Faculty Profiles - SHIOKAWA, Kazuo

Papers - SHIOKAWA, Kazuo

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Altitude development of postmidnight F region field-aligned irregularities observed using Equatorial Atmosphere Radar in Indonesia Reviewed

Tam Dao, Otsuka Yuichi, Shiokawa Kazuo, Ram S. Tulasi, Yamamoto Mamoru

GEOPHYSICAL RESEARCH LETTERS Vol. 43 ( 3 ) page： 1015-1022 2016.2

Longitudinal frequency variation of long-lasting EMIC Pc1-Pc2 waves localized in the inner magnetosphere Reviewed

K. -H. Kim, K. Shiokawa, I. R. Mann, J. -S. Park, H. -J. Kwon, K. Hyun, H. Jin, M. Connors

GEOPHYSICAL RESEARCH LETTERS Vol. 43 ( 3 ) page： 1039 - 1046 2016.2

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

Long-lasting (>20h) electromagnetic ion cyclotron (EMIC) Pc1-Pc2 waves were observed by the Athabasca (L =approximate to 4.6) induction magnetometer and Canadian Array for Realtime Investigations of Magnetic Activity (L =approximate to 4-6) fluxgate magnetometers on 5 April 2007. These waves showed a systematic frequency change with local time, the minimum frequency near dusk, and the maximum frequency near dawn. Assuming the plasmapause as a potential source region of the waves, we estimated the plasmapause location from localized proton enhancement (LPE) events observed at NOAA-Polar Orbiting Environmental Satellites and METOP-2 satellites. We found that the longitudinal frequency variation of EMIC waves has a clear correlation with the estimated plasmapause location and that the waves are in the frequency band between the equatorial helium and oxygen gyrofrequencies at the estimated plasmapause. With our analysis results we suggest that the LPE events are caused by wave-particle interaction with the helium band EMIC waves generated near the plasmapause.

DOI： 10.1002/2015GL067536

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EMIC waves observed at geosynchronous orbit under quiet geomagnetic conditions (Kp1) Reviewed

J. -S. Park, K. -H. Kim, K. Shiokawa, D. -H. Lee, E. Lee, H. -J. Kwon, H. Jin, G. Jee

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 121 ( 2 ) page： 1377 - 1390 2016.2

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

We statistically study the local time distribution of the helium band electromagnetic ion cyclotron (EMIC) waves observed at geosynchronous orbit when geomagnetic activity was low (Kp 1). In order to identify the geosynchronous EMIC waves, we use high time resolution magnetic field data acquired from GOES 10, 11, and 12 over a 2year period from 2007 and 2008 and examine the local time distribution of EMIC wave events. Unlike previous studies, which reported high EMIC wave occurrence in the postnoon sector with a peak around 1500-1600 magnetic local time (MLT) during magnetically disturbed times (i.e., storm and/or substorm), we observed that quiet time EMIC waves mostly occur in a region from morning (approximate to 0600MLT) to afternoon (approximate to 1600MLT) with a peak around 1100-1200MLT. To investigate whether the quiet time EMIC wave occurrence has a causal relationship with magnetospheric convection enhancement or solar wind dynamic pressure variations, we performed a superposed epoch analysis of solar wind parameters (solar wind speed, density, dynamic pressure, and interplanetary magnetic field B-z) and geomagnetic indices (AE and SYM-H). From the superposed epoch analysis we found that solar wind dynamic pressure variation is a more important parameter than AE and SYM-H for quiet time EMIC wave occurrence.

DOI： 10.1002/2015JA021968

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Pulsating proton aurora caused by rising tone Pc1 waves Reviewed

R. Nomura, K. Shiokawa, Y. Omura, Y. Ebihara, Y. Miyoshi, K. Sakaguchi, Y. Otsuka, M. Connors

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 121 ( 2 ) page： 1608 - 1618 2016.2

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

We found rising tone emissions with a dispersion of approximate to 1Hz per several tens of seconds in the dynamic spectrum of a Pc1 geomagnetic pulsation (Pc1) observed on the ground. These Pc1 rising tones were successively observed over approximate to 30min from 0250UT on 14 October 2006 by an induction magnetometer at Athabasca, Canada (54.7 degrees N, 246.7 degrees E, magnetic latitude 61.7 degrees N). Simultaneously, a Time History of Events and Macroscale Interactions during Substorms panchromatic (THEMIS) all-sky camera detected pulsations of an isolated proton aurora with a period of several tens of seconds, approximate to 10% variations in intensity, and fine structures of 3 degrees in magnetic longitudes. The pulsations of the proton aurora close to the zenith of ATH have one-to-one correspondences with the Pc1 rising tones. This suggests that these rising tones scatter magnetospheric protons intermittently at the equatorial region. The radial motion of the magnetospheric source, of which the isolated proton aurora is a projection, can explain the central frequency increase of Pc1, but not the shorter period (tens of seconds) frequency increase of approximate to 1Hz in Pc1 rising tones. We suggest that EMIC-triggered emissions generate the frequency increase of Pc1 rising tones on the ground and that they also cause the Pc1 pearl structure, which has a similar characteristic time.

