Changes between Version 1 and Version 2 of 2011WP/2011Stream2/OpenBoundaries

Timestamp:

2011-03-11T16:33:48+01:00 (13 years ago)

Author:

davestorkey

Comment:

--

2011WP/2011Stream2/OpenBoundaries

@@ -12 +12 @@
 Blah
 
-== High-level control and coding structure ==
+== Summary of main features ==
+
+ * The following algorithms will be included in the first implementation:
+   * Clamped and Flow Relaxation Scheme. (Clamped is FRS with rimwidth=1).
+   * Flather radiation condition on barotropic solution.
+   * NPO version of Orlanski radiation condition as currently included in OBC.
+     Plan to code ''implicit'' time-stepping for greater stability and to avoid
+     OBC restarts. May also code normal, and fully 2D Orlanski condition.
+   * "Mercator-style" barotropic boundary conditions.
+   * Tidal harmonic forcing (included in Flather boundary condition).
+
+ * There will be two ways of specifying the boundary geometry:
+   a. Using obc_par.h90 to define straight-line segments. One will be able to
+      define more than one segment for each of east, west, south, north 
+      boundaries.
+   b. Reading in the list of points from the data file as is now done in BDY.
+   
+ * The low-level code will use the BDY-style specification of the boundary
+   geometry (an unstructured list of gridpoints). If obc_par.h90 is used then
+   this will be converted to BDY-style arrays in the initialisation.   
+
+ * The read of external boundary data will be handled by fldread.F90 as is done
+   for the SBC fields. This is clean and flexible. In the future this will
+   permit online interpolation of boundary data.
+   
+ * It will be possible to define more than one open boundary set. This will
+   allow different boundary conditions to be applied on different boundaries.
+   
+   
+== Control and coding structure ==
 The namelist for the new module would look like this:
 
