a. Downloading Test Data

This page describes how to access test data sets required to run WRF-Var. If you don't know anything about WRF-Var, you should first read the Introduction section.

i. Required Data

The WRF-Var system requires three input files to run: a) A WRF first guess input format file, which is output from either the WPS (cold-start) or WRF itself (warm-start), b) Observations (in BUFR or ASCII little_r format), and c) A background error statistics file (containing background error covariances currently calculated via the NMC method). The use of these three data files in WRF-Var is described later in the tutorial.

The following table summarizes the above info:

Input Data

Format

Created By

 

First Guess

 

 

NetCDF

 

WRF Pre-processing System (WPS)

Or

WRF

 

 

Observations

 

 

ASCII

(NCEP-PREPBUFR also possible)

 

Observation Preprocessor (OBSPROC)

 

 

Background Error Statistics

 

 

Binary

 

WRF-Var gen_be utility

 

In the online tutorial, example input files are given. However, in your own work after the tutorial, you will need to create the input data sets yourselves.

ii. Downloading Test Data

In the online tutorial, we will store data in a directory defined by the environment variable $DAT_DIR. This directory can be in any location that can be read and written to from your current machine and which has at least 100 MB of free space available (for this test case; more space may be needed for other cases).  Type

            setenv DAT_DIR dat_dir

where dat_dir is your chosen directory. If the directory pointed to by $DAT_DIR does not already exist, create it now; then, change to this directory by typing

            cd $DAT_DIR

Download the tutorial test dataset for a CONUS 12 UTC 1 January 2003 test case from

http://www.mmm.ucar.edu/wrf/src/data/WRFV3-testdata.tar.gz

Once you have downloaded the WRFV3-testdata.tar.gz file to $DAT_DIR, extract it by typing

            gunzip WRFV3-testdata.tar.gz

            tar -xvf WRFV3-testdata.tar

You should then see a number of data files that will be used in the tutorial. To save space, remove the tar file by typing

            rm wrfvar-testdata.tar

iii. What next?

OK, now you have downloaded the necessary data, and you’re ready to pre-process the supplied observation file. Proceed to

b. The WRF-Var ObservationPreprocessor (OBSPROC)


Trouble Shooting:

1. Having trouble, ask mailto:wrfhelp@wrf-model.org.


 

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