## 5 Summary and Discussion
### Discussion  
When recording EN events, although this study only shows the EN events since 1979 calculated using ERA5 SST data, we combined climate data from the NCEP, part of the National Oceanic and Atmospheric Administration, to analyze EN events over a longer time scale since 1950. Statistical results that were not fundamentally different from those of ERA5 were observed. We found that the intensity of EN extreme events (ONI peak SSTA \(\geq\) 1.8 \({}^{\circ}\)C) has been gradually increasing over the past half-century. ONI peaked at 1.8 \({}^{\circ}\)C in 1958, 2.0 \({}^{\circ}\)C in 1965, 2.1 \({}^{\circ}\)C in 1972, 2.2 \({}^{\circ}\)C in 1982, 2.4 \({}^{\circ}\)C in 1997 and 2.6 \({}^{\circ}\)C in 2015. Such increases in the intensity of extreme EN events should prompt vigilance and increased awareness. It is also likely to be an example of how extreme weather events have become more extreme since global warming began. Correspondingly, the influence of EN on stratospheric ozone will be greater, highlighting the importance of studying EN.  
Conceptualization, Y.W., S.C. and Y.L.; methodology, Y.W., S.C., Y.L. and L.W.; software, Y.W., L.W. and Y.L.; validation, F.X. and S.C.; formal analysis, Y.W., S.C. and Y.L.; investigation, Y.W., S.C. and Y.L.; resources, Y.W., L.W. and Y.L.; data curation, Y.W. and L.W.; writing--original draft preparation, Y.W.; writing--review and editing, Y.W., F.X. and S.C.; visualization, Y.W. and Y.L.; supervision, F.X. and S.C.; project administration, F.X. and S.C.; funding acquisition, F.X., S.C. and L.W. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Guangdong Basic and Applied Basic Research Foundation (2023A1515011323), the National Natural Science Foundation of China (42005063), the Fundamental Research Funds for the Central Universities (202362001 and 202072010), the National Natural Science Foundation of China Key program (42130604), the Program for Scientific Research Start-Up Funds of Guangdong Ocean University (060302032107), the First-Class Discipline Plan of Guangdong Province (080503032101 and 231420003) and the China Scholarship Council (202208440223).  
Not applicable.  
Data Availability Statement: The ERA5 datasets from the study at [[https://cds.climate.copernicus.eu/](https://cds.climate.copernicus.eu/)]([https://cds.climate.copernicus.eu/](https://cds.climate.copernicus.eu/)) (accessed on 1 November 2023). Announcements and support for running WACCM can be found at [[https://www2.acom.ucar.edu/gcm/waccm](https://www2.acom.ucar.edu/gcm/waccm)]([https://www2.acom.ucar.edu/gcm/waccm](https://www2.acom.ucar.edu/gcm/waccm)) (accessed on 1 November 2023). And the ONI can be found at [[https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php](https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php)]([https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php](https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php)) (accessed on 1 November 2023).  
The authors would like to thank the editors and the reviewers for their valuable suggestions. The authors declare no conflict of interest. The authors declare no conflict of interest.