Provided by: gmt_4.5.11-1build1_amd64 bug

NAME

       mgd77convert - Translate between different formats of MGD77 files

SYNOPSIS

       mgd77convert NGDC-ids -Fa|c|m|t -T[+]a|b|m|t [ -L[w][e][+] ] [ -V ] [ -4 ]

DESCRIPTION

       mgd77convert  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.

       NGDC-ids
              Can be one or more of five kinds of specifiers:
              1) 8-character NGDC IDs, e.g., 01010083, JA010010etc., etc.
              2) 2-character <agency> codes which will return all cruises from each agency.
              3)  4-character  <agency><vessel>  codes,  which will return all cruises from those
              vessels.
              4) =<list>, where <list> is a table with NGDC IDs, one per line.
              5) If nothing is specified we return all cruises in the data base.
              (See mgd77info -L for agency and vessel codes).  The ".mgd77" or  ".nc"  extensions
              will  automatically  be  appended, if needed (use -I to ignore certain file types).
              Cruise files will be looked for first in the current directory and  second  in  all
              directories  listed  in  $MGD77_HOME/mgd77_paths.txt  [If $MGD77_HOME is not set it
              will default to $GMT_SHAREDIR/mgd77].

       -F     Specifies the format of the input (From) files.  Choose from a for  standard  MGD77
              ASCII  table  (with  extension  .mgd77),  c  for the new MGD77+ netCDF format (with
              extension .nc), revised MGD77T (tab-delimited; with extension .m77t) and  t  for  a
              plain ASCII tab-separated table dump (with extension .dat).  Use -FC to recover the
              original MGD77 setting from the MGD77+ file [Default will apply any E77 corrections
              encoded in the file].

       -T     Specifies  the  format  of the output (To) files.  Choose from a for standard MGD77
              ASCII table (with extension .mgd77), c for  the  new  MGD77+  netCDF  format  (with
              extension  .nc),  revised  MGD77T (tab-delimited; with extension .m77t) and t 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 + to
              override this policy.

OPTIONS

       No space between the option flag and the associated arguments.

       -L     Set the level of verification reporting [none]  and  where  to  send  such  reports
              [stderr].  Append a combination of w for warnings, e for errors, and + to send such
              log information to stdout.

       -V     Selects verbose mode, which will send progress  reports  to  stderr  [Default  runs
              "silently"].

       -4     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 faa, eot,
              mag,  diur  and msd 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].

EXAMPLES

       To  convert  01010047.mgd77  and  01010008.mgd77  to new netCDF .nc files, and capture all
       verification messages, try

       mgd77convert 01010047 01010008 -Fa -Tc -V -Lew+ > log.lis

       To convert 01010047.nc back to MGD77 ASCII and make sure it is identical to  the  original
       file, try (Bourne shell syntax)

       orig=`mgd77path 01010047 -Ic`
       mgd77convert 01010047 -Fc -Ta -V
       diff $orig 01010047.mgd77

       To convert 01010047.nc to a plain ASCII table for manual editing, overwriting any existing
       table, try

       mgd77convert 01010047 -Fc -T+t -V

       To recover the original NGDC MGD77 version of 01020051.nc and ignore any E77  corrections,
       use
       mgd77convert 01020051 -FC -Ta -V

FILE FORMATS

       mgd77convert  handles  four  different  formats.  (1)  The  MGD77  ASCII  tables  are  the
       conventional 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 making an MGD77 ASCII file for transmission to NGDC; users are more interested
       in  reading  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) NGDC has
       now  started  to  use  a  new  tab-delimited version of the MGD77 data, called MGD77T.  In
       addition to all the info in old MGD77 files it contains a few more quality flags for grav,
       mag,  and  bathymetry.   (4) 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.  It differs from format MGD77T in that missing items are written as NaNs.

OTHER TOOLS

       The MGD77+ netCDF files are CF-1.0 and COARDS compliant and can be examined with  general-
       purpose tools such as ncBrowse and ncView.

SEE ALSO

       mgd77manage(1), mgd77list(1), mgd77sample(1), mgd77track(1) x2sys_init(1)

REFERENCES

       Wessel,  P.,  and  W.  H.  F.  Smith, 2013, The Generic Mapping Tools (GMT) version 4.5.11
       Technical Reference & Cookbook, SOEST/NOAA.
       Wessel, P., and W. H. F. Smith, 1998, New,  Improved  Version  of  Generic  Mapping  Tools
       Released, EOS Trans., AGU, 79 (47), p. 579.
       Wessel,  P.,  and W. H. F. Smith, 1995, New Version of the Generic Mapping Tools Released,
       EOS Trans., AGU, 76 (33), p. 329.
       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.
       Wessel,  P.,  and  W.  H.  F.  Smith,  1991, Free Software Helps Map and Display Data, EOS
       Trans., AGU, 72 (41), p. 441.
       ncBrowse, see http://www.epic.noaa.gov/java/ncBrowse/
       ncView, see http://meteora.ucsd.edu/~pierce/ncview_home_page.html
       The     Marine     Geophysical     Data     Exchange     Format     -     "MGD77",     see
       http://www.ngdc.noaa.gov/mgg/dat/geodas/docs/mgd77.txt