Add a new implementation for the melt potential calculation

src/core/MOM.F90

@@ -275,6 +275,10 @@ module MOM
                                 !! average surface tracer properties (in meter) when
                                 !! bulk mixed layer is not used, or a negative value
                                 !! if a bulk mixed layer is being used.
+  real :: HFrz                  !< If HFrz > 0, melt potential will be computed.
+                                !! The actual depth over which melt potential is computed will
+                                !! min(HFrz, OBLD), where OBLD is the boundary layer depth.
+                                !! If HFrz <= 0 (default), melt potential will not be computed.
   real :: Hmix_UV               !< Depth scale over which to average surface flow to
                                 !! feedback to the coupler/driver (m) when
                                 !! bulk mixed layer is not used, or a negative value
@@ -1757,6 +1761,11 @@ subroutine initialize_MOM(Time, Time_init, param_file, dirs, CS, restart_CSp, &
                  "SSU, SSV. A non-positive value indicates no averaging.", &
                  units="m", default=0.)
   endif
+  call get_param(param_file, "MOM", "HFREEZE", CS%HFrz, &
+                 "If HFREEZE > 0, melt potential will be computed. The actual depth \n"//&
+                 "over which melt potential is computed will be min(HFREEZE, OBLD), \n"//&
+                 "where OBLD is the boundary layer depth. If HFREEZE <= 0 (default), \n"//&
+                 "melt potential will not be computed.", units="m", default=-1.0)
   call get_param(param_file, "MOM", "MIN_Z_DIAG_INTERVAL", Z_diag_int, &
                  "The minimum amount of time in seconds between \n"//&
                  "calculations of depth-space diagnostics. Making this \n"//&
@@ -2673,6 +2682,7 @@ subroutine extract_surface_state(CS, sfc_state)
   real :: dh                          !< thickness of a layer within mixed layer (meter)
   real :: mass                        !< mass per unit area of a layer (kg/m2)
   real :: T_freeze                    !< freezing temperature (oC)
+  real :: delT(SZI_(CS%G))            !< T-T_freeze (oC)
   logical :: use_temperature   !< If true, temp and saln used as state variables.
   integer :: i, j, k, is, ie, js, je, nz, numberOfErrors
   integer :: isd, ied, jsd, jed
@@ -2831,21 +2841,41 @@ subroutine extract_surface_state(CS, sfc_state)
     endif
   endif  ! (CS%Hmix >= 0.0)
 
+
   if (allocated(sfc_state%melt_potential)) then
-    !$OMP parallel do default(shared)
-    do j=js,je ; do i=is,ie
-      ! set melt_potential to zero to avoid passing values set previously
-      if (G%mask2dT(i,j)>0.) then
-        ! calculate freezing pot. temp. @ surface
-        call calculate_TFreeze(sfc_state%SSS(i,j), 0.0, T_freeze, CS%tv%eqn_of_state)
-        ! time accumulated melt_potential, in J/m^2
-        sfc_state%melt_potential(i,j) = sfc_state%melt_potential(i,j) +  (CS%tv%C_p * CS%GV%Rho0 * &
-                                        (sfc_state%SST(i,j) - T_freeze) * CS%Hmix)
-      else
-          sfc_state%melt_potential(i,j) = 0.0
-      endif! G%mask2dT
-    enddo ; enddo
-  endif
+  !$OMP parallel do default(shared)
+    do j=js,je
+      do i=is,ie
+        depth(i) = 0.0
+        delT(i) = 0.0
+      enddo
+
+      do k=1,nz ; do i=is,ie
+        depth_ml = min(CS%HFrz,CS%visc%MLD(i,j))
+        if (depth(i) + h(i,j,k)*GV%H_to_m < depth_ml) then
+          dh = h(i,j,k)*GV%H_to_m
+        elseif (depth(i) < depth_ml) then
+          dh = depth_ml - depth(i)
+        else
+          dh = 0.0
+        endif
+
+        ! p=0 OK, HFrz ~ 10 to 20m
+        call calculate_TFreeze(CS%tv%S(i,j,k), 0.0, T_freeze, CS%tv%eqn_of_state)
+        depth(i) = depth(i) + dh
+        delT(i) =  delT(i) + dh * (CS%tv%T(i,j,k) - T_freeze)
+      enddo ; enddo
+
+      do i=is,ie
+       if (G%mask2dT(i,j)>0.) then
+         ! time accumulated melt_potential, in J/m^2
+         sfc_state%melt_potential(i,j) = sfc_state%melt_potential(i,j) +  (CS%tv%C_p * CS%GV%Rho0 * delT(i))
+       else
+         sfc_state%melt_potential(i,j) = 0.0
+       endif! G%mask2dT
+      enddo
+    enddo ! end of j loop
+  endif   ! melt_potential
 
   if (allocated(sfc_state%salt_deficit) .and. associated(CS%tv%salt_deficit)) then
     !$OMP parallel do default(shared)