[A-CG44] Kuroshio Large Meander

[ACG44-05] Influence of the Kuroshio system and its large meander on the spatiotemporal variation in lightning strikes

*Yoshihiro Tachibana¹, Misa Kato¹, Satoru Kasuga¹, Erina Shigeta², Hiroko Sato², Michihiro Matsui² (1.Mie University, 2.Franklin Japan Corporation )

Keywords:Thunderbolt, Kuroshio large meander, winter lightning, Asian monsoon, Lightning climatology around Japan

Warm western boundary currents are associated with increased precipitation events, which are in turn conducive to the formation of lightning. The Asian monsoon regions, which experience the highest rainfall within their latitudinal zones, should similarly experience increased lightning frequency. Japan is unique in that both of these factors affect the frequency of lightning. However, despite the high population density and potential for natural disasters in Japan, the spatiotemporal variations in the occurrence of lightning around the country has not been clarified to date. Here we show that the incidence of lightning is influenced by the Kuroshio path system. Lightning is more likely to occur in areas with a high sea surface temperature (SST) than in areas with a relatively low SST. Not only the climatic values, but also the interannual variations in lingtning frequency linked to SST. Specifically, the Kuroshio Large Meander affects lightning occurrence, which is more prevalent in areas with warm SST anomalies associated with the meander activate the thunderbolts. The warm ocean, which supplies large amounts of water vapor and heat, is favorable for the development of lightning. The abundance of winter lightning, another peculiarity of regions affected by the Asian winter monsoon, is also linked to the Tsushima Warm Current, which flows through the Japan Sea and has its source in the Kuroshio. The temperature difference between the sea surface and the upper troposphere, which is an indicator of vertical deep mixing, is also a good indicator of the potential for lightning occurrence and the interannual variations therein. Similar relationships may exist in other oceans, particularly in other western boundary currents, where the ocean's own SST variability is greater than the other world oceans.