Bathymetric data, in essence information about the water depth and underwater topography of oceans and seas, is important in many aspects of marine research, administration and spatial planning as well as for management of marine and coastal environmentsand their resources. In coastal areas societal needs are at the forefront: safety of vessel navigation is the most prioritized rationale for bathymetric mapping close to the coast, around shoals and along shipping routes. This mapping is the basis for the production of nautical charts. Finally, bathymetry data is also essential for planning marine installations and infrastructure such as wind turbines, coastal defences, oil platforms and pipelines. Research and academia organisations, governmental agencies, industry and citizens can benefit significantly from access to good bathymetric data.
Even though bathymetric data are still sparse in many regions, significant international efforts are pursued in order to assemble all the data collected by various actors and make these available to the public. EMODnet Bathymetry is the major effort undertaken by Europe on this challenge.
Fig. EMODnet Batrhymetry portal view showing the Digital Terrain model with 1/8 * 1/8 arc minutes (circa 230 metres) resolution
A single-access point to bathymetric products and data
Launched in 2011, the EMODnet bathymetry portal (www.emodnet-bathymetry.eu) is an international reference point for bathymetric data and products. The most important product is the EMODnet Digital Terrain Model (DTM), last update in October 2016. The EMODnet DTM is a multilayer bathymetric product for Europe’s sea basins. Over the years many new surveys and composite DTMs have been gathered and included and today the DTM is based upon more than 7700 bathymetric survey data sets and composite DTMs that have been gathered from 31 data providers from 18 European countries. The collected survey data sets can be discovered and requested for access through the Common Data Index (CDI) data discovery and access service that also contains additional European survey data sets for global waters. The Composite DTMs can be discovered through the Sextant Catalogue service. Both discovery services have been integrated in the EMODnet Bathymetry web portal.
The resolution of the DTM is a grid with 1/8 * 1/8 arc minutes (circa 230 metres). In addition, there is a layer showing high-resolution bathymetry for selected coastal waters in Europe to test the concept of a multi-resolution product. Altogether the EMODnet DTM contains over one billion points which are divided over 16 tiles which can be downloaded freely in various formats through the Bathymetry Viewing and Download service.
EMODnet Bathymetry at work
Improving storm surge modelling in UK
The UK Met Office and the National Oceanography Centre (NOC) in Southampton are jointly developing a new storm surge forecast model for the UK. The new system uses NEMO as the underlying ocean model. In order to correctly forecast storm surge it is vital that the model's tidal solution is accurate, which in turn requires an accurate bathymetry. As part of the setup a number of different bathymetry products were tested, and the results compared with observations from tide gauges around the UK.
Using EMODnet bathymetry led to an overall improvement in the model tide solution compared with the previously used bathymetry data. Systematic biases in particular have been reduced. The figure shows errors in the M constituent (the most dominant in the UK region) for ports on the east coast, where there are significant improvements using EMODnet.
Fig. EMODnet has been selected as the bathymetry source for the new storm surge forecasting system by MetOffice UK because it has reduced the errors between the model outputs and real measurements significantly (blue are the errors using the EMODnet bathymetry compared to the errors using the previous bathymetry in red)
Enhancing marine geophysical data discovery and access in the North Atlantic
The Galway Statement was signed by the European Union, Canada, and the United States in May 2013 and, amongst other initiatives, has led to a new international mapping coordination effort. The intent of the Galway Statement is to foster cooperation and increase knowledge of the Atlantic Ocean through improved coordination and collaboration in ocean observation efforts.
To this purpose the Tri-Partite Galway Statement Implementation Committee established the Atlantic Seabed Mapping International Working Group (ASMIWG) to implement a seabed mapping strategy to underpin the objectives of the Galway Statement. The ASMIWG recommends that all bathymetric data that currently exists (and newly collected data) be identified and made accessible to the public through the establishment of a North Atlantic Data Portal.
This is why last year the NOAA National Centers for Environmental Information (NCEI) has integrated the CDI survey index layers and the overall DTM layer of EMODnet Bathymetry, using OGC services, in their prototype for a North Atlantic Data Viewer.
The viewer gives an impressive overview of the available surveys in NCEI and EMODnet Bathymetry together and the existing DTMs. This is a clear example of how bathymetry can also support ocean policy.
Satellites, clouds, citizens and new skills will be key to boosting the bathymetry portal in EMODnet phase III
The Directorate-General for Maritime Affairs and Fisheries (DG MARE) of the European Commission has just signed (December 2016) the new service contract for phase III of EMODnet with a new consortium for further developing the EMODnet Bathymetry portal. The new consortium is composed of 41 leading organisations from 20 countries, coordinated by the French Hydrographic Office (SHOM), 16 hydrographic offices and 17 marine research institutes. Overall 70 specialists in the field of bathymetry will work together to find the most suitable common methods to access the data from surveys, to provide standard delineation of the coastline and to further improve the resolution of the bathymetry DTM.
Besides the new skills brought into the consortium, among the main innovations that will characterise phase III for the bathymetry portal are the new technological approaches that will be adopted for data collection: satellite derived bathymetry and crowdsourced bathymetry. Satellite derived bathymetry (SDB) is a relatively new technique in hydrography for the development of bathymetric maps from shallow waters and coastal regions. The biggest advantage is that it can cover a large area against relatively low investment in time and resources. Another interesting novelty is bathymetry data crowdsourcing. This is becoming a real trend among yacht owners and sailing enthusiasts who are eager to collect and provide data. EMODnet intends to exploit these new trends to fill the existing gaps of in situ observations. With this additional data EMODnet aims to improve the resolution to 100 meters.
Finally, to further evolve the DMT, EMODnet will move from a desktop tool to a more collaborative environment, bringing it to the cloud. This will make DTM more cost-efficient and easier to access.
Contributing to the EMODnet bathymetry portal is even easier today: use the Ingestion portal!
To further speed up the bathymetry data collection process, a new EMODnet service has been recently released: the EMODnet Data Ingestion portal (www.emodnet-ingestion.eu). Submit your bathymetry data through this portal: it is quicker and a help desk is always available to support you.
 M2 is the “principal lunar semi-diurnal" constituent, also known as the M2 tidal constituent