Commission H: Waves in Plasmas (November 2010 – October 2013)
Edited by Yoshiharu Omura (omura@rish.kyoto-u.ac.jp)
Satoshi Yagitani (yagitani@reg.is.t.kanazawa-u.ac.jp)
Based on the papers published from November of 2010 to October of 2013, we compiled
major achievements in the field of plasma waves and related studies made by Japanesescientists and their collaborators. We categorize the studies into three groups as shownin Contents. Each section provides a specific summary of important scientificachievements rather than a comprehensive report of the whole research activities ofJapanese Commission H. On the other hand, the reference list attached at the end isintended to be used as a database of all papers we have collected from the JapaneseCommission H members.

Contents
H1. Space Observation and Experiment of Plasma Waves
H1.1

Magnetospheric Plasma Waves

H1.2

Lunar and Planetary Plasma Waves

H1.3

Ground Observation and Experiment of Plasma Waves

H2. Theory and Computer Experiment on Plasma Waves
H2.1

Acceleration and Scattering of Particles

H2.2

Generation and Propagation of Plasma Waves

H2.3

Development of Simulation Codes and Data Analysis Systems

H3. New Instruments and Sensors for Plasma Wave Experiments

References:

Published Papers (November 2010 – October 2013)1

H1. Space Observation and Experiment of Plasma Waves
H1.1

Magnetospheric Plasma Waves<Akebono>Natural plasma wave observations by the plasma wave and sounderexperiments and thermal ion observations by the suprathermal ion mass spectrometer
onboard the Akebono (EXOS-D) satellite at ~9000 km altitude in the polar
magnetosphere during the geomagnetic storms showed that ions in the region ofenhanced electron density in the polar cap were dominated by very-low-energy O+ ionswith upward velocities of 4-10 km s-1. These signatures are consistent with high-density
plasma supplied by the cleft ion fountain mechanism. Trajectory calculations of O+ ionsbased on the Akebono observations indicated that the velocities of the very-low-energy
upflowing O+ ions through the dayside polar cap are enough to reach the magnetosphere
under strong convection. Thus, the initially very-low-energy O+ ions can contributesignificantly to the ring current formation during geomagnetic storms since some of theO+ ions were transported into the ring current region with typical energies of ring
current ions (several tens of keV) in the trajectory calculations [Kitamura et al., 2010a].
To determine the characteristics and origin of observed storm-time electron
density enhancements in the polar cap, and to investigate the spatial extent(noon-midnight direction) of associated O+ ion outflows, Kitamura et al. [2010b]
analyzed nearly simultaneous observations of such electron density enhancements fromthe Akebono satellite and ion upflows from the Polar satellite during a geomagnetic
storm occurring on 6 April 2000. The Akebono satellite observed substantial electron
density enhancements by a factor of ~10-90 with a long duration of ~15 h at ~2 RE in thesouthern polar region. Velocity filtering of the ion outflow from the cleft ion fountain is
identified by the Polar satellite measurements in the polar cap at (~1.8-3.5 and ~7-4 RE).
This coordinated Akebono-Polar observation is consistent with the development ofstorm-time electron density enhancements in the polar cap as a result of the bulk
outflow of low-energy plasma as part of the cleft ion fountain. The large spatial scale,large ion fluxes, and the long duration indicate significant supply of very-low-energy O+
ions to the magnetosphere through this region.
Kitamura et al. [2011] constructed an empirical model of the electron density
profile with solar zenith angle (SZA) dependence in the polar cap during
geomagnetically quiet periods using 63 months of Akebono satellite observations at
solar maximum. The electron density profile exhibits a transition at ~2000 km altitude2

only under dark conditions. The electron density and scale height at low altitudes
change drastically, by factors of 25 (at 2300 km altitude) and 2.0, respectively, as the
SZA increases from 90° to 120°. Comparisons between the present statistical results andmodeling studies of the polar wind indicate that the plasma density profile (especially of
the O+ ion density) in the polar cap is strongly controlled by solar radiation onto theionosphere by changing ion and electron temperatures in the ionosphere during
geomagnetically quiet periods.
When the Akebono satellite passed through the plasmasphere, a series oflightning whistlers was often observed by its analogue wideband receiver (WBA).
Bayupati et al. [2012] analyzed two typical events representing the clear dispersion
characteristics of lightning whistlers along the trajectory of Akebono. The observed
trends of whistler dispersion were compared with the ones theoretically derived using a
dipole geomagnetic field model and two types of electron density profiles. They showedthat the observed trends basically agree with the theoretical results and small deviation
between them can be fitted by the optimization of electron density profile. This factdemonstrates that the dispersion analysis of lightning whistlers is a useful techniquefor reconstructing the electron density profile in the Earth’s plasmasphere.
Relativistic electron flux in the outer radiation belt tends to increase during
the high-speed solar wind stream (HSS) events. Miyoshi et al. [2013] demonstrate thatduring HSS events with the southward interplanetary magnetic field (IMF)-dominant
HSS (SBz-HSS), relativistic electrons are accelerated by whistler mode waves; however,during HSS events with the northward IMF-dominant HSS, this acceleration
mechanism is not effective. The differences in the responses of the outer radiation belt
flux variations are caused by the differences in the whistler mode wave-electroninteractions associated with a series of substorms. During SBz-HSS events, hot electron
injections occur and the thermal plasma density decreases due to the shrinkage of theplasmapause, causing large flux enhancement of relativistic electrons through whistler
mode wave excitation. These results explain why large flux enhancement of relativistic
electrons tends to occur during SBz-HSS events.
Akebono observed electromagnetic ion cyclotron (EMIC) waves in the deep
inner magnetosphere at L = 2.5–5 at altitudes of 3,300–8,700 km. The mode conversion,i.e., L mode (He+ band) -> R mode (He+ band) -> L mode (O+ band) was clearly identified
from the equator to high latitudes. In addition, rising tone structures are found,recently identified as EMIC triggered emissions, which could lead to bursty
precipitation of relativistic electrons. First, the ion composition ratio (H+, He+, O+) =(83%, 16%, 1%) are estimated from polarization analysis. Second, minimum resonant3

electron energies with the observed EMIC waves and triggered emissions are estimatedto be ∼1–10 MeV. The satellite trajectory during the wave observation was primarily
through the slot region of electron radiation belts. The collocation implies possible
contribution of EMIC waves to formation of the slot region of radiation belts after amagnetic storm [Sakaguchi et al., 2013].
<GEOTAIL>

A terrestrial myriametric radio burst (TMRB) might be a distinct radiation of
12–50 kHz. The TMRB may have a fan beam-like radiation pattern emitted by adiscrete, dayside source located along the pole-ward edge of magnetospheric cusp fieldlines [Fung et al., 2013].
A survey of ULF waves in the Pc 5 frequency range during the six year period(1995–2000) has been made for the field line resonance waves in the outermagnetosphere, using plasma flow and magnetic field measurements with the Geotail
spacecraft. On the morning side a series of wave trains often appears during several
hours. In contrast such a series of wave trains with a long duration is rarely observed in
the afternoon to evening sector. Most of waves in the afternoon sector are isolated, of
which duration is approximately one hour. The existence of a set of preferential
frequencies and the pronounced dawn-dusk asymmetry of wave occurrence and wave
features, which were found in ground-based and ionospheric measurements ofgeomagnetic ULF pulsations, were statistically confirmed. It is also noted that thebackground plasma flow is sunward in the evening sector without exception. Transverse
waves are generally observed in the condition of plasma β below 1.5. High β cases aremostly associated with events on the dusk side. As for the relation to solar windconditions, Pc 5 waves tend to occur under the condition of more radial than the average
IMF spiral angle, or of low cone angle [Kokubun, 2013].
The cross-shock electrostatic potential at the front of collision-less shocks plays
a key role in the distribution of energy at the shock front. Multipoint measurement inspace such as by the Cluster II mission has an ability to derive the spatio-temporalvariations at the shock front. A statistical study of the cross-shock potential calculated
for around 50 crossings of the terrestrial bow shock is presented. The statisticaldependency of the normalized cross-shock potential on the upstream Alfven Mach
number is in good agreement with analytical results that predict decrease of thecross-shock potential with increasing Mach number [Dimmock et al., 20112].
<CLUSTER, THEMIS>

