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Utility program to compare the ensemble mean to a group of ensemble member restart files, which can now be run in parallel. The program prints out a sorted order of which members are 'closest' to the mean, where the method used to determine 'close' is selectable by namelist option. It also creates a file with a single number or character string in it, for ease in scripting, which identifies the closest member.
The ensemble mean is computed from the input ensemble. The difference is computed point by point across the ensemble members. There is an option to restrict the computation to just a subset of the entire state vector by listing one or more generic quantities. In this case, only state vector items matching one of these quantities will contribute to the total difference value.
Available methods are:
This program could be used to select one or more ensemble members to run a free model forecast forward in time after the assimilation is finished. Each member is an equally likely representation of the model state. Using the ensemble mean may not be the best since the mean may not have self-consistent fine-scale structures in the data.
In addition to printing out data about all members to both the console and to the dart log file, this program creates a single output file containing information about the closest member. If the input restart data is in a single file, the output file 'closest_restart' contains a single number which is the ensemble member number. If the input restart data is in separate files, the output file contains the full filename of the closest member, e.g. 'filter_restart.0004' if member 4 is closest. For scripting the contents of this file can be used to copy the corresponding member data and convert it to the model input format for a free forecast, for example.
This namelist is read from the file input.nml. Namelists start with an ampersand '&' and terminate with a slash '/'. Character strings that contain a '/' must be enclosed in quotes to prevent them from prematurely terminating the namelist.
&closest_member_tool_nml input_restart_files = '' input_restart_file_list = '' output_file_name = 'closest_restart' ens_size = 1 difference_method = 4 use_only_qtys = '' single_restart_file_in = .false. /
|input_restart_files||character(len=256),dimension(ens_size x num_domains)||An array of filenames each containing a list DART restart data.|
|input_restart_file_list||character(len=256),dimension(num_domains)||A file containing a list of filenames for DART restart data, one for each domain.|
|output_file_name||character(len=256)||This is a file containing the member number that is closest to the ensemble mean.|
|ens_size||integer||Total number of ensemble members.|
|difference_method||integer||Select which method is used to compute 'distance' from mean:
|use_only_quantities||character(len=32)||If unspecified, all items in the state vector contribute to the total difference. If one or more quantities are listed here, only items in the state vector of these quantities contribute to the total difference. These are the generic quantities, such as QTY_TEMPERATURE, QTY_U_WIND_COMPONENT, QTY_DENSITY, etc. and not specific types like RADIOSONDE_TEMPERATURE. Consult the model interface code to determine which possible quantities are returned by the get_state_meta_data() routine.|
Below is an example of a typical namelist for the closest_member_tool.
&closest_member_tool_nml input_restart_files = '' input_restart_file_list = 'restart_list.txt' output_file_name = 'closest_restart.txt' ens_size = 3 single_restart_file_in = .false. difference_method = 4 use_only_qtys = '' /
where restart_list.txt contains
cam_restart_0001.nc cam_restart_0002.nc cam_restart_0003.nc
Currently single_restart_file_in is not supported. This is typically used for simpler models that have built in model advances such as lorenz_96.
|closest_member_tool||Invalid method number||Values 1-4 are supported|
|Contact:||DART core group|
|Revision:||$Revision: 12664 $|
|Source:||$URL: https://svn-dares-dart.cgd.ucar.edu/DART/releases/Manhattan/assimilation_code/programs/closest_member_tool/closest_member_tool.html $|
|Change Date:||$Date: 2018-06-12 16:04:36 -0600 (Tue, 12 Jun 2018) $|
|Change history:||try "svn log" or "svn diff"|