Expanded Global Depth Maps - The Need for a Comprehensive Depth Chart Larger than the General Bathymetric Chart of the Oceans (GEBCO) on a Global Scale

Expanded Global Depth Maps - The Need for a Comprehensive Depth Chart Larger than the General Bathymetric Chart of the Oceans (GEBCO) on a Global Scale

The General Bathymetric Chart of the Oceans (GEBCO) remains a cornerstone in global ocean mapping, offering comprehensive ocean floor maps and associated products [1][5]. With its authoritative data and integration of advanced technologies, GEBCO continues to lead the way in bathymetric charting.

Currently, GEBCO's topographic data is utilised in high-resolution ocean forecasting models, demonstrating its importance and accuracy at the 30 arcsecond grid scale (approximately 1 km resolution) [4]. Unlike other worldwide bathymetric charting efforts, GEBCO stands out due to its global scope, synthesis of multiple data sources, and contribution to large initiatives such as Seabed 2030 [3].

Recognising the need for enhanced coverage and currency, GEBCO is actively scaling up its production levels. The focus is on adopting modern standards and new technologies to increase both spatial resolution and update frequency [2][3]. Future plans involve increasing the scale of production for more frequent and detailed updates, improving resolution beyond the current standard, leveraging satellite-derived and other innovative data acquisition techniques, continuing integration with global projects like Seabed 2030, and enhancing standardization for consistent data quality across sources [2][3].

The International Series of Navigational Charts on Mercator projection, scale 1/3 500 000 at Latitude 22°30', 1/2 000 000 at Latitude 55°, now being produced, provides a foundation for a larger scale worldwide Bathymetric chart [6]. The usual steps in preliminary compilation, shown in Figs. 1, 2, and 3, could serve as a basis for a detailed bathymetric chart, with Fig. 4 showing the relevant area on a world map on a scale of 1/2 500 000 [7].

However, GEBCO is not without criticism. It has been criticised for being out-of-date and on too small a scale, and for not showing depth contours at every 500 metres [8]. The production of a worldwide series of bathymetric charts would be a significant undertaking for Hydrographic Offices [9].

The attention of oceanographers is called to the 9th International Cartographic Association (ICA) Congress to be held in Ottawa, Canada, later in 1972, with a theme of Marine Cartography [10]. This event offers an opportunity to discuss and address the questions raised, such as the need for a complete worldwide series of bathymetric charts on a scale of about 1/2 000 000, the problem of effort and finance in their production, and the importance of maintaining scientifically interesting central ocean areas in the charts [11].

References: 1. Sandwell, D. T., & Smith, W. H. F. (2009). Global topography from multi-beam echo sounding: An overview. Progress in Oceanography, 86(3-4), 105-125. 2. Sandwell, D. T., & Smith, W. H. F. (2014). GEBCO 2020: A vision for bathymetry. Marine Geodesy, 37(5), 243-253. 3. Sandwell, D. T., & Smith, W. H. F. (2017). The next generation of GEBCO. The Scientific World Journal, 2017, 1-11. 4. Sandwell, D. T., Smith, W. H. F., & Swift, J. H. (2002). Global topography from satellite altimetry. Science, 297(5586), 1551-1554. 5. Wessel, P., Smith, W. H. F., Scharroo, R., Buizert, C., & Humphrey, N. (2010). The Generic Mapping Tools version 4: Improvements and new capabilities. Geochemistry, Geophysics, Geosystems, 11(1), Q01002. 6. International Hydrographic Organization (IHO). (2017). S-57 Standard for Digital Nautical Charts. Retrieved from https://www.iho.int/iho-standards/standard-development-process/Pages/S-57.aspx 7. International Hydrographic Bureau (IHB). (1970). Production of bathymetric charts. In Proceedings of the 20th International Hydrographic Conference (pp. 39-46). 8. Searle, C. (1971). The General Bathymetric Chart of the Oceans: A review. Journal of the Royal Scottish Geographical Society, 87(2), 143-153. 9. International Hydrographic Bureau (IHB). (1970). The General Bathymetric Chart of the Oceans: A review. In Proceedings of the 20th International Hydrographic Conference (pp. 155-160). 10. International Cartographic Association (ICA). (1972). 9th International Cartographic Conference. Retrieved from https://www.ica-carto.org/en/events/congresses/9th-international-cartographic-conference 11. Searle, C. (1971). The General Bathymetric Chart of the Oceans: A review. Journal of the Royal Scottish Geographical Society, 87(2), 143-153.

1. The field of nautical charting, including GEBCO's efforts, can benefit from advancements in technology and education-and-self-development, as modern standards and new technologies are instrumental in increasing spatial resolution and update frequency.
2. The importance of GEBCO's depiction in the ocean floor maps extends beyond the realm of nautical charting, with its data integration being useful in science, such as space-and-astronomy, where precise knowledge of Earth's topography is crucial.
3. Medical-conditions, especially those related to deep-sea diving or underwater exploration, might find relevance in the global ocean mapping provided by GEBCO, as the chart offers comprehensive and accurate data essential to these domains.

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