Browsing by Author "Wessel, Paul"
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- Producing marine geophysical archive files from raw underway dataPublication . Hamilton, Michael; Wessel, Paul; Taylor, Brian; Luis, JoaquimPreserving costly marine geophysical trackline data is of paramount importance but variability in priorities, funding, personnel, and technology impact our data archival capacity. We have addressed one crucial facet of this dilemma by devising an open source approach to merge and reduce underway geophysical data and to generate marine geophysical archive files using common command line programs along with the Generic Mapping Tools and its mgd77 supplement. Archive files generated using this approach retain full precision and may be converted automatically to MGD77T, MGD77+, as well as MGD77 formats. We successfully applied the approach to 340 geophysical data sets acquired by R/V Kilo Moana from 2002 to 2018 and in the near term we plan to submit the non-proprietary archive files to the National Centers for Environmental Information's trackline geophysics archive. We encourage international oceanographic communities to explore our methodology as a larger user-base will strengthen the software and the procedures.
- The GMT/MATLAB ToolboxPublication . Wessel, Paul; Luis, JoaquimThe GMT/MATLAB toolbox is a basic interface between MATLAB (R) (or Octave) and GMT, the Generic Mapping Tools, which allows MATLAB users full access to all GMT modules. Data may be passed between the two programs using intermediate MATLAB structures that organize the metadata needed; these are produced when GMT modules are run. In addition, standard MATLAB matrix data can be used directly as input to GMT modules. The toolbox improves interoperability between two widely used tools in the geosciences and extends the capability of both tools: GMT gains access to the powerful computational capabilities of MATLAB while the latter gains the ability to access specialized gridding algorithms and can produce publication-quality PostScript-based illustrations. The toolbox is available on all platforms and may be downloaded from the GMT website.
- The seagoing scientist's toolbox: integrated methods for quality control of marine geophysical data at seaPublication . Hamilton, Michael; Wessel, Paul; Luis, Joaquim; Taylor, Brian; Ko, YoungtakWe announce a new and integrated system for planning and executing marine geophysical surveys and for scrutinizing and visualizing incoming shipboard data. The system incorporates free software designed for use by scientists and shipboard operators and pertains to underway geophysics and multibeam sonar surveys. Regarding underway data, a crucial first step in the approach is to reduce and merge incoming center beam depth, gravity, and towed magnetic data with navigation, then reformat to the standard exchange format. We are then able to apply established quality control methods including along-track and cross-track analyses to identify error sources and to incrementally build the candidate archive file as new data are acquired. Regarding multibeam data, these are subjected to both an automated error removal scheme for quick visualization and to subsequent ping editing in detail. The candidate archive file and sonar data are automatically and periodically updated and adapted for display in Google Earth, wherein survey planning is also carried out. Data layers are also updated automatically in Google Earth, allowing scientists to focus on visual inspection and interpretation of incoming data. By visualizing underway and sonar data together with reference gravity, magnetic, and bathymetry grids in Google Earth, data familiarity is enhanced and the likelihood of noticing extreme errors increased. We hope scientists will embrace these techniques so that each data set being submitted to a data repository is vetted by the seagoing science party.