diff --git a/ROMS/Nonlinear/Biology/cobalt.h b/ROMS/Nonlinear/Biology/cobalt.h
index 66e372bec..a6c246b0e 100644
--- a/ROMS/Nonlinear/Biology/cobalt.h
+++ b/ROMS/Nonlinear/Biology/cobalt.h
@@ -22,6 +22,9 @@
       USE mod_diags
       USE mod_mixing
       USE shapiro_mod
+# if defined ICE_MODEL || defined CICE_MODEL
+      USE mod_ice
+# endif
 !
 !  Imported variable declarations.
 !
@@ -38,6 +41,9 @@
      &                   LBi, UBi, LBj, UBj, N(ng), NT(ng),             &
      &                   IminS, ImaxS, JminS, JmaxS,                    &
      &                   nstp(ng), nnew(ng),                            &
+#ifdef ICE_MODEL
+     &                   liold(ng),                                     &
+#endif
 #ifdef MASKING
      &                   GRID(ng) % rmask,                              &
 # if defined WET_DRY
@@ -74,6 +80,9 @@
 #endif
 #ifdef COBALT_CARBON
      &                   FORCES(ng) % atmCO2,                           &
+# if defined ICE_MODEL || defined CICE_MODEL
+     &                   ICE(ng) % ai,                                  &
+# endif
 #endif
 #ifdef COBALT_IRON
      &                   FORCES(ng) % soluble_fe,                       &
@@ -113,6 +122,9 @@
      &                         LBi, UBi, LBj, UBj, UBk, UBt,            &
      &                         IminS, ImaxS, JminS, JmaxS,              &
      &                         nstp, nnew,                              &
+#ifdef ICE_MODEL
+     &                         liold,                                   &
+#endif
 #ifdef MASKING
      &                         rmask,                                   &
 # if defined WET_DRY
@@ -143,6 +155,9 @@
 #endif
 #ifdef COBALT_CARBON
      &                         atmCO2,                                  &
+# if defined ICE_MODEL || defined CICE_MODEL
+     &                         ai,                                      &
+# endif
 #endif
 #ifdef COBALT_IRON
      &                         soluble_fe, ironsed,                     &
@@ -193,6 +208,9 @@
       integer, intent(in) :: LBi, UBi, LBj, UBj, UBk, UBt
       integer, intent(in) :: IminS, ImaxS, JminS, JmaxS
       integer, intent(in) :: nstp, nnew
+#ifdef ICE_MODEL
+      integer, intent(in) :: liold
+#endif
 
 ! RD: cleaning of CPP  keys needed ASSUME_SHAPE, OXYGEN, CARBON !!!
 #ifdef ASSUMED_SHAPE
@@ -232,6 +250,11 @@
 #endif
 # ifdef COBALT_CARBON
       real(r8), intent(in) :: atmCO2(LBi:,LBj:)
+#  ifdef ICE_MODEL
+      real(r8), intent(in) :: ai(LBi:,LBj:,:)
+#  elif defined CICE_MODEL
+      real(r8), intent(in) :: ai(LBi:,LBj:)
+#  endif
 # endif
 # ifdef COBALT_IRON
       real(r8), intent(in) :: soluble_fe(LBi:,LBj:)
@@ -296,6 +319,11 @@
 #endif
 # ifdef COBALT_CARBON
       real(r8), intent(in) :: atmCO2(LBi:UBi,LBj:UBj)
+#  if defined ICE_MODEL
+      real(r8), intent(in) :: ai(LBi:UBi,LBj:UBj,2)
+#  elif defined CICE_MODEL
+      real(r8), intent(in) :: ai(LBi:UBi,LBj:UBj)
+#  endif
 # endif
 # ifdef COBALT_IRON
       real(r8), intent(in) :: soluble_fe(LBi:UBi,LBj:UBj)
@@ -771,7 +799,13 @@ IF ( Master ) WRITE(stdout,*) '>>>    After CALL FMS surface min/max(co3_ion) ='
 
