wiki:WRF4G2.0/Experiment

Version 37 (modified by carlos, 7 years ago) (diff)

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Experiment Configuration

In order to design a WRF4G experiment you need to edit a file called experiment.wrf4g. From this file, WRF4G will generate all WRF configuration files required to run the simulations planned for the experiment.

Configuration format

The configuration experiment file consists of sections, each led by a [section] header, followed by key = value entries. Lines beginning with # are ignored. Allowing sections are [DEFAULT] and [resource_name].

DEFAULT section

The DEFAULT section provides default values for all other sections. And its key values are:

  • name: Name of the experiment it MUST be unique.
  • max_dom: Number of domains.
  • date_time: Describe dates for a list of realizations with the following format : start_date | end_date | simulation_interval | simulation_length | chunk_size
    • start_date: Beginning of the list of realizations.
    • end_date: End of the list of realizations.
    • simulation_interval: Interval (in hours) between realizations (optional).
    • simulation_length: Length (in hours) of each realization (optional).
    • chunk_size: Length (in hours) of a temporal piece of a realization (optional). That means that every chunk_size a wrf-restart will be generated.
  • chunk_restart: Either yes or no (default value is yes). If you won't create a restart files when a chunk finishes.
  • calendar: Either standard or leap (default value is standard). Type of calendar to create realizations.
  • timestep_dxfactor: If present, the time step is computed as dx*timestep_dxfactor, in kilometers. Defaults to 6, as suggested by the WRF team for most applications. Under some circumstances (cfl problems) a lower value may be needed. In any case, the time step is adjusted to the highest value lower than timestep_dxfactor times dx fitting evenly in one hour period.
  • np: Number of processors requested in a parallel job.
  • requirements: Requirements for computing rerources where the experiment is going to run (for more information see advanced configuration).
  • environment: Experiment environment variables are configuration options for jobs (for more information see advanced configuration).
  • clean_after_run: Either yes or no (default value is no), indicating whether or not temporary simulation files should be removed. The maintenance of these files on running place could be desirable for debugging purposes.
  • save_wps: Either yes or no (default value is no), indicating whether boundary and initial conditions (real.exe output) should be preserved or not. They will be used if the experiment is relaunched again.
  • real_parallel: Either yes or no (default value is no), indicating whether the real.exe binary is compiled in serial or parallel mode.
  • wrf_parallel: Either yes or no (default value is yes), indicating whether the wrf.exe binary is compiled in serial or parallel mode.
  • domain_path: Path of the directory with the information about the domain of the simulations; this is, the files generated by geogrid.exe (nameslit.wps & geo_em.d[nn].nc).
  • preprocessor: Name (just the ending [NAME] section in 'preprocessor.[NAME]') of the necessary pre-processor useful to make the specific input data available for WRF model. Users could not be interested in the permanent WRF-necessary modification of any source of data. With the specification and design of a pre-processor, necessary WRF modifications (e.g.: ASCII to GRIB, variables re-coding, complete input data). Pre-processors are included in repository/apps/preprocessor/.
  • extdata_vtable: Vtable of the ungrib module to be used to decode provided GRIB input data.
  • extdata_path : Path to the input data. It must be consistent with the pre-processor design.
  • extdata_interval: Interval of the input data (in seconds). On multiple input data sources use the smallest one.
  • postprocessor: Users might be interested in the transformation of the WRF output files. A first generic post-process of the output will be automatically carried out if a valid name postprocessor.[NAME] is provided. Post-processors are included under the repository/apps/postprocessor/ directory.
  • wrfout_name_end_date: Either yes or no (default value is no).
  • app: wrf_all_in_one | bundle | /home/carlos/wrf4g/repository/apps/WRF/WRFbin-3.4.1_r2265_gfortran.tar.gz
  • namelist_version:Version of the namelist to use ( from 3.2 to 3.7 ).
  • namelist: Users are able to over-write or add parameters to the namelist file. The name must be the same as the namelist.input entry, with a prefix-flag and the record to where it belongs.
    • Single valued; NI_[namelist_parameter_name]_ _[record]: NI flag indicating that [namelist_parameter_name] of record [record] has a single value.
    • One value per all domains; NIN_[namelist_parameter_name]_ _[record]: NIN flag indicating that [namelist_paramter_name] of record [record] has the same value for all the domains of the experiment.
    • One value per domain; NIM_[namelist_name]_ _[record]: NIM flag indicating that [namelist_paramter_name] of record [record] has a different value for each experiment's domain.
  • multiple_parameters: Binary flag (0;No , 1: Yes) indicating whether or not the experiment is based on independent realizations with different values on the WRF-namelist.input file. When activated, it has to be accompanied by appropriated values of:
  • multiparams_variables: The set of parameters that we want to change (some or all of them) between realizations. It is given as a | separated WRF-namelist.input files (no record specification is necessary if the parameter already appears on the provided WRF-version namelist.input template. If not, it should be [parameter]__[record])
  • multiparams_combinations: Values of the changing parameters for each realization. Parameters should be separated by commas and realizations are separated by '/'.
  • multiparams_nitems: number of values that should have the namelist parameter. ${max_dom}, as many values as domains; 1, a single value.
  • multiparams_labels: the output of the experiment is organized with a folder for each realization. The pattern of the folder name for a given realization is [start_date]_[multiparams_combinations]('_' separated). However, users can provide a set of labels ('/' separated) for each realization, and the folder names will be '[start_date]_[multiparams_labels]'

Resource section

Each resource section has to begin with the line [resource_name] followed by key = value entries.

How to create one

You can write a experiment.wrf4g from scratch or use the templates that WRF4G provides by typing :

$ wrf4g exp test define --from-template single

Example

[DEFAULT]
# Experiment configuration
name                 = test
# Simulation domain
max_dom              = 1
# Experiment time-specification
#                      start_date          | end_date            | chunk_size_h
date_time            = 2011-08-28_12:00:00 | 2011-08-30_00:00:00 | 12
calendar             = standard
timestep_dxfactor    = 6
# Running options 
np                   = 1
requirements         = ARCH = "x86_64"
clean_after_run      = yes
save_wps             = no
real_parallel        = no
wrf_parallel         = yes
# Input data
domain_path          = /home/carlos/WRF4G_2_0/repository/domains/Santander_50km
# Vtables must exist as Vtable.[input_extdata]
extdata_vtable       = GFS
extdata_path         = /home/user/WRF4G_2_0/repository/input/NCEP/GFS
# Seconds between global analysis input times
extdata_interval     = 21600
preprocessor         = default
# Output
output_path          = /home/user/test/output
postprocessor        = SFC
wrfout_name_end_date = no
# app
app                  = wrf_all_in_one | bundle | /home/user/WRF4G_2_0/repository/apps/WRF/WRFbin-3.4.1_r2265_gfortran.tar.gz
# WRF-namelist parameters. Override namelist.input variables here
namelist_version     = 3.4.1
namelist             = spec_bdy_width     | 10
                       spec_zone          | 1
                       relax_zone         | 9
                       feedback           | 0
                       history_interval   | 180
                       frames_per_outfile | 3
                       e_vert             | 28
                       mp_physics         | 4
                       radt               | 15
                       ra_lw_physics      | 3
                       ra_sw_physics      | 3