A gamma-ray glow terminated byleader development of an inter-cloud discharge
in Japanese winter thunderstorm

Yuuki Wada (The University of Tokyo/RIKEN)
G. Bowers3, T. Enoto4, M. Kamogawa5, Y. Nakamura6,
T. Morimoto7, D. Smith8, Y. Furuta1, K. Nakazawa9,T. Yuasa, T. Tamagawa2, K. Makishima2, H. Tsuchiya10
1: Univ. of Tokyo, 2: RIKEN, 3: LANL, 4: Kyoto Univ., 5: Tokyo Gakugei Univ.,
6: Kobe City College of Tech., 7: Kindai Univ., 8: UCSC, 9:Nagoya Univ., 10: JAEA

Wada et al., GRL, submitted10th April 2018

European Geoscience Union General Assembly 2018 (EGU2018-5939)

Gamma-ray glows: stable electron acceleration

・Long-duration gamma-ray bursts associated with passage of a thundercloud.
5050＞ 3 MeVCount-rate history
4040 8 Dec. 2016
Ishikawa
35

Counts s-1

Count Rate (count/sec)

45

3030
25

20

20

15

10 minLasting~ minutes

1010
50002:30

02:40

02:40

02:50

03:00
Date (JST)03:00
Time (JST)03:10

detector

03:20

03:20

・Gamma-ray glow detection by- airborne experiments- mountain-top experiments(McCarthy & Parks 85, Eack+96, Kelley+15)(Moore+01, Chilingarian+10, 11, 16, Torii+09, Tsuchiya+12)

・Observations in Japanese winter thunderstorms- Low cloud-base altitude, large discharge current, powerful activity.
-> Suitable for on-ground gamma-ray observation.
(Torii+02,11, Tsuchiya+07,11,13, Kuroda+16)
10th April 2018

European Geoscience Union General Assembly 2018 (EGU2018-5939)

Gamma-ray glow termination by lightning

・Gamma-ray glows are sometimes terminated with lightning.
(McCharthy & Parks 86, Tsuchiya+13, Kelley+15, Chilingarian+17)

Tsuchiya+13

Lightning
Lightningdetector

・Lightning itself can be detected by radio monitors.
-> Radio monitors can be the “forth eye” to observe glows.
(besides gamma-ray, electric-field monitors and radar)・2D/3D mapping of lightning processes (e.g. lightning mapping array).
-> Does a combination of gamma-ray, electric-field, radar and radio
observations provide us clues to understand gamma-ray glows?
10th April 2018

European Geoscience Union General Assembly 2018 (EGU2018-5939)

On-ground observation in Noto Peninsula

・Two gamma-ray monitors and an electric field monitor in Noto Peninsula
・Low frequency radio monitor network along Toyama Bay (LF: 800 Hz - 500 kHz)Japan Sea

GROWTH detector (Enoto+17)- 3 inch BGO scintillator

Gamma-rayobservation siteNotoP

eni nsul a50 kmToyama
BayGODOT detector (Bowers+17)- 5 inch NaI scintillator

LF stations
Flat plate antenna
10th April 2018

European Geoscience Union General Assembly 2018 (EGU2018-5939)

Gamma-ray glow event on 11th Feb. 2017
BGO scintillator
0.2-7.0 MeV
5-sec binGamma-ray glow

Termination

NaI scintillator
0.3-20.0 MeV
5-sec binAtmospheric electric field

Positive pulse-> Lightningdischarge

120 sec

Gamma-ray monitors detected a gamma-ray glow termination event.
10th April 2018

European Geoscience Union General Assembly 2018 (EGU2018-5939)

Lightning Mapping with LF monitoring stations

・LF network detected leader development of an IC.

~70 km~300 ms

Termination timeof gamma-ray glow
t = 9310th April 2018

52 ms

European Geoscience Union General Assembly 2018 (EGU2018-5939)

Lightning Mapping with LF monitoring stations

・LF network detected leader development of an IC.

Gamma-ray monitors
IC process passednearby the monitors.

Termination timeof gamma-ray glowt = 93

10th April 2018

52 ms

European Geoscience Union General Assembly 2018 (EGU2018-5939)

Lightning Mapping with LF monitoring stations

・LF network detected leader development of an IC.
Distance fromgamma-ray monitors

Nearest pulses (< 1 km)
LF waveform Timing is consistent withglow termination.

Termination timeof gamma-ray glow

10th April 2018

European Geoscience Union General Assembly 2018 (EGU2018-5939)

Lightning Mapping with LF monitoring stations

・LF network detected leader development of an IC.
IC started away fromthe glow site.
15 km

Gamma-ray monitors

IC start point

10th April 2018European Geoscience Union General Assembly 2018 (EGU2018-5939)

Discussion

・Relativistic Runaway Electron Avalanche process (Grevich+92, Dwyer+12)
should be developed in thundercloud.
-> Accelerated and multiplied electrons emit gamma rays.
・A part of the IC processes passed nearby the glow site.
-> Destroyed the RREA process, then terminated the glow.
・The IC started away from the glow site, prior to the glow termination.
-> The glow did not initiate the IC in this case.
~70 kmpm
IC leader develo

IC start pointーー＋＋en t
7 km

Glow site
300 m~1 km

10th April 2018

European Geoscience Union General Assembly 2018 (EGU2018-5939)

Conclusion
・We performed observation of Japanese winter thunderstorms
with gamma-ray, electric-field and LF-band radio monitors.
・Gamma-ray monitors at the top of Noto Peninsula observed
a gamma-ray glow termination event on 11th February 2017.
・Electron-acceleration mechanism was destroyed by
IC processes passing nearby the gamma-ray observation site.
・The IC started away from the gamma-ray glow site.
The glow did not initiate the IC in this case.

Winter thunderstorms in Japan provide us fruitful scientific resultsof both gamma-ray glows and TGFs / photonuclear reactions!
10th April 2018

European Geoscience Union General Assembly 2018 (EGU2018-5939)