diff --git a/model/bin/build_utils.sh b/model/bin/build_utils.sh
index fe65b6d61..9ba0c087b 100755
--- a/model/bin/build_utils.sh
+++ b/model/bin/build_utils.sh
@@ -802,7 +802,7 @@ create_file_list()
                prop=
             sourcet="w3parall w3triamd w3gridmd $stx $flx $nlx $btx $is $uostmd"
                  IO='w3iogrmd'
-                aux="constants w3servmd w3arrymd w3dispmd w3gsrumd w3timemd w3nmlgridmd $pdlibyow $memcode"
+                aux="constants mpicomm w3servmd w3arrymd w3dispmd w3gsrumd w3timemd w3nmlgridmd $pdlibyow $memcode"
                 if [ "$scrip" = 'SCRIP' ]
                 then
                   aux="$aux scrip_constants scrip_grids scrip_iounitsmod"
@@ -819,42 +819,42 @@ create_file_list()
                prop=
             sourcet="$pdlibcode $pdlibyow $db $tr $trx $bt $setupcode $stx $flx $nlx $btx $is wmmdatmd w3parall $uostmd"
                  IO='w3iogrmd w3iorsmd'
-                aux="constants w3triamd w3servmd w3arrymd w3dispmd w3gsrumd w3timemd" ;;
+                aux="constants mpicomm w3triamd w3servmd w3arrymd w3dispmd w3gsrumd w3timemd" ;;
       ww3_bound)
                core=
                data="w3adatmd $memcode w3gdatmd w3wdatmd w3idatmd w3odatmd"
                prop="$smcm"
             sourcet="$pdlibcode $pdlibyow $db $bt $setupcode $tr $trx $stx $nlx $btx $is wmmdatmd w3parall w3triamd $uostmd"
                  IO='w3iobcmd w3iogrmd w3dispmd w3gsrumd'
-                aux="constants w3servmd w3timemd w3arrymd w3cspcmd w3nmlboundmd" ;;
+                aux="constants mpicomm w3servmd w3timemd w3arrymd w3cspcmd w3nmlboundmd" ;;
       ww3_bounc)
                core=
                data="w3adatmd $memcode w3gdatmd w3wdatmd w3idatmd w3odatmd"
                prop="$smcm"
             sourcet="$pdlibcode $pdlibyow $db $bt $setupcode $stx $nlx $btx $is wmmdatmd w3parall w3triamd $uostmd"
                  IO='w3iobcmd w3iogrmd w3dispmd w3gsrumd'
-                aux="constants w3servmd w3arrymd w3timemd w3cspcmd w3nmlbouncmd" ;;
+                aux="constants mpicomm w3servmd w3arrymd w3timemd w3cspcmd w3nmlbouncmd" ;;
       ww3_prep)
                core='w3fldsmd'
                data="$memcode w3gdatmd w3adatmd w3idatmd w3odatmd w3wdatmd wmmdatmd"
                prop=
             sourcet="$pdlibcode $pdlibyow $db $bt $setupcode w3triamd $stx $flx $nlx $btx  $is $uostmd"
                  IO="w3iogrmd $oasismd $agcmmd $ogcmmd $igcmmd"
-                aux="constants w3servmd w3timemd $tidecode w3arrymd w3dispmd w3gsrumd w3parall" ;;
+                aux="constants mpicomm w3servmd w3timemd $tidecode w3arrymd w3dispmd w3gsrumd w3parall" ;;
       ww3_prnc)
                core='w3fldsmd'
                data="$memcode w3gdatmd w3adatmd w3idatmd w3odatmd w3wdatmd wmmdatmd"
                prop=
             sourcet="$pdlibcode $pdlibyow $db $bt $setupcode w3triamd $stx $flx $nlx $btx $is w3parall $uostmd"
                  IO="w3iogrmd $oasismd $agcmmd $ogcmmd $igcmmd"
-                aux="constants w3servmd w3timemd w3arrymd w3dispmd w3gsrumd w3tidemd w3nmlprncmd" ;;
+                aux="constants mpicomm w3servmd w3timemd w3arrymd w3dispmd w3gsrumd w3tidemd w3nmlprncmd" ;;
       ww3_prtide)
                core='w3fldsmd'
                data="wmmdatmd $memcode w3gdatmd w3wdatmd w3adatmd w3idatmd w3odatmd"
                prop="$pr $smcm"
             sourcet="$pdlibcode $pdlibyow $db $bt $setupcode w3triamd $stx $nlx $btx $is w3parall $uostmd"
                  IO="w3iogrmd $oasismd $agcmmd $ogcmmd $igcmmd"
-                aux="constants w3servmd w3timemd w3arrymd w3dispmd w3gsrumd $tidecode" ;;
+                aux="constants mpicomm w3servmd w3timemd w3arrymd w3dispmd w3gsrumd $tidecode" ;;
       ww3_shel)
                core='w3fldsmd w3initmd w3wavemd w3wdasmd w3updtmd'
                data="wmmdatmd $memcode w3gdatmd w3wdatmd w3adatmd w3idatmd w3odatmd"
@@ -863,7 +863,7 @@ create_file_list()
             sourcet="$sourcet $is $db $tr $bs $refcode $igcode w3parall $uostmd"
                  IO="w3iogrmd w3iogomd w3iopomd w3iotrmd w3iorsmd w3iobcmd $oasismd $agcmmd $ogcmmd $igcmmd"
                  IO="$IO w3iosfmd w3partmd"
-                aux="constants w3servmd w3timemd $tidecode w3arrymd w3dispmd w3cspcmd w3gsrumd"
+                aux="constants mpicomm w3servmd w3timemd $tidecode w3arrymd w3dispmd w3cspcmd w3gsrumd"
                 aux="$aux w3nmlshelmd $pdlibyow" ;;
       ww3_multi|ww3_multi_esmf)
                if [ "$prog" = "ww3_multi" ]
@@ -879,7 +879,7 @@ create_file_list()
             sourcet="$pdlibcode $pdlibyow $setupcode w3parall w3triamd w3srcemd $dsx $flx $ln $st $nl $bt $ic $is $db $tr $bs $refcode $igcode $uostmd"
                  IO='w3iogrmd w3iogomd w3iopomd wmiopomd'
                  IO="$IO w3iotrmd w3iorsmd w3iobcmd w3iosfmd w3partmd $oasismd $agcmmd $ogcmmd $igcmmd"
-                aux="constants $tidecode w3servmd w3timemd w3arrymd w3dispmd w3cspcmd w3gsrumd $mprfaux"
+                aux="constants mpicomm $tidecode w3servmd w3timemd w3arrymd w3dispmd w3cspcmd w3gsrumd $mprfaux"
                 aux="$aux  wmunitmd w3nmlmultimd"
                 if [ "$scrip" = 'SCRIP' ]
                 then
@@ -899,7 +899,7 @@ create_file_list()
             sourcet="$pdlibcode $pdlibyow w3triamd w3srcemd $dsx $flx $ln $st $nl $bt $db $tr $bs $refcode $igcode $is $ic $uostmd"
                  IO='w3iogrmd w3iogomd w3iopomd wmiopomd'
                  IO="$IO w3iotrmd w3iorsmd w3iobcmd w3iosfmd w3partmd $oasismd $agcmmd $ogcmmd $igcmmd"
-                aux="constants w3servmd w3timemd w3arrymd w3dispmd w3cspcmd w3gsrumd $mprfaux $tidecode"
+                aux="constants mpicomm w3servmd w3timemd w3arrymd w3dispmd w3cspcmd w3gsrumd $mprfaux $tidecode"
                 aux="$aux  wmunitmd w3nmlmultimd"
                 if [ "$scrip" = 'SCRIP' ]
                 then
@@ -917,7 +917,7 @@ create_file_list()
                prop=
             sourcet="$pdlibcode $pdlibyow $db $bt $setupcode $tr $trx $stx $flx $nlx $btx $is $uostmd"
                  IO='w3iogrmd w3iogomd'
-                aux="constants w3servmd w3timemd w3arrymd w3dispmd w3gsrumd"
+                aux="constants mpicomm w3servmd w3timemd w3arrymd w3dispmd w3gsrumd"
                 aux="$aux" ;;
       ww3_ounf)
                core='w3initmd'
@@ -925,7 +925,7 @@ create_file_list()
                prop=
             sourcet="$pdlibcode $pdlibyow $db $bt $setupcode w3parall w3triamd $stx $flx $nlx $btx  $is $uostmd"
                  IO='w3iogrmd w3iogomd w3iorsmd w3iopomd'
-                aux="constants w3servmd w3timemd w3arrymd w3dispmd w3gsrumd"
+                aux="constants mpicomm w3servmd w3timemd w3arrymd w3dispmd w3gsrumd"
                 aux="$aux w3nmlounfmd $smco w3ounfmetamd w3metamd" ;;
       ww3_outp)
                core=
@@ -933,14 +933,14 @@ create_file_list()
                prop=
             sourcet="$pdlibcode $pdlibyow $setupcode $flx $ln $st $nl $bt $ic $is $db $tr $bs $igcode $uostmd"
                  IO='w3bullmd w3iogrmd w3iopomd w3partmd'
-                aux="constants w3servmd w3timemd w3arrymd w3dispmd w3gsrumd" ;;
+                aux="constants mpicomm w3servmd w3timemd w3arrymd w3dispmd w3gsrumd" ;;
       ww3_ounp)
                core=
                data="wmmdatmd w3parall w3triamd $memcode w3gdatmd w3wdatmd w3adatmd w3idatmd w3odatmd"
                prop=
             sourcet="$pdlibcode $pdlibyow $setupcode $flx $ln $st $nl $bt $ic $is $db $tr $bs $igcode $uostmd"
                  IO='w3bullmd w3iogrmd w3iopomd w3partmd'
-                aux="constants w3servmd w3timemd w3arrymd w3dispmd w3gsrumd"
+                aux="constants mpicomm w3servmd w3timemd w3arrymd w3dispmd w3gsrumd"
                 aux="$aux w3nmlounpmd" ;;
       ww3_trck)
                core=
@@ -948,21 +948,21 @@ create_file_list()
                prop=
             sourcet=
                  IO=
-                aux="constants w3servmd w3timemd w3gsrumd" ;;
+                aux="constants mpicomm w3servmd w3timemd w3gsrumd" ;;
       ww3_trnc)
                core=
                data="$memcode w3gdatmd w3odatmd"
                prop=
             sourcet=
                  IO=
-                aux="constants w3servmd w3timemd w3gsrumd w3nmltrncmd" ;;
+                aux="constants mpicomm w3servmd w3timemd w3gsrumd w3nmltrncmd" ;;
       ww3_grib)
                core=
                data="w3parall wmmdatmd w3triamd $memcode w3gdatmd w3wdatmd w3adatmd w3idatmd w3odatmd"
                prop=
             sourcet="$pdlibcode $pdlibyow $db $bt $setupcode $stx $flx $nlx $btx $is $uostmd"
                  IO='w3iogrmd w3iogomd'
-                aux="constants w3servmd w3timemd w3arrymd w3dispmd w3gsrumd"
+                aux="constants mpicomm w3servmd w3timemd w3arrymd w3dispmd w3gsrumd"
                 aux="$aux" ;;
       ww3_gspl)
                core='w3fldsmd'
@@ -970,14 +970,14 @@ create_file_list()
                prop=
             sourcet="$pdlibcode $pdlibyow $db $bt $setupcode wmmdatmd w3parall w3triamd $stx $flx $nlx $btx $is $uostmd"
                  IO="w3iogrmd  $oasismd $agcmmd $ogcmmd $igcmmd"
-                aux="constants w3servmd w3timemd w3arrymd w3dispmd w3gsrumd $tidecode" ;;
+                aux="constants mpicomm w3servmd w3timemd w3arrymd w3dispmd w3gsrumd $tidecode" ;;
       ww3_gint)
                core=
                data="w3parall wmmdatmd $memcode w3gdatmd w3wdatmd w3adatmd w3idatmd w3odatmd"
                  IO='w3iogrmd w3iogomd'
                prop=
             sourcet="$pdlibcode $pdlibyow $db $bt $st $nl $is $uostmd"
-                aux="constants w3triamd w3servmd  w3arrymd w3dispmd w3timemd w3gsrumd"
+                aux="constants mpicomm w3triamd w3servmd  w3arrymd w3dispmd w3timemd w3gsrumd"
                 aux="$aux" ;;
       gx_outf)
                core=
@@ -985,7 +985,7 @@ create_file_list()
                prop=
             sourcet="$pdlibcode $pdlibyow $db $bt $setupcode wmmdatmd w3parall w3triamd $stx $flx $nlx $btx $tr $bs $is $uostmd"
                  IO='w3iogrmd w3iogomd'
-                aux="constants w3servmd w3timemd w3arrymd w3dispmd w3gsrumd"
+                aux="constants mpicomm w3servmd w3timemd w3arrymd w3dispmd w3gsrumd"
                 aux="$aux" ;;
       gx_outp)
                core=
@@ -993,28 +993,28 @@ create_file_list()
                prop=
             sourcet="$pdlibcode $pdlibyow $db $bt $setupcode wmmdatmd w3parall w3triamd $ln $flx $st $nlx $btx $tr $bs $is $ic $uostmd"
                  IO='w3iogrmd w3iopomd'
-                aux="constants w3servmd w3timemd w3arrymd w3dispmd w3gsrumd" ;;
+                aux="constants mpicomm w3servmd w3timemd w3arrymd w3dispmd w3gsrumd" ;;
       ww3_systrk)
                core='w3strkmd'
                data="$memcode w3gdatmd w3adatmd w3idatmd w3odatmd w3wdatmd"
                prop=
             sourcet="$pdlibcode $pdlibyow $db $bt $setupcode wmmdatmd w3dispmd w3triamd $ln $stx $flx $nlx $btx $tr $bs $is $uostmd"
                  IO=
-                aux="constants w3servmd w3timemd w3arrymd w3gsrumd w3parall" ;;
+                aux="constants mpicomm w3servmd w3timemd w3arrymd w3gsrumd w3parall" ;;
       libww3|libww3.so)
                core='w3fldsmd w3initmd w3wavemd w3wdasmd w3updtmd'
                data='wmmdatmd w3gdatmd w3wdatmd w3adatmd w3idatmd w3odatmd'
                prop="$pr $smcm"
             sourcet="w3triamd w3srcemd $dsx $flx $ln $st $nl $bt $ic $is $db $tr $bs $refcode $igcode $uostmd"
                  IO='w3iogrmd w3iogomd w3iopomd w3iotrmd w3iorsmd w3iobcmd w3iosfmd w3partmd'
-                aux="constants w3servmd w3timemd $tidecode w3arrymd w3dispmd w3cspcmd w3gsrumd" ;;
+                aux="constants mpicomm w3servmd w3timemd $tidecode w3arrymd w3dispmd w3cspcmd w3gsrumd" ;;
       ww3_uprstr)
               core=
 	      data='wmmdatmd w3triamd w3gdatmd w3wdatmd w3adatmd w3idatmd w3odatmd'
               prop=
            sourcet="$memcode $pdlibcode $pdlibyow $flx $ln $st $nl $bt $ic $is $db $tr $bs $uostmd"
                 IO='w3iogrmd w3iogomd w3iorsmd'
-               aux="constants w3servmd w3timemd w3arrymd w3dispmd w3gsrumd"
+               aux="constants mpicomm w3servmd w3timemd w3arrymd w3dispmd w3gsrumd"
                aux="$aux w3parall w3nmluprstrmd" ;;
     esac
 
