FESOM · patrickscholz · Jan 28, 2026 · Feb 2, 2026 · Feb 5, 2026 · Feb 5, 2026
diff --git a/config/namelist.cvmix b/config/namelist.cvmix
@@ -71,7 +71,86 @@ idemix_surforc_vname = 'var706'      ! variable name in surface forcing file
 !idemix_botforc_vname = 'wave_dissipation'  ! variable name in bottom forcing file
 idemix_botforc_file  = '/albedo/pool/FESOM/fesom2.0/forcing/idemix/forcing_idemix_final_bin/FIN_STORMTIDE2_M2_plus_NYCANDER_CnoM2_bin_0.40deg.nc'         ! path to bottom forcing file,
 idemix_botforc_vname = 'stormt_M2_plus_nycand_CnoM2'  ! variable name in bottom forcing file
+/
+
+! ============================================================================
+! IDEMIX2 (INTERNAL WAVE ENERGY PARAMETERIZATION)
+! ============================================================================
+! Based on: F. Pohlmann,  C. Eden, D. Olbers and Z. Zhao (draft) Anisotropy  of 
+! internal tide generation and propagation in the consistent internal wave mixing 
+! closure IDEMIX
+! ============================================================================
+&param_idemix2
+! --- Time Scales ---
+idemix2_tau_v         = 172800.0     ! vertical symmetrization time scale [s] (2 days)
+idemix2_tau_h         = 1296000.0    ! horizontal symmetrization time scale [s] (15 days)
+
+! --- Spectral Parameters ---
+idemix2_gamma         = 1.570        ! spectral shape constant [dimensionless] (order 1)
+idemix2_jstar         = 5.0          ! spectral bandwidth in vertical modes [dimensionless]
+idemix2_mu0           = 0.33333333   ! dissipation parameter [dimensionless]
+
+! --- superbee-spectral advection scheme and Adams-Bashfort timestepping ---
+idemix2_enable_AB     = .true.
+idemix2_AB_epsilon    = 0.1_WP
 
+! --- Number of used spectral frequency bins
+idemix2_nfbin         = 52 
+
+! --- ensures idemix1 functionality ---
+idemix2_enable_hor_diff_expl = .false.
+idemix2_enable_hor_diff_impl_iter = .true.   ! from Pollman et al. (2017)
+idemix2_hor_diff_niter       = 5
+
+! --- shelf definition as distance from coast in meters
+idemix2_shelf_dist    = 300.e3
+
+! --- scal down baroclinic wave speed when not all modes are used ---
+idemix2_scal_cn = 1.0
+
+! --- maximum cutoff value for interal wave energy ---
+idemix2_Eiw_maxthresh= 0.1
+
+! --- M2 Forcing (Summed anisotropic M2-tide generation modes 1-2 (W/m2)) ---
+idemix2_enable_M2     = .false.
+idemix2_M2forc_file   = '/albedo/work/user/pscholz/forcing/IDEMIX2/idemix2_IT_forc_M2modes1-2_aniso.nc'
+idemix2_M2forc_vname  = 'Flux_to2'   ! variable name in surface forcing file
+idemix2_M2forc_zname  = 'phi'        ! zdim variable name in surface forcing file
+idemix2_tau_M2_shelf  = 7.0
+idemix2_tau_M2_oce    = 50.0
+
+! --- NIW Forcing (Summed anisotropic M2-tide generation modes 1-2 (W/m2)) ---
+idemix2_enable_niw    = .false.
+idemix2_fniw_usage    = 0.2          ! fraction of surface forcing used [dimensionless]
+idemix2_niwforc_file  = '/albedo/work/user/pscholz/forcing/IDEMIX/fourier_smooth_2005_cfsr_inert_rgrid.nc'
+idemix2_niwforc_vname = 'var706'
+idemix2_tau_niw_shelf = 7.0
+idemix2_tau_niw_oce   = 3.0
+
+! --- Bottom Forcing (Tidal Internal Waves) ---
+idemix2_enable_bot    = .true.
+idemix2_botforc_file  = '/albedo/pool/FESOM/fesom2.0/forcing/idemix/forcing_idemix_final_bin/FIN_STORMTIDE2_M2_plus_NYCANDER_CnoM2_bin_0.40deg.nc'         ! path to bottom forcing file,
+idemix2_botforc_vname = 'stormt_M2_plus_nycand_CnoM2'  ! variable name in bottom forcing file
+
+! --- Root Mean Square Topographic Height forcing ---
+idemix2_hrmsforc_file = '/albedo/work/user/pscholz/forcing/IDEMIX2/idemix2_hrms_Goff2023.nc'
+idemix2_hrmsforc_vname= 'HRMS'
+
+! --- Characteristic horizontal length scale of topographic feature ---
+idemix2_hlamforc_file = '/albedo/work/user/pscholz/forcing/IDEMIX2/idemix2_lambda_Goff2010.nc'
+idemix2_hlamforc_vname= 'LAMBDA'
+
+! --- apply one pass of area-weighted node smoothin after wave-wave interaction
+! --- the idemix2 only mode (no EM2 or Eniw) needs some additional smoothing otherwise instable 
+idemix2_smooth_Eiw_diss= .false.
+idemix2_smooth_Eiw     = .false.   ! smooth iwe2_E_iw(:,:,tip1) after wave-wave
+idemix2_smooth_alpha_c = .false.   ! smooth iwe2_alpha_c after parameter loop
+idemix2_smooth_niter   = 1
+
+! --- diagnostics
+idemix2_diag_Ecompart = .false.
+idemix2_diag_Eiw      = .false.
+idemix2_diag_WWI      = .false.
 /
 