4

Electromagnetic ion cyclotron (EMIC) triggered chorus emissions have recently
been a subject of several experimental, theoretical and simulation case studies, noting
their similarities with whistler-mode chorus. Grison et al. [2013] performed a survey of
8 years of Cluster data in order to increase the database of EMIC triggered emissions.
The results of this is that EMIC triggered emissions have been unambiguously observedfor only three different days. These three events are studied in detail. All cases havebeen observed at the plasmapause between 22 and 24 magnetic local time (MLT) andbetween –15 degrees and 15 degrees of magnetic latitude. Triggered emissions were also
observed for the first time below the local helium gyrofrequency. The number of eventswas too low to produce statistical results, nevertheless they pointed out a variety ofcommon properties of those waves.
A review has been made by Krasnoselskikh et al. [2013] to address a subset ofunresolved problems in collisionless shock physics from experimental point of view
making use of multi-point observations onboard Cluster satellites. The problems they
address are determination of scales of fields and of a scale of electron heating,identification of energy source of precursor wave train, an estimate of the role ofanomalous resistivity in energy dissipation process by means of measuring short scalewave fields, and direct observation of reformation process during one single shock front
crossing.
The width of the terrestrial collisionless shock front, which is one of the key
shock parameters, is reported. The width of the main shock transition layer is related to
the nature of the collisionless process that balances nonlinearity and therefore leads tothe formation of the shock itself. The shock width determines how the incoming plasma
particles interact with the macroscopic fields within the front and, therefore, theprocesses that result in the energy redistribution at the front.

Cluster and Themis

measurements at the quasi-perpendicular part of the terrestrial bow shock are used to
study the spatial scale of the magnetic ramp [Hobara et al., 2010].
Using waveform data obtained by one of the THEMIS satellites, Kurita et al.
[2013] reported properties of rising tone chorus elements without a gap at half the
gyrofrequency in a region close to the magnetic equator. The wave normal angle of thechorus elements is typically field-aligned in the entire frequency range of both
upper-band and lower-band chorus emissions. They found that the observed frequency
sweep rates are consistent with the estimation based on the nonlinear wave growththeory of Omura et al. (2008).
<CRRES, AMPTE, DE-1>

5

Using the magnetic field and plasma wave data obtained by the Combined
Release and Radiation Effects Satellite (CRRES), Nosé et al. [2011] search forenhancements of O+ ion density in the deep inner magnetosphere known as “the oxygen
torus.” They examined 4 events on the dayside in which toroidal standing Alfvén waves
appear clearly. From the frequency of the toroidal waves, the magnetospheric local massdensity is estimated by solving the MHD wave equation for realistic models of themagnetic field and the field line mass distribution.
Nosé et al. [2011] statistically studied the spatial characteristics of Pi2
pulsations

usingmagnetic

fieldobservations

in

the

magnetosphere

at

the

equatorial-orbiting Active Magnetospheric Particle Tracer Explorers (AMPTE)/Charge
Composition Explorer (CCE) and the polar-orbiting Dynamics Explorer 1 (DE 1)
satellites and on the ground at the low-latitude station Kakioka (KAK, L=1.23).

H1.2

Lunar and Planetary Plasma Waves
Tsugawa et al. [2011] performed a statistical analysis of narrowband whistler

mode waves in frequencies of near 1 Hz observed by Kaguya around the Moon. The
results suggest that the waves are mainly observed in the region of SZA = 40－90 deg
with north-south/dawn-dusk asymmetries and are associated with lunar crustal
magnetic anomalies.
Broadband whistler mode waves in the frequency range from 0.1 to 10 Hz are
frequently observed near the Moon in the solar wind. Their analyses using Kaguya
dataset reveal that the waves are mostly observed above lunar magnetic anomalies andare associated with energized electrons and reflected ions. They suggest thatnarrowband waves which were occasionally observed around the Moon can be formed
from the broadband waves [Tsugawa et al., 2012].
The waveform capture (WFC) onboard the KAGUYA spacecraft is designed tomeasure natural plasma waves generated around the moon and radio emissions which
propagate from the sun, the earth and other planets. In order to suppress the artificial
noises originated from the instruments onboard KAGUYA, Nishibe et al. [2012]
developed a new method to identify the relationship between each interference noisewith the noise source and reduce the noise in a systematic way according to the house
keeping data of the spacecraft.
Recent observations by KAGUYA revealed that type-II (T2) entry of the solar
wind protons into the near-Moon wake occurs when the IMF is dominated by the
non-radial components (i.e. BY and/or BZ). Nishino et al. [2013] categorized T2 entry
into two cases; T2 entry with magnetic connection to the lunar surface (T2MC) and T2
6

entry into magnetically detached regions (T2MD). Strong electron acceleration (up to
several hundred eV to 1 keV) along the magnetic field associated with the T2 entry is
prominent when the field line has its both ends in the solar wind, that is, when themagnetic field is detached from the lunar surface (T2MD).

On the other hand, no

significant electron acceleration is found in the T2MC cases although an enhancementof the electron flux associated with the T2 proton entry is evident. They also reported
that the T2 entry process takes place even under radial (BX-dominated) IMF condition.
These results indicate that, while the T2 entry of solar wind protons into the wake itself
does not require a special IMF condition but is a rather general phenomenon, thecharacteristic energy of associated electrons does show a strong dependence on themagnetic connectivity to the lunar surface [Nishino et al., 2013].

H1.3

Ground Observation and Experiment of Plasma Waves
Long-term (1976–2010) variations in reflection heights of tweek atmospherics

