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<title>MGD77CONVERT</title>
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<h1 align=center>MGD77CONVERT</h1>
<a href="#NAME">NAME</a><br>
<a href="#SYNOPSIS">SYNOPSIS</a><br>
<a href="#DESCRIPTION">DESCRIPTION</a><br>
<a href="#OPTIONS">OPTIONS</a><br>
<a href="#EXAMPLES">EXAMPLES</a><br>
<a href="#FILE FORMATS">FILE FORMATS</a><br>
<a href="#OTHER TOOLS">OTHER TOOLS</a><br>
<a href="#SEE ALSO">SEE ALSO</a><br>
<a href="#REFERENCES">REFERENCES</a><br>
<hr>
<a name="NAME"></a>
<h2>NAME</h2>
<p style="margin-left:11%; margin-top: 1em">mgd77convert
− Translate between different formats of MGD77
files</p>
<a name="SYNOPSIS"></a>
<h2>SYNOPSIS</h2>
<p style="margin-left:11%; margin-top: 1em"><b>mgd77convert</b>
<i>NGDC-ids</i> <b>−Fa</b>|<b>c</b>|<b>t
−T</b>[<b>+</b>]<b>a</b>|<b>b</b>|<b>t</b> [
<b>−L</b>[<b>w</b>][<b>e</b>][<b>+</b>] ] [
<b>−V</b> ] [ <b>−4</b> ]</p>
<a name="DESCRIPTION"></a>
<h2>DESCRIPTION</h2>
<p style="margin-left:11%; margin-top: 1em"><b>mgd77convert</b>
reads versions of MGD77 files and writes the same data in
(probably) another format to a new file in the current
directory. Both pre- and post-Y2K MGD77 formats can be
processed. <i><br>
NGDC-ids</i></p>
<p style="margin-left:22%;">Can be one or more of five
kinds of specifiers: <br>
1) 8-character NGDC IDs, e.g., 01010083, JA010010etc., etc.
<br>
2) 2-character <agency> codes which will return all
cruises from each agency. <br>
3) 4-character <agency><vessel> codes, which
will return all cruises from those vessels. <br>
4) =<list>, where <list> is a table with NGDC
IDs, one per line. <br>
5) If nothing is specified we return all cruises in the data
base. <br>
(See mgd77info <b>−L</b> for agency and vessel codes).
The ".mgd77" or ".nc" extensions will
automatically be appended, if needed (use <b>−I</b> to
ignore certain file types). Cruise files will be looked for
first in the current directory and second in all directories
listed in <b>$MGD77_HOME</b>/mgd77_paths.txt [If
<b>$MGD77_HOME</b> is not set it will default to
<b>$GMT_SHAREDIR</b>/mgd77].</p>
<table width="100%" border=0 rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−F</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Specifies the
format of the input (From) files. Choose from <b>a</b> for
standard MGD77 ASCII table (with extension .mgd77), <b>c</b>
for the new MGD77+ netCDF format (with extension .nc), and
<b>t</b> for a plain ASCII tab-separated table dump (with
extension .dat). Use <b>−FC</b> to recover the
original MGD77 setting from the MGD77+ file [Default will
apply any E77 corrections encoded in the file].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−T</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Specifies the
format of the output (To) files. Choose from <b>a</b> for
standard MGD77 ASCII table (with extension .mgd77), <b>c</b>
for the new MGD77+ netCDF format (with extension .nc), and
<b>t</b> for a plain ASCII tab-separated table dump (with
extension .dat). We will refuse to create the file(s) if
they already exist in the current directory. Prepend
<b>+</b> to override this policy.</p></td>
</table>
<a name="OPTIONS"></a>
<h2>OPTIONS</h2>
<p style="margin-left:11%; margin-top: 1em">No space
between the option flag and the associated arguments.</p>
<table width="100%" border=0 rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−L</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Set the level of
verification reporting [none] and where to send such reports
[stderr]. Append a combination of <b>w</b> for warnings,
<b>e</b> for errors, and <b>+</b> to send such log
information to stdout.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−V</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Selects verbose
mode, which will send progress reports to stderr [Default
runs "silently"].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−4</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">By default, the
storage types used in a MGD77+ netCDF file greatly exceed
the precision imposed by the ASCII MGD77 format. However,
for the five items <b>faa</b>, <b>eot</b>, <b>mag</b>,
