An arduous, three-week mission recently took a team of scientists and technicians from the U.S. Army Engineer Research and Development Center’s (ERDC) Cold Regions Research and Engineering Laboratory to the outer reaches of earthbound travel, all in an effort to help NASA better understand Arctic sea ice melting.
As part of NASA's ARCSIX research program, Dr. Chris Polashenski, Tricia Nelsen and Roy Hessner engineered and deployed specially modified, sensor-laden buoys into the Arctic Ocean north of Canada and Greenland near the North Pole.
"NASA’s ARCSIX is a mission trying to understand the melt of the Arctic sea ice, and specifically how clouds play into that,” said Polashenski, ERDC-CRREL’s principal investigator for the project. “As the sea ice goes away, more clouds form in the Arctic. Those clouds act as a blanket over the Arctic, causing it to warm further and possibly melt more sea ice. We're trying to figure out more about that feedback.”
ERDC-CRREL has been developing and deploying these types of buoys, named Ice Mast Balance Buoys, since 1997. To adapt them for the ARCSIX project, the team collaborated with Dartmouth College doctoral student Ian Raphael and the private company that manufacturers them, Cryosphere, to add new radiation sensors and remote communications systems.
After finalizing the new buoys, the team turned its attention to actually installing them in the sea ice themselves. Using a ski equipped DHC-6 Twin Otter aircraft, they landed on and drilled into and through the sea ice to install nine buoys and 10 weather stations in an array spread out over approximately 35,000-square miles. The buoys broadcast data back by satellite modem and include an array of autonomous sensors measuring ice properties, net radiation budget, meteorological variables, and Navy-relevant upper ocean properties on sea ice far offshore.
“We added radiation sensors so we could see how much sunlight was reaching the surface through the clouds and how much long-wave radiation was coming back from the clouds,” said Polashenski. “And then we also were measuring how thick the ice was and how the ice was melting from the top and the bottom, snowfall, and air temperature and barometric pressure, and a bunch of other things. The buoys are great because we can just keep adding more sensors to this platform to answer different questions that arise as we work through a program.”
The question of how clouds contribute to warming is of particular interest to scientists studying climate change, said Polashenski, because as the planet warms, clouds become more prevalent, trapping heat within the atmosphere that would otherwise escape into space.
“In many ways, the Arctic is the world's radiator,” said Polashenski. “It has a negative energy balance. Heat leaves the planet from the Arctic, and when we have a cloud over top of the Arctic, we actually restrict how much heat we can get out of the Arctic. So, understanding how the cloud cover in the Arctic is changing, and therefore how that’s changing the sea ice cover, is really important in the overall energy balance of the planet.”
Since their successful deployment, the buoys have continued to drift with the ice while reporting data, which the public can access in real time at cryosphereinnovation.com/data. The autonomous sites are now the foundation of NASA’s ongoing airborne sea ice observing campaign that is conducting regular overflights of the buoys out of Pituffik Space Force Base in Greenland.
Besides solving the technological challenges of designing and deploying buoys that not only include a wide array of complicated sensors, but can also withstand the harsh, Arctic conditions, the ARCSIX project presented the ERDC-CRREL team with significant logistical challenges associated with just getting to such desolate locations across a vast expanse of the Arctic ice shelf.
"This project was pretty interesting in that it is one of the most remote places that I've worked on the planet,” said Polashenski, who during his 20-plus year career at ERDC-CRREL has spent more than four years actually deployed in remote polar locations. “It is very, very hard to get to the area north of Greenland and north of the Canadian islands, simply because there's not much infrastructure anywhere nearby there.
“And while it's easy to fly a jet aircraft over that area because it has long enough range, it's really pretty challenging to actually land on the surface of the sea ice because the types of planes you can land on the surface with have a much shorter range,” he continued. “We were really constrained by how much fuel we could get and where we could get that fuel, and how much we could cache for ourselves and things like that. And bush planes are pretty much the only way to get there. The ice in this region, particularly at this time of year, is too thick for icebreaking ships. This and maybe the East Antarctic Plateau are the hardest places for us to get to on the planet.”