has been investigated for the first time based on very low frequency (VLF) observationsat Kagoshima, Japan. The variations in tweek reflection heights did not show simple
correlation with solar activity. Ohya et al. [2011] suggested that these variations intweek reflection heights could be caused by coupling of several ionization effects at the
D and lower E regions.
Daytime tweek atmospherics during the solar eclipse of 22 July 2009 werereported on the basis of VLF/ELF wave measurements at Moshiri and Kagoshima,
Japan, where the magnitudes of the solar eclipse were 0.458 and 0.966, respectively.
This was the first observation of tweek atmospherics during a low-magnitude eclipse(0.458). The phase variation in the LF transmitter signals were also observed during
the eclipse [Ohya et al., 2012].
Goto et al. [2012] examined the accuracy of the global core plasma model(GCPM) in the equatorial region by using long-term total electron content (TEC) dataobtained from several GPS tracking stations along the equator and a low Earth orbit
satellite. According to the statistical analysis of the GPS TEC, they found a remarkablefeature in bias errors in the GCPM-derived TEC. Most of the errors are found to
distribute in the topside ionosphere due to the simple representation of the density
there.
A high correlation between a pulsating auroral patch and grouped chorus
waves was observed at Syowa Station in Antarctica. The generation region of the chorus
waves was estimated from the latitude and longitude dependence of the equatorial
electron gyrofrequencies using the IGRF geomagnetic field model. The extent of the7estimated latitude and longitude was consistent with the spatial distribution of thehigh-correlation aurora-chorus region. This study supports the hypothesis that
pulsating aurora is caused by pitch angle scattering of high-energy electrons by whistler
mode chorus waves, via a cyclotron resonance at the equator [Ozaki et al., 2012a].
Using a single-site lightning location technique, a new portable lightning
location system was developed. The system incorporated an attitude detection
technique using inertial sensors to detect an accurate electromagnetic field vector ofsferics by palm-sized electromagnetic sensors which can have arbitrary attitude. The
palm-sized system detected the sferics within about several hundred km with theattitude detection technique [Ozaki et al., 2012b].
Sakaguchi et al. [2012a] analyzed Pc5 (1.7–6.7 mHz) oscillations of ionospheric
Doppler plasma velocity observed on a westward pointing beam 3 of the SuperDARNKing Salmon HF radar in Alaska during the solar maximum in 2002 and the minimumin 2007. Local time distributions of the ionospheric Pc5 oscillations showed peculiar
asymmetric characteristics in both years; that is, the occurrence probability had amaximum around the magnetic midnight, whereas backscatter echoes exhibited almost
no oscillation on the dayside. They compared these ionospheric Pc5 events withmagnetic field variations on the ground under the radar beam at Pebek and King
Salmon and the geostationary ETS-8 satellite at almost conjugate longitude. They
found only a few nightside events where both the radar and magnetometers detectedsimilar sinusoidal oscillations.
Interaction with EMIC (electromagnetic ion cyclotron) waves is thought to be a
key component contributing to the very rapid loss of both ring current and radiation belt
particles into the atmosphere. Estimated loss rates are heavily dependent on theassumed spatial distribution of the EMIC wave. Statistical maps of the spatial
distribution have been produced using in-situ satellite data. However, with limited
satellite data it is impossible to deduce the true spatial distribution. Sakaguchi et al.
[2012b] presented ground-based observations using all-sky imager and search coilmagnetometer networks, which provide the large-scale distribution and motion of the
EMIC wave-particle interaction regions.
Nomura et al. [2012] have investigated the polarization of Pc1 geomagnetic
pulsations and related proton auroras at subauroral latitudes, using an induction
magnetometer and an all-sky camera at Athabasca, Canada (54.7°N, 246.7°E, magnetic
latitude (MLAT) 61.7°N). Isolated proton auroras often appear in association with Pc1
pulsations, because of proton scattering by electromagnetic ion cyclotron (EMIC) waves
in the magnetosphere.
8The hodograph method enables estimating the latitudinal profile of the
field-line resonance (FLR) frequency (fR) using the data from two groundmagnetometers. Pilipenko et al. [2013] provides the full details of this method for the
first time, and uses a latitudinal chain of ground magnetometers to examine its validity
and usefulness. The hodograph method merges the widely-used amplitude-ratio andcross-phase methods in a sense that the hodograph method uses both the amplitude
ratio and the phase difference in a unified manner; further than that, the hodographmethod provides fR at any latitude near those of the two ground magnetometers. It is
accomplished by (1) making a complex number by using the amplitude ratio (phasedifference) as its real (imaginary) part; (2) drawing thus obtained complex numbers (onenumber for one frequency) in the complex plane to make a hodograph; and (3) fitting tothus obtained hodograph a model satisfying the FLR condition, which is a circle withthe assumption that the resonance width is independent of the latitude.
Geomagnetic field data with high time resolution (typically 1 s) have recently
become more commonly acquired by ground stations. Such high time resolution data
enable identifying Pi2 pulsations which have periods of 40–150 s and irregular(damped) waveforms. It is well-known that pulsations of this type are clearly observedat mid- and low-latitude ground stations on the nightside at substorm onset. Therefore,
with 1-s data from multiple stations distributed in longitude around the Earth’s
circumference, substorm onset can be regularly monitored [Nosé et al., 2012].
Tanaka et al. [2012] investigated a relationship between poleward moving
auroral arcs (PMAAs), quasi-stationary auroral patches (QSAPs), and Pc 5 geomagnetic
pulsations observed at the South Pole Station (74.3 CGLAT) in the interval 0800–1100
MLT. It was demonstrated that the PMAAs, Pc 5 pulsations in the north-south
component, and oscillations in the drift of the QSAPs in the east-west direction have
similar dominant periods and are well correlated with each other.

H2. Theory and Computer Experiment on Plasma Waves
H2.1

Acceleration and Scattering of Particles
Summers et al. [2011] presented new relativistic formulae for the self-limiting

K-P flux. They compared the theoretical K-P limit with observed Radiation Belts fluxes.
They include nonlinear wave growth effects in the calculation of extreme Radiation
Belts fluxes.
Lee et al. [2011] carried out a series of 2D simulations to study the beam
9

instability and cyclotron maser instability (CMI) with the initial condition that a
population of tenuous energetic electrons with a ring-beam distribution is present in amagnetized background plasma. Weakly relativistic cases are discussed with thering-beam kinetic energy ranging from 25 to 100 keV. The beam component leads to thetwo-stream or beam instability at an earlier stage, and the beam mode is coupled with
Langmuir or whistler mode, leading to excitation of beam-Langmuir or beam-whistler
waves.
Lee et al. [2012] demonstrated by a particle simulation that Z-mode waves
generated by the cyclotron maser instability can lead to a significant acceleration ofenergetic electrons. In the particle simulation, the initial electron ring distribution
leads to the growth of Z-mode waves, which then accelerate and decelerate the energetic
ring electrons. The initial ring distribution evolves into an X-like pattern in momentum
space, which can be related to the electron diffusion curves.
Lee et al. [2013] carried out a series of particle simulations to study electron
acceleration by Z-mode and whistler-mode waves generated by an electron ring
distribution. The electron ring distribution leads to excitations of X-mode waves mainlyin the perpendicular direction, Z-mode waves in the perpendicular and parallel
directions, and whistler-mode waves mainly in the parallel direction. The parallel Zand whistler-mode waves can lead to an effective acceleration of ring electrons. The
electron acceleration is mainly determined by the wave amplitude and phase velocity,which in turn is affected by the ratio of electron plasma to cyclotron frequencies. For the
initial kinetic energy ranging from 100 to 500 keV, the peak energy of the accelerated
electrons is found to reach 2–8 times the initial kinetic energy. They further studied theacceleration process by test-particle calculations in which electrons interact with one,
two, or four waves. The electron trajectories in the one-wave case are simple diffusion
curves. In the multi-wave cases, electrons are accelerated simultaneously bycounter-propagating waves and can have a higher final energy.
Nonlinear interaction between EMIC triggered emissions and electrons isstudied. Pitch angle scattering depends on rising frequency and magnetic field gradient.
Rapid precipitation of electrons by EMIC waves is confirmed by simulations [Omura
and Zhao, 2012].
Omura and Zhao [2013] showed that the anomalous cyclotron resonancebetween relativistic electrons and electromagnetic ion cyclotron (EMIC) triggeredemissions takes place very effectively near the magnetic equator because of thevariation of the ambient magnetic field. Efficient precipitations are caused by nonlinear
trapping of relativistic electrons by electromagnetic wave potentials formed by EMIC
10

triggered emissions. They derived the necessary conditions of the wave amplitude,
kinetic energies, and pitch angles that must be satisfied for the nonlinear wave trapping.
They have conducted test particle simulations with a large number of relativistic
electrons trapped by a parabolic magnetic field near the magnetic equator.