 ! ============================================================================

diff --git a/src/MOD_MESH.F90 b/src/MOD_MESH.F90
@@ -37,6 +37,7 @@ MODULE MOD_MESH
 real(kind=WP), allocatable, dimension(:)    :: elem_area
 real(kind=WP), allocatable, dimension(:,:)  :: edge_dxdy
 real(kind=WP), allocatable, dimension(:,:)  :: edge_cross_dxdy
+integer      , allocatable, dimension(:,:)  :: edge_up_dn_tri
 real(kind=WP), allocatable, dimension(:)    :: elem_cos
 real(kind=WP), allocatable, dimension(:)    :: metric_factor
 integer,       allocatable, dimension(:,:)  :: elem_neighbors
@@ -198,6 +199,7 @@ subroutine write_t_mesh(mesh, unit, iostat, iomsg)
     call write_bin_array(mesh%elem_edges,   unit, iostat, iomsg)
     call write_bin_array(mesh%elem_area,    unit, iostat, iomsg)
     call write_bin_array(mesh%edge_dxdy,    unit, iostat, iomsg)
+    call write_bin_array(mesh%edge_up_dn_tri,unit, iostat, iomsg)
 
     call write_bin_array(mesh%edge_cross_dxdy,     unit, iostat, iomsg)
     call write_bin_array(mesh%elem_cos,            unit, iostat, iomsg)
@@ -295,7 +297,7 @@ subroutine read_t_mesh(mesh, unit, iostat, iomsg)
     call read_bin_array(mesh%elem_edges,   unit, iostat, iomsg)
     call read_bin_array(mesh%elem_area,    unit, iostat, iomsg)
     call read_bin_array(mesh%edge_dxdy,    unit, iostat, iomsg)
-
+    call read_bin_array(mesh%edge_up_dn_tri,unit, iostat, iomsg)
     call read_bin_array(mesh%edge_cross_dxdy,     unit, iostat, iomsg)
     call read_bin_array(mesh%elem_cos,            unit, iostat, iomsg)
     call read_bin_array(mesh%metric_factor,       unit, iostat, iomsg)

diff --git a/src/MOD_PARTIT.F90 b/src/MOD_PARTIT.F90
@@ -86,6 +86,17 @@ module MOD_PARTIT
   integer, allocatable       :: s_mpitype_nod2D_i(:),   r_mpitype_nod2D_i(:)
   integer, allocatable       :: s_mpitype_nod3D(:,:,:), r_mpitype_nod3D(:,:,:)
 
+  ! Spectral bin (fbin) fields for IDEMIX2 halo exchange
+  ! Full spectral column exchanged at once (like standard nod3D exchanges full depth column).
+  ! Nodal fields: (peer, nfbin:nfbin, n_val) with n_val=1..3
+  ! Element fields: (peer, nfbin:nfbin) for 2D, (peer, nfbin:nfbin, n_val) for 3D with n_val=1..4
+  integer              :: nfbin_mpi = 0  ! number of spectral bins for MPI types (0 = not initialized)
+  integer, allocatable :: s_mpitype_nod3D_fbin(:,:,:),          r_mpitype_nod3D_fbin(:,:,:)
+  integer, allocatable :: s_mpitype_elem2D_fbin(:,:),           r_mpitype_elem2D_fbin(:,:)
+  integer, allocatable :: s_mpitype_elem2D_full_fbin(:,:),      r_mpitype_elem2D_full_fbin(:,:)
+  integer, allocatable :: s_mpitype_elem3D_fbin(:,:,:),         r_mpitype_elem3D_fbin(:,:,:)
+  integer, allocatable :: s_mpitype_elem3D_full_fbin(:,:,:),    r_mpitype_elem3D_full_fbin(:,:,:)
+
   integer            :: MPIERR
 
