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Barrow could be ocean observation hub Scientists present ideas for a future seafloor cabled observatory; seek industry views and needs; NSF to be asked for funding Alan Bailey Petroleum News
Considering that people have landed on the Moon and that space probes have revealed many of the secrets of planets in the Solar System, it is perhaps surprising that we know so little about what happens in the oceans that cover much of our own planet. The ocean waters seem to present a barrier to investigation as difficult to penetrate as the vacuum of outer space.
That’s a prime reason that several subsea ocean observatories are in various stages of planning and development around the coastline of the United States. And scientists hope that one of these observatories will come to fruition in Barrow at Alaska’s northwestern extremity, where sea ice makes subsea scientific investigation both challenging and interesting.
The scientists who are promoting the Barrow proposal convened a workshop in Anchorage on April 17, to explain their concepts to industry representatives and to garner ideas for what a Barrow observatory might achieve. Although the scientists envisage the observatory as being government funded, they see the observatory as a means for communities and industry on Alaska’s North Slope to gain a better understanding of the ocean environment.
“I think that the story that we have to tell is pretty compelling and offers a lot of opportunities for working together in a collaborative way to achieve similar sort of goals and ends,” Bernard Coakley, associate professor at the Geophysical Institute and in the Department of Geology and Geophysics at the University of Alaska Fairbanks, told the workshop attendees.
“There are few communities in the world that are as closely linked to the ocean as Barrow is,” Coakley added, referring to the importance of the Beaufort and Chukchi Seas to the way of life of the North Slope communities.
Cabled observatory The scientists propose building what is termed a cabled observatory at Barrow. The design of this type of observatory involves a subsea cable system that includes a fiber optic communications cable and a power supply cable. The cable system connects an onshore coastal station to one or more nodes on the seabed. Each node supports a cluster of observation instruments. Instruments could monitor sound, transmit moving images and monitor the physical and chemical properties of the water column, Coakley said. Other possibilities include seafloor seismometers and active acoustic instruments that make measurements using transmitted sound.
The current ideas for a Barrow cable observatory include two cable transects, one on either side of the Barrow Canyon, north of Barrow, with the furthest point of the observatory system lying about 150 kilometers offshore. Each transect could support a string of instruments from one or more nodes.
Coakley’s preliminary cost estimate for the observatory is about $70 million.
A similar type of cabled observatory planned for Monterey, Calif., and known as the Monterey Accelerated Research System or MARS is in the process of construction. The Barrow cabled observatory would adapt technology developed for MARS.
Alan Chave, a senior scientist from the Woods Hole Oceanographic Institute, provided some further insights into the observatory technology.
A cabled observatory node includes an instrument interface for controlling and gathering data from the various observation instruments, Chave explained. An optical transportation system with routers and switches, rather like the technology of a typical office data network, connects the instrument interface with the fiber optic cable that connects the node to the shore station. And a power supply unit in the node channels electrical power from the observatory’s power supply cable to the node and its associated instrumentation.
The communications system will allow the instruments to be controlled from the shore-base observatory station, as well as enabling the continuous and almost instantaneous monitoring of data from the observatory. And people could control the instruments and make observations from just about anywhere if the observatory is connected to the Internet.
Accurate timing Assigning accurate timings to data measurements has proved a particular challenge in this type of observatory configuration — it can take several milliseconds for signals to traverse a long fiber optic cable run, thus making shore based time measurement much too inaccurate, Chave said.
“Science needs to know what time it is to an accuracy perhaps as much as a microsecond,” he said.
Ground-based observation systems can resolve this issue by the use, for example, of global positioning system receivers. But because radio waves from GPS satellites do not travel through water, scientists have had to devise techniques for resetting seafloor clocks and measuring the time delay or latency along the fiber optic cables.
Plugging and unplugging subsea instruments presents another challenge. The Monterey researchers are investigating the use of autonomous underwater vehicles that could manage the instruments and also serve a role in relaying instructions to instruments and gathering data, Coakley said.
Chave thinks that seafloor wireless networking, using optical technology rather than radio technology, is a future possibility. That would avoid the “plugging in” problem and could enable scientists to move instruments around on the seafloor freely.
Underpinning the various technologies that could support a subsea observatory is the need for high levels of reliability, both for hardware and software, Chave said.
Advantages But why go to the trouble and expense of building a cabled observatory, when people can already make ocean observations using ships or moored buoys?
Coakley said that it is simply not possible to use a ship, for example, to make the types of observation that become possible from a cabled observatory. Building a cabled observatory, in effect, establishes a continuous scientific presence on the seafloor.
“In the Arctic, having all the ship time in the world wouldn’t let you do some of the things that a cabled seafloor observatory would enable,” Coakley said.
A moored buoy suffers from power supply constraints and the lack of continuous two-way communications. With a mooring, you drop it over the side and come back in a year to see if it worked, Coakley said.
“With cabled observatories you have the opportunity to see what is happening, see how it’s working, maybe fix some problems … and also control the experiment, change the sample rate, re-orient the sensor,” he said.
A cabled observatory at Barrow would also enable observations to be made under the sea ice.
