Producing marine geophysical archive files from raw underway data

Hamilton, Michael; Wessel, Paul; Taylor, Brian; Luís, Joaquim

doi:10.1016/j.cageo.2019.104321

Cited by 2 publications

(4 citation statements)

References 12 publications

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“…It is helpful, for example, to compare shipboard gravity to the latest satellite‐derived gravity grid (e.g., Sandwell et al, ) visually in Google Earth (www.google.com/earth/). The proposed methodology is divided into archive file assembly including reduction of potential field data (Hamilton et al, ), along‐track analysis (section ), crossover analysis (section ), sonar processing (section ), data visualization (section ), and automation at sea (section ). Brief examples of commands are interspersed in the text; however, the tools are undergoing development; hence, syntax will change as the tools evolve.…”

Section: Methodsmentioning

confidence: 99%

“…At sea, it is an iterative process by which the raw data are reformatted into the standard exchange format and a metadata header is compiled (Hamilton et al, ), and errors are detected along track using the GMT mgd77sniffer program, which outputs an errata table. When reviewing errata tables compiled from existing data sets, one typically reads the errata table with the aid of an errata review plot (e.g., Figure and ; Chandler & Wessel, ) and chooses which error flags to apply.…”

Section: Methodsmentioning

confidence: 99%

“…Quesnel et al () examined 2,411 magnetic surveys and by recomputing anomalies using comprehensive magnetic modeling and correcting for diurnal variation (which was not applied in most archived data sets), and by reducing intercruise discrepancies using COE analysis, substantially reduced magnetic field intensity COE from 179.6 to 35.9 nT. At the time of this writing, however, NCEI archives 5,245 depth, 2,965 magnetic, and 2,092 gravity tracks (Hamilton et al, ). COE corrections apply within the closed set of included tracks; hence, the corrections mentioned above are now outdated.…”

Section: Introductionmentioning

confidence: 99%

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The Seagoing Scientist's Toolbox: Integrated Methods for Quality Control of Marine Geophysical Data at Sea

Hamilton

Wessel

Luís

et al. 2019

Geochem Geophys Geosyst

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We 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.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Seagoing Scientist's Toolbox: Integrated Methods for Quality Control of Marine Geophysical Data at Sea

Hamilton

Wessel

Luís

et al. 2019

Geochem Geophys Geosyst

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“…The geophysical data include gravity grids (Smith and Sandwell 1995, Sandwell and Smith 2005, 2009Sandwell et al 2014), related datasets, such as EGM-96, EGM-2008, and archiving geophysical datasets (Hamilton et al 2019). The sediment thickness is computed in global grid (Divins 2003), glacial sediment thickness grids cover selected regions of the World ocean (Lindeque et al 2016, Wobbe et al 2014) such approaches are used in existing practical applications (Rosenheim et al 2008).…”

Section: Datamentioning

confidence: 99%

Dataset compilation by GRASS GIS for thematic mapping of Antarctica: Topographic surface, ice thickness, subglacial bed elevation and sediment thickness

Lemenkova¹

2021

Czech Polar Rep.

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This paper presents the GRASS GIS-based thematic mapping of Antarctica using scripting approach and associated datasets on topography and geophysics. The state-of-the art in cartographic development points at two important aspects. The first one comprises shell scripting promoted repeatability of the GIS technique, increased automatization in cartographic workflow, and compatibility of GRASS with Python, PROJ and GDAL libraries which enables advanced geospatial data processing: converting formats, re-projecting and spatial analysis. The second aspect is that data visualization greatly influences geologic research through improving the interpretation between the Antarctic glaciation and surface. This includes the machine learning algorithms of image classification enabling to distinguish between glacier and non-glacier surfaces through automatically partitioning data and analysis of various types of surfaces. Presented detailed maps of Antarctic include visualized datasets from the ETOPO1, GlobSed, EGM96 and Bedmap2 projects. The grids include bed and surface elevation, ETOPO1-based bathymetry and topography, bed, ice and sediment thickness, grounded bed uncertainty, subglacial bed elevation, geoid undulations, ice mask grounded and shelves. Data show the distribution of the present-day glacier, geophysical fields and topographic landforms for analysis of processes and correlations between the geophysical and geological phenomena. Advances in scripting cartography are significant contributions to the geological and glaciological research. Processing high-resolution datasets of Southern Ocean retrieved by remote sensing methods present new steps in automatization of the digital mapping, as presented in this research, and promotes comprehensive monitoring of geological, permafrost and glacial processes in Antarctica. All maps have been plotted using GRASS GIS version 7.8. with technical details of scripts described and interpreted.

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Producing marine geophysical archive files from raw underway data

Cited by 2 publications

References 12 publications

The Seagoing Scientist's Toolbox: Integrated Methods for Quality Control of Marine Geophysical Data at Sea

The Seagoing Scientist's Toolbox: Integrated Methods for Quality Control of Marine Geophysical Data at Sea

Dataset compilation by GRASS GIS for thematic mapping of Antarctica: Topographic surface, ice thickness, subglacial bed elevation and sediment thickness

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