diff --git a/model/src/cmake/src_list.cmake b/model/src/cmake/src_list.cmake
index d745be388..6bcb914c4 100644
--- a/model/src/cmake/src_list.cmake
+++ b/model/src/cmake/src_list.cmake
@@ -3,6 +3,7 @@ set(c_src w3getmem.c)
 # Core files always built
 set(ftn_src
   constants.F90
+  mpicomm.F90
   w3adatmd.F90
   w3arrymd.F90
   w3bullmd.F90
diff --git a/model/src/cmake/switches.json b/model/src/cmake/switches.json
index a7b9bc94f..37cd52a30 100644
--- a/model/src/cmake/switches.json
+++ b/model/src/cmake/switches.json
@@ -282,7 +282,7 @@
             },
             {
                 "name": "NL2",
-                "build_files": ["w3snl2md.F90", "mod_xnl4v5.f90", "serv_xnl4v5.f90", "mod_fileio.f90", "mod_constants.f90"],
+                "build_files": ["w3snl2md.F90", "mod_xnl4v5.f90", "serv_xnl4v5.f90", "mod_fileio.f90", "mod_constants.f90", "mod_mpicomm.f90"],
                 "conflicts": ["OMPG", "OMPH"]
             },
             {
diff --git a/model/src/mpicomm.F90 b/model/src/mpicomm.F90
new file mode 100644
index 000000000..3132dece4
--- /dev/null
+++ b/model/src/mpicomm.F90
@@ -0,0 +1,61 @@
+!> @file
+!> @brief Defines MPI communicator id as constants for global use.
+!>
+!> @author H. L. Tolman  @date 05-Jun-2018
+!>
+#include "w3macros.h"
+
+!>
+!> @brief Define some mpi constants for global use
+!>
+!> @author  J. M. Sexton  @date 19-Jul-2024
+!>
+!
+!
+!/ ------------------------------------------------------------------- /
+MODULE MPICOMM
+  !/
+  !/                  +-----------------------------------+
+  !/                  | WAVEWATCH III           NOAA/NCEP |
+  !/                  |           H. L. Tolman            |
+  !/                  |                        FORTRAN 90 |
+  !/                  | Last update :         19-Jul-2024 |
+  !/                  +-----------------------------------+
+  !/
+  !/    19-Jul-2024 : Add MPI SubCommunicator variable    ( version 7.xx )
+  !/
+  !/    Copyright 2009-2024 National Weather Service (NWS),
+  !/       National Oceanic and Atmospheric Administration.  All rights
+  !/       reserved.  WAVEWATCH III is a trademark of the NWS.
+  !/       No unauthorized use without permission.
+  !/
+  !  1. Purpose :
+  !
+  !     Define some mpi constants for global use
+  !
+  !  2. Variables and types :
+  !
+  !      Name                     Type  Scope    Description
+  !     ----------------------------------------------------------------
+  !      MPI_COMM_WW3             Int   Global   Value for mpi (sub)communicator for WW3
+  !      IS_EXTERNAL_COMPONENT    Bool  Global   General logical similar to IS_ESMF_COMPONENT
+  !     ----------------------------------------------------------------
+  !/ ------------------------------------------------------------------- /
+  !/
+  !
+
+  INTEGER :: MPI_COMM_WW3=0 !< MPI_COMM_WW3
+  !
+  ! Parameters in support of running as ESMF component
+  !
+  ! --- Flag indicating whether or not the model has been invoked as an
+  !     external Component.  This flag is set to true in the external
+  !     module during initialization.
+  LOGICAL :: IS_EXTERNAL_COMPONENT = .FALSE. !< IS_EXTERNAL_COMPONENT Flag for model invoked via external executable.
+  !
+  CONTAINS
+
+  !/
+  !/ End of module MPICOMM ------------------------------------------- /
+  !/
+END MODULE MPICOMM
diff --git a/model/src/w3gsrumd.F90 b/model/src/w3gsrumd.F90
index 9cd4beaf5..87a099d11 100644
--- a/model/src/w3gsrumd.F90
+++ b/model/src/w3gsrumd.F90
@@ -9631,7 +9631,7 @@ SUBROUTINE EXTCDE(IEXIT)
     LOGICAL             :: RUN
     CALL MPI_INITIALIZED ( RUN, IERR_MPI )
     IF ( RUN ) THEN
-      CALL MPI_ABORT ( MPI_COMM_WORLD, IEXIT, IERR_MPI )
+      CALL MPI_ABORT ( MPI_COMM_WW3, IEXIT, IERR_MPI )
     END IF
 #endif
     CALL EXIT(IEXIT)
diff --git a/model/src/w3initmd.F90 b/model/src/w3initmd.F90
index 044a18760..f6e7676b5 100644
--- a/model/src/w3initmd.F90
+++ b/model/src/w3initmd.F90
@@ -410,6 +410,7 @@ SUBROUTINE W3INIT ( IMOD, IsMulti, FEXT, MDS, MTRACE, ODAT, FLGRD,  FLGR2, FLGD,
          UA, UD, U10, U10D, AS
 #ifdef W3_MPI
     USE W3ADATMD, ONLY: MPI_COMM_WAVE, MPI_COMM_WCMP
+    USE MPICOMM, ONLY: MPI_COMM_WW3
 #endif
     USE W3IDATMD, ONLY: FLLEV, FLCUR, FLWIND, FLICE, FLTAUA, FLRHOA,&
          FLMDN, FLMTH, FLMVS, FLIC1, FLIC2, FLIC3,   &
diff --git a/model/src/w3servmd.F90 b/model/src/w3servmd.F90
index 600e6e572..3ae73bcef 100644
--- a/model/src/w3servmd.F90
+++ b/model/src/w3servmd.F90
@@ -79,6 +79,10 @@ MODULE W3SERVMD
   !/ ------------------------------------------------------------------- /
 
