The Nighttime Fire Observations eXperiment (NightFOX) - UAS wildfire measurements for air quality, fire weather forecasting, and satellite validations

Wildfires have a major impact on local and regional air quality and potentially play an interactive role in climate change. NOAA and NASA's FIREX-AQ field mission deployment, planned for 2019, is designed specifically to study wildfire emissions and subsequent chemical transformations, the impact of fire plumes on regional air quality, and the climate-relevant properties of wildfire aerosol. The intensity and emissions of a wildfire depend strongly on meteorological conditions and therefore exhibit a strong diurnal cycle. Fire plumes are frequently more concentrated at night due to lower nocturnal boundary layer heights, which leads to poorer air quality and higher pollution exposure in areas directly downwind of fires. Manned research aircraft flights are generally limited to daytime operations near wildfires due to potential dangers associated with nighttime operations. This limitation leaves a large data gap in the observations of wildfire emissions, plume distributions, fire perimeter, and meteorological data that a capable small UAS (sUAS) observation system would ideally fill. The Nighttime Fire Observations eXperiment (NightFOX) project aims to fill this critical data gap by developing and deploying a sUAS observation system utilizing two modular and easily swappable payloads. One payload will provide in situ measurements of CO₂, CO and fine- and coarse-mode aerosol size distributions in wildfire plumes for characterization of nighttime fire combustion efficiency and emissions. A filter sampler will collect aerosols for off-line composition analysis. The second payload will be flown over the fire to make remote sensing measurements of fire perimeter and fire radiative power using visible, short-, mid-, and long-wavelength IR observations. The remote sensing data, along with measured meteorological parameters, will be used to inform, test, and improve fire-atmosphere model WRF-SFIRE and to assess its suitability for calibration/validation of satellite wildfire observations. Initial test flights of both NightFOX instrument payloads have been conducted in preparation for the 2019 deployment. Instrument performance, flight results, and preliminary computational simulations will be presented.