DOI： 10.1002/2015JA021681

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Duskside enhancement of equatorial zonal electric field response to convection electric fields during the St. Patrick's Day storm on 17 March 2015 Reviewed

S. Tulasi Ram, T. Yokoyama, Y. Otsuka, K. Shiokawa, S. Sripathi, B. Veenadhari, R. Heelis, K. K. Ajith, V. S. Gowtam, S. Gurubaran, P. Supnithi, M. Le Huy

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 121 ( 1 ) page： 538 - 548 2016.1

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

The equatorial zonal electric field responses to prompt penetration of eastward convection electric fields (PPEF) were compared at closely spaced longitudinal intervals at dusk to premidnight sectors during the intense geomagnetic storm of 17 March 2015. At dusk sector (Indian longitudes), a rapid uplift of equatorial F layer to >550km and development of intense equatorial plasma bubbles (EPBs) were observed. These EPBs were found to extend up to 27.13 degrees N and 25.98 degrees S magnetic dip latitudes indicating their altitude development to similar to 1670km at apex. In contrast, at few degrees east in the premidnight sector (Thailand-Indonesian longitudes), no significant height rise and/or EPB activity has been observed. The eastward electric field perturbations due to PPEF are greatly dominated at dusk sector despite the existence of background westward ionospheric disturbance dynamo (IDD) fields, whereas they were mostly counter balanced by the IDD fields in the premidnight sector. In situ observations from SWARM-A and SWARM-C and Communication/Navigation Outage Forecasting System satellites detected a large plasma density depletion near Indian equatorial region due to large electrodynamic uplift of F layer to higher than satellite altitudes. Further, this large uplift is found to confine to a narrow longitudinal sector centered on sunset terminator. This study brings out the significantly enhanced equatorial zonal electric field in response to PPEF that is uniquely confined to dusk sector. The responsible mechanisms are discussed in terms of unique electrodynamic conditions prevailing at dusk sector in the presence of convection electric fields associated with the onset of a substorm under southward interplanetary magnetic field B-z.

DOI： 10.1002/2015JA021932

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Polar cap precursor of nightside auroral oval intensifications using polar cap arcs Reviewed

Zou Ying, Nishimura Yukitoshi, Lyons Larry R., Donovan Eric F., Shiokawa Kazuo, Ruohoniemi J. Michael, McWilliams Kathryn A., Nishitani Nozomu

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 120 ( 12 ) page： 10698-10711 2015.12

Isolated Proton Auroras and Pc1/EMIC Waves at Subauroral Latitudes Reviewed

Kaori Sakaguchi, Kazuo Shiokawa, Yoshizumi Miyoshi, Martin Connors

Auroral Dynamics and Space Weather page： 59 - 70 2015.11

Language：English Publishing type：Part of collection (book) Publisher：Wiley Blackwell

Isolated proton aurora (IPA) in the subauroral ionosphere is created by energetic proton precipitation through wave-particle interactions with electromagnetic ion cyclotron (EMIC) waves in the conjugate inner magnetosphere. In this study, spatial distribution and occurrence probability of IPAs were statistically investigated as a proxy for regions of EMIC wave occurrence using ground-based imaging data during 2006-2012 at Athabasca, Canada. The 7-year average of the IPA occurrence probability over the total observation interval was estimated to be 0.83%, and a factor of 5 change was found between maximum and minimum years. Local time (between 16 and 06 MLT) distribution shows double peaks at premidnight and at dusk. The occurrence probability increases with Kp, and the MLT location tends to shift duskward. The statistical distribution of IPA size shows a clear peak at a spatial size of 10,000 km2, and latitudinal and longitudinal lengths have peaks at 56 and 340 km, respectively, at the ionospheric altitude. The equatorial projections of IPA source locations and two-dimensional (2D) structures are estimated by magnetic field tracing. These spatial structures are essential to quantitatively estimate the loss rate of energetic particles, contributing to space weather studies.

