As the focus of ocean science increasingly moves towards understanding complex processes operating over basin scales and on decadal timescales, Sonardyne’s technologies have evolved to meet the needs of sustained ocean observation infrastructures. Central to this, is a company-wide focus on reliability in demanding environments and the development of solutions to meet the specific demands of the ocean science community. Geraint West, Global Business Manager at Sonardyne explains.
The drivers for ocean observing systems
In 2015, G7 science ministers meeting in Germany agreed that a step change in prediction, management and mitigation of future changes in the seas, oceans and their impacts on the environment, and human societies is necessary. This focus was further emphasised by the first United Nations World Ocean Assessment published in January 2016. A key enabler for addressing the issues posed, is the Global Ocean Observing System – an integrated system ranging from satellite to in-situ observations, but which is increasingly reliant on autonomous systems to achieve the full range of observations required at the range of geographic and temporal scales.
Transforming ocean observing with offshore technology
The growing emphasis on ocean observing systems is perfectly placed to access technology developments in the offshore industry where autonomous or remote monitoring of seabed infrastructure is one of our core strengths. Driven by the need to reduce costs and for improved situational awareness of offshore infrastructure, the industry has seen a drive towards the delivery of ever increasing volumes of data direct to operational decision makers’ desks. Central to this has been our development of low-power sensing solutions designed for long term seabed deployment, high bandwidth acoustic and optical telemetry, and optimised communications and positioning solutions for unmanned underwater and surface vehicles.
These technologies have proven track records in the offshore industry and the following case studies illustrate how we’ve been working with institutes around the world to use this know-how to address their ocean observation challenges.
Optimising coastal and deep ocean observatories
Our family of acoustic release transponders are workhorses for moored instruments and have often been deployed for years at a time in water depths from 6 to 6,000 metres. The low-cost Lightweight Release Transponder (LRT) – 500 metre rated and deployable for up to four years – exemplifies this versatility. It’s used to meet a range of oceanographic needs such as the deployment of seabed instrumentation including ADCP frames. They’ve also been used by the British Antarctic Survey to moor whale vocalisation recording equipment in the Antarctic, while Finland-based Luode Consulting have used LRTs under ice for year round monitoring of human impacts on water quality and ice thickness in Scandinavian waters. Our releases are complemented by a range of in-water wireless communications options, ranging from Modem Micro, optimised for simple applications by non-expert users, through to our 6G acoustic telemetry range, which supports data transfer up to 9kbps.
For high data volumes, there’s the BlueComm optical system which is capable of latency-free 10 Mb/s communications over a few hundred metres and is ideally suited for ‘fly-by’ data harvesting by unmanned vehicles. Indeed, this has been made possible through a joint venture set up with Woods Hole Oceanographic Institute (WHOI).
Extending endurance and capability
We have also been instrumental in the development of new capabilities in underwater geodesy based on existing low-risk offshore technology. Having been deployed in large arrays for multi-year monitoring of seabed structures and the seabed, Autonomous Monitoring Transponders (AMTs) are now being used to measure seabed tectonic deformation. AMTs can measure very fine scale strain across the seabed, as well as the shift of the whole submarine tectonic plate relative the GPS reference system – typically in the order of a few centimetres per year. They also log other sensor data, including bottom pressure for up to ten years to measure fault zone shear. During 2015, Geomar deployed an array of AMTs as part of its Geodetic Earthquake Observatory on the SEAfloor (GeoSEA), off Chile in depths down to 5,500 metres establishing it as the world’s first subduction zone acoustic monitoring system. Deployed for three years, data that precisely measures the relative movements between AMTs will be periodically collected via a Waveglider. Geomar has also previously deployed AMTs in the Sea of Marmara as well as more recently on the submerged flanks of Mount Etna.
Some of our latest systems can be deployed for 10 years on battery power alone and are capable of making hundreds of millions of measurements, securely storing the data and then telemetering it on demand. The Subsea Monitoring, Analysis and Reporting Transponder (SMART) is designed to provide advanced data collection and subsea processing. Incorporating standard sensors, it can also be interfaced with high bandwidth sensors such as accelerometers and can run sophisticated user- specified algorithms, as well as simple statistical data analyses and thresholding for critical event reporting.