   !!! remPtr_* are constructed during the runtime and shall not be dumped!!!

diff --git a/src/associate_part_ass.h b/src/associate_part_ass.h
@@ -69,4 +69,18 @@ if (allocated(partit%s_mpitype_nod2D)) then
 
    s_mpitype_nod3D(1:com_nod2D%sPEnum, lb:ub, 1:3) => partit%s_mpitype_nod3D(:,:,:)
    r_mpitype_nod3D(1:com_nod2D%rPEnum, lb:ub, 1:3) => partit%r_mpitype_nod3D(:,:,:)
-end if 
+end if
+
+nfbin_mpi => partit%nfbin_mpi
+if (allocated(partit%s_mpitype_nod3D_fbin)) then
+   s_mpitype_nod3D_fbin(      1:com_nod2D%sPEnum      , nfbin_mpi:nfbin_mpi, 1:3) => partit%s_mpitype_nod3D_fbin(      :,:,:)
+   r_mpitype_nod3D_fbin(      1:com_nod2D%rPEnum      , nfbin_mpi:nfbin_mpi, 1:3) => partit%r_mpitype_nod3D_fbin(      :,:,:)
+   s_mpitype_elem2D_fbin(     1:com_elem2D%sPEnum     , nfbin_mpi:nfbin_mpi     ) => partit%s_mpitype_elem2D_fbin(       :,:)
+   r_mpitype_elem2D_fbin(     1:com_elem2D%rPEnum     , nfbin_mpi:nfbin_mpi     ) => partit%r_mpitype_elem2D_fbin(       :,:)
+   s_mpitype_elem2D_full_fbin(1:com_elem2D_full%sPEnum, nfbin_mpi:nfbin_mpi     ) => partit%s_mpitype_elem2D_full_fbin(  :,:)
+   r_mpitype_elem2D_full_fbin(1:com_elem2D_full%rPEnum, nfbin_mpi:nfbin_mpi     ) => partit%r_mpitype_elem2D_full_fbin(  :,:)
+   s_mpitype_elem3D_fbin(     1:com_elem2D%sPEnum     , nfbin_mpi:nfbin_mpi, 1:4) => partit%s_mpitype_elem3D_fbin(     :,:,:)
+   r_mpitype_elem3D_fbin(     1:com_elem2D%rPEnum     , nfbin_mpi:nfbin_mpi, 1:4) => partit%r_mpitype_elem3D_fbin(     :,:,:)
+   s_mpitype_elem3D_full_fbin(1:com_elem2D_full%sPEnum, nfbin_mpi:nfbin_mpi, 1:4) => partit%s_mpitype_elem3D_full_fbin(:,:,:)
+   r_mpitype_elem3D_full_fbin(1:com_elem2D_full%rPEnum, nfbin_mpi:nfbin_mpi, 1:4) => partit%r_mpitype_elem3D_full_fbin(:,:,:)
+end if
diff --git a/src/associate_part_def.h b/src/associate_part_def.h
@@ -16,6 +16,13 @@
   integer, dimension(:),     pointer :: s_mpitype_nod2D_i, r_mpitype_nod2D_i
   integer, dimension(:,:,:), pointer :: s_mpitype_nod3D, r_mpitype_nod3D
 
+  integer, dimension(:,:,:), pointer :: s_mpitype_nod3D_fbin      , r_mpitype_nod3D_fbin
+  integer, dimension(:,:),   pointer :: s_mpitype_elem2D_fbin     , r_mpitype_elem2D_fbin
+  integer, dimension(:,:),   pointer :: s_mpitype_elem2D_full_fbin, r_mpitype_elem2D_full_fbin
+  integer, dimension(:,:,:), pointer :: s_mpitype_elem3D_fbin     , r_mpitype_elem3D_fbin
+  integer, dimension(:,:,:), pointer :: s_mpitype_elem3D_full_fbin, r_mpitype_elem3D_full_fbin
+  integer, pointer                   :: nfbin_mpi
+
   integer, pointer   :: MPIERR
   integer, pointer   :: MPIERR_IB       ! copy for icebergs LA: 2023-05-22
   integer, pointer   :: npes