Changeset 11632

Timestamp:

2019-10-01T20:57:51+02:00 (5 years ago)

Author:

clem

Message:

limit snow thickness after advection (with Prather) if snow load makes the ice-snow interface to deplet below sea surface (as for UM scheme)

File:

• NEMO/trunk/src/ICE/icedyn_adv_pra.F90 (modified) (2 diffs)

NEMO/trunk/src/ICE/icedyn_adv_pra.F90

@@ -229 +229 @@
       !
       ! --- Ensure non-negative fields --- !
-      ! Remove negative values (conservation is ensured)
-      !    (because advected fields are not perfectly bounded and tiny negative values can occur, e.g. -1.e-20)
+      !     Remove negative values (conservation is ensured)
+      !     (because advected fields are not perfectly bounded and tiny negative values can occur, e.g. -1.e-20)
       CALL ice_var_zapneg( zdt, pato_i, pv_i, pv_s, psv_i, poa_i, pa_i, pa_ip, pv_ip, pe_s, pe_i )
+      !
+      ! --- Ensure snow load is not too big --- !
+      CALL Hsnow( zdt, pv_i, pv_s, pa_i, pa_ip, pe_s )
       !
       IF( lrst_ice )   CALL adv_pra_rst( 'WRITE', kt )   !* write Prather fields in the restart file
@@ -576 +579 @@
       !
    END SUBROUTINE adv_y
+
+
+   SUBROUTINE Hsnow( pdt, pv_i, pv_s, pa_i, pa_ip, pe_s )
+      !!-------------------------------------------------------------------
+      !!                  ***  ROUTINE Hsnow  ***
+      !!
+      !! ** Purpose : 1- Check snow load after advection
+      !!              2- Correct pond concentration to avoid a_ip > a_i
+      !!
+      !! ** Method :  If snow load makes snow-ice interface to deplet below the ocean surface
+      !!              then put the snow excess in the ocean
+      !!
+      !! ** Notes :   This correction is crucial because of the call to routine icecor afterwards
+      !!              which imposes a mini of ice thick. (rn_himin). This imposed mini can artificially
+      !!              make the snow very thick (if concentration decreases drastically)
+      !!              This behavior has been seen in Ultimate-Macho and supposedly it can also be true for Prather
+      !!-------------------------------------------------------------------
+      REAL(wp)                    , INTENT(in   ) ::   pdt   ! tracer time-step
+      REAL(wp), DIMENSION(:,:,:)  , INTENT(inout) ::   pv_i, pv_s, pa_i, pa_ip
+      REAL(wp), DIMENSION(:,:,:,:), INTENT(inout) ::   pe_s
+      !
+      INTEGER  ::   ji, jj, jl   ! dummy loop indices
+      REAL(wp) ::   z1_dt, zvs_excess, zfra
+      !!-------------------------------------------------------------------
+      !
+      z1_dt = 1._wp / pdt
+      !
+      ! -- check snow load -- !
+      DO jl = 1, jpl
+         DO jj = 1, jpj
+            DO ji = 1, jpi
+               IF ( pv_i(ji,jj,jl) > 0._wp ) THEN
+                  !
+                  zvs_excess = MAX( 0._wp, pv_s(ji,jj,jl) - pv_i(ji,jj,jl) * (rau0-rhoi) * r1_rhos )
+                  !
+                  IF( zvs_excess > 0._wp ) THEN   ! snow-ice interface deplets below the ocean surface
+                     ! put snow excess in the ocean
+                     zfra = ( pv_s(ji,jj,jl) - zvs_excess ) / MAX( pv_s(ji,jj,jl), epsi20 )
+                     wfx_res(ji,jj) = wfx_res(ji,jj) + zvs_excess * rhos * z1_dt
+                     hfx_res(ji,jj) = hfx_res(ji,jj) - SUM( pe_s(ji,jj,1:nlay_s,jl) ) * ( 1._wp - zfra ) * z1_dt ! W.m-2 <0
+                     ! correct snow volume and heat content
+                     pe_s(ji,jj,1:nlay_s,jl) = pe_s(ji,jj,1:nlay_s,jl) * zfra
+                     pv_s(ji,jj,jl)          = pv_s(ji,jj,jl) - zvs_excess
+                  ENDIF
+                  !
+               ENDIF
+            END DO
+         END DO
+      END DO
+      !
+      !-- correct pond concentration to avoid a_ip > a_i -- !
+      WHERE( pa_ip(:,:,:) > pa_i(:,:,:) )   pa_ip(:,:,:) = pa_i(:,:,:)
+      !
+   END SUBROUTINE Hsnow