Add nlevels and ndata to arg_type derived type

CONTRIBUTORS.md

@@ -30,3 +30,6 @@
 | timgraham-Met    | Tim Graham             | Met Office            | 2026-05-20 |
 | tinyendian       | Wolfgang Hayek         | Earth Sciences New Zealand | 2026-05-04 |
 | Adrian-Lock      | Adrian Lock            | Met Office            | 2026-05-21 |
+| ukmo-juan-castillo  | Juan M. Castillo    | Met Office            | 2026-03-24 |
+| mcdalvi          | Mohit Dalvi            | Met Office            | 2026-06-19 |
+| cjohnson-pi      | Christine Johnson      | Met Office            | 2026-06-29 |

applications/coupled/example/iodef.xml

@@ -59,7 +59,6 @@
     <variable_definition>
       <variable_group id = "buffer">
         <variable id = "optimal_buffer_size" type = "string" >performance</variable>
-        <variable id = "buffer_factor_size" type = "double" >1.0</variable>
       </variable_group>
 
       <variable_group id = "parameters" >

applications/io_demo/example/iodef.xml

@@ -23,7 +23,6 @@
     <variable_definition>
       <variable_group id = "buffer">
         <variable id = "optimal_buffer_size" type = "string" >performance</variable>
-        <variable id = "buffer_factor_size" type = "double" >1.0</variable>
       </variable_group>
 
       <variable_group id = "parameters" >

applications/io_demo/source/driver/io_demo_checkpoint_mod.f90

@@ -15,7 +15,7 @@ module io_demo_checkpoint_mod
   use field_mod,              only: field_type
   use field_collection_mod,   only: field_collection_type
   use file_mod,               only: FILE_MODE_WRITE, FILE_MODE_READ
-  use io_context_mod,         only: io_context_type, callback_clock_arg
+  use io_context_mod,         only: io_context_type
   use linked_list_mod,        only: linked_list_type
   use lfric_xios_action_mod,  only: advance
   use lfric_xios_context_mod, only: lfric_xios_context_type
@@ -48,7 +48,6 @@ subroutine setup_checkpoint_io(modeldb, chi, panel_id)
 
     class(event_actor_type), pointer :: event_actor_ptr
     procedure(event_action), pointer :: context_advance
-    procedure(callback_clock_arg), pointer :: before_close
 
     character(len=str_max_filename) :: checkpoint_write_filename
     character(len=str_max_filename) :: checkpoint_read_filename
@@ -126,9 +125,8 @@ subroutine setup_checkpoint_io(modeldb, chi, panel_id)
     ! Add checkpoint context to clock events so that it is advanced at each timestep
     event_actor_ptr => cp_context
     context_advance => advance
-    before_close => null()
     call cp_context%initialise_xios_context( modeldb%mpi%get_comm(), chi, panel_id, &
-                                             modeldb%clock, modeldb%calendar, before_close )
+                                             modeldb%clock, modeldb%calendar )
 
     call modeldb%clock%add_event(context_advance, event_actor_ptr)
     call cp_context%set_active(.true.)

applications/io_demo/source/driver/io_demo_driver_mod.f90

@@ -33,7 +33,6 @@ module io_demo_driver_mod
                                          LOG_LEVEL_TRACE
   use mesh_mod,                   only : mesh_type
   use mesh_collection_mod,        only : mesh_collection
-  use model_clock_mod,            only : model_clock_type
   use multifile_field_setup_mod,  only : create_multifile_io_fields
   use multifile_io_mod,           only : init_multifile_io, step_multifile_io
   use io_benchmark_setup_mod,     only : create_io_benchmark_fields, &

applications/io_demo/source/driver/io_demo_temporal_mod.f90

@@ -17,7 +17,7 @@ module io_demo_temporal_mod
   use function_space_collection_mod,          only : function_space_collection
   use function_space_mod,                     only : function_space_type
   use fs_continuity_mod,      only: Wtheta
-  use io_context_mod,         only: io_context_type, callback_clock_arg
+  use io_context_mod,         only: io_context_type
   use linked_list_mod,        only: linked_list_type
   use lfric_xios_action_mod,  only: advance
   use lfric_xios_context_mod, only: lfric_xios_context_type
@@ -87,7 +87,6 @@ subroutine setup_temporal_io(modeldb, chi, panel_id)
 
     class(event_actor_type), pointer :: event_actor_ptr
     procedure(event_action), pointer :: context_advance
-    procedure(callback_clock_arg), pointer :: before_close
 
     call log_event( 'io_demo: Setting up temporal I/O', LOG_LEVEL_DEBUG )
 
@@ -125,9 +124,8 @@ subroutine setup_temporal_io(modeldb, chi, panel_id)
     end if
 
     ! Initialise the XIOS context attached to the temporal context object
-    before_close => null()
     call temporal_context%initialise_xios_context( modeldb%mpi%get_comm(), chi, panel_id, &
-                                             modeldb%clock, modeldb%calendar, before_close )
+                                             modeldb%clock, modeldb%calendar )
 
     ! Add context object to the model clock's event loop, this means that the
     ! temporal context will be advanced at each model time step, and the
@@ -137,6 +135,8 @@ subroutine setup_temporal_io(modeldb, chi, panel_id)
     call modeldb%clock%add_event(context_advance, event_actor_ptr)
     call temporal_context%set_active(.true.)
 
