SeaCycler: Bedford Institute of Oceanography Develops New Moored Profiler with Two-Way Satellite Communication

Wind, waves, currents, drift nets and ships are among the hazards that oceanographic instruments may encounter during deployment, as they gather data for research on a variety of issues from ecosystem productivity to ocean acidification and climate change. To address surface hazards and other challenges of gathering data in the ocean’s euphotic zone — the sunlit layer extending from the surface to 150 metres in depth — researchers at the Bedford Institute of Oceanography (BIO) have developed a new ocean profiling technology, called SeaCycler, with unique capabilities that open the door to new possibilities for oceanographic research.

The euphotic zone is very biologically active and is also the place where the ocean exchanges heat and gases, including carbon dioxide, with the atmosphere. These exchanges are among the processes under study by scientists exploring global climate change. “A considerable amount of research takes place in the euphotic zone, yet it is also a very challenging place to do science because waves and other surface hazards have a tendency to damage sensors and moorings,” says Fisheries and Oceans Canada (DFO) mechanical engineer Greg Siddall, who leads the SeaCycler development team.

What exactly is SeaCycler? The short answer: “a sub-surface, moored profiler with two-way satellite communication” to which scientist can attach a variety of sensors for gathering oceanographic data. The long answer includes a substantial list of novel features that would make just about any oceanographer giddy.

The Precursor of SeaCycler

Many features of SeaCycler were developed for its precursor, the Icycler, which was conceived in 1999 by now-retired Fisheries and Oceans Canada mechanical engineer George Fowler.

“George Fowler was instrumental in the development of Icycler and continues to lend his expertise to the design of SeaCycler, working on an emeritus basis,” says Siddall. “He’s the big thinker who developed almost all of the unique and rather novel concepts that are absolutely vital to this new technology.”

Icycler, or “Ice-Cycler” as its name implies, is a moored profiler developed to gather data under the Arctic ice. Since the Arctic Ocean is frozen over for eight months of the year, it had to withstand year-long deployments. Even more challenging, it had to be able to make measurements immediately under the ice, which moves around with tides and currents creating great potential for damage to sensors moored closer than 30 metres from the moving ice pack.

Fowler designed the Icycler to pop sensors up under the ice just long enough to make measurements then return to a safe hiding depth to avoid contact with sea ice. SeaCycler, which employs the same “pop up” capability, is designed for rugged, offshore, open-ocean research.

The development of the SeaCycler, which is even more technologically advanced, began in the Spring of 2005 following the first meeting of a consortium of co-funders, including Fisheries and Oceans Canada and partners from the United States, Great Britain and Germany.

How SeaCycler Works

SeaCycler can be moored to the sea floor in water as deep as 5,000 metres. Positioned between the anchor and the ocean surface is an instrument float, a platform to which up to seven sensors with a combined weight of up to 100 pounds can be connected. Each sensor connects to a central data logger that packages all gathered information into data files.

The mechanism float winds up and pays out cable like a winch to move the instrument float up and down. This enables the onboard sensors to “profile” the water column collecting data from all depths between 150-metres and the surface. Sampling can be continuous, occur at pre-programmed depths, or be event-triggered such as is required for early warming tsunami detection. As it moves, SeaCycler also monitors tension in the cable and will stop automatically instead of surfacing when dangerous storm waves are detected.

Located at the very top of the mooring is a small communications float that typically surfaces for only about 10 minutes per day, holding a small antenna above the waves to transmit data files via satellite to computers on shore and to receive new commands from scientists.

“Except for those 10 minutes, the SeaCycler has no ‘surface expression’, meaning there is nothing floating on the surface for most of the time, keeping it safe from surface hazards,” says Siddall. Oceanographic instruments left near the surface also tend gather barnacles, mussels and other marine organisms (a process known as biofouling), often causing them to stop working. The sensors on SeaCycler remain clean because they spend most of their time at a depth where light rarely penetrates.

Energy Conserving Technology

“One of the most unique aspects of SeaCycler is its energy conserving system, which was first developed for Icycler and has since been patented by the department. George Fowler developed a way to balance the movement of the profiler so it uses less energy and requires a smaller, lighter battery payload. The upward movement of the instrument and communication floats is balanced by the downward movement of the more buoyant mechanism float. SeaCycler conserves energy by moving the profiling package up faster than the winch moves down.

“Since SeaCycler is designed to do a 150-metre profile every day for a full year, it’s important to be smart about the way it uses the amount of battery power it can carry,” says Siddall.

Two-Way Satellite Communication

Another unique feature of SeaCycler is its two-way satellite communication capability, which enables scientists to receive data in ‘semi-real time’ and to send commands back to it. This feature makes it possible to remotely reprogram SeaCycler to adjust, among other things, the profiling schedule, how close to the surface the instrument float will rise, and whether or not it makes stops along the way. “This interactive capability provides a lot of flexibility and new potential for ocean research,” says Siddall.

Fisheries and Oceans Canada has also patented the communication float design, which was developed by George Fowler. It floats on the water sort of like a tilted log, keeping the antenna from being submerged by huge five-metre plus ocean waves.

Multi-Sensor Platform

Scientists can mount a wide variety of sensors on the instrument float to gather data on ocean parameters ranging from salinity, temperature, carbon dioxide and dissolved oxygen to nutrients, currents, light and so on. “It will always have a CTD (conductivity, temperature, depth) instrument onboard because that is really the backbone of oceanography research,” says Siddall.

“SeaCycler has yet to be given a dedicated science mission. At this point, we are still demonstrating what’s possible, refining the system to improve its control, and testing it under a variety of conditions,” says Siddall. Deployment number six was located about 250 kilometres offshore from Halifax, N.S., in water over one kilometre deep, enabling the team to test SeaCycler in open ocean conditions under 10-metre storm waves.

Although the technology is still under final development, it has already received international attention. The Ocean Observatories Initiative funded by the U.S. National Science Foundation is considering the use of SeaCyclers in four of their global mooring sites to observe complex ocean processes such as climate variability, ocean circulation and acidification. And Fisheries and Oceans Canada scientists are planning similar experiments using SeaCycler in the Labrador Sea, avoiding both waves and massive icebergs that frequent the area. Production of the devices would be carried out by Rolls-Royce Canada Limited, Naval Marine, based in Dartmouth, N.S., which licensed the technology from Fisheries and Oceans Canada.

“Short of using a research ship, there is nothing that can touch SeaCycler in terms of all of the things it can do,” says Siddall. “And it isn’t meant to do one particular thing. It’s a platform for scientists to mount their own research and sensors on, so what it can do really depends on what they want to measure.”