## 2 Materials and Methods
### Characteristics of the Ozone Valley over the TP Affected by Different Types of EN Events  
The statistical time of the ozone valley over the TP in this study is 44 years from 1979 to 2022. As is shown in Figure 2, the ozone valley is distributed horizontally in the TP and the Iranian Plateau, with a peak central intensity of approximately \(-1.2\) DU. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Time**} & **Beginning** & \multirow{2}{*}{**Duration/Month**} & **Spatial** & **Temporal** & **Peak** & \multirow{2}{*}{**Peak Time**} & **Impact Years** \\  & **Month** & & **Type** & **Type** & **SSTA/C** & & \\ \hline
1982.03–1983.06 & 03 & 16 & EP & SP & 2.27 & 1982.12 & 1983 \\
1986.10–1987.11 & 10 & 14 & EP & SU & 1.92 & 1987.06 & 1988 \\
1991.10–1992.06 & 10 & 9 & EP & SU & 1.93 & 1992.04 & 1992 \\
1993.03–1993.07 & 03 & 5 & CP & SP & 1.72 & 1993.05 & 1993 \\
1997.04–1998.05 & 04 & 14 & EP & SP & 2.44 & 1997.11 & 1998 \\
2002.04–2003.01 & 04 & 10 & CP & SP & 1.22 & 2002.11 & 2003 \\
2004.04–2004.08 & 04 & 5 & CP & SP & 0.70 & 2004.07 & 2005 \\
2009.10–2010.05 & 10 & 8 & CP & SU & 1.31 & 2010.04 & 2010 \\
2015.03–2016.06 & 04 & 16 & EP & SP & 2.44 & 2015.11 & 2016 \\
2019.03–2019.07 & 03 & 5 & CP & SP & 1.56 & 2019.05 & 2019 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Different types of EN events from 1979 to 2022. \begin{table}
\begin{tabular}{c c} \hline \hline \multirow{2}{*}{**Categories**} & \multicolumn{2}{c}{**The Year of the Ozone Valley in the Summer of the Following Year**} \\  & **Affected by the Peak of EN Events** \\ \hline EP & 1983, 1988, 1992, 1998, 2016 \\ CP & 1993, 2003, 2005, 2010, 2019 \\ SP & 1983, 1992, 1998, 2003, 2005, 2016, 2019 \\ SU & 1988, 1992, 2010 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Years of summer ozone valley affected by various EN events from 1979 to 2022. Figure 2: Average ozone valley in the Tibetan Plateau region during 1979\(-\)2022. The black lines represent the contours of TCO* = \(-0.6\); unit: DU. To demonstrate the influence of EN events on the Tibetan high-pressure ozone valley, the TCO* and TCO results in the summer of the following year of EN are compared with the 44-year mean climate results, and the t-test was carried out to show the intuitive differences (Figure 3). The negative value of the TCO* difference (blue area in Figure 3a) represents a deepening of the ozone valley, i.e., more ozone loss and more UV radiation exposure to the ground. Positive values (red areas in Figure 3a) indicate a shallower ozone valley and an increase in ozone. It can be seen from Figure 3a that the phenomenon of the ozone valley in the TP region in the following year of EN is weakened. The strongest effect was found in northeast China at 0.21 DU. It should be noted that the change in TCO* values here represents the difference in the shape of the ozone valley between the two periods, encompassing the effect of EN on the ozone across the entire latitude circle. Therefore, assessing the specific effects of EN events also requires consideration of TCO variations (Figure 3b), that is, the difference between the total ozone column content without zonal deviation and the climate average. The change in TCO can better measure the influence of EN on the local ozone content. The overall spatial pattern of TCO presents a relatively regular zonal distribution along the latitude circle. From the equator north to approximately 30\({}^{\circ}\) N, i.e., the middle and low latitudes on the south side of the TP, the difference in TCO is negative and becomes more negative approaching the equator. Conversely, north of 30\({}^{\circ}\) N, the difference in TCO is mainly positive, with a high-value area near 40\({}^{\circ}\) N. The two strong positive anomaly centers emerge in the northeast of China and the northwest of the TP, reaching 0.27 DU and 0.22 DU, respectively. Between 50\({}^{\circ}\) N and 60\({}^{\circ}\) N, two minor TCO negative anomaly regions are observed, with an intensity of approximately \(-\)0.15 DU.