Observatories to Examine Arctic Changes from Under the Ice

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,” says 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.

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