17:15 〜 18:45
[AAS08-P16] The Impact of NAO on the Anomalies of Winter Lightning in the European North Sea and Britain
キーワード：Lightning, NAO, European North Sea, Azores High
Winter thunderstorms are often accompanied by severe weather such as short-term heavy snowfall, hail, gusts, and sometimes intense lightning activities. With the improvement of lightning climate datasets, recent studies have been conducted on the relationship between lightning activity anomalies (such as abnormal lightning number, increase of super lightning with energy >106 J) and the climate system.
By using lightning data from the World Wide Lightning Location Network (WWLLN) and ERA5 datasets in 2010-2022, this study focuses on the impact of North Atlantic Oscillation (NAO) on winter (from December to January) lightning activity over the European North Sea and Britain (50-66°N, 20°W-15°E). The aim is to investigate the impacts of NAO on the circulation system and sea surface temperature (SST), as well as the relationship between NAO and lightning activity. The results show that NAO is the climate system that most directly affects winter lightning activity over the European North Sea, and the NAO index is significantly positively correlated with lightning number. The composite analysis shows that the positive phase of NAO is profit to lightning activities. This is not only due to the enhancement of frontogenesis of the enhanced North Atlantic Jet, but also the rising of SST along the west coast of Europe and the increase of water vapor transported by the Azores High.
During the winter season in 2014 (from December 2014 to January 2015), there is an abnormal increase in lightning number on the sea along the western coast of Northern Europe. The lightning number during this period increases to tens of times of the mean value and has an overall mean and probability distribute on difference from that of the winter lightning mean state, with a significance of 99%. The analysis shows that the cyclonic circulation anomaly generated by the Icelandic low pressure and the anti-cyclonic circulation anomaly generated by the Azores high pressure speed up the North Atlantic westerly jet and accelerate it by 4.5 m/s. The extreme positive anomaly of NAO is benefit to frontogenesis, the rise of SST and moisture transportation, resulting in the intense lightning activity over the European North Sea in 2024 winter.NAO anomalies contribute to the extreme lightning activity in winter in this region. Nevertheless, it must be pointed out that NAO is not the only factor affecting the abnormal winter lightning activity over this region, and other influencing factors need to be further explored.
By using lightning data from the World Wide Lightning Location Network (WWLLN) and ERA5 datasets in 2010-2022, this study focuses on the impact of North Atlantic Oscillation (NAO) on winter (from December to January) lightning activity over the European North Sea and Britain (50-66°N, 20°W-15°E). The aim is to investigate the impacts of NAO on the circulation system and sea surface temperature (SST), as well as the relationship between NAO and lightning activity. The results show that NAO is the climate system that most directly affects winter lightning activity over the European North Sea, and the NAO index is significantly positively correlated with lightning number. The composite analysis shows that the positive phase of NAO is profit to lightning activities. This is not only due to the enhancement of frontogenesis of the enhanced North Atlantic Jet, but also the rising of SST along the west coast of Europe and the increase of water vapor transported by the Azores High.
During the winter season in 2014 (from December 2014 to January 2015), there is an abnormal increase in lightning number on the sea along the western coast of Northern Europe. The lightning number during this period increases to tens of times of the mean value and has an overall mean and probability distribute on difference from that of the winter lightning mean state, with a significance of 99%. The analysis shows that the cyclonic circulation anomaly generated by the Icelandic low pressure and the anti-cyclonic circulation anomaly generated by the Azores high pressure speed up the North Atlantic westerly jet and accelerate it by 4.5 m/s. The extreme positive anomaly of NAO is benefit to frontogenesis, the rise of SST and moisture transportation, resulting in the intense lightning activity over the European North Sea in 2024 winter.NAO anomalies contribute to the extreme lightning activity in winter in this region. Nevertheless, it must be pointed out that NAO is not the only factor affecting the abnormal winter lightning activity over this region, and other influencing factors need to be further explored.