   ! module default
+#ifdef W3_MPI
+  USE MPICOMM, ONLY: MPI_COMM_WW3
+#endif
+  !
   implicit none
 
   PUBLIC
@@ -864,7 +868,7 @@ SUBROUTINE EXTCDE ( IEXIT, UNIT, MSG, FILE, LINE, COMM )
         IF (PRESENT(COMM)) THEN
           WRITE(*,'(/A,I6/)') 'EXTCDE COMM=', COMM
         END IF
-        CALL MPI_ABORT ( MPI_COMM_WORLD, IEXIT, IERR_MPI )
+        CALL MPI_ABORT ( MPI_COMM_WW3, IEXIT, IERR_MPI )
       END IF
     END IF
 #endif
diff --git a/model/src/w3strkmd.F90 b/model/src/w3strkmd.F90
index a776a36bb..d395419fc 100644
--- a/model/src/w3strkmd.F90
+++ b/model/src/w3strkmd.F90
@@ -28,6 +28,10 @@ MODULE W3STRKMD
   !/       No unauthorized use without permission.
   !/
   use constants, only: file_endian
+#ifdef W3_MPI
+  USE MPICOMM, ONLY: MPI_COMM_WW3
+#endif
+  !
   IMPLICIT NONE
   !
   !  1. Purpose :
@@ -470,8 +474,8 @@ SUBROUTINE waveTracking_NWS_V2 (intype     ,tmax       , &
     !/ ------------------------------------------------------------------- /
 
 #ifdef W3_MPI
-    CALL MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)
-    CALL MPI_COMM_SIZE(MPI_COMM_WORLD, nproc, ierr)
+    CALL MPI_COMM_RANK(MPI_COMM_WW3, rank, ierr)
+    CALL MPI_COMM_SIZE(MPI_COMM_WW3, nproc, ierr)
 #endif
     NULLIFY( sysA )
     NULLIFY( maxSys )
@@ -942,9 +946,9 @@ SUBROUTINE waveTracking_NWS_V2 (intype     ,tmax       , &
 #endif
 
