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<title>GrADS Utilities: bufrscan</title>
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<h2><b>bufrscan</b></h2>
<p> <span class="plaintext">BUFR (Binary Universal Form for the Representation
of meteorological data) is a World Meteorological Organization (WMO) standard
for storing observational data (aka sequence or in-situ data). BUFR is self-describing
data format and can store a large amount of data and metadata in a small amount
of disk space by using look-up tables and bit-by-bit packing. Bufrscan is an
external GrADS utility that reads BUFR messages and prints out ascii values.
</span>
<p class="plaintext">Individual elements of a BUFR message are uniquely described
by three numbers: F, X, and Y. F is a type indicator and may be 0, 1, 2, or
3. X is a class or category indicator and varies between 0 and 63. Y indicates
an entry within an X class, and varies between 0 and 255. The F,X,Y trio provides
the required decoder table reference, so that the data value may be retrieved
from the BUFR element. A group of BUFR elements forms a subset; a group of subsets
forms a message; any number of messages may be concatenated together to form
a BUFR file.
<p class="plaintext">The syntax for bufrscan is as follows:
<p><code>bufrscan [-h] [-d] <em>tablepath filename</em></code>
<p>Where:
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<td width="97"><code>-h</code></td>
<td width="551" class="plaintext">Prints the BUFR message headers (default)
</td>
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<td><code>-d</code></td>
<td class="plaintext">Prints the BUFR message contents</td>
</tr>
<tr>
<td><code><em>tablepath</em></code></td>
<td class="plaintext">Directory containing BUFR decoding tables (e.g. /usr/local/grads/lib/tables)</td>
</tr>
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<td><code><em>filename</em></code></td>
<td class="plaintext">BUFR message file to be decoded</td>
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</table>
</ul>
<p class="plaintext">When using the -h option to print out the headers, the output
from bufrscan will list the F, X, Y values for each element as well as the type
of information in the element (given in parentheses). For elements that are
type 'numeric' or 'text', a variable name and description are also printed.
(<a href="bufr.sample.headers">Example header output</a>)
<p class="plaintext">When using the -d option to print out the data, the output
from bufrscan will list message number, subset number (in parentheses), replication
factor [in square brackets], the F,X,Y values, and then the decoded data value.
(<a href="bufr.sample.data">Example data output</a>)
<p class="plaintext">Many BUFR files also contain a lookup table that was designed
to be used with the data in the file. The tables are packed into the BUFR format
the same way the data are. If a BUFR file contains a decoding table, the information
in that table will override the lookup values in the standard decoding tables
underneath the <code><em>tablepath</em></code> directory.
<p class="plaintext">There is a GrADS interface for BUFR, which means that BUFR
data can be read directly in their native format and are handled as a GrADS
station data set with all the associated display an analysis capabilities. GrADS
requires a specially-formatted descriptor file to read BUFR data; the output
from bufrscan is used to compose the descriptor file. The document on the <a href="bufrformat.html">
BUFR Format</a> has more information on how to generate BUFR descriptor files.
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