“Getting continuous access to the water column under the ice is something that we really, really want … to understand what going on in the Arctic Ocean,” Coakley said.
And, located at the boundary between the Chukchi and Beaufort seas, Barrow sits in a particularly advantageous location for ocean observations. A variety of ocean and coastal currents flow through the region, impacting the biologic activity, the chemistry of the water column and the behavior of the sea ice. Processes occurring in the ocean also impact the North Slope communities.
Shore-based instrumentation Barrow is already a major site for shore-based instrumentation, such as radar for monitoring the sea ice build up and movement. That raises intriguing possibilities for integrating subsea observations with observations from land based instruments, Coakley said. For example, it might be possible to relate ice movements and ice ridging seen on radar to what is happening in the water column under the ice.
Coakley also said that an objective of the Barrow cabled observatory would be to support another government sponsored program known as the Study of Environmental Arctic Change. And the National Oceanic and Atmospheric Administration has a large investment in instrumentation in the Barrow area, he said. A federal government-funded research facility called the Barrow Global Climate Change Research Facility is also under construction. These various scientific programs together with the cabled observatory could turn Barrow into a world-renowned location for studying the oceans, Coakley thinks.
But the scientists involved in the cabled observatory proposal also see important benefits to the North Slope communities, particularly in terms of the ability to monitor what is happening in the ocean. Harry Brower Jr., deputy director for wildlife management for the North Slope Borough and chairman of the Alaska Eskimo Whaling Commission, commented to the workshop attendees about how bringing Arctic science to the Arctic could help all stakeholders in the region gain a better understanding of the natural world. He said that the North Slope communities are particularly concerned about global warming and its potential impact on whaling.
“There is a special sense of urgency in expanding our knowledge base,” Brower said.
Coakley and others organized a workshop in Barrow in February 2005, to identify North Slope community needs from the observatory and to engage the local people in the project.
“Everybody found a lot to be enthusiastic about,” Coakley said.
In November a workshop in Monterey focused on the technical aspects of the project and worked up a conceptual design, using experience gained from the MARS project and other cabled observatory initiatives.
Construction issues Although the Barrow observatory will adapt technology developed in the MARS project, the Arctic environment is very different from the California coast where MARS is being implemented: the construction of the Barrow observatory will face some significant new challenges.
In particular, ice scouring in the shallow nearshore water could rip apart a seafloor cable system. That possibility will necessitate burying the cable to depths at least below the pressure effects of ice dragging on the seafloor and out to water depths where ice scouring ceases to pose a threat. The cable will also need to be buried well back from and below the coastline to avoid coastal erosion exposing and breaking the cable. These burial requirements will require the cable coming from the shore station to pass through a 4 or 5 kilometer directionally drilled hole that emerges through the seafloor under the deeper water, Coakley thinks.
Planning and designing the cable laying will require some extensive work, mapping ice gouge zones and other ocean floor features that could impact where and how to place the cable. And the nature of the seafloor will determine what type of fiber optic cable to use in different places — some types of cable are more rugged than others.
“We need data to identify the best cable location,” Coakley said.
Coakley said that he has been working on a joint Minerals Management Service and National Science Foundation project to map critical areas on the Beaufort shelf. And detailed seafloor surveys using high-resolution sonar and seismic techniques will be needed.
A future design consideration is the possibility of a second cable landing along the Beaufort Sea coast at Prudhoe Bay.
“A second landing at Prudhoe Bay would insulate us against a single point of failure,” Coakley said.
A second landing would also enable the deployment of a string of instruments across the Beaufort Sea shelf, he said.
Data transportation Transporting the observatory data into the Internet will present another set of issues.
“Basically what we’re talking about is Barrow cable observatory taking a fire hose full of data and pointing it right at Barrow,” Coakley said.
But to meet the vision of enabling users distant from the North Slope to access data and control instruments, that fire hose load of data has to be able to stream into the Internet outside Barrow. Barrow does not currently have enough communications network bandwidth to carry the amount of data involved.
And Chave said that making observatory instrumentation widely available would raise other issues. For example, what would be the policies for the use of the observatory? Would there be security or legal concerns? What computer tools would need to be available for people to access the observatory data?
NSF funding The planners of the Barrow cabled observatory hope to obtain funding for the observatory through the National Science Foundation — NSF has endorsed ocean observatories in general, Coakley said.
Coakley is in the process of preparing a proposal to NSF for a desktop study and an environmental permitting study. The desktop study will evaluate existing bathymetric data from the Barrow area and suggest what additional data are needed for planning and design of the observatory. The study will also evaluate the environment in which the observatory would be installed. The permitting study will evaluate the permit requirements for the observatory construction.
The scientists also plan to hold a second Monterey workshop to identify how to adapt the MARS technology for the Arctic environment. They also plan to work more with the Barrow community.
Coakley also sees a need for a couple of committees, to enable people who are interested and enthusiastic to help guide direction for the project.
“We need to get a science steering committee together,” Coakley said. “… We would also like to form an industry liaison committee — people from industry … who’d like to be a bridge between industry and the science community.”
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