Documentation provided herein is intended to assist with utilizing the along-track and cross-over analysis tools released via the Generic Mapping Tools under the GNU General Public License. Example scripts are illustrative and should not be construed as presciptive. Adjustment of the commands will be necessary in order to achieve the desired result.
Section I. Along-track Analysis Documentation
E77 errata format specification
Creating/Using E77 errata tables
MGD77 supplement man pages
X2SYS supplement man pages
GMT man pages
Section II. Example Code:
These were derived for the Seagoing Scientist's Toolbox  and Producing marine geophysical archive file  publications but can potentially assist in other applications.
Section IIa. Archive file assembly (Data records / Header / Magnetic Reduction / Gravity Reduction)
ship2mgd77: Produce MGD77T/MGD77+ archive files from raw underway geophysical data (source code)
KM1609 Day 342: Sample raw underway geophysical data for testing archive file production (download 7.5
Section IIb. At sea quality control
2.1 Along-track analysis
See Section I and Section 2.4 SCRIPT A.
2.2 Cross-over analysis
LINK: Tools for analyzing intersecting tracks: The x2sys package
LINK: X2SYS supplement man pages
2.3 Sonar processing
LINK: SURVEY Tools
2.4 Data visualization
SCRIPT A: Building a candidate archive file, automating along-track analysis, and preparing KML wiggles for display in Google Earth
SCRIPT B: Creating gravity and magnetic anomaly wiggles for display in Google Earth
SCRIPT C: Creating a KML navigation log
SURVEY COMMAND (To create ship position KML): survey shipposition
SURVEY COMMAND (To update waypoint KML): survey waypoints -k
SURVEY COMMAND (To create ship speed PDF): survey shipspeed
SURVEY COMMAND (To create magnetic anomaly PDF): survey magnetics
SURVEY COMMAND (To create gravity anomaly PDF): survey gravity
SURVEY COMMAND (To preprocess sonar data and create sonar KML): survey swath2kml -a A
2.5 Automation at sea>
SCRIPT A: Create an auto-refreshing KML container
SCRIPT B: Loop for iteratively building archive file as new data come in
CRONTAB: Update KML layers and PDF plots at fixed time intervals, from KM1609 survey
- Hamilton, M, Wessel, P, Luis, J, Taylor, B, and Ko, YT (2019): The seagoing scientist’s toolbox: Integrated methods for quality control of marine geophysical data at sea, Geochem. Geophys. Geosys, 20, 1–10. https://doi.org/10.1029/2018GC007891.
- Hamilton, M, Wessel, P, Taylor, B, and Luis, J (2019): Producing marine geophysical archive files from raw underway data,Comp & Geosci,133, http://doi.org/10.1016/j.cageo.2019.104321.
- Chandler, M. T., and P. Wessel (2012), Errata-based correction of marine geophysical trackline data, Geochem. Geophys. Geosyst., 13, Q10004, doi:10.1029/2012GC004294.
- Chandler, M. T. (2011), Tectonic history of the Greater Ontong Java Plateau and Errata-based correction of marine geophysical trackline data. Ch. 4, PhD Dissertation, University of Hawaii. (51.5
- Chandler, M. T., and P. Wessel (2008), Improving the quality of marine geophysical track line data: Along-track analysis, J. Geophys. Res., 113, B02102, doi:10.1029/2007JB005051.
- Chandler, M. T., and P. Wessel, (2007), Fall 2007 AGU Poster (7.5
- Wessel, P., and M. T. Chandler, (2007), The mgd77 Supplement to the Generic Mapping Tools. Computers & Geosciences, 33, 62-75.
- Chandler, M. T. (2006), Improving the Quality Control of Marine Geophysical Trackline Data. MS Thesis, University of Hawaii. (8.0
- Chandler, M. T., and P. Wessel, (2004), Fall 2004 AGU Poster (7.0
Maintained by Michael Hamilton ○ Last modified: November 05 2019.