QA/QC and DTM production details
For each maritime region bathymetric survey data and aggregated bathymetry data sets have been collated from public and research organizations. These have been processed and quality controlled and used to produce regional Digital Terrain Models (DTM). Thereafter these have been integrated into the EMODnet DTM for European seas.
The 2016 DTM version has a grid size of 1/8 * 1/8 arc minutes, while the 2018 version has an increased resolution of 1/16 * 1/16 arc minutes. Each grid cell has the following information:
- x,y coordinates
- minimum waterdepth in meters to LAT
- average waterdepth in meters to LAT
- maximum waterdepth in meters to LAT
- standard deviation of waterdepth in meters
- number of values used for interpolation over the grid cell
- interpolation flag (identification of extrapolated cells)
- average waterdepth smoothed by means of a spline function in meters to LAT
- an indicator of the offsets between the average and smoothed waterdepth as a % of the waterdepth
- reference to the prevailing source of data with metadata.
Note: The water depth values are in meters with reference to LAT.
The DTM values have been determined from 4 possible sources of data:
- Bathymetric survey data = high resolution data sets from single and multibeam surveys that are referenced via the CDI Data Discovery and Access service
- Digital Terrain Model data = composite data sets produced and delivered by a number of external data providers such as Hydrographic Offices derived from their internal bathymetric database and based upon historic surveys. The aggregated data sets are referenced via the Sextant Catalogue service
- Satellite Derived Bathymetry data = composite data sets produced from Landsat 8 images, in particular for coastal stretches in Greece and Spain. The SDB data sets are referenced via the Sextant Catalogue service
- GEBCO 2014 30” gridded data, used to complete area coverage in case there are no survey data or composite data sets available to the partners.
It is accepted that the accuracy and precision of the gridded data will vary over the basins in question. No new data has or will be collected specifically for this project. In case of multiple survey data for a cell, all surveys will be used for the calculations after having filtered datasets not satisfying to the QA/QC criteria.
GLOBE software: this software has been developed and is maintained by IFREMER. It has been customized for the EMODnet Bathymetry methodology and EMODnet Bathymetry partners are encouraged to make use of this software for processing their data contributions and for generating local and regional DTM's that are contributing to the EMODnet DTM. The EMODnet DTMs are provided in GLOBE NetCDF format and can be visualised by using the 3D visualisation tool of GLOBE software. More info about the GLOBE software can be found here