Ocean hazard detection and warning
Following the Boxing Day Tsunami of 2004, we worked with the Indian National Institute of Ocean Technology (NIOT) to develop a long range warning system for the Indian Ocean. The system comprises a high resolution bottom pressure recorder (BPR), acoustically linked to a surface buoy, which in turn transmits data to a shore control centre.
Each BPR uses the US National Oceanic and Atmospheric Administration (NOAA) algorithm to detect a tsunami by comparing the measured pressure to the predicted tidal pressure calculated from the previous three hour history. Deployed in 2007, the NIOT system is made up of four stations operating in waters up to 3,500 metres, with each BPR capable of operation for up to two years between servicing. Since then, Sonardyne has supplied tsunami detection systems to Ecuador, Colombia and Greece, the latter being cabled to shore rather than acoustically telemetered to the surface.
With the latest 6G technology and optimised battery systems, there is potential to deploy instruments on the seabed for 10 years at a time. Replacing surface buoys with long endurance, low power autonomous surface vehicles can also significantly reduce maintenance costs, as shown in 2011/12 by use of a Waveglider to harvest BPR data in collaboration with NOAA’s National Data Buoy Centre and Liquid Robotics.
Adding value to underwater sampling
Our Ultra-Short Baseline (USBL) positioning technology has been widely adopted by ocean scientists, including WHOI’s National Deep Submergence Facility, for tracking specialist scientific manned and unmanned submersibles in all water depths. While safety of operations is a primary driver, precise geolocation of samples is critical to the scientific value of a range these and other operations including seabed coring, camera platforms and towed bodies.
The National Oceanography Centre’s (NOC) Hydraulic Benthic Interactive Sampler (HyBIS) is an example. Designed as a video guided seabed sampler, our Ranger USBL has enabled HyBIS to deploy instrumentation over methane hydrate and seafloor gas vents in the Arctic, as well as collect HD imagery, geological, biological, fluid, gas and other chemical samples, including from the deepest known (5,216 metres) hydrothermal vents at the Mid-Cayman Spreading Centre.
Our USBL systems are accompanied by inertial and Doppler Velocity Log (DVL) technologies making us unique in offering all-in-one subsea vehicle navigation. Recently, we worked with the Schmidt Ocean Institute to configure an integrated solution for their new deep-rated ROV SuBastian. We delivered a SPRINT inertial navigation system, Syrinx 600 kHz DVL and a Wideband Mini Transponder 6, to complement the Ranger 2 system installed on their research ship Falkor. This solution ensures robust positioning even in the most challenging acoustic and bottom topography situations, with Syrinx providing the high altitude (<175 metres) capability normally only available from a 300 kHz DVL and the high precision and accuracy of a 1200 kHz DVL. Features such as lightweight titanium housings provide valuable space and weight savings that free up scientific payload.
New solutions for new challenges
Ships and static delayed-mode data collection by moorings have traditionally been central to ocean observation. However, the rapidly rising cost of operating a vessel and the desire for real-time (or at least near-real time) data, has driven the increasing use of autonomous and remotely accessible systems to deliver data direct to the scientist’s desk. These are complemented by our commitment to custom engineering innovative solutions for you, underpinning our contribution to transforming how ocean science is undertaken at sea – just as we have done in the offshore industry.
Nowhere is this crossover better illustrated than our involvement with Fugro GEOS, the NOC, the British Geological Survey, Plymouth Marine Laboratory and the University of Southampton in the Energy Technologies Institute Carbon Capture and Storage (CCS) measurement, modelling and verification project (see Baseline Issue 12). This collaboration between industry and academia is a compelling model which is integrating offshore technology with scientific know-how to deploy a highly integrated system of autonomous seabed and in-water platforms to monitor CCS storage sites.
As scientists strive to understand the oceans from the regional to basin scale on decadal as well as daily/weekly timescales, the demand for timely and distributed observational technology is only set to increase. We’ll therefore continue to focus on precision and reliability, while innovating to meet the emergent challenges of ocean observation.