DOI： 10.1002/9781118978719.ch5

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A direct link between chorus emissions and pulsating aurora on timescales from milliseconds to minutes: A case study at subauroral latitudes Reviewed

Ozaki Mitsunori, Yagitani Satoshi, Sawai Kaoru, Shiokawa Kazuo, Miyoshi Yoshizumi, Kataoka Ryuho, Ieda Akimasa, Ebihara Yusuke, Connors Martin, Schofield Ian, Katoh Yuto, Otsuka Yuichi, Sunagawa Naoki, Jordanova Vania K.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 120 ( 11 ) page： 9617-9631 2015.11

Coordinated airglow observations between IMAP/VISI and a ground-based all-sky imager on concentric gravity wave in the mesopause Reviewed

S. Perwitasari, T. Sakanoi, A. Yamazaki, Y. Otsuka, Y. Hozumi, Y. Akiya, A. Saito, K. Shiokawa, S. Kawamura

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 120 ( 11 ) page： 9706 - 9721 2015.11

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

We present a study of concentric gravity waves (CGWs) event from the coordinated observation between Ionosphere, Mesosphere, upper Atmosphere, and Plasmasphere mapping (IMAP)/Visible and near-Infrared Spectral Imager (VISI), all-sky camera at Rikubetsu, Multi-functional Transport Satellite (MTSAT), Tropical Rainfall Measuring Mission, and MF radar at Wakkanai combined with Modern-Era Retrospective Analysis for Research and Application data. IMAP/VISI is the first space-based imager that capable of imaging the airglow in the mesosphere and lower thermosphere region in the nadir-looking direction. Therefore, it has a unique ability to observe a great extend of CGWs propagation. Arc-like shaped, part of CGWs pattern was observed around themesopause (similar to 95 km) in the O-2 762 nm airglow emission obtained by IMAP/VISI at 1204 UT on 18 October 2012. Similar patterns were also observed by the all-sky imager at Rikubetsu (43.5 degrees N, 143.8 degrees E) in OI 557.7 nm and OH band airglow emissions from similar to 1100 to 1200 UT. Horizontal wavelengths of the observed small-scale gravity waves are similar to 50 km (OH band and OI 557.7nm) and similar to 67 km (O-2 762 nm). The source is suggested to be a deep convective activity over Honshu Island which likely was an enhanced convective activity related to a typhoon in the south of Japan. The data showed that the CGWs could propagate up to similar to 1400-1500km horizontally from the source to the mesopause but not farther away. Using atmospheric temperature profiles obtained by Thermospheric Ionosphere Mesosphere Energetics Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry, we conclude that this long-distance propagation of the waves could be caused by thermal duct in the middle atmosphere. The arc-like shaped instead of full circle pattern points out that the wind filtering effect is significant for the particular direction of wave propagation.

DOI： 10.1002/2015JA021424

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Spatiotemporally resolved electrodynamic properties of a Sun-aligned arc over Resolute Bay Reviewed

G. W. Perry, H. Dahlgren, M. J. Nicolls, M. Zettergren, J. -P. St-Maurice, J. L. Semeter, T. Sundberg, K. Hosokawa, K. Shiokawa, S. Chen

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 120 ( 11 ) page： 9977 - 9987 2015.11

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

Common volume measurements by the Resolute Bay Incoherent Scatter Radar-North (RISR-N) and Optical Mesosphere and Thermosphere Imagers (OMTI) have been used to clarify the electrodynamic structure of a Sun-aligned arc in the polar cap. The plasma parameters of the dusk-to-dawn drifting arc and surrounding ionosphere are extracted using the volumetric imaging capabilities of RISR-N. Multipoint line-of-sight RISR-N measurements of the plasma drift are inverted to construct a time sequence of the electric field and field-aligned current system of the arc. Evidence of dramatic electrodynamic and plasma structuring of the polar cap ionosphere due to the arc is described. One notable feature of the arc is a meridionally extended plasma density depletion on its leading edge, located partially within a downward field-aligned current region. The depletion is determined to be a by-product of enhanced chemical recombination operating on a time scale of 15 min. A similarly shaped electric field structure of over 100 mV/m and line-of-sight ion temperatures nearing 3000 K were collocated with the depletion.

