Researchers from the Woods Hole Oceanographic Institution (WHOI) are venturing this month to the North Pole to deploy instruments that will make year-round observations of the water beneath the Arctic ice cap. Scientists will investigate 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.
The Arctic expedition is part of a multi-year, multi-institutional program to establish 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.
Arctic research specialist Rick Krishfield and engineering assistant Kris Newhall will lead the WHOI expedition this spring, deploying two autonomous ice-based observatories between 88° and 90° North. The observatories are similar in design to moored, open-ocean buoys, though they will be anchored to the ice instead of the seafloor. 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.”
A key element of WHOI’s contribution to the observing system is the ice-tethered profiler (ITP). Invented by Toole, Krishfield, and colleagues, the ITP climbs up and down a mooring string each day, detecting the temperature, salinity, and oxygen content at various points in the water column. 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. That data is made available to the science community and public within hours via the Internet.
In the past, scientists have studied Arctic waters through expeditions on icebreakers and ice-locked ships, or by setting traditional moorings that had to be recovered after months or years of data collection. But few have tried to send Arctic Ocean data back in real time, year-round, for multiple years. Six WHOI ice-based observatories have been tested in the waters north of Alaska over the past three years, and researchers are confident that they can take the ice-tethered profiler system all the way to the top of the world.
The water measurements are necessary because there is more than enough heat stored in the waters entering the Arctic from the Atlantic and Pacific 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 installing their observatories in April 2007, WHOI researchers plan to deploy 11 more this summer in collaboration with scientists from the United States, France, Germany, Japan, Russia, and Canada. Several more ITPs will be deployed in 2008, as Krishfield, Toole, and colleagues work toward spreading an array of autonomous observatories across the region and sustaining them over time.
“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. “That would allow us to provide a snapshot of the ‘weather’ in the Arctic Ocean for at least the next couple of years.”
In addition to their own ice-tethered profilers, Krishfield and Newhall will deploy ice mass balance buoys and an Arctic Ocean flux buoy for colleagues from the Cold Regions Research and Engineering Laboratory (U.S. Army Corps of Engineers) and the Naval Postgraduate School. WHOI is also collaborating with scientists from the University of Washington, Oregon State University, the Japan Marine Science and Technology Center, and the National Oceanic and Atmospheric Administration’s Pacific Marine Environmental Laboratory, all of which are deploying instruments to measure what is happening above, within, and below the ice.
The ice camp team will be accompanied by a photographer and writer, who will file daily dispatches and conduct live teleconferences with students and museum visitors across the United States as part of an education effort known as “Live from the Poles.”
