The waters south of the Vineyard will soon become among the best studied in the world. At the continental shelf break, some 80 miles south of South Beach where North America begins its descent toward the abyssal plain, a huge swath has been identified by scientists to be monitored, dissected and measured in resolutions and over time scales unprecedented in oceanography.
Called the Pioneer Array, the project is part of a larger international effort called the Ocean Observatories Initiative, designed to better understand some of the basic ocean processes that drive the weather, ocean currents and life on earth.
Two weeks ago Woods Hole senior scientist Bob Weller returned from a trip aboard the research vessel Oceanus where he had just deployed three test moorings in the future site of the array. Mr. Weller explained the need for the new approach.
“When you think of the ocean which covers 75 per cent of the world, it’s amazing that we don’t have records in time of how it’s been changing,” he said. “This will push U.S. ocean science to the cutting edge.”
Historically oceanographers have mostly relied on research cruises to measure things like temperature and salinity in the ocean, but an animation on the Woods Hole Pioneer Array Web site perhaps best demonstrates the new concept. In the video, a three-dimensional block of ocean water is shown teeming with robotic scouts, some tethered to moorings bobbing up and down the water column like elevators while automated robotic gliders and propeller-driven vehicles called AUVs whiz past, occasionally stopping at sea floor stations to recharge their batteries and relay information up a cable to the ocean surface, where it is then beamed to a satellite in space.
The equipment, designed to last 25 years, is armed with sensors to measure everything from salinity and temperature, to water velocity and chlorophyll levels over time in the dynamic region at the shelf break where warm tropical water from the Gulf Stream mixes with cooler coastal water from high latitudes, creating one of the most ecologically diverse environments in the world and supporting everything from phytoplankton to sperm whales.
“It’s a fascinating problem because it’s a place where there’s a very high level of ecosystem diversity, but from the physics side we don’t really understand how those nutrients are being supplied,” said Woods Hole senior scientist Al Plueddemann. “That’s the simplest fundamental problem we’re trying to get at. We know shelf break front regions are special places for ecosystem dynamics; we just don’t really know how they work.”
But Mr. Plueddeman admits that some of the technology is still speculative at this point.
“The sea floor recharging station for the AUVs are among a half a dozen or so of what you might call technology reaches we’re trying to achieve with this program,” he said. “They’re in the design phase. Recharging station prototypes have been developed previously and tested so it’s not absolutely the first time it’s ever been done but it’s never been done in a sustained manner like we’re trying to do.”
The array will be composed of seven moorings, covering a 25-by-five-mile rectangle that will be supplemented by two propeller-driven AUVs puttering around a larger 40 by 60-mile area, which will be further supplemented by two long-range gliders that will transect a 70 by 100-mile area. Together they will give scientists an unprecedented multi-scale, vertical and horizontal view of the ocean.
“It takes an unreasonable number of moorings unreasonably close together to actually measure the whole system in the horizontal so we basically fill in between the moorings with the two types of autonomous vehicles,” said Mr. Plueddemann.
The array will be fully deployed in 2015 and will run for five years, at which point it can be relocated anywhere in the world the science community deems fit.
The work will not only provide insight into the ecology of the shelf break south of the Vineyard, but as part of the larger Ocean Observatories Initiative, along with three other research sites, one on the West Coast and two near the Arctic, it will provide insight into how man is influencing the planet as a whole.
“Over half of the CO2 that we’re generating now by burning fossil fuel is absorbed in the ocean and redistributed but we don’t really know in detail how that works — we can’t really model it or predict the way it works because we don’t have good observations,” said Mr. Weller. “From a real practical sense we as a society are engaged in trying to understand how man’s changing the world but we’re not observing and understanding and capturing in models the processes in 75 per cent of the world, i.e. the oceans.”
In many ways, Mr. Plueddemann said, the Martha’s Vineyard Coastal Observatory, a Woods Hole ocean research station launched a decade ago and familiar to beachgoers as the derrick-like silhouette a mile off South Beach, was a precursor to the Pioneer Array. He hopes it can be linked to the ambitious new project.
“The continental shelf is a continuous system and it doesn’t stop where gliders stop, there’s a continuity of processes all the way to the coast,” Mr. Plueddemann said. “There are proposals from some groups to send a glider back and forth from the [Vineyard coastal obervatory] to the Pioneer Array. The array and the coastal observatory are inevitably going to be linked in the scientific analysis but the hope is to link them more physically with the gliders.”
Inevitably occupying such a large and productive area of the ocean presents possible conflicts with the commercial fishing community. While Dukes County Fishermen’s Association president Warren Doty said no Vineyard fishermen work the area near the contintental shelf break, Mr. Plueddemann has met a number of times in recent months with fishermen from New Bedford, Rhode Island and Long Island about their concerns.
“We’re both worried about the same thing in the most general sense,” he said. “We need to find a way to share the physical space of the ocean. Researchers and commercial fishermen have shared space in the ocean for decades but what’s different here is the sustained nature over five years. Their concerns are, will this disrupt where I can fish? What would happen if I catch your AUV?”
But he is confident the details can be hashed out. For the rest of us, Mr. Plueddemann hopes the Pioneer Array and the Ocean Observatories Initiative inspires something like a sense of wonder.
“We’re hoping there’s a little piece of this that just engages the general public,” he said. “This is unique for oceanographic science. Just like we can sit and watch the Mars rover as an average Joe, the vision for the Ocean Observatories Initiative is that the average person can log on and see what’s going on in the ocean today.”