+    call temporal_context%close_context_definition()
+
     ! Set current context back to main
     call modeldb%io_contexts%get_io_context("io_demo", io_context)
     call io_context%set_current()

applications/io_demo/source/driver/multifile_io/multifile_io_mod.F90

@@ -20,7 +20,7 @@ module multifile_io_mod
   use multifile_file_setup_mod,only: init_multifile_files
   use inventory_by_mesh_mod,   only: inventory_by_mesh_type
   use io_context_collection_mod, only: io_context_collection_type
-  use io_context_mod,          only: io_context_type, callback_clock_arg
+  use io_context_mod,          only: io_context_type
   use log_mod,                 only: log_event, log_level_error, &
                                      log_level_trace, log_level_info, &
                                      log_scratch_space
@@ -29,7 +29,6 @@ module multifile_io_mod
   use lfric_xios_action_mod,   only: advance_read_only
   use mesh_mod,                only: mesh_type
   use mesh_collection_mod,     only: mesh_collection
-  use model_clock_mod,         only: model_clock_type
   use step_calendar_mod,       only: step_calendar_type
 
   use multifile_io_nml_iterator_mod, only: multifile_io_nml_iterator_type
@@ -121,12 +120,10 @@ subroutine step_multifile_io(modeldb, chi_inventory, panel_id_inventory)
     character(str_def) :: time_start
 
     procedure(event_action), pointer :: context_advance
-    procedure(callback_clock_arg), pointer :: before_close
 
     nullify(mesh)
     nullify(chi)
     nullify(panel_id)
-    nullify(before_close)
 
     call iter%initialise(modeldb%config%multifile_io)
     do while (iter%has_next())
@@ -162,9 +159,10 @@ subroutine step_multifile_io(modeldb, chi_inventory, panel_id_inventory)
         call io_context%initialise_xios_context( modeldb%mpi%get_comm(),      &
                                                  chi, panel_id,               &
                                                  modeldb%clock, tmp_calendar, &
-                                                 before_close,                &
                                                  start_at_zero=.true. )
 
+        call io_context%close_context_definition()
+
         ! Attach context advancement to the model's clock
         context_advance => advance_read_only
         event_actor_ptr => io_context

applications/lbc_demo/example/iodef.xml

@@ -48,7 +48,6 @@
     <variable_definition>
       <variable_group id = "buffer">
         <variable id = "optimal_buffer_size" type = "string" >performance</variable>
-        <variable id = "buffer_factor_size" type = "double" >1.0</variable>
       </variable_group>
 
       <variable_group id = "parameters" >

applications/lbc_demo/example/mesh_config.nml

@@ -16,15 +16,16 @@
 /
 
 &planar_mesh
-  edge_cells_x    = 30
-  edge_cells_y    = 30
-  domain_size     = 24.0, 22.0
-  domain_centre   = 0.0, 0.0
-  periodic_x      = .false.
-  periodic_y      = .false.
-  create_lbc_mesh = .true.
-  lbc_rim_depth   = 6
-  lbc_parent_mesh = 'primary'
+  edge_cells_x     = 30
+  edge_cells_y     = 30
+  domain_size      = 24.0, 22.0
+  domain_centre    = 0.0, 0.0
+  periodic_x       = .false.
+  periodic_y       = .false.
+  create_lbc_mesh  = .true.
+  lbc_rim_depth    = 6
+  lbc_parent_mesh  = 'primary'
+  stretch_function = 'uniform'
 /
 
 &partitions

applications/simple_diffusion/example/iodef.xml

@@ -23,7 +23,6 @@
     <variable_definition>
       <variable_group id = "buffer">
         <variable id = "optimal_buffer_size" type = "string" >performance</variable>
-        <variable id = "buffer_factor_size" type = "double" >1.0</variable>
       </variable_group>
 
       <variable_group id = "parameters" >

applications/skeleton/example/iodef.xml

@@ -59,7 +59,6 @@
     <variable_definition>
       <variable_group id = "buffer">
         <variable id = "optimal_buffer_size" type = "string" >performance</variable>
-        <variable id = "buffer_factor_size" type = "double" >1.0</variable>
       </variable_group>
 