H2.2

Generation and Propagation of Plasma Waves
According to recently developed nonlinear cyclotron resonance theory, thegeneration of a whistler-mode rising-tone chorus element is determined by a pair ofcoupled nonlinear ordinary differential equations referred to as “chorus equations.”
Summers et al. [2012] generalize the chorus equations to an arbitrary energetic electron
distribution, and calculate the associated threshold wave amplitude for sustained
nonlinear growth.
Chorus emissions grow as an absolute nonlinear instability near the magnetic
equator because of the presence of an electromagnetic electron hole in velocity space.
The transition process from the linear wave growth at a constant frequency to thenonlinear wave growth with a rising tone frequency is due to formation of a resonantcurrent –JB antiparallel to the wave magnetic field. The rising-tone frequency
introduces a phase shift to the electron hole at the equator and results in a resonantcurrent component antiparallel to the wave electric field –JE, which causes thenonlinear wave growth [Omura and Nunn, 2011].
The frequency and amplitude characteristics of chorus emissions are studied
by performing electron hybrid code simulations with different initial number densities
of energetic electrons. Chorus emissions with rising tones are generated in all
simulation runs except for the simulation assuming the lowest number density. The
frequency sweep rates of reproduced chorus vary depending on the variation of the wave
amplitude of respective chorus elements. Katoh and Omura [2011] found that thetheoretically estimated frequency sweep rates are consistent with the simulation
results.
Triggered emissions are excited with triggering wave amplitude above athreshold. The frequency sweep rate of emission does not depend on the triggering
amplitude. An electromagnetic electron hole is found in generation of a triggeredemission [Hikishima and Omura, 2012].
Katoh and Omura [2013] have conducted numerical experiments with different
spatial inhomogeneities to understand properties of the chorus generation process.
They assume the same initial condition of energetic electrons at the magnetic equator in11

all simulation runs. The simulation results reveal that the spectral characteristics ofchorussignificantly

vary

dependingonthemagnetic

field

inhomogeneity.

Whistler-mode emissions are generated and propagate away from the equator in all
simulation runs, but distinct chorus elements with rising tones are only reproduced in
the cases of small inhomogeneities. In the simulation that had the smallest
inhomogeneity, they find excitation of broadband hiss-like emission (BHE) whose
amplitudes are comparable to discrete chorus elements found in other simulation runs.
Summers et al. [2013] examined the growth of magnetospheric whistler-mode
waves which comprises a linear growth phase followed by a nonlinear growth phase.
They constructed time-profiles for the wave amplitude that smoothly match at thetransition between linear and nonlinear wave growth. This matching procedure canonly take place over a limited “matching region.”

They constructed this matchingregion and determined how the matching wave amplitude varies throughout the region.
Recently much progress has been made in the simulation and theoreticalunderstanding of rising frequency triggered emissions and rising chorus. Both PIC andVlasov VHS codes produce risers in the region downstream from the equator toward
which the VLF waves are traveling. The VHS code only produces fallers or downward
hooks with difficulty due to the coherent nature of wave particle interaction across theequator. With the VHS code Nunn and Omura [2012] now confine the interaction region
to be the region upstream from the equator, where inhomogeneity factor S is positive.
Shoji and Omura [2011] performed hybrid simulations to reproduce the EMIC
triggered emissions. They developed a self-consistent one-dimensional hybrid code witha cylindrical geometry of the background magnetic field. They assumed a parabolic
magnetic field to model the dipole magnetic field in the equatorial region of the innermagnetosphere. Triggering EMIC waves are driven by a left-handed polarized externalcurrent assumed at the magnetic equator in the simulation model.
Shoji et al. [2011] performed a self-consistent hybrid simulation with a
one-dimensional cylindrical magnetic flux model approximating the dipole magnetic
field of the Earth’s inner magnetosphere. In the presence of energetic protons with asufficient density and temperature anisotropy, multiple EMIC triggered emissions are
reproduced due to the nonlinear wave growth mechanism of rising-tone chorus
emissions, and a constant frequency wave in the He+ EMIC branch is subsequently
generated.
Shoji and Omura [2012] investigated the generation process of the EMIC
triggered emissions in the He+ branch and associated precipitation of the energetic
protons using a one-dimensional hybrid simulation with a cylindrical parabolic
12

magnetic geometry. The simulation results show a good agreement with the nonlinear
wave growth theory.
Shoji and Omura [2013] reproduced EMIC triggered emissions in the Earth’s
magnetosphere by real scale hybrid simulations with cylindrical magnetic geometry.
They obtained spontaneously triggered nonlinear EMIC waves with rising frequencies
in the H+ band of the EMIC dispersion relation. The proton holes in the phase space areformed. They have also derived the theoretical optimum wave amplitude for triggering
process of the EMIC nonlinear wave growth. The optimum wave amplitude and thenonlinear transition time show a good agreement with the present simulation result.
The nonlinear wave growth over a limited time forms a subpacket structure of a rising
tone emission. The formation process of a subpacket is repeated because of a new
triggering wave generated by the phase-organized protons, which are released from theprevious subpacket. Then, the EMIC triggered emission is formed as a train of
subpackets generated at different rising frequencies.
Summers et al. [2012] obtained Equations of nonlinear convective growth of achorus wave. The convective growth of a chorus wave is followed by saturation. The
saturation is due to adiabatic effects and the decrease in resonant current.
Using a well-established magnetospheric very-low-frequency (VLF) ray tracing
method, Yamaguchi et al. [2013] trace the propagation of individual rising- andfalling-frequency elements of VLF chorus from their generation point in the equatorial
region of the magnetosphere through to at least one reflection at the lower-hybrid
resonance point. They track the motion in the equatorial plane of the whole chorus
element, paying particular regard to movement across field lines, rotation, andcompression or expansion of the wave pulse. With a generation point for rising chorus at
the equator, it was found the element wave pulse remained largely field aligned in thegeneration regions.
Coalescence of mirror-mode structure results in magnetic peaks and dips.
Magnetic dips are generated in 2D low ion beta models. Magnetic peaks are formed in
2D high ion beta models and all 3D models [Shoji et al., 2012].
The fundamental nature of ULF waves in the Pc5 range driven by periodic
variation of solar-wind dynamic pressure is studied by using a global MHD simulation.
It is shown that a spectrum of the magnetospheric ULF wave induced from the periodic
variation has a harmonic structure due to nonlinear behavior of magnetospheric
response to the solar wind variation [Fujita et al., 2011].

13

H2.3

Development of Simulation Codes and Data Analysis Systems
Dimmock et al. [2011] presented comparison of 3 different techniques that can beused to estimate the cross shock potentials. The first technique is the estimate taking only
into account the projection of the measured components onto the shock normal. The second
uses the ideal MHD condition to estimate the third electric field component. The last method
is based on the structure of the electric field in the Normal Incidence Frame (NIF) for which
only the potential component along the shock normal and the motional electric field exist.
Surprisingly all three methods lead to the same order of magnitude for the cross shockpotential. The resulting electrostatic potential appears too high in comparison with thetheoretical results for low Mach number shocks. This shows the variability of the potential,
interpreted in the frame of the non-stationary shock model.

Photoelectron flows around a spacecraft and a double-probe electric field sensor
are studied by means of plasma particle simulations. The stray photoelectron current
flowing from a spacecraft into a probe can be reduced by operating the probe nearly at
the plasma potential. The analysis also revealed side effects of a guard electrodeenhancing a stray photoelectron current from the electrode itself [Miyake et al., 2012].
Umeda et al. [2012] developed a numerical method for analyzing the linear
dispersion relation for Maxwellian ring-beam velocity distributions. The obtained linear
properties are confirmed by direct comparison with full particle simulation results.
Kakad et al. [2013] performed one-dimensional fluid simulation of ion acoustic(IA) solitons propagating parallel to the magnetic field in electron-ion plasmas byassuming a large system length. To model the initial density perturbations (IDP), they
employed a KdV soliton type solution. Their simulation demonstrates that thegeneration mechanism of IA solitons depends on the wavelength of the IDP. The shortwavelength IDP evolve into two oppositely propagating identical IA solitons, whereas
the long wavelength IDP develop into two indistinguishable chains of multiple IA
solitons through a wave breaking process.
The plasmaspheric virtual resonance (PVR) and the transient Alfven wave
bouncing between the ionospheres in both hemispheres (the transient response, TR) are
regarded as the possible generation mechanisms of the Pi2 pulsations. However, theglobal MHD simulation of a substorm [Tanaka et al., 2010] did not reproduce such wave
modes because of insufficient ionospheric reflection of the Alfven wave, numericaltransfer of the Alfven wave across the field lines, and no plasmasphere. Furthermore, it
is noted that the substorm current wedge (SCW) which is a driver of the TR is not
reproduced in the global MHD simulation. Fujita and Tanaka [2013] search the sourcesof the Pi2 pulsations in the global MHD simulation, namely, the compressional wave in14