 #ifdef W3_MPI
-      CALL MPI_BCAST(maxI,1,MPI_INTEGER,0,MPI_COMM_WORLD,IERR)
-      CALL MPI_BCAST(maxJ,1,MPI_INTEGER,0,MPI_COMM_WORLD,IERR)
-      CALL MPI_BCAST(maxTs,1,MPI_INTEGER,0,MPI_COMM_WORLD,IERR)
+      CALL MPI_BCAST(maxI,1,MPI_INTEGER,0,MPI_COMM_WW3,IERR)
+      CALL MPI_BCAST(maxJ,1,MPI_INTEGER,0,MPI_COMM_WW3,IERR)
+      CALL MPI_BCAST(maxTs,1,MPI_INTEGER,0,MPI_COMM_WW3,IERR)
 #endif
 
       !        Allocate the wsdat structure
@@ -1177,13 +1181,13 @@ SUBROUTINE waveTracking_NWS_V2 (intype     ,tmax       , &
                      wsdat(tsA)%lat(i,j), &
                      wsdat(tsA)%lon(i,j)/)
                 CALL MPI_SEND(COMMARR1,44,MPI_REAL,irank, &
-                     (tag1+1),MPI_COMM_WORLD,IERR)
+                     (tag1+1),MPI_COMM_WW3,IERR)
               END IF
               IF (rank.EQ.irank) THEN
                 !                         WRITE(6,*) '<< Receiving: rank,irank,tag1=', &
                 !                                rank,irank,(tag1+1)
                 CALL MPI_RECV(COMMARR1,44,MPI_REAL,0,(tag1+1), &
-                     MPI_COMM_WORLD,MPI_STATUS,IERR)
+                     MPI_COMM_WW3,MPI_STATUS,IERR)
                 wsdat(tsA)%par(i,j)%hs = COMMARR1(1:10)
                 wsdat(tsA)%par(i,j)%tp = COMMARR1(11:20)
                 wsdat(tsA)%par(i,j)%dir = COMMARR1(21:30)
@@ -1197,12 +1201,12 @@ SUBROUTINE waveTracking_NWS_V2 (intype     ,tmax       , &
               IF (rank.EQ.0) THEN
                 CALL MPI_SEND(wsdat(tsA)%date,1, &
                      MPI_DOUBLE_PRECISION,irank, &
-                     (tag1+2),MPI_COMM_WORLD,IERR)
+                     (tag1+2),MPI_COMM_WW3,IERR)
               END IF
               IF (rank.EQ.irank) THEN
                 CALL MPI_RECV(wsdat(tsA)%date,1, &
                      MPI_DOUBLE_PRECISION,0,(tag1+2), &
-                     MPI_COMM_WORLD,MPI_STATUS,IERR)
+                     MPI_COMM_WW3,MPI_STATUS,IERR)
               END IF
 
               IF (rank.EQ.0) THEN
@@ -1211,14 +1215,14 @@ SUBROUTINE waveTracking_NWS_V2 (intype     ,tmax       , &
                 COMMARR2 = (/wsdat(tsA)%par(i,j)%ipart(:), &
                      wsdat(tsA)%par(i,j)%checked/)
                 CALL MPI_SEND(COMMARR2,11, &
-                     MPI_INTEGER,irank,(tag1+3),MPI_COMM_WORLD,IERR)
+                     MPI_INTEGER,irank,(tag1+3),MPI_COMM_WW3,IERR)
               END IF
               IF (rank.EQ.irank) THEN
                 !                         WRITE(6,*) '<< Receiving: rank,irank,tag1=', &
                 !                                rank,irank,(tag1+3)
                 CALL MPI_RECV(COMMARR2,11, &
                      MPI_INTEGER,0,(tag1+3), &
-                     MPI_COMM_WORLD,MPI_STATUS,IERR)
+                     MPI_COMM_WW3,MPI_STATUS,IERR)
                 wsdat(tsA)%par(i,j)%ipart(:) = COMMARR2(1:10)
                 wsdat(tsA)%par(i,j)%checked = COMMARR2(11)
               END IF
@@ -1228,7 +1232,7 @@ SUBROUTINE waveTracking_NWS_V2 (intype     ,tmax       , &
         END IF
       END DO
 
-      CALL MPI_Barrier(MPI_COMM_WORLD,IERR)
+      CALL MPI_Barrier(MPI_COMM_WW3,IERR)
 #endif
 
 
@@ -1416,7 +1420,7 @@ SUBROUTINE waveTracking_NWS_V2 (intype     ,tmax       , &
 #endif
 
 #ifdef W3_MPI
-    CALL MPI_Barrier(MPI_COMM_WORLD,IERR)
+    CALL MPI_Barrier(MPI_COMM_WW3,IERR)
 
     !!     Define communicator for array of integers in structure "system"
     !      DOMSIZE = maxI*maxJ
@@ -1447,13 +1451,13 @@ SUBROUTINE waveTracking_NWS_V2 (intype     ,tmax       , &
           !              Send results from current rank to rank 0 (blocking)
           !               WRITE(20,*) '>> Sending: rank,tsA,tag1=',rank,tsA,tag1
           CALL MPI_SEND(maxSys(tsA),1,MPI_INTEGER,0,tag1, &
-               MPI_COMM_WORLD,IERR)
+               MPI_COMM_WW3,IERR)
           !               WRITE(20,*) 'Rank, IERR=',rank,IERR
         END IF
         IF (rank.EQ.0) THEN
           !               WRITE(20,*) '<< Receiving: rank,tsA,tag1=',rank,tsA,tag1
           CALL MPI_RECV(maxSys(tsA),1,MPI_INTEGER, &
-               irank,tag1,MPI_COMM_WORLD,MPI_STATUS,IERR)
+               irank,tag1,MPI_COMM_WW3,MPI_STATUS,IERR)
           !              Allocate structure at this time level
           ALLOCATE( sysA(tsA)%sys(maxSys(tsA)) )
           DO ic = 1,maxSys(tsA)
@@ -1501,14 +1505,14 @@ SUBROUTINE waveTracking_NWS_V2 (intype     ,tmax       , &
               !                 WRITE(20,*) '>> Sending: rank,irank,tag2=', &
               !                             rank,irank,(tag2+1)
               CALL MPI_SEND(sysA(tsA)%sys(ic)%i(:),DOMSIZE, &
-                   MPI_INTEGER,0,(tag2+1),MPI_COMM_WORLD,REQ(1),IERR)
+                   MPI_INTEGER,0,(tag2+1),MPI_COMM_WW3,REQ(1),IERR)
             END IF
             IF (rank.EQ.0) THEN
               !                 WRITE(20,*) '<< Receiving: rank,irank,tag2=', &
               !                             rank,irank,(tag2+1)
               CALL MPI_RECV(sysA(tsA)%sys(ic)%i(:),DOMSIZE, &
                    MPI_INTEGER,irank,(tag2+1), &
-                   MPI_COMM_WORLD,MPI_STATUS,REQ(2),IERR)
+                   MPI_COMM_WW3,MPI_STATUS,REQ(2),IERR)
             END IF
             !               CALL MPI_WAITALL(2,REQ,ISTAT,IERR)
 