        ! convert ppmv to partial pressure in atm
        !pCO2atm(i,j)  = atmCO2(i,j) * 1.0e-6
+#ifdef ICE_MODEL
+       pCO2atm  = (1.0 - ai(i,j,liold)) * atmCO2(i,j) * 1.0e-6
+#elif defined CICE_MODEL
+       pCO2atm  = (1.0 - ai(i,j)) * atmCO2(i,j) * 1.0e-6
+#else
        pCO2atm  = atmCO2(i,j) * 1.0e-6
+#endif
        !pCO2surf(i,j) = cobalt%pco2_csurf(i,j) * 1.0e-6
        pCO2surface = cobalt%pco2_csurf(i,j) * 1.0e-6
 
diff --git a/ROMS/Utility/checkdefs.F b/ROMS/Utility/checkdefs.F
index 1be7be23f..482248c96 100644
--- a/ROMS/Utility/checkdefs.F
+++ b/ROMS/Utility/checkdefs.F
@@ -1731,6 +1731,13 @@ SUBROUTINE checkdefs
       is=LEN_TRIM(Coptions)+1
       Coptions(is:is+13)=' M2TIDE_DIFF,'
 #endif
+#ifdef MASK_HACK
+!
+      IF (Master) WRITE (stdout,20) 'MASK_HACK',                        &
+     &   'Land/Sea masking'
+      is=LEN_TRIM(Coptions)+1
+      Coptions(is:is+11)=' MASK_HACK,'
+#endif
 #ifdef MASKING
 !
       IF (Master) WRITE (stdout,20) 'MASKING',                          &
@@ -2944,6 +2951,15 @@ SUBROUTINE checkdefs
       is=LEN_TRIM(Coptions)+1
       Coptions(is:is+11)=' T_PASSIVE,'
 # endif
+# ifdef TS_HSIMT
+!
+      IF (Master) WRITE (stdout,20) 'TS_HSIMT',                         &
+     &   'Flux corrected HSIMT 3D advection of tracers'
+      is=LEN_TRIM(Coptions)+1
+      Coptions(is:is+10)=' TS_HSIMT,'
+      itrcHadv=itrcHadv+1
+      itrcVadv=itrcVadv+1
+# endif
 # if defined TS_MIX_CLIMA && \
     (defined TS_DIF2      || defined TS_DIF4)
 !
@@ -3062,7 +3078,7 @@ SUBROUTINE checkdefs
 # endif
 # if !(defined TS_MPDATA       || defined TS_A4HADVECTION || \
        defined TS_C2HADVECTION || defined TS_C4HADVECTION || \
-       defined TS_U3HADVECTION)
+       defined TS_U3HADVECTION || defined TS_HSIMT)
 !
       IF (Master) WRITE (stdout,20) 'TS_C4HADVECTION',                  &
      &   'Fourth-order centered horizontal advection of tracers'
@@ -3140,7 +3156,7 @@ SUBROUTINE checkdefs
 # endif
 # if !(defined TS_MPDATA       || defined TS_A4VADVECTION || \
        defined TS_C2VADVECTION || defined TS_C4VADVECTION || \
-       defined TS_SVADVECTION)
+       defined TS_SVADVECTION  || defined TS_HSIMT)
 !
       IF (Master) WRITE (stdout,20) 'TS_C4VADVECTION',                  &
      &   'Fourth-order centered vertical advection of tracers'
diff --git a/ROMS/Utility/get_grid.F b/ROMS/Utility/get_grid.F
index 299a541d7..3fd976e61 100644
--- a/ROMS/Utility/get_grid.F
+++ b/ROMS/Utility/get_grid.F
@@ -209,9 +209,9 @@ SUBROUTINE get_grid (ng, model)
         exit_flag=2
         RETURN
       END IF
-#  ifdef BERING_STRAIT
-      IF (.not.find_string(var_name,n_var,'mask2',vindex)) THEN
-        IF (Master) WRITE (stdout,10) 'mask2', TRIM(ncname)
+#  ifdef MASK_HACK
+      IF (.not.find_string(var_name,n_var,'mask3',vindex)) THEN
+        IF (Master) WRITE (stdout,10) 'mask3', TRIM(ncname)
         exit_flag=2
         RETURN
       END IF
@@ -568,7 +568,7 @@ SUBROUTINE get_grid (ng, model)
      &                          EWperiodic(ng), NSperiodic(ng),         &
      &                          GRID(ng) % pmask)
 #  endif
-#  ifdef BERING_STRAIT
+#  ifdef MASK_HACK
 !
 !  Read in Land/Sea masking at PSI-points.
 !
diff --git a/makefile b/makefile
index d2f307d0e..3d7b095d5 100644
--- a/makefile
+++ b/makefile
@@ -498,6 +498,7 @@ ifdef USE_REPRESENTER
 endif
 ifdef USE_SEAICE
  includes +=	ROMS/Nonlinear/SeaIce
+ includes +=	ROMS/SeaIce
 endif
 ifdef USE_TANGENT
  includes +=	ROMS/Tangent \