Far North Science

WHOI researchers Kris Newhall, Rick
Krishfield and John Kemp assemble a tripod
to deploy the sensor beneath the ice.
Credit: Chris Linder /WHOI

Want to fathom the heat hidden within the cryosphere’s inland sea?

Then you must penetrate the North Pole itself.

Researchers from Woods Hole Oceanographic Institution traveled this week to an ice station on the Arctic Ocean north of Alaska to begin eavesdropping on the mysterious, life-rich ocean layers beneath the floes.

The goal of this frigid game of peek-beneath-the-ice will be to deploy two instrument-packed buoys for an extraordinary trans-polar tour.

Over the next few weeks, WHOI Arctic research specialist Rick Krishfield and engineering assistant Kris Newhall will lead a team that will lodge the buoys in the ice — one at the North Pole (90 ° North) and the other two degrees south — and then leave them to drift for up to three years.

Rick Krishfield

The task will be a big step toward monitoring the Arctic Ocean on a large scale, where a fleet of autonomous buoys will measure the marine world a half-mile deep and then use satellite phones to send daily reports to scientists snug and warm inside the labs far away.

The researchers want to find out “how the waters in the upper layers of the Arctic Ocean — which insulate surface ice from warmer, deeper waters — are changing from season to season and year to year as global climate fluctuates,” according to a WHOI news release posted on-line this week.

These autonomous “ice-based observatories” resemble regular research buoys that get moored to the ocean floor and record temperature and salinity throughout the water column. But instead of bobbing in place on waves and wind, these buoys will follow the ice.

The instruments will slowly drift with the natural movement of the ice while observing water properties in the top 800 meters of the Arctic Ocean. The buoys are designed to last three years, about the same lifespan as the ice floes that support them.

“The goal of the WHOI observing system is to document and understand annual change through sustained observations of the polar ice pack, the overlying atmosphere, and upper ocean water properties,” said John Toole, principal investigator for the project and a senior scientist in the WHOI Physical Oceanography Department.

“Many climate models suggest the Arctic ice cover will melt within 50 years. We want to measure the changes in the water — particularly the layered structure of the ocean — in order to understand what mechanisms might lead the ice cap to melt from below. The impacts for the ecosystem, the regional and global climate, and for commerce would be enormous.”

Invented by WHOI scientists and engineers,
the ice-tethered profiler climbs up and down a
mooring line suspended from the ice, detecting the
temperature, salinity, and oxygen content. The
instrument sends data through the mooring wire
to the surface buoy on the ice, which relays the
data by satellite phone back to researchers
in Woods Hole.
Credit: Jayne Doucette /WHOI

This expedition is part of a larger program to create a real-time, autonomous Arctic Observing Network. The WHOI researchers will work out of the North Pole Environmental Observatory, a yearly research camp on the ice that is organized and led by the University of Washington’s Polar Science Center.

The sensor that drops below the buoy to take measurements, called the “ice-tethered profiler,” was concocted by Toole, Krishfield, and others at WHOI. Part marine weather station, part elevator, the device will move up and down the mooring cable every day. Along the way, it will gauge temperature, salinity and oxygen at various depths. This is the fundamental information that oceanographers use to analyze the marine world.

The instrument then relays the data up the mooring wire to the top-side buoy, which then makes a long-distance call to Woods Hole. The data goes out to scientists and public within hours via the Internet.

In a way, using buoys to gather data once reachable only by icebreakers or ice-bound ships illustrates the revolution in marine science triggered by remote sensing and tiny computers. Just as tags can be attached to whales and fish, or robotic subs can visit the seafloor, these buoys will enable people to scrutinize the planet’s harshest environment 24-hours per day regardless of weather or season. During the past three years, WHOI teams tested six different “ice-based observatories” north of Alaska and say they are ready for the top of the world.

Senior Engineering Assistant John Kemp
leaps across a melt pond in the Beaufort Sea.
Credit: Christopher Linder/WHOI

The project will also help answer a mystery: Why doesn’t the ice cap simply melt away and be gone? The WHOI news release explains more:

The water measurements are necessary because there is more than enough heat stored in the waters entering the Arctic from the Atlantic to quickly melt the entire ice cap. That warmer water, however, gets sequestered about 300-500 meters down in the ocean, beneath the “halocline,” a layer that separates the fresher and cooler water near the surface from the deeper waters. Toole, Krishfield, and colleagues want to see if that phenomenon is stable or changing with time.

After they finish installing the buoys in April, the WHOI team will deploy 11 more buoys this summer with the help of scientists from the United States, France, Germany, Japan, Russia, and Canada, the release said. More will go out in 2008.

“We envision putting as many as 20 of these systems in the central Arctic, distributing them over the pack ice, and having them simultaneously send data back,” said Krishfield in the release. “That would allow us to provide a snapshot of the ‘weather’ in the Arctic Ocean for at least the next couple of years.”