@@ -1516,92 +1520,92 @@ SUBROUTINE waveTracking_NWS_V2 (intype     ,tmax       , &
               !                 WRITE(20,*) '>> Sending: rank,irank,tag2=', &
               !                             rank,irank,(tag2+2)
               CALL MPI_SEND(sysA(tsA)%sys(ic)%j(:),DOMSIZE, &
-                   MPI_INTEGER,0,(tag2+2),MPI_COMM_WORLD,REQ(1),IERR)
+                   MPI_INTEGER,0,(tag2+2),MPI_COMM_WW3,REQ(1),IERR)
             END IF
             IF (rank.EQ.0) THEN
               !                 WRITE(20,*) '<< Receiving: rank,irank,tag2=', &
               !                             rank,irank,(tag2+2)
               CALL MPI_RECV(sysA(tsA)%sys(ic)%j(:),DOMSIZE, &
                    MPI_INTEGER,irank,(tag2+2), &
-                   MPI_COMM_WORLD,MPI_STATUS,REQ(2),IERR)
+                   MPI_COMM_WW3,MPI_STATUS,REQ(2),IERR)
             END IF
             !               CALL MPI_WAITALL(2,REQ,ISTAT,IERR)
 
             IF (rank.EQ.irank) THEN
               !                 WRITE(20,*) '>> Sending: rank,tag2=',rank,(tag2+3)
               CALL MPI_SEND(sysA(tsA)%sys(ic)%lon(:),DOMSIZE, &
-                   MPI_REAL,0,(tag2+3),MPI_COMM_WORLD,REQ(1),IERR)
+                   MPI_REAL,0,(tag2+3),MPI_COMM_WW3,REQ(1),IERR)
             END IF
             IF (rank.EQ.0) THEN
               !                 WRITE(20,*) '<< Receiving: rank,tag2=',rank,(tag2+3)
               CALL MPI_RECV(sysA(tsA)%sys(ic)%lon(:),DOMSIZE, &
                    MPI_REAL,irank,(tag2+3), &
-                   MPI_COMM_WORLD,MPI_STATUS,REQ(2),IERR)
+                   MPI_COMM_WW3,MPI_STATUS,REQ(2),IERR)
             END IF
             !               CALL MPI_WAITALL(2,REQ,ISTAT,IERR)
 
             IF (rank.EQ.irank) THEN
               !                 WRITE(20,*) '>> Sending: rank,tag2=',rank,(tag2+4)
               CALL MPI_SEND(sysA(tsA)%sys(ic)%lat(:),DOMSIZE, &
-                   MPI_REAL,0,(tag2+4),MPI_COMM_WORLD,REQ(1),IERR)
+                   MPI_REAL,0,(tag2+4),MPI_COMM_WW3,REQ(1),IERR)
             END IF
             IF (rank.EQ.0) THEN
               !                 WRITE(20,*) '<< Receiving: rank,tag2=',rank,(tag2+4)
               CALL MPI_RECV(sysA(tsA)%sys(ic)%lat(:),DOMSIZE, &
                    MPI_REAL,irank,(tag2+4), &
-                   MPI_COMM_WORLD,MPI_STATUS,REQ(2),IERR)
+                   MPI_COMM_WW3,MPI_STATUS,REQ(2),IERR)
             END IF
             !               CALL MPI_WAITALL(2,REQ,ISTAT,IERR)
 
             IF (rank.EQ.irank) THEN
               !                 WRITE(20,*) '>> Sending: rank,tag2=',rank,(tag2+5)
               CALL MPI_SEND(sysA(tsA)%sys(ic)%hs(:),DOMSIZE, &
-                   MPI_REAL,0,(tag2+5),MPI_COMM_WORLD,REQ(1),IERR)
+                   MPI_REAL,0,(tag2+5),MPI_COMM_WW3,REQ(1),IERR)
             END IF
             IF (rank.EQ.0) THEN
               !                 WRITE(20,*) '<< Receiving: rank,tag2=',rank,(tag2+5)
               CALL MPI_RECV(sysA(tsA)%sys(ic)%hs(:),DOMSIZE, &
                    MPI_REAL,irank,(tag2+5), &
-                   MPI_COMM_WORLD,MPI_STATUS,REQ(2),IERR)
+                   MPI_COMM_WW3,MPI_STATUS,REQ(2),IERR)
             END IF
             !               CALL MPI_WAITALL(2,REQ,ISTAT,IERR)
 
             IF (rank.EQ.irank) THEN
               !                 WRITE(20,*) '>> Sending: rank,tag2=',rank,(tag2+6)
               CALL MPI_SEND(sysA(tsA)%sys(ic)%tp(:),DOMSIZE, &
-                   MPI_REAL,0,(tag2+6),MPI_COMM_WORLD,REQ(1),IERR)
+                   MPI_REAL,0,(tag2+6),MPI_COMM_WW3,REQ(1),IERR)
             END IF
             IF (rank.EQ.0) THEN
               !                 WRITE(20,*) '<< Receiving: rank,tag2=',rank,(tag2+6)
               CALL MPI_RECV(sysA(tsA)%sys(ic)%tp(:),DOMSIZE, &
                    MPI_REAL,irank,(tag2+6), &
-                   MPI_COMM_WORLD,MPI_STATUS,REQ(2),IERR)
+                   MPI_COMM_WW3,MPI_STATUS,REQ(2),IERR)
             END IF
             !               CALL MPI_WAITALL(2,REQ,ISTAT,IERR)
 
             IF (rank.EQ.irank) THEN
               !                 WRITE(20,*) '>> Sending: rank,tag2=',rank,(tag2+7)
               CALL MPI_SEND(sysA(tsA)%sys(ic)%dir(:),DOMSIZE, &
-                   MPI_REAL,0,(tag2+7),MPI_COMM_WORLD,REQ(1),IERR)
+                   MPI_REAL,0,(tag2+7),MPI_COMM_WW3,REQ(1),IERR)
             END IF
             IF (rank.EQ.0) THEN
               !                 WRITE(20,*) '<< Receiving: rank,tag2=',rank,(tag2+7)
               CALL MPI_RECV(sysA(tsA)%sys(ic)%dir(:),DOMSIZE, &
                    MPI_REAL,irank,(tag2+7), &
-                   MPI_COMM_WORLD,MPI_STATUS,REQ(2),IERR)
+                   MPI_COMM_WW3,MPI_STATUS,REQ(2),IERR)
             END IF
             !               CALL MPI_WAITALL(2,REQ,ISTAT,IERR)
 
             IF (rank.EQ.irank) THEN
               !                 WRITE(20,*) '>> Sending: rank,tag2=',rank,(tag2+8)
               CALL MPI_SEND(sysA(tsA)%sys(ic)%dspr(:),DOMSIZE, &
-                   MPI_REAL,0,(tag2+8),MPI_COMM_WORLD,REQ(1),IERR)
+                   MPI_REAL,0,(tag2+8),MPI_COMM_WW3,REQ(1),IERR)
             END IF
             IF (rank.EQ.0) THEN
               !                 WRITE(20,*) '<< Receiving: rank,tag2=',rank,(tag2+8)
               CALL MPI_RECV(sysA(tsA)%sys(ic)%dspr(:),DOMSIZE, &
                    MPI_REAL,irank,(tag2+8), &
-                   MPI_COMM_WORLD,MPI_STATUS,REQ(2),IERR)
+                   MPI_COMM_WW3,MPI_STATUS,REQ(2),IERR)
             END IF
             !               CALL MPI_WAITALL(2,REQ,ISTAT,IERR)
 
@@ -1609,85 +1613,85 @@ SUBROUTINE waveTracking_NWS_V2 (intype     ,tmax       , &
               !                 WRITE(20,*) '>> Sending: rank,irank,tag2=', &
               !                             rank,irank,(tag2+9)
               CALL MPI_SEND(sysA(tsA)%sys(ic)%hsMean,1,MPI_REAL, &
-                   0,(tag2+9),MPI_COMM_WORLD,IERR)
+                   0,(tag2+9),MPI_COMM_WW3,IERR)
             END IF
             IF (rank.EQ.0) THEN
               !                 WRITE(20,*) '<< Receiving: rank,irank,tag2=', &
               !                             rank,irank,(tag2+9)
               CALL MPI_RECV(sysA(tsA)%sys(ic)%hsMean,1,MPI_REAL, &
-                   irank,(tag2+9),MPI_COMM_WORLD,MPI_STATUS,IERR)
+                   irank,(tag2+9),MPI_COMM_WW3,MPI_STATUS,IERR)
             END IF
 