the inner magnetosphere for the PVR and the Alfven wave injected to the ionosphere for
the TR. In conclusion, there appears a compressional signal in the inner magnetospherewhen the high-speed Earthward flow at the substorm onset surges in the inner edge ofthe plasma sheet.
It is often discussed that the fourth methodology for science research is“informatics.” The first methodology is a theoretic approach, the second one isobservation and/or experiment, and the third one is computer simulation. Informatics is
a new methodology for data intensive science, which is a new concept based on the factthat most scientific data are digitalized and the amount of data is huge. Data-oriented
science is considered as the forth paradigm for coming big data science, including polar
research. The facilities to support informatics are cloud systems. Herein Murata et al.
[2013a] propose a cloud system especially designed for science. The basic concepts,
design, resources, implementation, and applications of the “National Institute ofInformation and Communications Technology (NICT) science cloud” are discussed. The
NICT Science Cloud is designed and constructed as a basis for data-oriented sciencesince 2010. They demonstrated information and communication technologies (ICT)designed to transfer, steward, process and publicize large-scale data acquired andanalyzed in solar-terrestrial physics. The NICT Science Cloud is a cloud systemdesigned for scientific researches, and expected as a new infrastructure for big data
sciences. Not only parallelization of CPU as in super-computers, but I/O and network
throughput parallelization are crucial for the big data science. A high-performance
visualization system is constructed on the NICT Science Cloud using Gfarm/Pwrake
middleware.
Cross-sectional studies have become important for an improved understandingof various Solar-Terrestrial Physics (STP) fields, given the great variety and different
types of observations from the Sun to the Earth. In order to better combine, compare,and analyze different types of data together, the Solar-Terrestrial data Analysis, andthe Reference System (STARS) has been developed. Cross-sectional study requires
cooperative work. STARS has two functions for cooperative work, the “Stars Project List
(SPL)” and the “Event Listing.” The SPL is used for exchanges of plotting informationby cooperating persons. The event list database provides all users of STARS hints forrecognizing typical occurrences of STP phenomena [Kunitake et al., 2013].
To optimize space weather research and information services, it is important toestablish a comprehensive system that enables us to analyze observation andsimulation data in an integrated manner. For this, Watari et al. [2013] recently
constructed a new computing environment called the “Space Weather Cloud Computing
15

System” of NICT. Currently, the Space Weather Cloud contains a high performancecomputer, a distributed mass storage system using the Grid Data Farm (Gfarm)technology, servers for analysis and visualization of data, a job service based on the
RCM (R&D Chain Management) system, servers for the STARS system.
In Watanabe et al. [2013], an outline of a planned system for the global
space-weather monitoring network of NICT is given. This system can manage datacollection much more easily than our current system by installations of autonomous
recovery, periodical state monitoring, and dynamic warning procedures. According to a
provisional experiment using a network simulator, the new system will work underlimited network conditions, e.g., a 160 msec delay, a 10 % packet loss rate, and a 500
Kbps bandwidth.
For data intensive science on cloud systems, we need development oftechniques for DIC (Data-Intensive Computing) as well as HTC (High-Through-put
Computing), MTC (Many-Task Computing), and HPC (High-Performance Computing).
The DIC is a new concept of large-scale data processing paying attentions to data
distribution, data-parallel execution, and harnessing data locality by scheduling ofcomputations close to the data. As the data file size is getting larger, I/O time to read
and/or write data is not negligible compared with data processing time. Murata et al.
[2013a] herein developed a DIC technique on a science cloud using Gfarm/Pwrake. The
Gfarm/Pwrake has been developed as an integrated system of both distributed filesystem and parallel data processing system. With identifying file system nodes (FSN)and processing client node (CN) and giving higher priority to process files on the local
disk than on remote disks, they succeeded in progress of total performance in processing
large-scale data files.
Murata et al. [2013b] designed meta-data of the STARS along with the RSS1.0
document. In order to describe the meta-data of the STARS beyond RSS1.0 vocabulary,
they defined original vocabularies for the STARS resources using RDF Schema. Theirsystem works as follows. The RSS1.0 documents generated on data sites areautomatically collected by a meta-data collection agent. The agent extracts meta-data tostore them in an XML database. The XML database provides advanced retrieval
processing that has considered property and relation.
Kubota et al. [2013] presented a new concept of analysis using visualization oflarge quantities of simulation data. The time development of 3D objects with hightemporal resolution provides the opportunity for scientific discovery. They visualized
large quantities of simulation data using the visualization application “Virtual Aurora”
based on AVS (Advanced Visual Systems) and the parallel distributed processing at
16

“Space Weather Cloud” in NICT based on Gfarm technology. They introduced two
results of high temporal resolution visualization: the magnetic flux rope generation
process and dayside reconnection using a system of magnetic field line tracing.
Isoda et al. [2013] presented the high time and spatial resolution visualizations
in 3D of the global MHD simulations. The Virtual Aurora, a tool designed based on the
AVS, is developed on the purpose of adapting to the parallel processing with the
distributed file system, Gfarm/Pwrake to process huge amount of simulation data files.
The new technique is included, as the tracing of fluid elements. It will helpful forunderstanding the convection in the magnetosphere.
Nagatsuma et al. [2013] present an operation system to acquire, to transfer
and to storage data for world-wide observation networks, which is named as “WONM(Wide-area Observation Network Monitoring) system, developed in NICT. This systemprovides us with easier management of data collection than legacy systems by means ofautonomous system recovery, periodical state monitoring, and dynamic warning
procedures. They have equipped world-wide observatories for space weather prediction
and research works with this system connected with the NICT Science Cloud.
Demonstration and discussion are presented concerning with this challenging system,
especially from the viewpoint that they easily operate world-wide observatories on a
web application.

H3. New Instruments and Sensors for Plasma Wave Experiments
For future scientific missions, reduction in the resource requirements ofplasma wave receivers without loss of performance is important. Fukuhara et al. [2012]
introduce a miniaturized on-board instrument for the observation of plasma waves
using analogue application-specific integrated circuit (ASIC) techniques. The developed
ASIC functions as a system chip to filter and amplify signals detected by plasma wave
sensors. Miniaturization of the analogue circuit using the ASIC leads to the realizationof a tiny plasma wave receiver. The overall size of the developed plasma wave receivercircuit board is less than 1/20 that of a conventional receiver used in previous scientificmissions. The power consumptions of the system chip and the plasma wave receiver are
165 and 525 mW, respectively.
Data processing for plasma wave instrument onboard spacecraft shall be done
under quite limited resources of CPU and memory. Matsuda et al. [2012] investigated asignal processing method to derive power spectrum and phase information of plasma
17

