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# mgd77track

mgd77track - Plot track-line map of MGD77 cruises

## Synopsis

mgd77track NGDC-ids -R[unit]xmin/xmax/ymin/ymax[r] -Jparameters [ -A[c][size][,spacing] ] [ -B[p|s]parameters ] [ -Cf|g|e ] [ -Dastartdate ] [ -Dbstopdate ] [ -F ] [ -Gd|tgap ] [ -Iignore ] [ -K ] [ -Ltrackticks ] [ -O ] [ -P ] [ -Sastartdist[u] ] [ -Sbstopdist[u] ] [ -TT|t|dms,mc,mfs,mf,mfc ] [ -U[just/dx/dy/][c|label] ] [ -V[level] ] [ -W[-|+][pen] ] [ -X[a|c|f|r][x-shift[u]] ] [ -Y[a|c|f|r][y-shift[u]] ] [ -ccopies ] [ -p[x|y|z]azim/elev[/zlevel][+wlon0/lat0[/z0]][+vx0/y0] ] [ -t[transp] ]

Note: No space is allowed between the option flag and the associated arguments.

## Description

mgd77track reads NGDC MGD77 cruises and creates PostScript code that will plot one or more ship tracks on a map using the specified projection. The PostScript code is written to standard output.

## Required Arguments

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].

-Jparameters (more ...)
  Select map projection.

-Rwest/east/south/north[/zmin/zmax][r]
  west, east, south, and north specify the region of interest, and you may specify them in decimal degrees or in [+-]dd:mm[:ss.xxx][W|E|S|N] format. Append r if lower left and upper right map coordinates are given instead of w/e/s/n. The two shorthands -Rg and -Rd stand for global domain (0/360 and -180/+180 in longitude respectively, with -90/+90 in latitude). Alternatively, specify the name of an existing grid file and the -R settings (and grid spacing, if applicable) are copied from the grid. Using -Runit expects projected (Cartesian) coordinates compatible with chosen -J and we inversely project to determine actual rectangular geographic region. For perspective view (-p), optionally append /zmin/zmax. In case of perspective view (-p), a z-range (zmin, zmax) can be appended to indicate the third dimension. This needs to be done only when using the -Jz option, not when using only the -p option. In the latter case a perspective view of the plane is plotted, with no third dimension.

## Optional Arguments

-A[c][size][,spacing]
  Append c to annotate using the MGD77 cruise ID [Default uses the filename prefix]. Optional size is the font size in points. The leg annotation font is controlled by FONT_LABEL. By default, each leg is annotated every time it enters the map region. Alternatively, append ,spacing to place this label every spacing units apart along the track. Append one of the units k (km), n (nautical mile), d (day), or h (hour).

-B[p|s]parameters (more ...)
  Set map boundary intervals.
-Cf|g|e
  Select procedure for along-track distance calculation:
    f Flat Earth distances. g Great circle distances [Default]. e Geodesic distances on current GMT ellipsoid.
-Dastartdate
  Do not plot data collected before startdate (yyyy-mm-ddBD(T)[hh:mm:ss]) [Default is first day].
-Dbstopdate
  Do not plot data collected after stopdate (yyyy-mm-ddBD(T)[hh:mm:ss]). [Default is last day].
-F
  Do not apply the error bit flags if present in a MGD77+ file [Default will apply these flags upon reading the data].
-Gd|tgap
  Let successive point separations exceeding dgap (km) or tgap (minutes) indicate a break in the track where we should not draw a line [no gaps recognized]. Repeat to use both types of gap checking.
-Iignore
  Ignore certain data file formats from consideration. Append a|c|t to ignore MGD77 ASCII, MGD77+ netCDF, or plain table files, respectively. The option may be repeated to ignore more than one format. [Default ignores none].

-K (more ...)
  Do not finalize the PostScript plot.
-Ltrackticks
  To put time/distance log-marks on the track. E.g. a500ka24ht6h means (a)nnotate every 500 km (k) and 24 h(ours), with (t)ickmarks every 500 km and 6 hours. Alternatively you may use the modifiers d (days) and n (nautical miles).

-O (more ...)
  Append to existing PostScript plot.

-P (more ...)
  Select “Portrait” plot orientation.
-Sastartdist[u]
  Do not plot data that are less than startdist meter along track from port of departure. Append k for km, m for miles, or n for nautical miles [Default is 0 meters].
-Sbstopdist[u]
  Do not plot data that are more than stopdist meter along track from port of departure. Append k for km, m for miles, or n for nautical miles [Default is end of track].
-TT|t|dms,mc,mfs,mf,mfc
  Controls the attributes of the three kinds of markers (T for the first time marker in a new day, t for additional time markers in the same day, and d for distance markers). For each of these you can specify the 5 comma-separated attributes markersize, markercolor, markerfontsize, markerfont, and markerfontcolor. Repeat the -T option for each marker type.

-U[just/dx/dy/][c|label] (more ...)
  Draw GMT time stamp logo on plot.
-W[-|+][pen]
  Append pen used for the trackline. [Defaults: width = default, color = black, style = solid]. A leading + will use the lookup color (via -C) for both symbol fill and outline pen color, while a leading - will set outline pen color and turn off symbol fill.

-X[a|c|f|r][x-shift[u]]

-Y[a|c|f|r][y-shift[u]] (more ...)
  Shift plot origin.

-V[level] (more ...)
  Select verbosity level [c].

-ccopies (more ...)
  Specify number of plot copies [Default is 1].

-p[x|y|z]azim/elev[/zlevel][+wlon0/lat0[/z0]][+vx0/y0] (more ...)
  Select perspective view.

-t[transp] (more ...)
  Set PDF transparency level in percent.

-^
  Print a short message about the syntax of the command, then exits (NOTE: on Windows use just -).
+
  Print an extensive usage (help) message, including the explanation of any module-specific option (but not the GMT common options), then exits.
-?
  Print a complete usage (help) message, including the explanation of options, then exits.
--version
  Print GMT version and exit.
--show-datadir
  Print full path to GMT share directory and exit.

## Examples

To generate a Mercator plot of the track of the cruise 01010007 in the area 70W to 20E, 40S to 20N, using a Mercator scale of 0.1inch/degree, label the tracks with 10 points characters, annotate the boundaries every 10 degrees, draw gridlines every 5 degrees, and mark the track every day and 1000 km, with ticks every 6 hours and 250 km, and send the plot to the default printer, enter the following command:

>     gmt mgd77track 01010007 -R70W/20E/40S/20N -Jm0.1 -B10g5 -A10 \
>                    -La1da1000kf6hf250k \| lpr

## See Also

mgd77info, psbasemap, mgd77list

## References

The Marine Geophysical Data Exchange Format - MGD77, see http://www.ngdc.noaa.gov/mgg/dat/geodas/docs/mgd77.txt

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