Changeset 13310

Timestamp:

2020-07-16T11:13:15+02:00 (4 years ago)

Author:

clem

Message:

zdftke: orca1 crashes after 6 months unless implicit drags is used or the input of energy below sea-ice is increased. We chose here to remove the dependency of ice fraction in the surface condition on tke (back to old formulation). The rest of the changes are just there to prevent roundoff errors.

File:

• NEMO/releases/r4.0/r4.0-HEAD/src/OCE/ZDF/zdftke.F90 (modified) (6 diffs)

NEMO/releases/r4.0/r4.0-HEAD/src/OCE/ZDF/zdftke.F90

@@ -233 +233 @@
       DO jj = 2, jpjm1            ! en(1)   = rn_ebb taum / rau0  (min value rn_emin0)
          DO ji = fs_2, fs_jpim1   ! vector opt.
-            en(ji,jj,1) = MAX( rn_emin0, ( ( 1._wp - fr_i(ji,jj) ) * zbbrau + &
-               &                                     fr_i(ji,jj)   * zbbirau ) * taum(ji,jj) ) * tmask(ji,jj,1)
+!! clem: this should be the right formulation but it makes the model unstable unless drags are calculated implicitly
+!!       one way around would be to increase zbbirau 
+!!          en(ji,jj,1) = MAX( rn_emin0, ( ( 1._wp - fr_i(ji,jj) ) * zbbrau + &
+!!             &                                     fr_i(ji,jj)   * zbbirau ) * taum(ji,jj) ) * tmask(ji,jj,1)
+            en(ji,jj,1) = MAX( rn_emin0, zbbrau * taum(ji,jj) ) * tmask(ji,jj,1)
          END DO
       END DO
@@ -304 +307 @@
             DO ji = fs_2, fs_jpim1   ! vector opt.
                zus  = zcof * SQRT( taum(ji,jj) )           ! Stokes drift
-               zus3(ji,jj) = ( 1._wp - zice_fra(ji,jj) ) * zus * zus * zus * tmask(ji,jj,1) ! zus > 0. ok
+               zus3(ji,jj) = MAX( 0._wp, 1._wp - zice_fra(ji,jj) ) * zus * zus * zus * tmask(ji,jj,1) ! zus > 0. ok
             END DO
          END DO         
@@ -310 +313 @@
             DO jj = 2, jpjm1
                DO ji = fs_2, fs_jpim1   ! vector opt.
-                  IF ( zus3(ji,jj) /= 0. ) THEN               
+                  IF ( zus3(ji,jj) /= 0._wp ) THEN               
                      ! vertical velocity due to LC   
                      IF ( pdepw(ji,jj,jk) - zhlc(ji,jj) < 0 .AND. wmask(ji,jj,jk) /= 0. ) THEN
@@ -420 +423 @@
                DO ji = fs_2, fs_jpim1   ! vector opt.
                   en(ji,jj,jk) = en(ji,jj,jk) + rn_efr * en(ji,jj,1) * EXP( -pdepw(ji,jj,jk) / htau(ji,jj) )   &
-                     &                                 * ( 1._wp - zice_fra(ji,jj) ) * wmask(ji,jj,jk) * tmask(ji,jj,1)
+                     &                                 * MAX( 0._wp, 1._wp - zice_fra(ji,jj) ) * wmask(ji,jj,jk) * tmask(ji,jj,1)
                END DO
             END DO
@@ -429 +432 @@
                jk = nmln(ji,jj)
                en(ji,jj,jk) = en(ji,jj,jk) + rn_efr * en(ji,jj,1) * EXP( -pdepw(ji,jj,jk) / htau(ji,jj) )   &
-                  &                                 * ( 1._wp - zice_fra(ji,jj) ) * wmask(ji,jj,jk) * tmask(ji,jj,1)
+                  &                                 * MAX( 0._wp, 1._wp - zice_fra(ji,jj) ) * wmask(ji,jj,jk) * tmask(ji,jj,1)
             END DO
          END DO
@@ -442 +445 @@
                   zdif = rhftau_scl * MAX( 0._wp, zdif + rhftau_add )  ! apply some modifications...
                   en(ji,jj,jk) = en(ji,jj,jk) + zbbrau * zdif * EXP( -pdepw(ji,jj,jk) / htau(ji,jj) )   &
-                     &                                 * ( 1._wp - zice_fra(ji,jj) ) * wmask(ji,jj,jk) * tmask(ji,jj,1)
+                     &                                 * MAX( 0._wp, 1._wp - zice_fra(ji,jj) ) * wmask(ji,jj,jk) * tmask(ji,jj,1)
                END DO
             END DO