Table of Contents

4.1   Introduction
4.2   Six easy steps to making a WRF simulation
4.3   Flow Diagram of the WRF EMS
4.4   WRF EMS Environment variables
4.5   The wrf_clean.pl script

 

4.1     Introduction

This chapter provides a very brief introduction to making a simulation with the WRF EMS. Much more information will be provided in the following chapters; however, this diversion serves to ameliorate the confusion and cluelessness that may overwhelm a user when setting up and running a NWP system for the first time. It also may serve to better explain the flow chart of the system provided in Chapter 4.3.

 

4.2      Six easy steps to making a WRF simulation

Running the WRF EMS is easy. The steps are as follows:

1. Create a WRF domain (< some domain>) with configuration GUI (Chapter 5)

2. Change directories to $WRF/runs/<some domain>

3. Configure your model run

4. Execute wrf_prep.pl to process your initialization data (Chapter 6)

5. Execute wrf_run.pl to execute your simulation (Chapter 7)

6. Execute wrf_post.pl to post-process your forecast files (Chapter 8)

Note that

•  Steps 4 through 6 may be accomplished by running wrf_autorun.pl (Chapter 9)

•  There is an option for synchronous post processing in wrf_post.pl (Chapter 7)

•  Additional steps are required for running NMM nested simulations (Chapter 11)

It's that easy.

 

4.3      Flow Diagram of the WRF EMS

 

4.4      WRF EMS Environment variables

The WRF EMS system is designed to run in a T or Cshell (/bin/tcsh or /bin/csh) environment. Following installation, you will find a WRF.cshrc file in the top level of the WRF EMS directory that contains various environment variables used to run the system. This file must be sourced by the user prior to executing any of the run-time scripts; otherwise bad stuff will happen. Fortunately, if the installation went smoothly, then this file will automatically be sourced each time the WRF user logs in. You probably have them set right now.

Once this file is sourced you will have the following variables in your environment:

$WRF		Top level of the SOO/STRC WRF EMS release
$WRF_BIN	$WRF/bin	Location of the precompiled binaries
$WRF_DATA	$WRF/data	Location of the static data sets
$WRF_ETC	$WRF/etc	Location of the FSL scripts
$WRF_STRC	$WRF/strc	Location of the WRF EMS run-time scripts
$WRF_RUN	$WRF/runs	Location of the user domains
$WRF_UTIL	$WRF/util	Location of various utilities
$WRF_UTIL	$WRF/docs	Location of WRF EMS documents

That's not all of them but it is good enough for starters. For more variables take a look at the WRF.cshrc file.

 

4.5      The wrf_clean.pl script

The wrf_clean.pl script is a useful utility provided to help you keep your computational domain directories free of unnecessary files and directories. If the WRF.cshrc file is sources at login, the user can execute the utility by running "wrf_clean" from one of the domain directories. While it is recommended that you run "wrf_clean -help" to view all the options, here are a few examples:

% wrf_clean --level 4

When executed from a domain directory, the above command will return the directory to a newly created state except that it will not remove any of the user configuration files. This command is typically run before making real-time simulations.

% wrf_clean --level 3

When run from a domain directory, the above command will return the directory to a prerun state. It will not delete any of the GRIB files located in the <domain>/grib directory or the user configuration files.

% wrf_clean --domain <domain directory>

The above command will completely delete a computational domain directory and ancillary files.