<b>diur</b> and <b>msd</b> we use 2-byte integers with
implied precisions of 0.1 mGal, 0.1 nTesla, and 1 m as in
the MGD77 format. It is possible that at some point these
items will need to be stored as 4-byte ints which would
allow precisions of 1 fTesla, 1 nGal, and 0.01 mm,
respectively. This option activates such storage [Default
uses 2-byte integers].</p></td>
</table>
<a name="EXAMPLES"></a>
<h2>EXAMPLES</h2>
<p style="margin-left:11%; margin-top: 1em">To convert
01010047.mgd77 and 01010008.mgd77 to new netCDF .nc files,
and capture all verification messages, try</p>
<p style="margin-left:11%; margin-top: 1em"><b>mgd77convert</b>
01010047 01010008 <b>−Fa −Tc −V
−Lew+</b> > log.lis</p>
<p style="margin-left:11%; margin-top: 1em">To convert
01010047.nc back to MGD77 ASCII and make sure it is
identical to the original file, try (Bourne shell
syntax)</p>
<p style="margin-left:11%; margin-top: 1em">orig=‘<b><A HREF="mgd77path.html">mgd77path</A></b>
01010047 <b>−Ic</b>‘ <b><br>
mgd77convert</b> 01010047 <b>−Fc −Ta
−V</b> <br>
diff $orig 01010047.mgd77</p>
<p style="margin-left:11%; margin-top: 1em">To convert
01010047.nc to a plain ASCII table for manual editing,
overwriting any existing table, try</p>
<p style="margin-left:11%; margin-top: 1em"><b>mgd77convert</b>
01010047 <b>−Fc −T+t −V</b></p>
<p style="margin-left:11%; margin-top: 1em">To recover the
original NGDC MGD77 version of 01020051.nc and ignore any
E77 corrections, use <b><br>
mgd77convert</b> 01020051 <b>−FC −Ta
−V</b></p>
<a name="FILE FORMATS"></a>
<h2>FILE FORMATS</h2>
<p style="margin-left:11%; margin-top: 1em"><b>mgd77convert</b>
handles three different formats. (1) The MGD77 ASCII tables
are the established standard for distribution of underway
geophysical data to and from the NGDC data center. Normally,
only the ship-operations people and the cruise PI might be
involved in <i>making</i> an MGD77 ASCII file for
transmission to NGDC; users are more interested in
<i>reading</i> such files. (2) The MGD77+ netCDF format was
developed to fascilitate the use of MGD77 data by
scientists. It contains all the information of the original
MGD77 file and if you convert back and forth you end up with
the original. However, file sizes are typically ~30% of the
original ASCII format and is much faster to operate on. (3)
The plain ASCII tab-separated dump is available for users
who need to manually edit the content of a MGD77 file. This
is usually easier to do when the columns are tab-separated
than when they are all crunched together in the MGD77
punch-card format.</p>
<a name="OTHER TOOLS"></a>
<h2>OTHER TOOLS</h2>
<p style="margin-left:11%; margin-top: 1em">The MGD77+
netCDF files are CF-1.0 and COARDS compliant and can be
examined with general-purpose tools such as ncBrowse and
ncView.</p>
<a name="SEE ALSO"></a>
<h2>SEE ALSO</h2>
<p style="margin-left:11%; margin-top: 1em"><i><A HREF="mgd77manage.html">mgd77manage</A></i>(1),
<i><A HREF="mgd77list.html">mgd77list</A></i>(1), <i>mgd77sample</i>(1),
<i><A HREF="mgd77track.html">mgd77track</A></i>(1) <i><A HREF="x2sys_init.html">x2sys_init</A></i>(1)</p>
<a name="REFERENCES"></a>
<h2>REFERENCES</h2>
<p style="margin-left:11%; margin-top: 1em">Wessel, P., and
W. H. F. Smith, 2009, The Generic Mapping Tools (GMT)
version 4.5.0 Technical Reference & Cookbook,
SOEST/NOAA. <br>
Wessel, P., and W. H. F. Smith, 1998, New, Improved Version
of Generic Mapping Tools Released, EOS Trans., AGU, 79 (47),
p. 579. <br>
Wessel, P., and W. H. F. Smith, 1995, New Version of the
Generic Mapping Tools Released, EOS Trans., AGU, 76 (33), p.
329. <br>
Wessel, P., and W. H. F. Smith, 1995, New Version of the
Generic Mapping Tools Released,
http://www.agu.org/eos_elec/95154e.html, Copyright 1995 by
the American Geophysical Union. <br>
Wessel, P., and W. H. F. Smith, 1991, Free Software Helps
Map and Display Data, EOS Trans., AGU, 72 (41), p. 441. <br>
ncBrowse, see <i>http://www.epic.noaa.gov/java/ncBrowse/</i>
<br>
ncView, see
<i>http://meteora.ucsd.edu/~pierce/ncview_home_page.html</i>
<br>
The Marine Geophysical Data Exchange Format -
"MGD77", see
<i>http://www.ngdc.noaa.gov/mgg/dat/geodas/docs/mgd77.txt</i></p>
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