 {{{
 !-----------------------------------------------------------------------
-&namobc        !  unstructured open boundaries               ("key_obc")
-!-----------------------------------------------------------------------
-   cn_mask     =  ''                      !  name of mask file (ln_mask=T)
-   cn_dta      = 'obcdata1', 'obcdta2'    !  root name of data file
-   nn_freq     = 6         , -1           !  frequency of data in file (hours)
-                                          !  negative value => months
-   cn_type     = 'daily'   , 'yearly'     !  'yearly','monthly','daily' files
-   ln_clim     = .false.   , .true.       !  climatological data or not
-   ln_tint     = .true.    , .true.       !  time interpolation of boundary
-                                          !  data or not
-   
-   nn_dyn         = 0, 1,   !  Choice of schemes for velocities
-   nn_tra         = 0, 1,   !  Choice of schemes for T and S 
+&namobc        !  one-way open boundaries                    ("key_obc")
+!-----------------------------------------------------------------------
+   nb_obc         = 2       !  Number of open boundary sets
+   cn_mask        = ''      !  name of mask file (ln_mask=T)
+   nn_dyn         = 1, 0,   !  Choice of schemes for velocities
+   nn_tra         = 1, 1,   !  Choice of schemes for T and S 
    nn_barotropic  = 1, 0,   !  Choice of schemes for barotropic solution
    nn_ice_lim2    = 0, 0,   !  Choice of schemes for ice (LIM2)
@@ -35 +57 @@
    ln_mask        = .false.,.false.,  !  boundary mask from filbdy_mask (T), boundaries are on edges of domain (F)
    ln_tides       = .false.,.false.,  !  Apply tidal harmonic forcing with Flather condition
-   nn_rimwidth    =  1, 9,            !  width of the relaxation zone
+   nn_rimwidth    =  9, 1,            !  width of the relaxation zone
    nn_dtactl      =  1, 1,            !  = 0, bdy data are equal to the initial state
                                       !  = 1, bdy data are read in 'bdydata   .nc' files
@@ -41 +63 @@
                                       !  = 1, the total volume of the system is conserved
  /
+!-----------------------------------------------------------------------
+&namobc_dta     !  one-way open boundaries                   ("key_obc")
+!-----------------------------------------------------------------------
+!               !  file name          ! frequency (hours) ! variable  ! time interp. !  clim  ! 'daily'/ ! weights  ! rotation !
+!               !                     !  (if <0  months)  !   name    !   (logical)  !  (T/F) ! 'monthly' ! filename ! pairing  !
+   bn_tem      = 'obcdta_grid_T'      ,        24          , 'votemper',   .true.     , .false., 'daily'  , ''       , ''
+   bn_sal      = 'obcdta_grid_T'      ,        24          , 'vosaline',   .true.     , .false., 'daily'  , ''       , ''
+   bn_uvel     = 'obcdta_grid_U'      ,        24          , 'vozocrtx',   .true.     , .false., 'daily'  , ''       , ''
+   bn_vvel     = 'obcdta_grid_V'      ,        24          , 'vomecrty',   .true.     , .false., 'daily'  , ''       , ''
+   bn_ssh      = 'obcdta_bt_grid_T'   ,         6          , 'sossheig',   .true.     , .false., 'daily'  , ''       , ''
+   bn_ubar     = 'obcdta_bt_grid_U'   ,         6          , 'vozocrtx',   .true.     , .false., 'daily'  , ''       , ''
+   bn_vbar     = 'obcdta_bt_grid_V'   ,         6          , 'vomecrty',   .true.     , .false., 'daily'  , ''       , ''
+
+   cn_dir      = './obcdta'      !  root directory for the location of the boundary data files
+/      
+!-----------------------------------------------------------------------
+&namobc_dta     !  one-way open boundaries                   ("key_obc")
+!-----------------------------------------------------------------------
+!               !  file name          ! frequency (hours) ! variable  ! time interp. !  clim  ! 'daily'/ ! weights  ! rotation !
+!               !                     !  (if <0  months)  !   name    !   (logical)  !  (T/F) ! 'monthly' ! filename ! pairing  !
+   bn_tem      = 'obcdta_clim_grid_T' ,        -1          , 'votemper',   .true.     , .true., 'yearly'  , ''       , ''
+   bn_sal      = 'obcdta_clim_grid_T' ,        -1          , 'vosaline',   .true.     , .true., 'yearly'  , ''       , ''
+
+   cn_dir      = './obcdta'      !  root directory for the location of the boundary data files
+/      
 }}}
 
-You can define several boundary streams. The example here has two streams
-defined. The number of streams is defined by the '''cn_dta''' parameter which is
-the filename root. For '''cn_dta'''=''bdydta1'', it will look for files called
-''bdydta1_grid_T.nc'', ''bdydta1_grid_U.nc'' etc. For each stream you select
-which boundary conditions you want to apply to which fields using '''nn_dyn''',
-'''nn_tra''', '''nn_barotropic''' etc. Zero means do not apply open boundary
-conditions. The other numbers refer to different schemes. For example,
-'''nn_tra'''=0 means don't apply open boundary conditions to T and S,
-'''nn_tra'''=1 might mean apply FRS conditions, '''nn_tra'''=2 might mean apply
-radiation conditions etc. 
+It is possible to define more than one open boundary set in case you want to use
+different boundary conditions for different boundaries. For instance one might
+want to apply different algorithms on the east and west boundaries of a domain,
+or one might want to apply boundary conditions from an external model over part
+of the open boundary but climatological boundary conditions over another part of
+the open boundary (as in the example above). 
+
+For each open boundary set you define which conditions to apply to each set of
+variables using '''nn_dyn''', '''nn_tra''' etc. For example:
+
+        '''nn_tra''' = 0        :       Apply no boundary condition (land
+                                        boundary)
+        '''nn_tra''' = 1        :       Clamped/relaxation boundary condition
+        '''nn_tra''' = 2        :       Normal radiation condition
+        '''nn_tra''' = 3        :       NPO radiation condition
+        etc.
+        
+There is a separate '''&namobc_dta''' namelist for each boundary set, which
+defines the input data files using the '''FLD''' structure from fldread.F90.
+(This will allow for online interpolation of boundary conditions in the future).
 
 For each set of variables there is a module which applies the boundary