Sensitivity of the WRF-Chem v4.4 simulations of ozone and formaldehyde and their precursors to multiple bottom-up emission inventories over East Asia during the KORUS-AQ 2016 field campaign

page1932In this study, the WRF-Chem v4.4 model was utilized to evaluate the sensitivity of Oinline-formula₃ simulations with three bottom-up emission inventories (EDGAR-HTAP v2 and v3 and KORUS v5) using surface and aircraft data in East Asia during the Korea-United States Air Quality (KORUS-AQ) campaign period in 2016. All emission inventories were found to reproduce the diurnal variations of Oinline-formula₃ and its main precursor NOinline-formula₂ as compared to the surface monitor data. However, the spatial distributions of the daily maximum 8 h average (MDA8) Oinline-formula₃ in the model do not completely align with the observations. The model MDA8 Oinline-formula₃ had a negative (positive) bias north (south) of 30° N over China. All simulations underestimated the observed CO by 50 %–60 % over China and South Korea. In the Seoul Metropolitan Area (SMA), EDGAR-HTAP v2 and v3 and KORUS v5 simulated the vertical shapes and diurnal patterns of Oinline-formula₃ and other precursors effectively, but the model underestimated the observed Oinline-formula₃, CO, and HCHO concentrations. Notably, the model aromatic volatile organic compounds (VOCs) were significantly underestimated with the three bottom-up emission inventories, although the KORUS v5 shows improvements. The model isoprene estimations had a positive bias relative to the observations, suggesting that the Model of Emissions of Gases and Aerosols from Nature (MEGAN) version 2.04 overestimated isoprene emissions. Additional model simulations were conducted by doubling CO and VOC emissions over China and South Korea to investigate the causes of the model Oinline-formula₃ biases and the effects of the long-range transport on the Oinline-formula₃ over South Korea. The doubled CO and VOC emission simulations improved the model Oinline-formula₃ simulations for the local-emission-dominant case but led to the model Oinline-formula₃ overestimations for the transport-dominant case, which emphasizes the need for accurate representations of the local VOC emissions over South Korea.