       <variable_group id = "parameters" >

components/driver/source/driver_io_mod.F90

@@ -20,7 +20,7 @@ module driver_io_mod
   use field_mod,               only: field_type
   use inventory_by_mesh_mod,   only: inventory_by_mesh_type
   use io_context_collection_mod, only: io_context_collection_type
-  use io_context_mod,          only: io_context_type, callback_clock_arg
+  use io_context_mod,          only: io_context_type
   use log_mod,                 only: log_event, log_level_error, &
                                      log_level_trace, log_level_info, &
                                      log_scratch_space
@@ -47,6 +47,19 @@ subroutine filelist_populator(files_list, modeldb)
     end subroutine filelist_populator
   end interface
 
+  abstract interface
+    !> @brief Callback interface for bespoke IO configuration
+    !> @param[in] config    configuration to be passed in at call site
+    !> @param[in] clock     Clock to be passed in at call site
+    subroutine io_configuration_callback(config,clock)
+      use config_mod, only: config_type
+      use clock_mod, only : clock_type
+      implicit none
+      type(config_type), intent(in) :: config
+      class(clock_type), intent(in) :: clock
+    end subroutine io_configuration_callback
+  end interface
+
 contains
 
   !> @brief  Initialises the model I/O
@@ -82,9 +95,10 @@ subroutine init_io( context_name,       &
     procedure(filelist_populator), &
                    pointer, optional, intent(in)    :: populate_filelist
     character(len=str_def), optional, intent(in)    :: alt_mesh_names(:)
-    procedure(callback_clock_arg), optional         :: before_close
+    procedure(io_configuration_callback), &
+                            optional                :: before_close
 
-    procedure(callback_clock_arg), pointer :: before_close_ptr
+    type(lfric_xios_context_type), pointer :: context
 
     logical(l_def) :: use_xios_io
 
@@ -93,20 +107,22 @@ subroutine init_io( context_name,       &
     ! Allocate IO context type based on model configuration
     if ( use_xios_io ) then
 #ifdef USE_XIOS
-      if (present(before_close)) then
-        before_close_ptr => before_close
-      else
-        before_close_ptr => null()
-      end if
-
       call init_xios_io_context( context_name,       &
                                  mesh_name,          &
                                  modeldb,            &
                                  chi_inventory,      &
                                  panel_id_inventory, &
-                                 before_close_ptr,   &
                                  populate_filelist,  &
                                  alt_mesh_names )
+
+      call modeldb%io_contexts%get_io_context(context_name, context)
+      call context%set_current()
+      if (present(before_close)) then
+        call before_close(modeldb%config, modeldb%clock)
+      end if
+
+      call context%close_context_definition()
+
 #else
       call log_event( "Cannot use XIOS I/O: model has not been built with " // &
                       "XIOS enabled", log_level_error )
@@ -154,7 +170,6 @@ end subroutine init_empty_io_context
   !> @param[in] modeldb             Model state
   !> @param[in] chi_inventory       Contains the model's coordinate fields
   !> @param[in] panel_id_inventory  Contains the model's panel ID fields
-  !> @param[in] before_close        Routine to be called before context closes
   !> @param[in] populate_filelist   Optional procedure for creating a list of
   !!                                file descriptions used by the model I/O
   !> @param[in] alt_mesh_names      Optional array of names for other meshes
@@ -164,7 +179,6 @@ subroutine init_xios_io_context( context_name,       &
                                    modeldb,            &
                                    chi_inventory,      &
                                    panel_id_inventory, &
-                                   before_close,       &
                                    populate_filelist,  &
                                    alt_mesh_names )
 
@@ -175,7 +189,6 @@ subroutine init_xios_io_context( context_name,       &
     class(modeldb_type),                 intent(inout) :: modeldb
     type(inventory_by_mesh_type),        intent(in)    :: chi_inventory
     type(inventory_by_mesh_type),        intent(in)    :: panel_id_inventory
-    procedure(callback_clock_arg), pointer, intent(in) :: before_close
     procedure(filelist_populator), &
                    pointer, optional,    intent(in)    :: populate_filelist
     character(len=str_def), optional,    intent(in)    :: alt_mesh_names(:)
@@ -255,7 +268,6 @@ subroutine init_xios_io_context( context_name,       &
                                                chi, panel_id,          &
                                                modeldb%clock,          &
                                                modeldb%calendar,       &
-                                               before_close,           &
                                                alt_coords,             &
                                                alt_panel_ids )
       deallocate(alt_coords)
@@ -264,8 +276,7 @@ subroutine init_xios_io_context( context_name,       &
       call io_context%initialise_xios_context( modeldb%mpi%get_comm(), &
                                                chi, panel_id,          &
                                                modeldb%clock,          &
-                                               modeldb%calendar,       &
-                                               before_close )
+                                               modeldb%calendar )
     end if
 
