## 3 Results
### Ratio Characteristic of Long-Range Transport Component
Regarding the correlation between CO and CO\({}_{2}\), CO\({}_{2}\) displayed a relatively homogenous concentration throughout the study period. However, CO concentration was obviously increased during the event period. That is, the increasing rate of CO as an origin of CO\({}_{2}\) was not related to the CO\({}_{2}\) increase during the event period, meaning that the ratio of CO/CO\({}_{2}\) could be used as an indicator for external influxes. To examine SOA inflow by SNA, we examined the correlation between [NO\({}_{3}\)\({}^{-}\)/SO\({}_{4}\)\({}^{2-}\)] and [NH\({}_{4}\)\({}^{+}\)/SO\({}_{4}\)\({}^{2-}\)] and the correlation between NH\({}_{3}\) and NO. Figure 7 shows a linear relationship between [NO\({}_{3}\)\({}^{-}\)/SO\({}_{4}\)\({}^{2-}\)] and [NO\({}_{4}\)\({}^{+}\)/SO\({}_{4}\)\({}^{2-}\)]. Meanwhile, it was confirmed that NH\({}_{3}\) increased more than NO during the event period. In PM\({}_{2.5}\) compositions, PM\({}_{2.5}\) introduced during the event period flowed into the study area in a type of SOA based on SNA. However, NO\({}_{2}\) and SO\({}_{2}\) were not introduced in gas states because they completely reacted with NH\({}_{3}\). On the other hand, it was confirmed that the remaining NH\({}_{3}\) was introduced into the study area after reacting with atmospheric NO\({}_{2}\) and SO\({}_{2}\). Therefore, a linear relationship between [NO\({}_{3}\)\({}^{-}\)/SO\({}_{4}\)\({}^{2-}\)] and [NH\({}_{4}\)\({}^{+}\)/SO\({}_{4}\)\({}^{2-}\)] in PM\({}_{2.5}\) could play a role as an indicator that NH\({}_{3}\)/NO increases atmospheric NH\({}_{3}\) due to external influxes. The correlation between eBC and EC during the event period also showed a linear proportional relationship, with an eBC/EC ratio of approximately 2.0. It was hard to evaluate external influxes based on the ratio of eBC to EC. However, when data on 28 January and 1 February, which had strong external influxes during the event period, were analyzed, the ratio of eBC/EC could be used as an evaluation index for strong external influxes because it increased from 2.0 to 2.4 or higher. \begin{table}
\begin{tabular}{c c c c c c c} \hline  & **Compound** & **Unit** & **Overall Average** & **LRT (\({}^{\text{th}}\)) Periods** & **Other Periods** & **Ratio (\({}^{\text{th}}\))** \\ \hline
**Gas** & CO & ppb & 202.175 & 283.010 & 184.521 & 1.534 \\  & NH\({}_{3}\) & ppb & 6.974 & 14.748 & 5.366 & 2.749 \\ PM\({}_{2.5}\) & PM\({}_{2.5}\) mass & \(\upmu\)g/m\({}^{3}\) & 21.869 & 50.863 & 15.388 & 3.305 \\  & eBC & \(\upmu\)g/m\({}^{3}\) & 0.916 & 1.943 & 0.692 & 2.807 \\  & CC & \(\upmu\)g/m\({}^{3}\) & 4.816 & 7.577 & 4.184 & 1.811 \\  & EC & \(\upmu\)g/m\({}^{3}\) & 0.453 & 0.789 & 0.376 & 2.101 \\  & WSOC & \(\upmu\)g/m\({}^{3}\) & 3.186 & 5.239 & 2.716 & 1.929 \\  & NO\({}_{3}\)\({}^{-}\) & \(\upmu\)g/m\({}^{3}\) & 5.149 & 17.172 & 2.397 & 7.163 \\  & SO\({}_{4}\)\({}^{2-}\) & \(\upmu\)g/m\({}^{3}\) & 2.754 & 5.928 & 2.028 & 2.923 \\  & NH\({}_{4}\)\({}^{+}\) & \(\upmu\)g/m\({}^{3}\) & 2.452 & 6.821 & 1.452 & 4.696 \\ \hline \end{tabular} \({}^{(\text{th})}\) Long-range transport; \({}^{(\text{th})}\) ratio of long-range transport to other periods.  
\end{table} 
Table 2: Concentrations of tracer components for long-range transport.