ARM-ACME V wraps-up field campaign in Alaska

ARM-ACME V Principal Investigator Sébastien Biraud in the cabin of the G-1 aircraft next to the greenhouse-gas-monitoring instruments. Image courtesy of John Hubbe, AAF Payload Director.
ARM-ACME V Principal Investigator Sébastien Biraud in the cabin of the G-1 aircraft next to the greenhouse-gas-monitoring instruments. Image courtesy of John Hubbe, AAF Payload Director.

After a successful sixteen-week data collection campaign, scientists are ready to explore their data. In June 2015, the Atmospheric Radiation Measurement (ARM) Climate Research Facility launched the ARM Airborne Carbon Measurement V (ARM-ACME V), an aerial campaign focused on capturing data from the sky to better understand warming in the Arctic.

The ARM-ACME V team measured trace gas concentrations, aerosols, and cloud properties with the ultimate goals of finding out why current climate models underestimate how rapidly the Arctic is warming. By characterizing atmospheric gas mixing ratios (i.e., volume of gas per volume of air), scientists hope to improve the estimates of the volume of gases like carbon dioxide and methane being emitted from natural (i.e., permafrost degradation) and anthropogenic (i.e., oil and gas exploitation) sources. Permafrost is thawing at an accelerated pace due to rising air temperature, and this degradation releases carbon dioxide and methane—two greenhouse gases that affect the amount of heat that can reach or leave the Earth.

The Eye in the Sky

The ARM-ACME V team—led by Sébastien Biraud from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory—ran the 38-flight campaign from June 1 to September 15, using the ARM Aerial Facility’s (AAF) Gulfstream-159 (G-1) research aircraft. Most typically, the G­-1 carried out airborne measurements over Alaska’s North Slope flying so-called tundra flights just 500 feet above ground in rectangle-shaped flight patterns. Most tundra flights went over Oliktok Point, Barrow, Atqasuk, Ivotuk, and Toolik Lake.

Oliktok Point and Barrow are also ARM's ground-measurement sites that take similar data. The flights specifically over these sites will provide validation of the ground-based cloud retrievals applied to operational and long-term remote-sensing measurements.

"Given the usual challenging weather in the North Slope and there being snow in August, this is the best and most complete data set I've ever collected," said Biraud. "Because we flew so often over a longer period of time, about every four days over three months, we were able to see changes at synoptic and seasonal scales. As a surprise, we still observed methane concentration enhancements, even though the snow covering the ground acted as a lid would on a bottle."

G-1 aircraft flying just over 500 feet above the polygon-shaped tundra. Photo courtesy of Sébastien Biraud, ARM-ACME V Principal Investigator.
G-1 aircraft flying just over 500 feet above the polygon-shaped tundra. Photo courtesy of Sébastien Biraud, ARM-ACME V Principal Investigator.

The ARM-ACME V campaign flight patterns and instrumentation were specifically designed to collect trace gas concentrations, aerosol, and cloud properties. According to Beat Schmid, Technical Director of the AAF at Pacific Northwest National Laboratory, the team consisted of approximately five people at any given time, a much smaller team than usual for the AAF. On average, the team consisted of two pilots, two scientists, and a mechanic.

"This was a great mission that wasn't a typical [AAF] campaign. Some of the team members stayed in Alaska for a total of 60 days, three weeks at a time, to catch great data," said Schmid. "With the small team working together, everyone was very involved in capturing the best data."

Collection Collaboration

Sharing collected observations with other research groups is key to improving understanding of the carbon cycle in the Arctic. This will naturally occur because the ARM-ACME V has established strong collaboration with other federal agencies gathering measurements in Alaska: the National Aeronautics and Space Administration (NASA, CARVE mission), National Oceanic and Atmospheric Administration (NOAA, Global Greenhouse Gas Reference Network), National Science Foundation (NSF, Long Term Ecological Research site), and San Diego University.

In addition to trace gases, ARM-ACME V also collected aerosol and cloud data in different environments. Over the next few months, the team will process the collected data and compare the measurements to models.

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The ARM Climate Research Facility is a national scientific user facility funded through the U.S. Department of Energy's Office of Science. The ARM Facility is operated by nine Department of Energy national laboratories, including Lawrence Berkeley National Laboratory in California.