Changeset 12334 for NEMO/branches/UKMO/NEMO_4.0.1_remove_0.1m_snow_test/src/ICE/icethd_zdf_bl99.F90

Timestamp:

2020-01-21T16:04:26+01:00 (5 years ago)

Author:

dancopsey

Message:

Make isnow a fraction of the sea ice that is snow covered.

File:

• NEMO/branches/UKMO/NEMO_4.0.1_remove_0.1m_snow_test/src/ICE/icethd_zdf_bl99.F90 (modified) (4 diffs)

NEMO/branches/UKMO/NEMO_4.0.1_remove_0.1m_snow_test/src/ICE/icethd_zdf_bl99.F90

@@ -94 +94 @@
       REAL(wp) ::   ztsu_err  =  1.e-5_wp     ! range around which t_su is considered at 0C 
       REAL(wp) ::   zdti_bnd  =  1.e-4_wp     ! maximal authorized error on temperature 
-      REAL(wp) ::   zhs_min   =  0.01_wp      ! minimum snow thickness for conductivity calculation 
+      REAL(wp) ::   zhs_min   =  0.1_wp       ! minimum snow thickness for conductivity calculation 
       REAL(wp) ::   ztmelts                   ! ice melting temperature
       REAL(wp) ::   zdti_max                  ! current maximal error on temperature 
@@ -101 +101 @@
       REAL(wp) ::   zfac                      ! dummy factor
       !
-      REAL(wp), DIMENSION(jpij) ::   isnow        ! switch for presence (1) or absence (0) of snow
+      REAL(wp), DIMENSION(jpij) ::   isnow        ! fraction of sea ice that is snow covered (for thermodynamic use only)
       REAL(wp), DIMENSION(jpij) ::   ztsub        ! surface temperature at previous iteration
       REAL(wp), DIMENSION(jpij) ::   zh_i, z1_h_i ! ice layer thickness
@@ -147 +147 @@
       !------------------
       DO ji = 1, npti
-         isnow(ji) = 1._wp - MAX( 0._wp , SIGN(1._wp, - h_s_1d(ji) ) )  ! is there snow or not
+
+         ! If the snow thickness drops below zhs_min then reduce the snow fraction instead
+         IF( h_s_1d(ji) < zhs_min ) THEN
+           isnow(ji) = h_s_1d(ji) / zhs_min
+           zh_s(ji) = zhs_min * r1_nlay_s
+         ELSE
+           isnow(ji) = 1.0_wp
+           zh_s(ji) = h_s_1d(ji) * r1_nlay_s
+         END IF
+
          ! layer thickness
          zh_i(ji) = h_i_1d(ji) * r1_nlay_i
-         zh_s(ji) = h_s_1d(ji) * r1_nlay_s
+
       END DO
       !
@@ -156 +165 @@
       ELSEWHERE                         ;   z1_h_i(1:npti) = 0._wp
       END WHERE
-      !
-      WHERE( zh_s(1:npti) > 0._wp   )       zh_s(1:npti) = MAX( zhs_min * r1_nlay_s, zh_s(1:npti) )
       !
       WHERE( zh_s(1:npti) > 0._wp   )   ;   z1_h_s(1:npti) = 1._wp / zh_s(1:npti)