac_pnd(ji,jj,jl), 1._wp - zafrac_snw ) ! make sure (a_ip_eff + a_s_fra) <= 1
                ELSE
-                  zafrac_snw = 1._wp                   !--- thick snow fully shades melt ponds and ice
                   zafrac_pnd = 0._wp
-                  zafrac_ice = 0._wp
-               ENDIF
+               ENDIF
+               zafrac_ice = MAX( 0._wp, 1._wp - zafrac_pnd - zafrac_snw ) ! max for roundoff errors
                !
                !---------------!