The THEMIS reveal
morphology of Pc4 pulsations
excited after substorm onset andAuroral streamer
波多江 真紀1), 吉川 顕正2), 魚住 禎司3)
1) Department of Earth and Planetary Sciences, Graduate School of Sciences, KyushuUniversity2) Department of Earth and Planetary Sciences, Faculty of Sciences, Kyushu University
3) International Center for Space Weather Science and Education, Kyushu University

Outline・Introduction
・Background・Purpose of study
・Research techniques
・Aurora structure and data
・Summary・Future work

Introduction
・Substorm-Tail reconnection triggering
substorm onset-Substorm is categorized into
three stage, Growth phase,Expansion phase, Recoveryphase.
Growthphase
Pi2ExpansionphaseFig.1

earth’magnetosphere

http://www.aeronomie.be/en/news-press/2013-09-18-vanallen-plasmasphere.htm

Pc4

RecoveryphaseIntroduction・magnetic pulsation-many magnetic pulsations in the magnetosphere-In particular, Pi2 and Pc4 are related to the substorm

TypePeriod
Frequency
Range[sec] range[mHz]Pc1

0.2-5200-5000

Pc2

5-10

100-200

Pc3

10-45

22.2-100

Pc445-150

6.67-22.2

Pc5

150-600

1.67-6.67

Pc6＞600＜1.67

Pi11-40

25-1000

Pi240-150

6.67-25

Pi3＞150＜6.67

Waveform・Features

Continuous
regular

Irregular

Table1 Hydromagnetic pulsation are classified into waveform and period RangeBackgroundPi2・Shishime(2013)

Pc4・Observating on high latitude station andsynchronous orbit that nightside Pc4 pulsations
excited by substorm events.
・Pi2 occurs on substorm onset,and then Pc4 occurs
from expansion phase to recovery phase of substorm.

AE Index
Fig.2 MAGDAS/CPMN station
Red point：210 degree meridianchainstation
black point：Africa magnetic equator
star：ETS-VIII projected ground point

Fig.3 the upper 2009/05/22 21:00～24:00LT BPF plot
the lower AE Index
http://magdas.serc.kyushuu.ac.jp/station/index.html

Background〇Wave classification
・Pc4→Alfven wave
・Pi2
→Magnetic sound wave

Fig.4 Conceptual diagram

Purpose of study
・They results suggest that Pi2 occurs on substorm onset,
and then Pc4 occurs from expansion phase to recovery phaseof substorm.
・substorm and Pc4 pulsations are related.
↓・The THEMIS reveal morphology of Pc4 pulsations excited after
substorm onset and Auroral streamer

Research techniques
・THEMIS mission-5 satellite which was launched by NASA in 2/2007 incooperation with all-sky cameras on the ground and fieldobservation, launched aim to elucidate the mechanism of thesubstorm. Learn more about each satellite to magnetic
particles, temperature and global head e-flow, etc.

Fig.6 THEMIS speace crafts inmagnetsphere

http://themis.ssl.berkeley.edu/overview.shtml

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Aurora structure(Westward travelling surge/S-fractal aurora)-westward front of expansion
auroral-going westward with S-fractalaurora-Dots indicate upward FAC, andUp ward
crosses are downward FAC

Down ward

Fig.6 J.C. SAMSON and G.ROSTOKER(1982)Aurora structure(N-S Auroral/N-S aligned arc)-elimination from center ofWestward travelling surge-propagation to low
latitudeFig.7 J.C. SAMSON and G.ROSTOKER(1982)

Researchtechniques-current structure reveal from
Magnetic field data of thestation surge shows-the structure in the earth
project on magnetosphere-reveal auroral streamer
magnetosphereinAurora structure
(WTS)

WTS

〇Magnetic field data and Band-pass filter＊2008/3/2〇FSMI〇INUVUT 07:03:51

Fig.6 2008/3/2 UT07:03:51
WTS

7:00

7:00

Fig.8 2008/3/2 Pc4 data

UT 07:07:03

Fig.9 2008/3/2 UT07:07:03

Aurora structure(Pulsating aurora)-Brighness is uniform , shape is Arc-Brighness of Aurora patch fluctuates quasi-periodically from a few
seconds to a few tens of seconds

Fig.10 2008/3/11 movie snkq

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Aurora structure(Pulsating aurora)Fig.11 2008/3/5 movie fsmiFig.13 2008/3/11

Fig.12 current structure torch and omega band

fsmi data

http://polaris.nipr.ac.jp/~SD/sdjapan/wor
kshop/2016NIPR/15-SATO_Omega.pdf

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Aurora structure(Pulsating aurora)Fig.14 2008/3/11 movie snkq

Fig.15 2008/3/11

snkq dataSummary〇サージのアクティビティの伝播
・サージの伝播によってPi2like(transient Pc4)の現れるアクティビティの移動を確認することができた→オーロラストリーマーが夕方側にフローを起こしているのではないか？
〇Pc4likeな波の伝播・サージ以外のオーロラの構造でもPc4likeな波が見えた→現在パルセーティングオーロラとPc4の波が起こるということは言われていないので他のイベントも確認し統計解析を行っていくFuture work・磁気データからメソスケールでの大規模な等価電流系の推定を行っていく。
→M-Iカップリングの電流系を明らかにしていく・オーロラ画像において、オーロラの流線の可視化を行い、オーロラ画像からオーロラの自動検出を行う。
→プラズマフローを明らかにしていく