             IF (rank.EQ.irank) THEN
               !                 WRITE(20,*) '>> Sending: rank,irank,tag2=', &
               !                             rank,irank,(tag2+10)
               CALL MPI_SEND(sysA(tsA)%sys(ic)%tpMean,1,MPI_REAL, &
-                   0,(tag2+10),MPI_COMM_WORLD,IERR)
+                   0,(tag2+10),MPI_COMM_WW3,IERR)
             END IF
             IF (rank.EQ.0) THEN
               !                 WRITE(20,*) '<< Receiving: rank,irank,tag2=', &
               !                             rank,irank,(tag2+10)
               CALL MPI_RECV(sysA(tsA)%sys(ic)%tpMean,1,MPI_REAL, &
-                   irank,(tag2+10),MPI_COMM_WORLD,MPI_STATUS,IERR)
+                   irank,(tag2+10),MPI_COMM_WW3,MPI_STATUS,IERR)
             END IF
 
             IF (rank.EQ.irank) THEN
               !                 WRITE(20,*) '>> Sending: rank,irank,tag2=', &
               !                             rank,irank,(tag2+11)
               CALL MPI_SEND(sysA(tsA)%sys(ic)%dirMean,1,MPI_REAL, &
-                   0,(tag2+11),MPI_COMM_WORLD,IERR)
+                   0,(tag2+11),MPI_COMM_WW3,IERR)
             END IF
             IF (rank.EQ.0) THEN
               !                 WRITE(20,*) '<< Receiving: rank,irank,tag2=', &
               !                             rank,irank,(tag2+11)
               CALL MPI_RECV(sysA(tsA)%sys(ic)%dirMean,1,MPI_REAL, &
-                   irank,(tag2+11),MPI_COMM_WORLD,MPI_STATUS,IERR)
+                   irank,(tag2+11),MPI_COMM_WW3,MPI_STATUS,IERR)
             END IF
 
             IF (rank.EQ.irank) THEN
               !                 WRITE(20,*) '>> Sending: rank,irank,tag2=', &
               !                             rank,irank,(tag2+12)
               CALL MPI_SEND(sysA(tsA)%sys(ic)%sysInd,1,MPI_INTEGER,&
-                   0,(tag2+12),MPI_COMM_WORLD,IERR)
+                   0,(tag2+12),MPI_COMM_WW3,IERR)
             END IF
             IF (rank.EQ.0) THEN
               !                 WRITE(20,*) '<< Receiving: rank,irank,tag2=', &
               !                             rank,irank,(tag2+12)
               CALL MPI_RECV(sysA(tsA)%sys(ic)%sysInd,1,MPI_INTEGER,&
-                   irank,(tag2+12),MPI_COMM_WORLD,MPI_STATUS,IERR)
+                   irank,(tag2+12),MPI_COMM_WW3,MPI_STATUS,IERR)
             END IF
 
             IF (rank.EQ.irank) THEN
               !                 WRITE(20,*) '>> Sending: rank,irank,tag2=', &
               !                             rank,irank,(tag2+13)
               CALL MPI_SEND(sysA(tsA)%sys(ic)%nPoints,1,MPI_INTEGER,&
-                   0,(tag2+13),MPI_COMM_WORLD,IERR)
+                   0,(tag2+13),MPI_COMM_WW3,IERR)
             END IF
             IF (rank.EQ.0) THEN
               !                 WRITE(20,*) '<< Receiving: rank,irank,tag2=', &
               !                             rank,irank,(tag2+13)
               CALL MPI_RECV(sysA(tsA)%sys(ic)%nPoints,1,MPI_INTEGER,&
-                   irank,(tag2+13),MPI_COMM_WORLD,MPI_STATUS,IERR)
+                   irank,(tag2+13),MPI_COMM_WW3,MPI_STATUS,IERR)
             END IF
 
             IF (rank.EQ.irank) THEN
               !                 WRITE(20,*) '>> Sending: rank,irank,tag2=', &
               !                             rank,irank,(tag2+14)
               CALL MPI_SEND(sysA(tsA)%sys(ic)%grp,1,MPI_INTEGER,&
-                   0,(tag2+14),MPI_COMM_WORLD,IERR)
+                   0,(tag2+14),MPI_COMM_WW3,IERR)
             END IF
             IF (rank.EQ.0) THEN
               !                 WRITE(20,*) '<< Receiving: rank,irank,tag2=', &
               !                             rank,irank,(tag2+14)
               CALL MPI_RECV(sysA(tsA)%sys(ic)%grp,1,MPI_INTEGER,&
-                   irank,(tag2+14),MPI_COMM_WORLD,MPI_STATUS,IERR)
+                   irank,(tag2+14),MPI_COMM_WW3,MPI_STATUS,IERR)
             END IF
           END DO
         END IF
       END IF
     END DO
 
-    CALL MPI_Barrier(MPI_COMM_WORLD,IERR)
+    CALL MPI_Barrier(MPI_COMM_WW3,IERR)
 
