This shape file shows the coverage of raw multibeam bathymetry data published during the EU Horizon 2020 iAtlantic project for Milestone 13. The underlying raw data are unprocessed and may contain outliers. The coverage may change slightly once the data are being processed. The raw MBES data were published within work package 2 of the EU Horizon 2020 project iAtlantic - Integrated Assessment of Atlantic Marine Ecosystem in Space and Time (https://www.iatlantic.eu/). This publication is the outline of a compilation of all the above mentioned datasets and aimed to give an overview of where multibeam data exist and about the area covered. Note that this publication does not contain any depth information, it only informs about the covered area. All of the underlying raw datasets are linked below with further information on how and where they were acquired. The following cruises are included:
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RV Meteor:
M156 EM710 (2019)
M156 EM122 (2019)
M156 Total Area: 25267.149949 km²
M61-1 HS (2004) Area: 9134.686848 km²
M61-2 HS (2004) Area: 9714.855025 km²
M62-3 HS (2004) Area: 25028.338653 km²
M62-4 HS (2004) Area: 70137.035777 km²
M68-3 EM122 (2006)
M68-3 EM710 (2006)
M68-3 Total Area: 9080.020747 km²
M78-3A EM122 (2009) Area: 19410.644047 km²
M78-3A EM710 (2009) Area: 274.146303 km²
M82-0 Total Area: 1343.151663 km²
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RV Maria S. Merian:
MSM17-1 EM122 (2010) Area: 173871.40310 km²;
MSM19-3 EM122 (2011) Area: 55813.358391 km²
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RV Sonne datasets (Brix et al. 2020, 2021, 2022):
SO280 EM122 Transit (2020) Area: 32996.51 km²
SO276 Transit (2020) Area: 24553.707472 km²
SO286 EM122 (2021) Area: 49013.305085 m²
Low-lying coral reef islands harbour a distinct, yet highly threatened biological and cultural diversity that is increasingly exposed to climate change impacts. The combination of low elevation, small size, sensitivity to changes in boundary conditions (sea level, waves and currents, locally generated sediment supply) and at some locations high population densities, is why low-lying reef islands (LRIs) are considered among the most vulnerable environments on Earth to climate change. To date, their global distribution and influence of climatic, oceanographic, and geologic setting are only poorly documented or restricted to smaller scales. Here, I present the first detailed global analysis of LRIs utilising freely available global datasets to produce a global reef island database (GRID) and associated intrinsic and extrinsic characteristics that can be used within a coastal vulnerability index (CVI). All datasets used to create the GRID were released between 30 November 2015 and 3 August 2023, while the current version of the GRID database was completed in November 2024. When developing the GRID, LRIs are defined as landmasses <30 km² located on or within 1 km of coral reef and with an elevation of <16 m. Development of the GRID required: 1) the creation of a global shoreline vector file containing the geographic distribution of LRIs and 2) the development of a comprehensive global database of LRIs including eight intrinsic and ten extrinsic variables extracted from global datasets. Intrinsic variables include: 1) human populations, 2) island area, 3) island perimeter, 4) mean elevation, 5) island circularity/shape, 6) underlying reef type, 7) geographic isolation and 8) distance to the nearest neighbouring reef island. Extrinsic variables include: 1) mean water depth, 2) standard deviation of mean water depth, 3) mean annual significant wave height, 4) mean annual wave period, 5) mean spring tidal range, 6) relative tidal range, 7) wave-tide regime, 8) relative wave exposure, 9) relative tropical storm exposure and 10) year-2100 projected median sea level rise rate. The GRID was initially derived from version 2.1 of the UNEP-WCMC Global Island Database, a global shoreline vector file based on geometry data from Open Street Map® (OSM) and released in November 2015. The initial vector file was projected using the Mollweide projection, an equal-area pseudo cylindrical map projection chosen for its accurate derivation of area, especially in regions close to the equator, where most LRIs are located. The final GRID contains 34,404 individual LRIs distributed throughout tropical regions of the world's oceans, amassing a total land area of nearly 11,000 km² with approximately 60,740 km of shoreline and housing around 2.6 million people. While intrinsic variables are typically spatially homogenous, LRIs are generally highly spatially clustered throughout the GRID with respect to extrinsic variables. The spatial distribution of LRIs within the GRID was validated using: 1) published data and 2) quantitative accuracy assessments using satellite imagery. Spatial distributions of LRIs captured in the GRID are extremely consistent with those published in the literature (r² = 0.96) and those derived from independent analysis of satellite imagery (r² = 0.94). Finally, the GRID was used to develop an island vulnerability index (IVI) for each LRI on a scale of 0-1 with 0 representing no vulnerability and 1 representing maximum vulnerability. The GRID database is provided as a tab-delimited text file as well as ESRI shapefiles (points and polygons in WGS84 and Mollweide projection) and a comma-separated value file.