Changes between Version 11 and Version 12 of doc/app/examples/coupled

Timestamp:

Jan 10, 2011 3:26:43 PM (14 years ago)

Author:

maronga

Comment:

--

doc/app/examples/coupled

@@ -3 +3 @@
 
 Starting from version 3.4 PALM allows coupled atmosphere-ocean model runs. If MPI-2 support is available, '''mrun''' starts the coupled model as two concurrent executables, the atmosphere version and the ocean version in analogy with the modular structure of PALM.\\\\
-The coupler establishes a one-way interaction between the atmosphere and the ocean. The atmosphere sends its bottom surface fluxes (temperature, humidity, momentum) to the ocean. The ocean sends its top surface temperature and top horizontal velocity to the atmosphere. The atmosphere assumes saturation of humidity at its bottom surface. For calculations with [../../inipar#humidity humidity] = ''.T.'' the atmospheric evaporation leads to a salinity flux in the ocean (see e.g. Steinhorn 1991, JPO 21, p. 1681).\\\\
+The coupler establishes a one-way interaction between the atmosphere and the ocean. The atmosphere sends its bottom surface fluxes (temperature, humidity, momentum) to the ocean. The ocean sends its top surface temperature and top horizontal velocity to the atmosphere. The atmosphere assumes saturation of humidity at its bottom surface. For calculations with [../../inipar#humidity humidity] = ''.T.'' the atmospheric evaporation leads to a salinity flux in the ocean (see e.g. Steinhorn 1991, JPO 21, p. 1681).\\
+\\
 If the full MPI-2 standard is available, it can be activated by adding the preprocessor directive {{{-D__mpi2}}} to {{{cpp_options}}} in the {{{.mrun.config}}} configuration file. Otherwise, PALM will use a coupling via MPI1. Please note that coupling with different horizontal grid size and different number of processors in ocean and atmosphere is only possible with MPI-1. To start a coupled model run, this must be requested with the '''mrun''' option {{{-Y}}} {{{“#1 #2”}}}, where {{{#1}}} is the number of processors for the atmospheric and {{{#2}}} the number of processors for the oceanic version of PALM. This tells '''mrun''' to start two PALM executables. Coupled runs are only possible in parallel mode, which means that the '''mrun''' option {{{-K parallel}}} must also be set. The '''mrun''' call for coupled runs has to include the following coupling-related options:
 {{{
@@ -50 +51 @@
 The coupled ocean model filenames in the first column (e.g. [../../iofiles#PARIN_O PARIN_O]) must be specified as given [../../iofiles here]; the file connection identifiers (e.g.  {{{d3o#}}}) and the file name extension (e.g.  {{{_o_p3d}}}) may be changed at the user's discretion.\\\\
 The coupler requires the following parameters to be equal in both [../../iofiles#PARIN PARIN] and [../../iofiles#PARIN_O PARIN_O]: [../../d3par#dt_coupling dt_coupling], [../../d3par#end_time end_time], [../../d3par#restart_time restart_time], [../../d3par#dt_restart dt_restart]. Furthermore the model domain length in x- and y-direction in ocean and atmosphere has to be same. In the coupled atmosphere executable, [../../inipar#bc_pt_b bc_pt_b] is internally set and does not need to be prescribed; in the coupled ocean executable, [../../inipar#bc_uv_t bc_uv_t] is internally set ('' 'neumann' '') and does not need to be prescribed. The coupled ocean parameter file [../../iofiles#PARIN_O PARIN_O] should include dummy REAL value assignments to both [../../inipar#top_momentumflux_u top_momentumflux_u] and [../../inipar#top_momentumflux_v top_momentumflux_v] (e.g. top_momentumflux_u = 0.0, top_momentumflux_v = 0.0) to enable the momentum flux coupling.\\\\
-The coupling interval [../../d3par#dt_coupling dt_coupling] must be explicitly set. In order to ensure synchronous coupling throughout the simulation, dt_coupling should be chosen larger than [../../d3par#dt_max dt_max].\\\\
-It's also possible to perform precursor runs (one atmospheric and one oceanic) followed by a coupled restart run. In order to achieve this, the parameter [../../inipar#coupling_start_time coupling_start_time] must be set according to the [[attachment:precursor_run_control.pdf|precursor run control documentation]],
+The coupling interval [../../d3par#dt_coupling dt_coupling] must be explicitly set. In order to ensure synchronous coupling throughout the simulation, dt_coupling should be chosen larger than [../../d3par#dt_max dt_max].\\
+\\
+=== Precursor runs ===
+It's also possible to perform precursor runs (one atmospheric and one oceanic), followed by a coupled restart run to save computational time owing to different spin-up times in atmosphere and ocean. To use the precursor run control, the parameter [../../inipar#coupling_start_time coupling_start_time] must be set in both, the precursor runs as well as in the coupled restart run.\\
+\\
+==== Configuration ({{{.mrun.config}}}) ====
+For the precursor runs the following relation must be valid:\\
+\\
+{{{ end_time - coupling_start_time = 0}}}.\\
+\\
+Here, {{{coupling_start_time}}} refers to the time period, in which the precursor runs shall run uncoupled. In the output data, the time will show negative values during this period. In the restart run, {{{coupling_start_time}}} must be set equal to the settings in the precursor runs. 
+For the coupled restart run the following relation must be valid:\\
+\\
+{{{ 
+end_time - coupling_start_time = X,
+}}}
+where {{{X}}} is equal in the atmospheric and the oceanic model.
+\\
+===== Example =====
+Precursor run (atmosphere):\\
+{{{
+end_time            = 3600.0
+coupling_start_time = 3600.0
+}}}
+\\
+\\
+Precursor run (ocean):\\
+{{{
+end_time            = 40000.0
+coupling_start_time = 40000.0
+}}}
+\\
+Coupled restart run (atmosphere):\\
+{{{
+end_time            = 23600.0
+coupling_start_time = 3600.0
+}}}
+\\
+Coupled restart run (ocean):\\
+{{{
+end_time            = 60000.0
+coupling_start_time = 40000.0
+}}}
+\\
+
+==== Starting ({{{mrun}}})====
+The atmospheric precursor run can be started like a usual atmospheric run:\\
+\\
+{{{
+mrun -d examplerun . . . -X8 -r “d3# . . . restart”,
+}}}
+\\
+while the oceanic precursor run requires the {{{-y}}} option:\\
+\\
+{{{
+mrun -d examplerun . . . -X8 -r “d3o# . . . restart” -y\\
+}}}
+\\
+The coupled restart then is carried out by:\\
+\\
+{{{
+mrun -d examplerun . . . -X16 -r “d3f d3of . . . restart” -Y "8 8".
+}}}
+\\