wave applicable to onboard data processing. They proposed a more efficient processing
method adopting high performance FFT routines according to pre-implemented tables
for trigonometric functions and demonstrated that the proposed method is fast enoughto apply to the onboard data processing. They also evaluated the accuracy of calculation
for phase properties of plasma wave signal even in the low-frequency resolution
condition using vector averaging method.
The Energization and Radiation in Geospace (ERG) project for solar cycle 24 will
explore how relativistic electrons in the radiation belts are generated during spacestorms. This geospace exploration project consists of three research teams: theSPRINT-B/ERG satellite observation team, the ground-based network observation team,and the integrated data analysis/simulation team [Miyoshi et al., 2012].
In the upcoming JAXA/ERG satellite mission, Wave Particle Interaction
Analyzer (WPIA) will be installed as an onboard software function. Katoh et al. [2013]
studied the statistical significance of the WPIA for measurement of the energy transfer
process between energetic electrons and whistler-mode chorus emissions in the Earth’s
inner magnetosphere. The WPIA measures a relative phase angle between the wave
vector E and velocity vector v of each electron and computes their inner product W,
where W is the time variation of the kinetic energy of energetic electrons interactingwith plasma waves. They evaluated the feasibility by applying the WPIA analysis to thesimulation results of whistler-mode chorus generation.
A dual-resonant search coil (DRSC) is designed as a wideband magnetometerfor natural electromagnetic waves in the near-Earth environment. Since the frequency
response of a search coil is determined by its resonant frequency, its bandwidth can beincreased by using multiple resonances. Two resonances are obtained by capacitive
coupling with negative mutual inductance between two coils. The resulting
measurement band of the DRSC is from 10 Hz to 1 MHz for a sensor 100 mm in length,
25 mm in diameter, and 0.11 kg in mass [Ozaki et al., 2013].

18

References:

Published Papers (November 2010 – October 2013)

Bayupati, I. P. A., Y. Kasahara, and Y. Goto [2012], “Study of Dispersion of Lightning
Whistlers Observed by Akebono Satellite in the Earth’s Plasmasphere,” IEICE Trans.
Commun., E95-B(11), 3472-3479.
Dimmock, A. P., M. A.Balikhin, and Y. Hobara [2011], “Comparison of three methods forthe estimation of cross-shock electric potential using Cluster data,” Ann. Geophys., 29,815-822, doi:10.5194/angeo-29-815-2011.
Dimmock, A. P., M. A. Balikhin, V. V. Krasnoselskikh, S. N. Walker, S. D. Bale, and Y.
Hobara [2012], “A statistical study of the cross-shock electric potential at low Mach
number, quasi-perpendicular bow shock crossings using Cluster data,” J. Geophys. Res.,
117, A02210, doi:10.1029/2011JA017089.
Fujita, S., T. Tanaka, and T. Motoba [2011], “Long-period ULF waves driven by periodic
solar wind disturbances,” in The Dynamic Magnetosphere, edited by W. Liu, and M.
Fujimoto, IAGA Special Sopron Book Series 3, doi:10.1007/978-94-007-0501-2_3,
Springer, pp. 39-45.
Fujita, S., and T. Tanaka [2013], “Possible generation mechanisms of the Pi2 pulsations
estimated from a global MHD simulation,” Earth Planets Space, 65, pp. 453-461.
Fukuhara, H., H. Kojima, K. Ishii, S. Okada, and H. Yamakawa [2012], “Tiny waveformreceiver with a dedicated system chip for observing plasma waves in space,”

Measurement science and technology, doi: 10.1088/0957-0233/23/10/105903.
Fung, S. F., K. Hashimoto, H. Kojima, S. A. Boardsen, L.N. Garcia, H. Matsumoto, J. L.
Green, and B. W. Reinisch [2013], “Terrestrial Myriametric Radio Burst Observed by
IMAGE and Geotail Satellites,” J. Geophys. Res., DOI: 10.1002/jgra.50149.
Goto, Y., Y. Kasahara, and T. Ide [2012], “Improvement of Equatorial Density
Distribution of the Global Core Plasma Model using GPS-derived TEC,” Radio Science,
47(RS0F12), doi:10.1029/2011RS004763.
Grison, B., O. Santolik, N. Cornilleau-Wehrlin, A. Masson, M. J. Engebretson, J. S.
19

Pickett, Y. Omura, P. Robert, and R. Nomura [2013], “EMIC triggered chorus emissions
in Cluster data,” J. Geophys. Res., 118, doi:10.1002/jgra.50178.
Hikishima, M., and Y. Omura [2012], “Particle simulations of whistler-mode rising-toneemissions triggered by waves with different amplitudes,” J. Geophys. Res., 117, A04226,
doi:10.1029/2011JA017428.
Hobara, Y., M. Balikhin, V. Krasnoselskikh, M. Gedalin, and H. Yamagishi [2010],“Statistical study of the quasi‐perpendicular shock ramp widths,” J. Geophys. Res.,
115, A11106, doi:10.1029/2010JA015659.
Isoda, F., K. T. Murata, H. Watanabe, K. Fukazawa, K. Yamamoto, O. Tatebe, M.
Tanaka, and E. Kimura [2013], “High Performance of Big Data Processing via NICT
Science Cloud,” (in Japanese), IEICE-SC2013-4, Vol. IEICE-113, No.86, pp.19-24.
Kakad, A., Y. Omura, and B. Kakad [2013], “Experimental evidence of ion acoustic
soliton chain formation and validation of nonlinear fluid theory,” Phys. Plasmas, 20,062103.
Katoh, Y., and Y. Omura [2011], “Amplitude dependence of frequency sweep rates ofwhistlermode

chorusemissions,”J.

Geophys.

Res.,

116,

A07201,

doi:10.1029/2011JA016496.
Katoh, Y., and Y. Omura [2013], “Effect of the background magnetic field inhomogeneity
on generation processes of whistler-mode chorus and broadband hiss-like emissions,” J.
Geophys. Res., doi: 10.1002/jgra.50395.
Katoh, Y., M. Kitahara, H. Kojima, Y. Omura, S. Kasahara, M. Hirahara, Y. Miyoshi, K.
Seki, K. Asamura, T. Takashima, and T. Ono [2013], “Significance of Wave-Particle
Interaction Analyzer for direct measurements of nonlinear wave-particle interactions,”
Ann. Geophys., 31, 503?512.
Kitamura, N., Y. Nishimura, T. Ono, Y. Ebihara, N. Terada, A. Shinbori, A. Kumamoto,T. Abe, M. Yamada, S. Watanabe, A. Matsuoka, and A. W. Yau [2010a], “Observationsof very-low-energy (<10 eV) ion outflows dominated by O+ ions in the region ofenhanced electron density in the polar cap magnetosphere during geomagnetic storms,”
20

J. Geophys. Res., 115, A00J06, doi:10.1029/2010JA015601.
Kitamura, N., Y. Nishimura, M. O. Chandler, T. E. Moore, N. Terada, T. Ono, A.
Shinbori, and A. Kumamoto [2010b], “Storm-time electron density enhancement in thecleft ion fountain,” J. Geophys. Res., 117, A11212, doi:10.1029/2012JA017900.
Kitamura, N., Y. Ogawa, Y. Nishimura, N. Terada, T. Ono, A. Shinbori, A. Kumamoto, V.
Truhlik, and J. Smilauer [2011], “Solar zenith angle dependence of plasma density andtemperature in the polar cap ionosphere and low-altitude magnetosphere during
geomagnetically quiet periods at solar maximum,” J. Geophys. Res., 116, A08227,
doi:10.1029/2011JA016631.
Kokubun, S. [2013], “ULF waves in the outer magnetosphere: Geotail observation 1
transverse waves,” Earth Planets Space, 65, pp. 411-433.
Krasnoselskikh, V., M. Balikhin, S. N. Walker, S. Schwartz, D. Sundkvist, V. Lobzin, M.
Gedalin, S. D. Bale, F. Mozer, J. Soucek, Y. Hobara, and H. Comisel [2013], “Thedynamic quasiperpendicular shock: Cluster discoveries,” Space Science Reviews, doi:
10.1007/s11214-013-9972-y.
Kubota, Y., K. Yamamoto, K. Fukazawa, and K. T. Murata [2013], “Visualization of theFlux Rope Generation Process Using Large Quantities of MHD Simulation Data,” Data
Science Journal, Vol.12, pp.WDS134-WDS138.
Kunitake, M., K. Yamamoto, S. Watari, K. Ukawa, H. Kato, E. Kimura, Y. Murayama,
and K. T. Murata [2013], “Solar-Terrestrial Data Analysis and Reference System(STARS) – Its High Potentiality for Collaborative Research,” Data Science Journal,
Vol.12, pp.WDS225-WDS228.
Kurita, S., Y. Katoh, Y. Omura, V. Angelopoulos, C. M. Cully, O. Le Contel, and H.
Misawa [2012], “THEMIS observation of chorus elements without a gap at half the
gyrofrequency,” J. Geophys. Res., VOL. 117, A11223, doi:10.1029/2012JA018076.
Lee, K. H., Y. Omura, and L. C. Lee [2011], “A 2D simulation study of Langmuir,
whistler, and cyclotron maser instabilities induced by an electron ring-beam
distribution,” Phys. Plasmas 18, 092110; doi: 10.1063/1.3626562.
21

