Evaluating the uncertainties of a top-down mass balance emissions estimation method using aircraft measurements of industrial facilities in South Korea

A top-down mass balance emissions estimation technique can be used to quantify large point sources that include multiple sources and can capture emissions that are missed by bottom-up inventories. To demonstrate the reliability of this method, we applied it with in situ aircraft observations from three seasons (Spring, Fall, Winter) between 2019-2021 around industrial facilities in Taean, South Korea. A research aircraft maneuvered around each facility, at multiple altitudes, to map out the concentration and generate an estimate of the total flux. Measurements include trace gases (SO2, CO2, CO, NO2, O3, VOCs) and aerosols. We select key flights to demonstrate the uncertainties of different factors of the method, including ground extrapolation, interpolation technique, and number of altitudes sampled. Based on this summary of uncertainties, strategies for improving future aircraft campaigns through optimization of flight time and flight path planning will be described. Additionally, overall trends in emissions between industrial facility type and over seasons, including during the COVID-19 pandemic, will be discussed.