PBI に伴う Pi2 地磁気振動と対応するオーロラの準周期的変動と内部磁気圏の電磁場振動

今城魚住

3)

1)峻 , 西村

2)幸敏 , 吉川
4)禎司 , Shinichi Ohtani ,中溝5)

顕正

1)3)

,葵 , V. Angelopoulos

6)1) Dept. Earth Planet. Sci., Kyushu Univ., 2) AOS, UCLA, 3) ICSWSE, Kyushu Univ.,4) APL, Johns Hopkins Univ., 5) NICT, 6) EPSS/IGPP, UCLAIUGONET研究集会2016/10/18-19

Auroral phenomena and Pi2 pulsations-3.0

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RANK

ESKI
FCHU
GILLPi 2• 25 nT

RANK

ESKI
7O

FCHU
GILL

substorm onset location'UT (hr)

Lyons et al. [1999]

PBI onset location (possible)•Pi2 pulsations are irregular geomagnetic oscillations that occur with various auroral phenomena,such as substorms, pseudo breakups, and poleward boundary intensifications (PBI).

•PBIs have the different source location and the physical process from those of substorms.

Why are PBIs and substorms associated with the same pulsation?

study have an irregular period and amplitude even thoughduring very quite geomagnetic condition. Our observations
would be attributed to source dependent signature rather
than plasmaspheric cavity mode. However, we need a direct

A09218

PBI-related Pi2 pulsations

NISHIMURA ET AL

he interval of
The orbit isand (bottom)

the PBI-Pi2
urbances, thethe westward
ns at middle/
t local times,
and no phaseobservationsy Kepko et al.
nd duration ofegion, whereations in ourKim et al.
[2002]
Figure 15. (a) bzMFA, byMFA, and Exy for event E. Thesmoothed traces in bzMFA and byMFA and Exy are filtered (2 –10 mHz). (b) Comparison of the byMFA component at Polarand the H-component at OUL and YOR.

Is the signature of theplasmaspheric resonance observed
14 of 15in theinner magnetosphere?

Nishimura et al., [2012]
Is the signature of FAC oscillating
related-Pi2 pulses observed near
the poleward boundary?

The magnetic and electric fieldobservations by the RBSP satellites

Spatial-temporal comparison
between auroral and groundmagnetic field

2013-02-06/06:59:47 event (Kp=0)

Ground based and satellite location
mcgrgakosnaprank
g15
g13
ptrs
pgeo fsmi fcc
rbsp_aredr
pina kapu ott
rbsp_bswno
tucsatellites: RBSP A,B (EMFISIS, EFW), GOES 13, 15 (fluxgate)
all sky imager: THEMIS ASI (RANK, SMAP)
ground-based magnetometer : THEMIS GMAGS, MAGDAS/CPMN

2013-02-06/06:59:47 event (Kp=0)

magnetic midnight
75°

70°

packet 1 packet 2 packet 3

Keogram and nightside magnetogram (packet 1)
KeogramQuasi-periodic auroral
emission associated with PBI

high lat.
poleward of PBI
high lat.
equatorward of PBI

Z phase reversal
across the PBI latitude

H phase reversal
at middle latitude
mid lat.

low lat.

Keogram and nightside magnetogram (packet 2,3)?

longitudinal profile at midlatitude
dusk

midnightdawn

D phase reversal

magnetic vector distribution (300 s hp-filtered)negative perturbation

positive perturbation

1 nT
5 nT

The pattern of magnetic vectors is consistent withoscillation of a pair of FACs [e.g., Lester et al., 1983]

Dayside Pi2higherlatitude

equatorialenhancement

Z phase reversal

nightside
low-latitude

Nightside Pi2 and dayside Pi2 are very similar[e.g., Sutcliffe and Yumoto, 1989].

Pi2 in inner magnetosphere: RBSP and GOES observation(300 s hp-filtered)
ab
g13
g15

Comparison of compressional component
rb a
rb a40 s

rb b
g13
g13
40 s

g15
g1540 sMagnetic and electric fields of compressive mode
rb a

rb b

~11 s resolution

Other examples of auroral signatures of PBI-Pi22599

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END
Acknowledgement
This work was supported in part by JSPS Core-to-Core Program, B. Asia-Africa Science Platforms,
by Grant-in-Aid for JSPS Fellows (15J02300), and by JSPS KAKENHI (15H05815). U.S.
Geological Survey magnetometers: Original data provided by the USGS Geomagnetism Program(http://geomag.usgs.gov). S. Mende and C. T. Russell for use of the GMAG data and NSF for support
through grant AGS-1004814. S. Mende and E. Donovan for use of the ASI data, the CSA for logisticalsupport in fielding and data retrieval from the GBO stations, and NSF for support of GIMNAST throughgrant AGS-1004736. The work by the EFW team was conducted under JHU/APL contract 922613(RBSP-EFW). This work was supported by EMFISIS funding provided by JHU/APL contracts 967399
and 921647 under NASA’s prime contract NAS5-01072. The GOES 13 and 15 magnetic field data areproduced in real time by the NOAA Space Weather Prediction Center (SWPC) and are distributed by
the NOAA National Geophysical Data Center (NGDC). We acknowledge the Inter-University
Upper Atmosphere Global Observation Network (IUGONET) project funded by the Ministry ofEducation, Culture, Sports, Science and Technology (MEXT), Japan.