Grid development

The GEBCO_2022 Grid is a continuous, global terrain model for ocean and land with a spatial resolution of 15 arc seconds. It uses as a ‘base’ version 2.4 of the SRTM15+ data set between latitudes of 50° South and 60° North. This data set is a fusion of land topography with measured and estimated seafloor topography. This version of SRTM15+ is similar to version 2.1 [Tozer et al., 2019] but includes additional data sets. It uses predicted depths based on the V31 gravity model [Sandwell et al., 2019].

The SRTM15+ base grid has been augmented with the gridded bathymetric data sets developed by the four Seabed 2030 Regional Centers to produce the GEBCO_2022 Grid. The Regional Centers have compiled gridded bathymetric data sets, largely based on multibeam data, for their areas of responsibility. These regional grids were then provided to the Global Center. For areas outside of the polar regions (primarily south of 60°N and north of 50°S), these data sets are in the form of 'sparse grids', i.e. only grid cells that contain data were populated. For the polar regions, complete grids were provided due to the complexities of incorporating data held in polar coordinates.

The compilation of the GEBCO_2022 Grid from these regional data grids was carried out at the Global Center, with the aim of producing a seamless global terrain model. For the 2020 and 2021 releases of the GEBCO grid, the data sets provided as sparse grids by the Regional Centers were included on to the base grid without any blending. This led to discontinuities at the boundary between the regional grids and the base grids in some areas, largely in regions where the base grid is not constrained by measured data, i.e. areas of large differences between the data sets.

For the 2022 Grid, the sparse regional grids have been included on to the base grid using a ‘remove-restore’ blending procedure (Smith and Sandwell, 1997; Becker, Sandwell and Smith, 2009 and Hell and Jakobsson, 2011). This is a two-stage process of computing the difference between the new data and the ‘base’ grid and then gridding the difference and adding the difference back to the existing ‘base’ grid. The aim is to achieve a smooth transition between the 'new' and 'base' data sets with the minimum of perturbation of the existing base data set. However, please note that there may be differences between the 2022 and 2021 grid in regions outside areas of measured data due to the grid merging process. For the polar data sets supplied in the form of complete grids these data sets were included using feather blending techniques from GlobalMapper software version 23.1.0 made available by Blue Marble Geographics. Some additional edits were made to the final grid to remove erroneous values identified in the previous grid and notified to the Global Centre.

The GEBCO_2022 Grid includes data sets from a number of international and national data repositories and regional mapping initiatives. Information on the data sets included in the grid is given in our data contributors list.

Please see the accompanying documentation for more information on the development of the grid Adobe PDF of the documentation to accompany the GEBCO_2022 Grid (0.1 MB).

Ice-surface elevation and under-ice topography

The GEBCO_2022 grid is made available in two versions, containing:

land and ice surface elevation information

under-ice topography information for Greenland and Antarctica

The information for ice-surface elevation and under-ice topography/bathymetry is taken from IceBridge BedMachine Greenland, Version 4.6 (Morlighem, M. et al. 2017) and data based on MEaSUREs BedMachine Antarctica, Version 2 (Morlighem, M. et al 2020).

Land Data

The land data in the GEBCO Grid are taken directly from SRTM15+ V2.4 data set for all areas outside the Polar regions – see the SRTM15_plus data set documentation for more information. South of 60°S, the land/ ice-surface elevation topography is largely determined from MEaSUREs BedMachine Antarctica, Version 2 (Morlighem, M. et al 2020). For areas north of 60°N, land data are largely taken from the Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) data set (Danielson, J.J., and Gesch, D.B., 2011).