東京工業大学 理工学研究科 基礎物理学専攻 寺澤研究室 修士2年 樋口千夏 Statistical study of lightning activity: Periodicity and possible link with solar activity 東京工業大学　理工学研究科　基礎物理学専攻 寺澤研究室　修士2年　樋口千夏　

Contents Introduction Analysis and result discussion summary ・Solar activity ・Lightning activity Analysis and result discussion summary 1

Contents Introduction Analysis and result discussion summary ・Solar activity ・Lightning activity Analysis and result discussion summary

Variation on solar related parameter F10.7 TSI GCR year [count] [W/m^2] [ 10^-22W /m^2Hz] F10.7：solar radio flux(10.7cm) proxy of UV flux TSI：Total Solar Irradiance GCR：Galactic Cosmic Ray (Using neutron monitor data) GCR 11-year period min max 2

Variation on solar related parameter F10.7 PSD[/Hz] TSI GCR E GCR Solar flare CMEs period[day] 27~30-day period 3

Contents Introduction Analysis and result discussion summary ・Solar activity ・Lightning activity Analysis and result discussion summary

Schumann resonance(SR) (Sato,2003) Freq[Hz] Spectral intensity 7.8 14 20 5

28-day periodicity of global lightning activity ＜observation＞ ・at Syowa station in Antarctica (69.018S,39.506E) ・using search coil magnetometer ＜data＞ ・2000/2~2003/1 ・1~100Hz magnetic field data ＜SR power spectrum＞ (Sato,2003) 28-day 11 4～6 ・~5,~10-day periodicity ⇒Correlated with planetary wave activity in the tropical region ・~28-day periodicity ⇒Influence of solar activity? Power spectrum [day] 6

Cross-spectral analysis between global lightning activity and solar parameters (Sato,2003) parameter Period at the power-spectral peak[day] Period at the cross-spectral peak[day] Coherence Phase(θSR-θpar) [°] (timelags[day]) F10.7 27.8 26.9 0.56 +20-90(2-7) Cosmic Ray(CR) 30.7 30.5 0.47 - Sun Spot Number(SSN) 27.7 27.0 0.57 Kp 26.2 25.6 0.53 0(0) Dst 27.2 25.3 MeV electron 28.6 29.9 0.52 +110(8) MeV ion 33.1 31.6 0.58 Tropical cloud coverage(>8km) 24.0 0.65 ±180(0) ※Kp/Dst：Geomagnetic disturbance index 7

Possible scenario of solar influence on lightning activity ＜regional influence＞ Exp. UV ---temperature/wind modulation in stratosphere⇒vertical circulation⇒convective activity in troposphere GCR ---ionization⇒CCN⇒cloud ---ionization⇒electric breakdown Indirect influence ＜global influence＞ Exp. GCR ---ionization⇒modulation of conductivity in atmosphere through global electric circuit Direct influence 8

Madden – Julian Oscillation What is MJO? Madden – Julian Oscillation --intraseasonal(20-60days) variability in the tropical atmosphere --eastward propagation at 4-8m/s through the Indian and Pacific ocean --characterized by pressure,cloud amount,rainfall (Madden and Julian,1972) 9

Contents Introduction Analysis and result discussion summary ・Solar activity ・Lightning activity Analysis and result discussion summary

1.Lightning activity in Japan (45 prefectures) ＜data＞ ・ extract from the weather record in JMA ・1989/1～2010/12 ・in Japan(except Hokkaido and Okinawa) Time profile of lightning data in Japan Monthly distribution [%] where lightning activity occurs The number of prefectures year 10 month

※method of Histogram analysis ②  ③  ④  ⑤  ⑥  ①  where lightning activity occur The number of prefecture day period[day] 1 2 3 4 5 6 power 1（④） 1（⑥） 2（①⑤） 1（②） 1（③） power Period[day] 11

Histogram analysis of lightning activity in Japan(45) (a)The number of prefectures where lightning activity occurs：more 1 (b)more 5 (d)more 11 (e)more 12 (f)more 13 (g)more 14 (c)more 10 period[day] power ― 3σ ― average There is a ~29-day periodicity in lightning which occur in more 12 prf. 12

1.Lightning activity in Japan (32 prefectures) ＜data＞ ・extract from the weather record in JMA ・1989/1～2010/12 ・In Japan(except Hokkaido and Okinawa) 　・except the area along the sea of Japan Time profile of lightning data in Japan Monthly distribution [%] where lightning activity occur The number of prefectures year month 13

Histogram analysis of lightning activity in Japan(32) ― 3σ ― average ― 3σ ― average 28-29-day 51-day ― 3σ ― average ＜data＞ ・extract from the weather record in JMA ・1989/1～2010/12 ・in Japan ・except the area along the sea of Japan period[day] power ・March-October ・the number of prefectures where lightning activity occurs: more 9 ・the number of prefectures where lightning activity occurs: more 8 ・the number of prefectures where lightning activity occurs: more 7 28-29,51-day periodicity ⇒influence of solar activity? MJO? 14

※method of corrrelation analysis 34day 34 34 34 parameter peak ・・・・　 lightning Ｃ ＋ parameter ・・・・　= ・・・・=　 lightning 15

Correlation between Ｆ10.7/GCR-lightning(J) F10.7 time lag[day] Lightning(J) GCR F10.7 time lag[day] (1989-2010,Mar-Oct) ― 3σ ― 2σ 16

Correlation between F10.7-lightning (2000-2004/9,Mar-Oct) time　lag[day] Lightning(J) F10.7 Lightning In Africa ― 3σ ― 2σ between F10.7 and ・lightning in Africa: 　positive correlation (time lag:0day) ・lightning in Japan (time lag:20day) 　negative correlation (time lag:7day) 18

Possible scenario of solar influence on lightning activity ＜regional influence＞ Exp. UV ---temperature/wind modulation in stratosphere⇒vertical circulation⇒convective activity in troposphere GCR ---ionization⇒CCN⇒cloud ---ionization⇒electric breakdown Indirect influence ＜global influence＞ Exp. GCR ---ionization⇒modulation of conductivity in atmosphere through global electric circuit ? Direct influence 19

Contents Introduction Analysis and result discussion summary ・Solar activity ・Lightning activity Analysis and result discussion summary

Similarity between spectrum of lightning and OLR in WPWP (Takahashi,2010) Lightning in Japan OLR in WPWP period[day] PSD ― max ― min PSD 20

Possible scenario for F10.7-MJO-lightning ~28-day ~40-60-day F10.7 ~27-day ? MJO ~6m/s ~20day ~28-day low low low pressure low low low Africa ~12000km Japan 21

Contents Introduction Analysis and result discussion summary ・Solar activity ・Lightning activity Analysis and result discussion summary

summary ＜periodicity of lightning in Japan＞ ・There are ~28,51-day periodicity for 3 sigma significance in lightning which occur in more 9 prefectures except along the sea of Japan . ⇒influence of solar activity or MJO ?? ＜correlation between solar activity and lightning＞ ・There is a good correlation between lightning in Japan and F10.7/GCR for 3 sigma significance. The response is indirect influence of F10.7/GCR on lightning since there are response time lags. ・There is a good correlation with no time lag between lightning in Africa and F10.7 for ~3 sigma significance. ⇒possible link between F10.7, MJO and lightning 22