Taking in Some Arctic Air

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As the DC-8 spirals closer to Inuvik, Canada, a view emerges of the huge Mackenzie River and the standing water that flanks it. Credit: NASA/Katy Mersmann

by Katy Mersmann / SKIES OVER ALASKA AND CANADA /

The Arctic Boreal and Vulnerability Experiment (ABoVE) covers 2.5 million square miles of tundra, forests, permafrost and lakes in Alaska and Northwestern Canada. ABoVE scientists are using satellites and aircraft to study this formidable terrain as it changes in a warming climate.

In some ways, NASA’s DC-8 feels like a commercial airplane, with its blue leather seats and tiny bathrooms in the back. But once the plane starts to spiral down over Arctic towns, I remember I’m riding on a flying laboratory studying the amount and distribution of carbon dioxide and methane in the atmosphere.

Over the course of these big, looping spirals, the plane descends from a cruising altitude of about 30,000 feet down to just about 100 feet above the ground. The pilots fly us over the runway, as though we’re about to land, before pulling up at the last minute and returning to the sky, a maneuver known as a “missed approach.”

The DC-8 crew take turns flying out from Fairbanks, Alaska. Credit: NASA/Katy Mersmann

The whole process of spiraling down is a little scary the first few times we do it, but it’s necessary as an accuracy check for our science instruments, and by the third or fourth spiral down, it’s become a somewhat routine experience for me.

From the windows, I get a good look at the varied Arctic landscapes—twisting, braided rivers, carpets of spruce trees, and broad expanses of flat tundra all spread out underneath us. Each of those landscapes offers interesting scientific insights into how carbon emissions are changing as the climate warms.

As the DC-8 flies low over McGrath, Alaska, a tableau appears of spruce trees lining the Kuskokwim River. Spruce trees are native to the Arctic forest regions, but after frequent wildfires, some have been replaced by deciduous plants. Credit: NASA/Katy Mersmann

The plane is carrying five instruments designed to measure the spatial distribution of carbon dioxide from the air. They’re placed along the plane in place of some the seats and are operated by scientists monitoring screens mounted on their sides.

Someday, a descendent of these instruments will fly on the Active Sensing of Carbon dioxide Emissions over Nights, Days and Seasons, or ASCENDS, satellite, and the spiraling helps the researchers verify their measurements by flying right through the columns of air they’re studying from far above.

Jim Abshire is the project lead for the ASCENDS campaign. He sits near the front of the plane, plugged into the communications system and periodically checking with each instrument’s operators, making sure everything is running smoothly and requesting the occasional altitude change from the plane’s navigators.

He describes the spiral down maneuvers as a check on the lidar measurement systems, specifically ensuring that the instruments are sensitive enough to make precise measurements from space.

As Earth’s climate continues to warm, the Arctic warms much faster, and the subsequent changes in the Arctic regions are resulting in some soils releasing more carbon. More carbon in the atmosphere traps heat, causing more warming, which in turn causes the Arctic soils to release even more carbon, a process called the carbon-climate feedback.

Understanding this vicious cycle is one of the primary goals of the Arctic Boreal Vulnerability Experiment (ABoVE), a NASA campaign that includes the ASCENDS flights, as well as many other experiments, all designed to better understand how the rapid environmental change in the Arctic regions of the world impact ecosystems and society.