     !      CALL MPI_TYPE_FREE(MPI_INT_DOMARR,IERR)
     !      CALL MPI_TYPE_FREE(MPI_REAL_DOMARR,IERR)
diff --git a/model/src/ww3_multi.F90 b/model/src/ww3_multi.F90
index e3101b7c2..14e257aa6 100644
--- a/model/src/ww3_multi.F90
+++ b/model/src/ww3_multi.F90
@@ -95,6 +95,10 @@ PROGRAM W3MLTI
   USE OMP_LIB
 #endif
   !/
+#ifdef W3_MPI
+  USE MPICOMM, ONLY: MPI_COMM_WW3
+#endif
+  !
   IMPLICIT NONE
   !
 #ifdef W3_MPI
@@ -119,7 +123,7 @@ PROGRAM W3MLTI
   ! 0.  Initialization necessary for driver
   ! 0.a General I/O: all can start with initialization in wmmdatmd
   !
-  ! 0.b MPI environment: Here, we use MPI_COMM_WORLD
+  ! 0.b MPI environment: Here, we use MPI_COMM_WW3
   !
 #ifdef W3_OMPH
   FLHYBR = .TRUE.
@@ -135,7 +139,9 @@ PROGRAM W3MLTI
   ENDIF
 #endif
 #ifdef W3_MPI
-  MPI_COMM = MPI_COMM_WORLD
+  MPI_COMM_WW3=MPI_COMM_WORLD !< MPI_COMM_WW3
+
+  MPI_COMM = MPI_COMM_WW3
   CALL MPI_COMM_SIZE ( MPI_COMM, NMPROC, IERR_MPI )
   CALL MPI_COMM_RANK ( MPI_COMM, IMPROC, IERR_MPI )
   IMPROC = IMPROC + 1
diff --git a/model/src/ww3_ounp.F90 b/model/src/ww3_ounp.F90
index a1533c73b..bf1d55883 100644
--- a/model/src/ww3_ounp.F90
+++ b/model/src/ww3_ounp.F90
@@ -213,6 +213,10 @@ PROGRAM W3OUNP
   USE W3NMLOUNPMD
   USE NETCDF
   !
+#ifdef W3_MPI
+  USE MPICOMM, ONLY: MPI_COMM_WW3
+#endif
+  !
   IMPLICIT NONE
   !
 #ifdef W3_MPI
@@ -355,8 +359,9 @@ PROGRAM W3OUNP
   !
 #ifdef W3_MPI
   CALL MPI_INIT      ( IERR_MPI )
-  CALL MPI_COMM_SIZE ( MPI_COMM_WORLD, NAPROC, IERR_MPI )
-  CALL MPI_COMM_RANK ( MPI_COMM_WORLD, IAPROC, IERR_MPI )
+  MPI_COMM_WW3=MPI_COMM_WORLD !< MPI_COMM_WW3
+  CALL MPI_COMM_SIZE ( MPI_COMM_WW3, NAPROC, IERR_MPI )
+  CALL MPI_COMM_RANK ( MPI_COMM_WW3, IAPROC, IERR_MPI )
   IAPROC = IAPROC + 1  ! this is to have IAPROC between 1 and NAPROC
 #endif
   !
diff --git a/model/src/ww3_prnc.F90 b/model/src/ww3_prnc.F90
index e107a1f43..78bb0175c 100644
--- a/model/src/ww3_prnc.F90
+++ b/model/src/ww3_prnc.F90
@@ -225,6 +225,10 @@ PROGRAM W3PRNC
   USE W3NMLPRNCMD
   USE NETCDF
   !
+#ifdef W3_MPI
+  USE MPICOMM, ONLY: MPI_COMM_WW3
+#endif
+  !
   IMPLICIT NONE
   !
 #ifdef W3_MPI
@@ -440,8 +444,9 @@ PROGRAM W3PRNC
   !
 #ifdef W3_MPI
   CALL MPI_INIT      ( IERR_MPI )
-  CALL MPI_COMM_SIZE ( MPI_COMM_WORLD, NAPROC, IERR_MPI )
-  CALL MPI_COMM_RANK ( MPI_COMM_WORLD, IAPROC, IERR_MPI )
+  MPI_COMM_WW3=MPI_COMM_WORLD !< MPI_COMM_WW3
+  CALL MPI_COMM_SIZE ( MPI_COMM_WW3, NAPROC, IERR_MPI )
+  CALL MPI_COMM_RANK ( MPI_COMM_WW3, IAPROC, IERR_MPI )
   IAPROC = IAPROC + 1  ! this is to have IAPROC between 1 and NAPROC
 #endif
   !
@@ -1696,18 +1701,18 @@ PROGRAM W3PRNC
       IF (NAPROC.GT.1) THEN
         CALL MPI_GATHERV(TIDE1DL, SLICE * TIDE_MF * NFIELDS * 2, MPI_REAL, &
              TIDE1D, NELEM * TIDE_MF * NFIELDS * 2, CUMUL * TIDE_MF * NFIELDS * 2, &
-             MPI_REAL, NAPOUT-1, MPI_COMM_WORLD, IERR_MPI)
+             MPI_REAL, NAPOUT-1, MPI_COMM_WW3, IERR_MPI)
 #endif
 
 #ifdef W3_MPI
         IF (IAPROC.EQ.NAPOUT) THEN
           CALL MPI_GATHERV(MPI_IN_PLACE,NELEM(IAPROC), &
                MPI_LOGICAL, TIDALCOMP(:,IY), NELEM, CUMUL, MPI_LOGICAL, NAPOUT-1,     &
-               MPI_COMM_WORLD, IERR_MPI)
+               MPI_COMM_WW3, IERR_MPI)
         ELSE
           CALL MPI_GATHERV(TIDALCOMP(CUMUL(IAPROC)+1:CUMUL(IAPROC)+NELEM(IAPROC),IY),NELEM(IAPROC), &
                MPI_LOGICAL, TIDALCOMP(:,IY), NELEM, CUMUL, MPI_LOGICAL, NAPOUT-1,     &
-               MPI_COMM_WORLD, IERR_MPI)
+               MPI_COMM_WW3, IERR_MPI)
         END IF
 #endif
 
diff --git a/model/src/ww3_prtide.F90 b/model/src/ww3_prtide.F90
index 1168cd1ab..dfea89471 100644
--- a/model/src/ww3_prtide.F90
+++ b/model/src/ww3_prtide.F90
@@ -139,6 +139,10 @@ PROGRAM W3PRTIDE
   USE W3TIDEMD
   USE W3IDATMD
   !
+#ifdef W3_MPI
+  USE MPICOMM, ONLY: MPI_COMM_WW3
+#endif
+  !
   IMPLICIT NONE
   !
 #ifdef W3_MPI
@@ -254,8 +258,9 @@ PROGRAM W3PRTIDE
   !
 #ifdef W3_MPI
   CALL MPI_INIT      ( IERR_MPI )
-  CALL MPI_COMM_SIZE ( MPI_COMM_WORLD, NAPROC, IERR_MPI )
-  CALL MPI_COMM_RANK ( MPI_COMM_WORLD, IAPROC, IERR_MPI )
+  MPI_COMM_WW3=MPI_COMM_WORLD !< MPI_COMM_WW3
+  CALL MPI_COMM_SIZE ( MPI_COMM_WW3, NAPROC, IERR_MPI )
+  CALL MPI_COMM_RANK ( MPI_COMM_WW3, IAPROC, IERR_MPI )
   IAPROC = IAPROC + 1  ! this is to have IAPROC between 1 and NAPROC
 #endif
   !
@@ -673,11 +678,11 @@ PROGRAM W3PRTIDE
 #ifdef W3_MPI
         IF (NAPROC.GT.1) THEN
           CALL MPI_GATHERV(FX1DL, SLICE, MPI_REAL, FX1D, NELEM, &
-               CUMUL, MPI_REAL, NAPOUT-1, MPI_COMM_WORLD, IERR_MPI)
+               CUMUL, MPI_REAL, NAPOUT-1, MPI_COMM_WW3, IERR_MPI)
           CALL MPI_GATHERV(FY1DL, SLICE, MPI_REAL, FY1D, NELEM, &
-               CUMUL, MPI_REAL, NAPOUT-1, MPI_COMM_WORLD, IERR_MPI)
+               CUMUL, MPI_REAL, NAPOUT-1, MPI_COMM_WW3, IERR_MPI)
           CALL MPI_GATHERV(FA1DL, SLICE, MPI_REAL, FA1D, NELEM, &
-               CUMUL, MPI_REAL, NAPOUT-1, MPI_COMM_WORLD, IERR_MPI)
+               CUMUL, MPI_REAL, NAPOUT-1, MPI_COMM_WW3, IERR_MPI)
         ELSE
           FX1D = FX1DL
           FY1D = FY1DL
@@ -768,11 +773,11 @@ PROGRAM W3PRTIDE
 #ifdef W3_MPI
         IF (NAPROC.GT.1) THEN
           CALL MPI_GATHERV(FX1DL, SLICE, MPI_REAL, FX1D, NELEM,&
-               CUMUL, MPI_REAL, NAPOUT-1, MPI_COMM_WORLD, IERR_MPI)
+               CUMUL, MPI_REAL, NAPOUT-1, MPI_COMM_WW3, IERR_MPI)
           CALL MPI_GATHERV(FY1DL, SLICE, MPI_REAL, FY1D, NELEM,&
-               CUMUL, MPI_REAL, NAPOUT-1, MPI_COMM_WORLD, IERR_MPI)
+               CUMUL, MPI_REAL, NAPOUT-1, MPI_COMM_WW3, IERR_MPI)
           CALL MPI_GATHERV(FA1DL, SLICE, MPI_REAL, FA1D, NELEM,&
-               CUMUL, MPI_REAL, NAPOUT-1, MPI_COMM_WORLD, IERR_MPI)
+               CUMUL, MPI_REAL, NAPOUT-1, MPI_COMM_WW3, IERR_MPI)
         ELSE
           FX1D = FX1DL
           FY1D = FY1DL
diff --git a/model/src/ww3_sbs1.F90 b/model/src/ww3_sbs1.F90
index 94778b10d..1ca5571a9 100644
--- a/model/src/ww3_sbs1.F90
+++ b/model/src/ww3_sbs1.F90
@@ -177,6 +177,10 @@ PROGRAM W3SBS1
   USE WMMDATMD, ONLY: MDSE, MDST, MDSS, NMPROC, IMPROC, NMPSCR,   &
        NRGRD, STIME, ETIME
   !/
+#ifdef W3_MPI
+  USE MPICOMM, ONLY: MPI_COMM_WW3
+#endif
+  !
   IMPLICIT NONE
   !
 #ifdef W3_MPI
@@ -203,11 +207,11 @@ PROGRAM W3SBS1
   ! 0.  Initialization necessary for driver
   ! 0.a General I/O: all can start with initialization in wmmdatmd
   !
-  ! 0.b MPI environment: Here, we use MPI_COMM_WORLD
+  ! 0.b MPI environment: Here, we use MPI_COMM_WW3
   !
 #ifdef W3_MPI
   CALL MPI_INIT      ( IERR_MPI )
-  MPI_COMM = MPI_COMM_WORLD
+  MPI_COMM = MPI_COMM_WW3
   CALL MPI_COMM_SIZE ( MPI_COMM, NMPROC, IERR_MPI )
   CALL MPI_COMM_RANK ( MPI_COMM, IMPROC, IERR_MPI )
   IMPROC = IMPROC + 1
diff --git a/model/src/ww3_shel.F90 b/model/src/ww3_shel.F90
index 4bb888b48..de14d2b82 100644
--- a/model/src/ww3_shel.F90
+++ b/model/src/ww3_shel.F90
@@ -307,6 +307,9 @@ PROGRAM W3SHEL
 
