This month, engineers at NASA’s Jet Propulsion Laboratory in Southern California are testing a spacecraft sensor that will help measure how quickly Arctic sea ice is disappearing. And while that instrument won’t launch for another year, scientists started preparing for its use during a recent field campaign in the Canadian wilderness.
Researchers spent two weeks in April flying above the Arctic Ocean, often watching sunrise from an altitude of 1,500 feet (457 meters) in a World War II-era plane. A variety of cutting-edge sensors used to measure the thickness of sea ice and snow were aboard the plane, including a stand-in for the microwave radiometer now undergoing testing at JPL. Measuring sea ice thickness is tricky, requiring a number of precise figures, including how high the sea ice rises above water, the depth of snow on top of that ice, and microwave emissions from the surface.
Flights were timed to the passage of satellites overhead so coordinated observations could be taken of the same features. Combining the airborne and satellite data will improve scientists’ ability to measure sea ice and understand how climate conditions are evolving across the Arctic.
In recent decades, the extent and thickness of Arctic sea ice have changed. Improving measurements of those changes helps scientists better understand the Arctic system while supporting navigation, weather and ocean research, and future satellite observations. As Arctic shipping activity increases, the region is also becoming strategically and economically more significant.
According to Sahra Kacimi of JPL, who served as the field campaign’s science lead, ongoing warming in the Arctic could potentially impact public safety and economic interests.
Find out what Arctic sea ice looked like as scientists studied it from the air — and using space-based instruments — during a field campaign this past April.
Frequent flyers
Kacimi has spent years studying sea ice using satellite data, but the top-down view she gets from space is different than peering out a plane’s window.
The bewildering diversity of sea ice creates otherworldly landscapes. The ice can be attached to land or adrift in the ocean; it can be rough or smooth. Driven by winds and ocean currents, the ice is constantly shifting, breaking apart, and deforming. Cracks can open into long stretches of exposed ocean, and collisions between floes can push ice rubble into massive ridges that extend for miles.
Some sea ice lasts only one season, while thicker ice can survive for several years (though multiyear sea ice is becoming less common in many parts of the Arctic). Entire ecosystems are affected by these changes, down to the arctic foxes and hares the scientists spotted throughout the trip.
Improving estimates of sea ice thickness helps scientists better understand how the region is changing and supports long-term observations of the Arctic environment. The NASA team logged about 50 hours in the air over the two-week campaign, conducting flights over drifting ice near the town of Inuvik before studying ice fixed to the shore of another location, a hamlet called Cambridge Bay.
For the Inuvik portion of the campaign, the team coordinated with the Surface Water and Ocean Topography (SWOT) mission, a satellite jointly developed by NASA and the French space agency, CNES (Centre National d’Études Spatiales), with JPL leading the United States component of the mission. Though it was designed to map the height of the globe’s sea and fresh water, SWOT can also measure the amount of sea ice above the waterline.
In Cambridge Bay, the NASA team joined researchers from ESA (European Space Agency), Germany’s Alfred Wegener Institute, and Canada’s University of Calgary. During this part of the campaign, coordinated flights soared over a field camp and under the tracks of satellite missions such as NASA’s Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) and ESA’s CryoSat-2.
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To improve sea ice thickness estimates, ESA is developing, with cooperation from NASA, a new polar mission called Copernicus Polar Ice and Snow Topography Altimeter (CRISTAL). During the April airborne campaign, scientists flew instruments similar to what CRISTAL will carry, including the microwave radiometer now being tested at JPL.
“Combining observations from space, air, and ground surface instruments is essential for developing and validating algorithms for current and future missions,” Kacimi said.
For the scientists, it was also a chance to meet locals who see the Arctic’s changes up close. Kacimi spoke to community leaders and students at a STEM camp about how disappearing ice is affecting their communities.
“I’m used to looking at sea ice from space and thinking about its role in the global climate, but for people living in the Arctic, it carries a much deeper meaning,” Kacimi said.