Seminar

Abstract

Air quality forecasts using chemical models provide key information for affected communities and smoke management efforts, yet many models fail to accurately predict ozone (O3) and particulate matter levels during fire events. Furthermore, smoke from fires absorbs solar radiation and provides condensation nuclei for clouds, impacting weather forecast parameters such as surface temperature and precipitation. Major sources of simulation uncertainty are satellite-based emissions and model representations of chemistry. First, I will discuss an analysis of the first Amazon Basin-wide aircraft measurements of O3 during both transition seasons. Extremely low background values of O3 were observed in remote regions, while elevated O3 was seen in areas impacted by fires. Model errors in low NOx chemistry contributed to simulation overestimates of O3 in clean conditions. Next, I will describe ongoing research on the effect of model aerosol-radiation-cloud interaction representation complexity on meteorological forecasting skill over South America during a heavy smoke period. Third, I will detail a study utilizing the first fire emissions estimates based on airborne absorption measurements (University of Colorado Solar Occultation Flux (CU SOF) instrument) during the highly destructive October 2017 northern California wildfires. The CU SOF carbon monoxide emissions estimates reduce the uncertainty to about a factor of two compared to four orders of magnitude in the satellite-based inventories. We scaled WRF-Chem emissions to the SOF-based estimates and included diurnal cycle and spatial information obtained from Geostationary Operational Environmental Satellite (GOES)-16 retrievals of Fire Radiative Power (FRP), resulting in significant improvement in simulated plume transport. The WRF-Chem simulations are used to explore O3 and secondary organic aerosol (SOA) production from fire emissions. Finally, I will discuss plans to use FIREX-AQ field and satellite observations to improve the WRF-Chem model’s ability to simulate wildfire emissions, plume rise, and atmospheric composition.

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Megan Bela earned a BS in Environmental Engineering and a MS in Environmental Fluid Mechanics and Hydrology from Stanford University. She then worked in Brazil as a Fulbright Scholar at the University of Sao Paulo, and as research scientist at the National Institute for Space Research. She completed her PhD in Atmospheric and Oceanic Sciences from the University of Colorado. In 2016, she joined NOAA as an NRC Postdoctoral Fellow in the Global Systems Division.