 #ifdef W3_OMPG
   USE OMP_LIB
+#endif
+#ifdef W3_MPI
+  USE MPICOMM, ONLY: MPI_COMM_WW3
 #endif
   IMPLICIT NONE
   !
@@ -487,7 +490,9 @@ PROGRAM W3SHEL
 #endif
 
 #ifdef W3_MPI
-    MPI_COMM = MPI_COMM_WORLD
+    MPI_COMM_WW3=MPI_COMM_WORLD !< MPI_COMM_WW3
+
+    MPI_COMM = MPI_COMM_WW3
 #endif
 #ifdef W3_OASIS
   END IF
diff --git a/model/src/ww3_strt.F90 b/model/src/ww3_strt.F90
index b4bcad3ca..5e5b5ca68 100644
--- a/model/src/ww3_strt.F90
+++ b/model/src/ww3_strt.F90
@@ -241,6 +241,10 @@ PROGRAM W3STRT
   USE W3IDATMD, ONLY: W3NINP
 #endif
   !/
+#ifdef W3_MPI
+  USE MPICOMM, ONLY: MPI_COMM_WW3
+#endif
+  !
   IMPLICIT NONE
   !
 #ifdef W3_MPI
@@ -324,8 +328,9 @@ PROGRAM W3STRT
   !
 #ifdef W3_MPI
   CALL MPI_INIT      ( IERR_MPI )
-  CALL MPI_COMM_SIZE ( MPI_COMM_WORLD, NAPROC, IERR_MPI )
-  CALL MPI_COMM_RANK ( MPI_COMM_WORLD, IAPROC, IERR_MPI )
+  MPI_COMM_WW3=MPI_COMM_WORLD !< MPI_COMM_WW3
+  CALL MPI_COMM_SIZE ( MPI_COMM_WW3, NAPROC, IERR_MPI )
+  CALL MPI_COMM_RANK ( MPI_COMM_WW3, IAPROC, IERR_MPI )
   IAPROC = IAPROC + 1
 #endif
   !
diff --git a/model/src/ww3_systrk.F90 b/model/src/ww3_systrk.F90
index cb25a1e72..576977f3a 100644
--- a/model/src/ww3_systrk.F90
+++ b/model/src/ww3_systrk.F90
@@ -58,6 +58,10 @@ PROGRAM WW3_SYSTRK
   !/
   USE W3STRKMD
   USE W3TIMEMD, ONLY: TDIFF
+#ifdef W3_MPI
+  USE MPICOMM, ONLY: MPI_COMM_WW3
+#endif
+  !
   IMPLICIT NONE
 #ifdef W3_MPI
 
@@ -168,8 +172,10 @@ PROGRAM WW3_SYSTRK
   !     Start of parallel region
   CALL MPI_INIT(ierr)
 
-  CALL MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)
-  CALL MPI_COMM_SIZE(MPI_COMM_WORLD, nproc, ierr)
+  MPI_COMM_WW3=MPI_COMM_WORLD !< MPI_COMM_WW3
+
+  CALL MPI_COMM_RANK(MPI_COMM_WW3, rank, ierr)
+  CALL MPI_COMM_SIZE(MPI_COMM_WW3, nproc, ierr)
 
 #endif
   !     Open log file
@@ -343,34 +349,34 @@ PROGRAM WW3_SYSTRK
 
 #ifdef W3_MPI
   !     MPI communication block
-  CALL MPI_BCAST(filename,80,MPI_CHARACTER,0,MPI_COMM_WORLD,IERR)
+  CALL MPI_BCAST(filename,80,MPI_CHARACTER,0,MPI_COMM_WW3,IERR)
   CALL MPI_BCAST(tstart,1,MPI_DOUBLE_PRECISION,0, &
-       MPI_COMM_WORLD,IERR)
+       MPI_COMM_WW3,IERR)
   CALL MPI_BCAST(tend,1,MPI_DOUBLE_PRECISION,0, &
-       MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(dt,1,MPI_REAL,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(ntint,1,MPI_INTEGER,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(minlon,1,MPI_REAL,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(maxlon,1,MPI_REAL,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(minlat,1,MPI_REAL,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(maxlat,1,MPI_REAL,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(mxcwt,1,MPI_INTEGER,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(mycwt,1,MPI_INTEGER,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(dirKnob,1,MPI_REAL,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(perKnob,1,MPI_REAL,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(hsKnob,1,MPI_REAL,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(wetPts,1,MPI_REAL,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(dirTimeKnob,1,MPI_REAL,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(tpTimeKnob,1,MPI_REAL,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(seedLon,1,MPI_REAL,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(seedLat,1,MPI_REAL,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(noutp,1,MPI_INTEGER,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(lonout,100,MPI_REAL,0,MPI_COMM_WORLD,IERR)
-  CALL MPI_BCAST(latout,100,MPI_REAL,0,MPI_COMM_WORLD,IERR)
+       MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(dt,1,MPI_REAL,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(ntint,1,MPI_INTEGER,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(minlon,1,MPI_REAL,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(maxlon,1,MPI_REAL,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(minlat,1,MPI_REAL,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(maxlat,1,MPI_REAL,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(mxcwt,1,MPI_INTEGER,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(mycwt,1,MPI_INTEGER,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(dirKnob,1,MPI_REAL,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(perKnob,1,MPI_REAL,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(hsKnob,1,MPI_REAL,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(wetPts,1,MPI_REAL,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(dirTimeKnob,1,MPI_REAL,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(tpTimeKnob,1,MPI_REAL,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(seedLon,1,MPI_REAL,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(seedLat,1,MPI_REAL,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(noutp,1,MPI_INTEGER,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(lonout,100,MPI_REAL,0,MPI_COMM_WW3,IERR)
+  CALL MPI_BCAST(latout,100,MPI_REAL,0,MPI_COMM_WW3,IERR)
 #endif
 
 #ifdef W3_MPI
-  CALL MPI_Barrier(MPI_COMM_WORLD,IERR)
+  CALL MPI_Barrier(MPI_COMM_WW3,IERR)
 #endif
 
   CALL waveTracking_NWS_V2 (intype     ,tmax       , &