     ! Attach context advancement to the model's clock

components/lfric-xios/integration-test/lfric_xios_context_test.f90

@@ -9,7 +9,6 @@
 program lfric_xios_context_test
 
   use field_mod,              only: field_type
-  use io_context_mod,         only: callback_clock_arg
   use lfric_xios_context_mod, only: lfric_xios_context_type
   use lfric_xios_driver_mod,  only: lfric_xios_initialise, lfric_xios_finalise
   use log_mod,                only: log_event, log_level_info
@@ -23,7 +22,6 @@ program lfric_xios_context_test
   type(test_db_type)                         :: test_db
   type(lfric_xios_context_type), allocatable :: io_context
 
-  procedure(callback_clock_arg), pointer :: before_close => null()
 
   call test_db%initialise()
   call lfric_xios_initialise( "test", test_db%comm, .false. )
@@ -34,8 +32,7 @@ program lfric_xios_context_test
   call io_context%initialise( "test_io_context", 1, 10 )
   call io_context%initialise_xios_context( test_db%comm,                    &
                                            test_db%chi,  test_db%panel_id,  &
-                                           test_db%clock, test_db%calendar, &
-                                           before_close )
+                                           test_db%clock, test_db%calendar )
   deallocate(io_context)
 
   ! ============================== Finish test =================================

components/lfric-xios/integration-test/lfric_xios_cyclic_temporal_test.f90

@@ -13,7 +13,6 @@ program lfric_xios_cyclic_temporal_test
   use event_actor_mod,        only: event_actor_type
   use field_mod,              only: field_type, field_proxy_type
   use file_mod,               only: FILE_MODE_READ, FILE_MODE_WRITE
-  use io_context_mod,         only: callback_clock_arg
   use lfric_xios_action_mod,  only: advance
   use lfric_xios_context_mod, only: lfric_xios_context_type
   use lfric_xios_driver_mod,  only: lfric_xios_initialise, lfric_xios_finalise
@@ -28,7 +27,6 @@ program lfric_xios_cyclic_temporal_test
   type(test_db_type)                                 :: test_db
   type(lfric_xios_context_type), target, allocatable :: io_context
 
-  procedure(callback_clock_arg), pointer :: before_close
   type(linked_list_type),        pointer :: file_list
   class(event_actor_type),       pointer :: context_actor
   procedure(event_action),       pointer :: context_advance
@@ -63,11 +61,9 @@ program lfric_xios_cyclic_temporal_test
                                                     freq=1,                               &
                                                     fields_in_file=test_db%temporal_fields ) )
 
-  before_close => null()
   call io_context%initialise_xios_context( test_db%comm,                    &
                                            test_db%chi,  test_db%panel_id,  &
-                                           test_db%clock, test_db%calendar, &
-                                           before_close )
+                                           test_db%clock, test_db%calendar )
 
 
   context_advance => advance

components/lfric-xios/integration-test/lfric_xios_temporal_interp_test.f90

@@ -13,7 +13,6 @@ program lfric_xios_temporal_interp_test
   use event_actor_mod,        only: event_actor_type
   use field_mod,              only: field_type, field_proxy_type
   use file_mod,               only: FILE_MODE_READ, FILE_MODE_WRITE
-  use io_context_mod,         only: callback_clock_arg
   use lfric_xios_action_mod,  only: advance
   use lfric_xios_context_mod, only: lfric_xios_context_type
   use lfric_xios_driver_mod,  only: lfric_xios_initialise, lfric_xios_finalise
@@ -29,7 +28,6 @@ program lfric_xios_temporal_interp_test
   type(test_db_type)                                 :: test_db
   type(lfric_xios_context_type), target, allocatable :: io_context
 
-  procedure(callback_clock_arg), pointer :: before_close
   type(linked_list_type),        pointer :: file_list
   class(event_actor_type),       pointer :: context_actor
   procedure(event_action),       pointer :: context_advance
@@ -65,12 +63,9 @@ program lfric_xios_temporal_interp_test
                                                     freq=1,                               &
                                                     fields_in_file=test_db%temporal_fields ) )
 
-  before_close => null()
   call io_context%initialise_xios_context( test_db%comm,                    &
                                            test_db%chi,  test_db%panel_id,  &
-                                           test_db%clock, test_db%calendar, &
-                                           before_close )
-
+                                           test_db%clock, test_db%calendar )
 
   context_advance => advance
   context_actor => io_context