It has often been said that we know more about the Moon than we do about the deep oceans. Yet with growing awareness of the role of the oceans in climate change, there is a renewed urgency to learn more about the world beneath the waves.
Ocean measurements have traditionally been made from ships and moored or floating buoys but for long-term monitoring a network of underwater observation stations is essential.
‘Many countries are moving towards permanent programmes to get measurements from the deep ocean,’ says Paolo Favali, coordinator of the EU-funded EMSODEV project.
One such venture is EMSO, the European Multidisciplinary Seafloor and water column Observatory, one of 21 collaborative facilities recognised as a European Research Infrastructure Consortium (ERIC).
At present, EMSO has eight regional facilities in the Atlantic, Mediterranean and Black Sea and three shallow-water test sites off the coasts of Ireland, France and Spain. The facilities are managed by their host institutions and until now have used a variety of designs.
‘Each facility has a different technical approach in terms of architecture, even if the measurements we perform are similar,’ says Favali.
The EMSODEV partners have designed a standard instrument package – called an EGIM (EMSO generic instrument module) – to enhance the interoperability and standardise data gathering from any of the EMSO facilities.
‘The EGIM allows us to collect comparable data that can be used to better constrain models – for instance climatic models – using data coming from polar and more temperate areas,’ Favali says. ‘This helps policymakers to make proper decisions on the management of their marine and coastal zones.’
The EGIM instruments are contained in a barrel-shaped framework, just over a metre high, and can operate at depths of over 4 800 metres, either on the sea floor or moored at a chosen depth. A prototype and two production modules are already onsite.Each of the three modules is equipped to measure seven ‘essential ocean variables’, namely temperature, conductivity, pressure, dissolved oxygen, turbidity, ocean currents and sound. They can include up to four other instruments such as a carbon dioxide sensor, a seismometer or a video camera.
Modules are connected to base either by an undersea cable or by a satellite link from a surface buoy. Instruments can return data to shore at fixed intervals or in real time.
An associated data-management platform and portal ensures that data is readily available to researchers who need it. Likely applications are in geosciences, physical oceanography, biogeochemistry and marine ecology.
The prototype EGIM was tested for six months at EMSO-OBSEA (Spain) in shallow water before a one-year deep-sea experiment at EMSO Azores on the Mid-Atlantic Ridge. One of the two production modules is operating at a site north of the Canary Islands at over 3 500 metres water depth, while the other is waiting to be installed off the east coast of Sicily (2 100 metres) in cabled configuration.
EMSODEV ended in 2019 but the work is continuing. The Portuguese partner has secured funding to build two more EGIMs and plans are afoot to install an EGIM in Cambridge Bay in northern Canada, following a cooperation agreement between EMSO and Ocean Networks Canada.
However, the ambition is for EMSO to join with several other organisations interested in the oceans to create a European Ocean Observing System. ‘The idea is to have integration of in situ measurements, both in space and time, with information coming from Earth observation satellites,’ Favali explains. ‘An integrated point of view is the way to better understand the complex processes of the Earth.’