Atmospheric Chemistry Program Seminar
Open to Public
Mass fluxes of radical precursors in wildfire plumes:
Kyle Zarzana, postdoc,
Volkamer Group (1/2 seminar)
Constraining wildfire emission inventories using airborne flux measurements
Johana Romero-Alvarez, postdoc,
Volkamer Group (1/2 seminar)
1. Biomass burning emits a complex mixture of gases and particles that can vary rapidly over short spatial and temporal scales. Secondary chemistry driven in part by gas-phase radicals leads to downwind formation of ozone and particles which affect climate and adversely impact public health. Quantifying the emissions of radical precursors such as NO2, HONO, and carbonyls such as HCHO is an important first step to constraining their role in smoke chemistry, but this can be difficult due to plume inhomogeneities. Column measurements along the direct solar beam integrate over the vertical variability, and when made from an airborne platform can be used to determine mass fluxes on the scale of a wildfire. In this talk I will be presenting measurements from the Biomass Burning Flux Measurements of Trace Gases and Aerosols (BB-FLUX) campaign that was conducted in the northwest United States during the summer of 2018. The University of Colorado Solar Occultation Flux (SOF) and the Zenith Sky Differential Optical Absorption Spectroscopy (ZS-DOAS) instruments were deployed on the University of Wyoming King Air research aircraft, and these instruments measured column densities of numerous gases, including but not limited to CO, NH3, C2H6, HCN, PAN, HONO, NO2, and HCHO. Using a combination of data from these two instruments I will present estimates of radical fluxes from wildfires. Additionally, I will briefly touch on several other aspects of our BB-FLUX work, including determining carbon fluxes as well as linking the fire radiative energy measured from space with the aircraft derived fluxes.
2. Wildfire emit significant amounts of trace gases and particulate matter that impact atmospheric processes and human health, and accurate emissions are required to quantify determine the impacts of fires. Numerous inventories have been developed to estimate emissions using either measurements of fire radiative energy or of the burned area. These inventories often vary by several orders of magnitude, even for inert species such as CO, and until recently opportunities to valid these models have been limited. The University of Colorado Solar Occultation Flux (CU SOF) instrument can determine highly time resolved fluxes for many species from wildfires, and during the summer of 2018 was deployed as part of the Biomass Burning Flux Measurements of Trace Gases and Aerosols (BB-FLUX) campaign in the northwest United States. Over 100 fluxes measurements of a variety of species including but not limited to CO, NH 3 , small alkanes, and HCN, were performed on 18 different fires spanning different fuel types, fuel loadings, and fire intensities. Additionally, highly detailed measurements of the fire areas were made post campaign by the National Ecological Observatory Network and the US Forest Service. This rich dataset provides a unique opportunity to evaluate and constrain emission inventories. Comparisons between the measured fluxes and the FRP-based emissions inventory used in HRRR-Smoke will be presented as well as experimentally derived conversion factors of FRP to pyrogenic CO emissions.