Identification of New Pollution Hotspots From Satellite‐Based Emission Inventory Under a Local Circulation‐Dominated Environment Over Complex Topography

Abstract This study aims to identify local circulation‐dominated pollution hotspots using satellite‐based emission data sets and large eddy simulations (LES). The top‐down nitrogen oxides (NOx) emissions based on satellite data provide improved accuracy, enabling clearer identification of pollution hotspots. A comparison between the top‐down NOx emissions and government emission inventories was conducted to highlight the significance of the new emission method in shaping pollution hotspots. The Taiwan Vector Vorticity Equation cloud‐resolving model (TaiwanVVM) was used to better resolve turbulence structures in local circulations and boundary‐layer processes. Coupled with a chemical module, the formation and evolution of pollution hotspots at the local scale were clearly examined in the high‐resolution LES of TaiwanVVM. The composite results showed similar daytime pollution patterns even under different emission inventories. However, there was a significant difference in the nighttime pollution hotspots. Detailed analysis revealed that the lee vortices influenced pollution hotspot locations and facilitated offshore pollution transport, effectively reducing onshore concentrations even when boundary layer heights were low around midnight. Through the case study, differences in emission source inventories directly contributed to nighttime concentration differences, while variations in chemical processes also influenced the formation of pollution hotspots. This study emphasizes the importance of satellite‐based emission inventories in identifying new pollution hotspots and highlights the role of lee vortices in shaping these hotspots, providing valuable insights for emission regulation and for adapting to future climate scenarios using semi‐realistic simulations.