We clarified the seasonal variations of PAN pollution, influencing factors, its mechanisms, and impacts on O₃ based on OBM and GAM models. PAN presented inhibition and promotion effects on O₃ under low and high RO_x levels. Monitoring of PAN and its precursors, and the quantification of its impacts on O₃ formation, significantly guide photochemical pollution control. The analysis methods used in this study provide a reference for study of the formation mechanisms of PAN and O₃ in other regions.

Based on the OBM-MCM model analyses, the study aims to clarify (1) the pollution characteristics of O3 and its precursors, (2) the atmospheric oxidation capacity and radical chemistry, and (3) the O₃ formation mechanism and sensitivity analysis. The results are expected to enhance the understanding of the O₃ formation mechanism with low O₃ precursor levels and provide scientific evidence for O₃ pollution control in coastal cities.

Intense and localised emissions of pollutants are common in urban environments, in which turbulence cannot mix these segregated pollutants efficiently in the atmosphere. Despite their relatively high resolution, regional models cannot resolve such segregation and assume instantaneous mixing of these pollutants in their model grids, which potentially induces significant error in the subsequent chemical calculation, based on our calculation with a model that explicitly resolves turbulent motions.

We provide a statistical framework for detecting trends of multiple autocorrelated time series from sparsely sampled profile data. The result is a better and more consistent quantification of trend estimates of vertical profile data. The focus was placed on the long-term ozone time series from commercial aircraft and balloon-borne ozonesonde measurements. This framework can be applied to other trace gases in the atmosphere.

Ozone, carbon monoxide and relative humidity were measured by two China Airlines aircraft equipped with IAGOS instruments during the summer of 2016. We examined landing and take-off profiles near Taipei (Taiwan), in the vicinity of three typhoons, in relation to ERA-5 meteorological reanalyses. Upstream of the storms, these data suggest that air is transported downwards from the stratosphere. Downstream, the troposphere is cleaner and moister due to the uplift of marine boundary layer air.