Changeset 6323 for branches/2015/nemo_v3_6_STABLE/NEMOGCM/NEMO/OPA_SRC/SBC/albedo.F90

Timestamp:

2016-02-18T09:20:22+01:00 (8 years ago)

Author:

cetlod

Message:

3.6 stable : keep exactly the same albedo old scheme, see ticket #1678

File:

• branches/2015/nemo_v3_6_STABLE/NEMOGCM/NEMO/OPA_SRC/SBC/albedo.F90 (modified) (5 diffs)

branches/2015/nemo_v3_6_STABLE/NEMOGCM/NEMO/OPA_SRC/SBC/albedo.F90

@@ -30 +30 @@
 
    INTEGER  ::   albd_init = 0      !: control flag for initialization
-   
+  
+   REAL(wp) ::   rmue     = 0.40    !  cosine of local solar altitude
+   REAL(wp) ::   ralb_oce = 0.066   ! ocean or lead albedo (Pegau and Paulson, Ann. Glac. 2001)
+   REAL(wp) ::   c1       = 0.05    ! snow thickness (only for nn_ice_alb=0)
+   REAL(wp) ::   c2       = 0.10    !  "        "
+   REAL(wp) ::   rcloud   = 0.06    ! cloud effect on albedo (only-for nn_ice_alb=0)
+ 
    !                             !!* namelist namsbc_alb
    INTEGER  ::   nn_ice_alb
@@ -83 +89 @@
       INTEGER  ::   ji, jj, jl         ! dummy loop indices
       INTEGER  ::   ijpl               ! number of ice categories (3rd dim of ice input arrays)
-      REAL(wp), PARAMETER ::   ralb_oce = 0.066   ! ocean or lead albedo (Pegau and Paulson, Ann. Glac. 2001)
-      REAL(wp), PARAMETER ::   c1       = 0.05    ! snow thickness (only for nn_ice_alb=0)
-      REAL(wp), PARAMETER ::   c2       = 0.10    !  "        "
-      REAL(wp), PARAMETER ::   rcloud   = 0.06    ! cloud effect on albedo (only for nn_ice_alb=0)
       REAL(wp)            ::   ralb_im, ralb_sf, ralb_sm, ralb_if
       REAL(wp)            ::   zswitch, z1_c1, z1_c2
@@ -125 +127 @@
          END WHERE
      
-         z1_c1 = 1. / c1
-         z1_c2 = 1. / c2
-         !  Computation of the snow/ice albedo 
          DO jl = 1, ijpl
             DO jj = 1, jpj
@@ -133 +132 @@
                   ! freezing snow
                   ! no effect of underlying ice layer IF snow thickness > c1. Albedo does not depend on snow thick if > c2
-                  zswitch = MAX( 0._wp , SIGN( 1._wp , ph_snw(ji,jj,jl) - c1 ) )
-                  zalb_sf = ( 1._wp - zswitch ) * ( zalb_it(ji,jj,jl) + ph_snw(ji,jj,jl) &
-                     &                          * ( ralb_sf - zalb_it(ji,jj,jl) ) * z1_c1 )  &
-                     &     +          zswitch   * ralb_sf  
-                  
+                  !                                        !  freezing snow        
+                  zswitch   = 1._wp - MAX( 0._wp , SIGN( 1._wp , - ( ph_snw(ji,jj,jl) - c1 ) ) )
+                  zalb_sf   = ( 1._wp - zswitch ) * (  zalb_it(ji,jj,jl)  &
+                     &                           + ph_snw(ji,jj,jl) * ( ralb_sf - zalb_it(ji,jj,jl) ) / c1  )   &
+                     &        +         zswitch   * ralb_sf  
+
                   ! melting snow
-                  ! no effect of underlying ice layer. Albedo does not depend on snow thick IF > c2    
-                  zswitch = MAX( 0._wp , SIGN( 1._wp , ph_snw(ji,jj,jl) - c2 ) )
-                  zalb_sm = ( 1._wp - zswitch ) * ( ralb_im + ph_snw(ji,jj,jl) &
-                     &                          * ( ralb_sm - ralb_im ) * z1_c2 )   &
-                     &     +          zswitch   *   ralb_sm 
-                  
+                  ! no effect of underlying ice layer. Albedo does not depend on snow thick IF > c2
+                  zswitch   = MAX( 0._wp , SIGN( 1._wp , ph_snw(ji,jj,jl) - c2 ) )
+                  zalb_sm = ( 1._wp - zswitch ) * ( ralb_im + ph_snw(ji,jj,jl) * ( ralb_sm - ralb_im ) / c2 )   &
+                      &     +         zswitch   *   ralb_sm 
+                  !
                   ! snow albedo
-                  zswitch = MAX( 0._wp , SIGN( 1._wp , pt_ice(ji,jj,jl) - rt0_snow ) )   
-                  zalb_st = zswitch * zalb_sm + ( 1.0 - zswitch ) * zalb_sf
-                  
-                  ! Ice/snow albedo   
-                  zswitch             = MAX( 0._wp , SIGN( 1._wp , - ph_snw(ji,jj,jl) ) )
-                  pa_ice_cs(ji,jj,jl) = ( 1._wp - zswitch ) * zalb_st + zswitch *  zalb_it(ji,jj,jl)
+                  zswitch  =  MAX( 0._wp , SIGN( 1._wp , pt_ice(ji,jj,jl) - rt0_snow ) )   
+                  zalb_st  =  zswitch * zalb_sm + ( 1._wp - zswitch ) * zalb_sf
+               
+                  ! Ice/snow albedo
+                  zswitch   = 1._wp - MAX( 0._wp , SIGN( 1._wp , - ph_snw(ji,jj,jl) ) )
+                  pa_ice_cs(ji,jj,jl) =  zswitch * zalb_st + ( 1._wp - zswitch ) * zalb_it(ji,jj,jl)
+                  !
                END DO
             END DO
          END DO
+
          pa_ice_os(:,:,:) = pa_ice_cs(:,:,:) + rcloud       ! Oberhuber correction for overcast sky
 
@@ -228 +229 @@
       REAL(wp), DIMENSION(:,:), INTENT(out) ::   pa_oce_cs   !  albedo of ocean under clear sky
       !!
-      REAL(wp) ::   rmue   = 0.40    !  cosine of local solar altitude
-      !!----------------------------------------------------------------------
-      !
-      pa_oce_cs(:,:) = 0.05 / ( 1.1 * rmue**1.4 + 0.15 )   ! Parameterization of Briegled and Ramanathan, 1982              
-      pa_oce_os(:,:) = 0.06                                ! Parameterization of Kondratyev, 1969 and Payne, 1972
+      REAL(wp) :: zcoef 
+      !!----------------------------------------------------------------------
+      !
+      zcoef = 0.05 / ( 1.1 * rmue**1.4 + 0.15 )   ! Parameterization of Briegled and Ramanathan, 1982
+      pa_oce_cs(:,:) = zcoef 
+      pa_oce_os(:,:) = 0.06                       ! Parameterization of Kondratyev, 1969 and Payne, 1972
       !
    END SUBROUTINE albedo_oce