FIREX-AQ Deployment

From July through September 2019 the FIREX-AQ field campaign took place. This was a major campaign organized by NASA and NOAA, which involved four aircraft and both fixed and mobile ground based observing capabilities. ACOM had experiments on board the NASA DC-8 (Apel Group, TOGA-TOF; Hall Group, actinic flux), one of the NOAA Twin Otters (Weinheimer Group, NO, NO2 and O3), and the Aerodyne Mobile Lab (Hall Group, actinic flux).

The mission began with DC-8 flights out of Palmdale, CA, designed for student participation (Student Airborne Research Program; SARP). The DC-8 then flew to Boise, ID, where it met the two NOAA Twin Otters, one equipped with chemical measurements, and the other with remote sensing instrumentation. Boise served as a base to investigate the smoke from western wildfires. In mid-August the DC-8 transitioned to Salina, KS, to study agricultural fires in the southeast U.S. In general, the fire season was less active than 2018, when the WE-CAN experiment took place. The fires were more isolated and often not as easily accessible from the Boise base.

Altogether, the DC-8 flew 3 SARP flights out of Palmdale, 13 flights out of Boise, and 7 out of Salina. As a result of the long range of the aircraft, it was able to access fires as far away as Northern Arizona from Boise, and flew several large survey flights to investigate fires in California, Arizona and Utah on the same day. It was also able to fly detailed flight patterns over fires in Montana, Idaho and Washington, most notably the Williams Flats fire where it performed the first in situ sampling of a pyrocumulonimbus cloud generated by the fire, as well as 1-day old aged smoke downwind of the fire.

The Twin Otters were much more restricted in range, and had to concentrate on fires closer to the base of operations in Boise. Typically, the planes would take off in the early afternoon, transit to a fire then refuel, take off again for a detailed set of measurements, refuel, then sample again before returning. In this way, the same fire could be sampled in the late afternoon, at dusk and after sunset. The slow speed and maneuverability of the Twin Otter did mean that it could sample in mountain valleys if the conditions were favorable. The Chemistry Twin Otter flew 39 flight legs over 16 days, including 11 night flights.

The combination of airborne and ground-based sampling, along with remote sensing of the optical properties of the smoke will lead to a better understanding of the nature of emissions from these fires, along with improved knowledge of how the plumes age as they are transported away from the fires.

WIlliams Flats fire
Figure 1. View of the WIlliams Flats fire from the NASA DC-8. Photo by Samuel Hall. Click for larger image.
Inside the Chemistry Twin Otter

Figure 2. Inside the Chemistry Twin Otter (the NO-NO2 instrument is in the first rack on the right). Photo by Geoff Tyndall. Click for larger image.