Lee, K. H., Y. Omura, and L. C. Lee [2012], “Electron acceleration by Z-mode waves
associated with cyclotron maser instability,” Phys. Plasmas 19, 122902; doi:
10.1063/1.4772059.
Lee, K. H., Y. Omura, and L. C. Lee [2013], “Electron acceleration by Z-mode andwhistler-mode waves,” Phys. Plasmas, 20, 112901; doi: 10.1063/1.4829439.
Matsuda, S., Y. Kasahara, and Y. Goto [2012], “Study on onboard data processing forphase property of plasma wave measured by spacecraft,” IEICE Trans. Commun.,
J95-B(11), 1584-1593.
Miyake, Y., H. Usui, H. Kojima, and H. Nakashima [2012], “Plasma particle simulations
on stray photoelectron current flows around a spacecraft,” J. Geophys. Res., 117,
A09210, doi:10.1029/2012JA017673.
Miyoshi, Y., T. Ono, T. Takashima, K. Asamura, M. Hirahara, Y. Kasaba, A. Matsuoka,
H. Kojima, K. Shiokawa, K. Seki, M. Fujimoto, T. Nagatsuma, C. Z. Cheng, Y. Kazama,
S. Kasahara, T. Mitani, H. Matsumoto, N. Higashio, A. Kumamoto, S. Yagitani, Y.
Kasahara, K. Ishisaka, L. Blomberg, A. Fujimoto, Y. Katoh, Y. Ebihara, Y. Omura, M.
Nosé, T. Hori, Y. Miyashita, Y.-M. Tanaka, T. Segawa, and ERG Working Group [2012],“The Energization and Radiation in Geospace Project,” 10.1029/2012GM001304, inDynamics of the Earth's Radiation Belts and Inner Magnetosphere, Geophys. Monogr.
Ser., vol 199, edited by D. Summers, I.R. Mann, D. N. Baker, and M. Schulz, pp.265-279,
AGU, Washington, D.C.
Miyoshi, Y., R. Kataoka, Y. Kasahara, A. Kumamoto, T. Nagai, and M. F. Thomsen[2013], “High-speed solar wind with southward interplanetary magnetic field causes
relativistic electron flux enhancement of the outer radiation belt via enhanced conditionof whistler waves,” Geophys. Res. Lett., 40, 1–6, doi:10.1002/grl.50916
Murata, K. T., S. Watari, T. Nagatsuma, M. Kunitake, H. Watanabe, K. Yamamoto, Y.
Kubota, H. Kato, T. Tsugawa, K. Ukawa, K. Muranaga, E. Kimura, O. Tatebe, K.
Fukazawa, and Y. Murayama [2013a], “A Science Cloud for Data Intensive Sciences,”
Data Science Journal, Vol.12, pp.WDS139-WDS146.

22

Murata, K. T., H. Watanabe, K. Yamamoto, F. Isoda, E. Kimura, O. Tatebe, M. Tanaka,
K. Ukawa, K. Muranaga, and Y. Suzuki [2013b], “The NICT Science Cloud: distributed
storage system and parallel data processing applicable for polar research data,”
International Forum on Polar Data Activities in Global Data Systems, Program and
Abstracts, pp.108-109.
Nagatsuma, T., K. T. Murata, K. Yamamoto, T. Tsugawa, H. Kitauchi, T. Kondo, H.
Ishibashi, M. Nishioka, and M. Okada [2013], “Operation of data acquisition, transfer
and storage system for world-wide observation networks,” International Forum on Polar
Data Activities in Global Data Systems, Program and Abstracts, pp.110-111.
Nishibe, M., Y. Goto, and Y. Kasahara [2012], “Reduction of interference noises on wave
spectrograms observed by the KAGUYA spacecraft,” IEICE Trans. Commun., J95-B(11),1567-1575.
Nishino, M. N., M. Fujimoto, Y. Saito, H. Tsunakawa, Y. Kasahara, M. Kawamura, M.
Matsushima, F. Takahashi, H. Shibuya, H. Shimizu, Y. Goto, K. Hashimoto, Y. Omura,
A. Kumamoto, T. Ono, and S. Yokota [2013], “Type-II Entry of Solar Wind Protons into
the Lunar Wake: Effects of Magnetic Connection to the Night-side Surface,” Planetary
and Space Science, 87, 106-114, doi:10.1016/j.pss.2013.08.017.
Nomura, R., K. Shiokawa, K. Sakaguchi, Y. Otsuka, and M. Connors [2012],“Polarization of Pc1/EMIC waves and related proton auroras observed at subauroral
latitudes,” J. Geophys. Res, 117, A02318, doi:10.1029/2011JA017241.
Nosé, M., K. Takahashi, R. R. Anderson, and H. J. Singer [2011], “Oxygen torus in the
deep inner magnetosphere and its contribution to recurrent process of O+-rich ring
current formation,” J. Geophys. Res., 116, A10224, doi:10.1029/2010JA016651.
Nosé, M., T. Iyemori, L. Wang, A. Hitchman, J. Matzka, M. Feller, S. Egdorf, S. Gilder, N.
Kumasaka, K. Koga, H. Matsumoto, H. Koshiishi, G. Cifuentes-Nava, J. J. Curto, A.
Segarra, and C. Çelik [2012], “Wp index: A new substorm index derived fromhigh-resolution geomagnetic field data at low latitude,” Space Weather, 10, S08002,
doi:10.1029/2012SW000785.
Nunn, D., and Y. Omura [2012], “A computational and theoretical analysis of falling23

frequency VLF emissions,” J. Geophys. Res., 117, A08228, doi:10.1029/2012JA017557.
Ohya, H., K. Shiokawa, and Y. Miyoshi [2011], “Long-term variations in the tweek
reflection height in the D- and lower E-region ionosphere,” J. Geophys. Res., 116,
A10322, doi:10.1029/2011JA016800.
Ohya, H., F. Tsuchiya, H. Nakata, K. Shiokawa, Y. Miyoshi, K. Yamashita, and Y.
Takahashi [2012], “Reflection height of daytime tweek atmospherics during the solar
eclipse of 22 July 2009,” J. Geophys. Res., 117, A11310, doi:10.1029/2012ja018151.
Omura, Y., and D. Nunn [2011], “Triggering process of whistler mode chorus emissions
in the magnetosphere,” J. Geophys. Res., 116, A05205, doi:10.1029/2010JA016280.
Omura Y., D. Nunn, and D. Summers [2012], “Generation processes of whistler-mode
chorus emissions: Current status of nonlinear wave growth theory,” AGU Monograph“Dynamics

oftheEarth'sRadiation

Belts

and

Inner

Magnetosphere,”

10.1029/2012GM001347.
Omura, Y., and Q. Zhao [2012], “Nonlinear pitch angle scattering of relativistic electrons
by EMIC waves in the inner magnetosphere,” J. Geophys. Res., 117, A08227,
doi:10.1029/2012JA017943.
Omura, Y., and Q. Zhao [2013], “Relativistic electron microbursts due to nonlinear
pitch-angle scattering by EMIC triggered emissions,” J. Geophys. Res., doi:
10.1002/jgra.50477.
Ozaki, M., S. Yagitani, K. Ishizaka, K. Shiokawa, Y. Miyoshi, A. Kadokura, H.
Yamagishi, R. Kataoka, A. Ieda, Y. Ebihara, N. Sato, and I. Nagano [2012a], “Observed
correlation between pulsating aurora and chorus waves at Syowa Station in Antarctica:
A case study,” J. Geophys. Res., 117, A08211, doi:10.1029/2011JA017478.
Ozaki, M., S. Yagitani, K. Miyazaki, and I. Nagano [2012b], “Development of a new
portable lightning location system,” IEICE Transactions on Communications, Vol.E95-B,
No.1, pp.308-312.
Ozaki, M., S. Yagitani, K. Takahashi, and I. Nagano [2013], “Dual-Resonant Search Coil24

for Natural Electromagnetic Waves in the Near-Earth Environment,” IEEE Sensors
Journal, vol.13, issue 2, pp.644-650.
Pilipenko, V. A., H. Kawano, and I. R. Mann [2013], “Hodograph method to estimate thelatitudinal profile of the field-line resonance frequency using the data from two groundmagnetometers,” Earth Planets Space, 65, 435–446.
Sakaguchi, K., T. Nagatsuma, T. Ogawa, T. Obara, and O. A. Troshichev [2012a],“Ionospheric Pc5 plasma oscillations observed by the King Salmon HF radar and theircomparison with geomagnetic pulsations on the ground and in geostationary orbit,” J.
Geophys. Res, 117, A03218, doi:10.1029/2011JA016923.
Sakaguchi, K., Y. Miyoshi, E. Spanswick, E. Donovan, I. R. Mann, V. Jordanova, K.
Shiokawa, M. Connors, and J. C. Green [2012b], “Visualization of ion cyclotron wave
and particle interaction in the inner magnetosphere via THEMIS-ASI observations,” J.
Geophys. Res, 117, A10204, doi:10.1029/2012JA018180.
Sakaguchi, K., Y. Kasahara, M. Shoji, Y. Omura, Y. Miyoshi, T. Nagatsuma, A.
Kumamoto, and A. Matsuoka [2013], “Akebono observations of EMIC waves in the slot
region of the radiation belts,” Geophys. Res. Lett., 40, 1-5, doi:10.1002/2013GL058258.
Shoji, M., and Y. Omura [2011], “Simulation of electromagnetic ion cyclotron triggeredemissions in the Earth’s inner magnetosphere,” J. Geophys. Res., 116, A05212,
doi:10.1029/2010JA016351.
Shoji, M., Y. Omura, B. Grison, J. Pickett, I. Dandouras, and M. Engebretson [2011],“Electromagnetic ion cyclotron waves in the helium branch induced by multiple
electromagnetic ion cyclotron triggered emissions,” Geophys. Res. Lett., 38, L17102,
doi:10.1029/2011GL048427.
Shoji, M., and Y. Omura [2012], “Precipitation of highly energetic protons by helium
branch electromagnetic ion cyclotron triggered emissions,” J. Geophys. Res., VOL. 117,
A12210, doi:10.1029/2012JA017933.
Shoji, M., Y. Omura, and L.-C. Lee [2012], “Multidimensional nonlinear mirror-mode
structures

in

the

Earth'smagnetosheath,”
25

J.

Geophys.

Res.,

117,

A08208,doi:10.1029/2011JA017420.
Shoji, M., and Y. Omura [2013], “Triggering process of electromagnetic ion cyclotron
rising tone emissions in the inner magnetosphere,” J. Geophys. Res., 118, 5553–5561,
doi:10.1002/jgra.50523.
Summers, D., R. Tang, and Y. Omura [2011], “Effects of nonlinear wave growth on
extremeradiation

belt

electronfluxes,”J.

Geophys.

Res.,

116,

A10226,

doi:10.1029/2011JA016602.
Summers, D., Y. Omura, Y. Miyashita, and D.-H. Lee [2012], “Nonlinear spatiotemporal
evolution of whistler mode chorus waves in Earth's inner magnetosphere,” J. Geophys.
Res., 117, A09206, doi:10.1029/2012JA017842.
Summers, D., R. Tang, and Y. Omura [2012], “Linear and nonlinear growth ofmagnetospheric whistler mode waves,” 10.1029/2012GM001298, in Dynamics of the
Earth's Radiation Belts and Inner Magnetosphere, Geophys. Monogr. Ser., vol 199,
edited by D. Summers, I.R. Mann, D. N. Baker, and M. Schulz, pp.265-279, AGU,
Washington, D.C.
Summers D., R. Tang, Y. Omura, and D. H. Lee [2013], “Parameter spaces for linear andnonlinear whistler-mode waves,” Phys. Plasmas, 20, 072110; doi: 10.1063/1.4816022.
Tanaka, Y.-M., Y. Ebihara, S. Saita, A. Yoshikawa, Y. Obana, and A. T. Weatherwax[2012], “Poleward moving auroral arcs observed at the South Pole Station and theinterpretation

by

field

line

resonances,”

J.

Geophys.

Res.,

117,

A09305,

doi:10.1029/2012JA017899.
Teramoto, M., K. Takahashi, M. Nosé, D.-H. Lee, and P. R. Sutcliffe [2011], “Pi2pulsations in the inner magnetosphere simultaneously observed by the Active
Magnetospheric Particle Tracer Explorers/Charge Composition Explorer and Dynamics
Explorer 1 satellites,” J. Geophys. Res., 116, A07225, doi:10.1029/2010JA016199.
Tsugawa, Y., N. Terada, Y. Katoh, T. Ono, H. Tsunakawa, F. Takahashi, H. Shibuya, H.
Shimizu, and M. Matsushima [2011], “Statistical analysis of monochromatic whistler
waves near the Moon detected by Kaguya,” Ann. Geophys., 889-893.
26

Tsugawa, Y., Y. Katoh, N. Terada, T. Ono, H. Tsunakawa, F. Takahashi, H. Shibuya, H.
Shimizu, M. Matsushima, Y. Saito, S. Yokota, and M. N. Nishino [2012], “Statistical
study of broadband whistler-mode waves detected by Kaguya near the Moon,” Geophys.
Res. Lett., 39, L16101, doi:10.1029/2012GL052818.
Umeda, T., S. Matsukiyo, T. Amano, and Y. Miyoshi [2012], “A numericalelectromagnetic

lineardispersion

relationforMaxwellian

ring-beam

velocity

distributions,” Physics of Plasmas, Vol.19, No.7, 072107 (8pp.).
Watanabe, H., K. Yamamoto, T. Tsugawa, T. Nagatsuma, S. Watari, Y. Murayama, andK. T. Murata [2013], “An Integrated Management System of Multipoint Space Weather
Observation,” Data Science Journal, Vol.12, pp.WDS175-WDS178.
Watari, S., H. Kato, K. T. Murata, K. Yamamoto, H. Watanabe, Y. Kubota, and M.
Kunitake [2013], “Research Environment and Information Service of Space Weather
Cloud,” Data Science Journal, Vol.12, pp.WDS209-WDS212.
Yamaguchi, K., T. Matsumuro, Y. Omura, and D. Nunn [2013], “Ray tracing ofwhistler-mode chorus elements: implications for generation mechanisms of rising andfalling tone emissions,” Ann. Geophys., 31, 665-673.

27