DOI： 10.1002/2015JA021790

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Statistical study of ELF/VLF emissions at subauroral latitudes in Athabasca, Canada Reviewed

Martinez-Calderon Claudia, Shiokawa Kazuo, Miyoshi Yoshizumi, Ozaki Mitsunori, Schofield Ian, Connors Martin

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 120 ( 10 ) page： 8455-8469 2015.10

On the formation and origin of substorm growth phase/onset auroral arcs inferred from conjugate space-ground observations Reviewed

T. Motoba, S. Ohtani, B. J. Anderson, H. Korth, D. Mitchell, L. J. Lanzerotti, K. Shiokawa, M. Connors, C. A. Kletzing, G. D. Reeves

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 120 ( 10 ) page： 8707 - 8722 2015.10

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

Magnetotail processes and structures related to substorm growth phase/onset auroral arcs remain poorly understood mostly due to the lack of adequate observations. In this study we make a comparison between ground-based optical measurements of the premidnight growth phase/onset arcs at subauroral latitudes and magnetically conjugate measurements made by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) at 780km in altitude and by the Van Allen Probe B (RBSP-B) spacecraft crossing L values of 5.0-5.6 in the premidnight inner tail region. The conjugate observations offer a unique opportunity to examine the detailed features of the arc location relative to large-scale Birkeland currents and of the magnetospheric counterpart. Our main findings include (1) at the early stage of the growth phase the quiet auroral arc emerged 4.3 degrees equatorward of the boundary between the downward Region 2 (R2) and upward Region 1 (R1) currents; (2) shortly before the auroral breakup (poleward auroral expansion) the latitudinal separation between the arc and the R1/R2 demarcation narrowed to 1.0 degrees; (3) RBSP-B observed a magnetic field signature of a local upward field-aligned current (FAC) connecting the arc with the near-Earth tail when the spacecraft footprint was very close to the arc; and (4) the upward FAC signature was located on the tailward side of a local plasma pressure increase confined near L5.2-5.4. These findings strongly suggest that the premidnight arc is connected to highly localized pressure gradients embedded in the near-tail R2 source region via the local upward FAC.

DOI： 10.1002/2015JA021676

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Multi-instrument, high-resolution imaging of polar cap patch transportation Reviewed

E. G. Thomas, K. Hosokawa, J. Sakai, J. B. H. Baker, J. M. Ruohoniemi, S. Taguchi, K. Shiokawa, Y. Otsuka, A. J. Coster, J. -P. St.-Maurice, K. A. McWilliams

RADIO SCIENCE Vol. 50 ( 9 ) page： 904 - 915 2015.9

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

Transionospheric radio signals in the high-latitude polar cap are susceptible to degradation when encountering sharp electron density gradients associated with discrete plasma structures, or patches. Multi-instrument measurements of polar cap patches are examined during a geomagnetic storm interval on 22 January 2012. For the first time, we monitor the transportation of patches with high spatial and temporal resolution across the polar cap for 1-2 h using a combination of GPS total electron content (TEC), all-sky airglow imagers (ASIs), and Super Dual Auroral Radar Network (SuperDARN) HF radar backscatter. Simultaneous measurements from these data sets allow for continuous tracking of patch location, horizontal extent, and velocity despite adverse observational conditions for the primary technique (e.g., sunlit regions in the ASI data). Spatial collocation between patch-like features in relatively coarse but global GPS TEC measurements and those mapped by high-resolution ASI data was very good, indicating that GPS TEC can be applied to track patches continuously as they are transported across the polar cap. In contrast to previous observations of cigar-shaped patches formed under weakly disturbed conditions, the relatively narrow dawn-dusk extent of patches in the present interval (500-800 km) suggests association with a longitudinally confined plasma source region, such as storm-enhanced density (SED) plume. SuperDARN observations show that the backscatter power enhancements corresponded to the optical patches, and for the first time we demonstrate that the motion of the optical patches was consistent with background plasma convection velocities.

DOI： 10.1002/2015RS005672

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Statistical study of auroral fragmentation into patches Reviewed

Hashimoto Ayumi, Shiokawa Kazuo, Otsuka Yuichi, Oyama Shin-ichiro, Nozawa Satonori, Hori Tomoaki, Lester Mark, Johnsen Magnar Gullikstad

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 120 ( 8 ) page： 6207-6217 2015.8

Plasma bubble monitoring by TEC map and 630 nm airglow image Reviewed

H. Takahashi, C. M. Wrasse, Y. Otsuka, A. Ivo, V. Gomes, I. Paulino, A. F. Medeiros, C. M. Denardini, N. Sant'Anna, K. Shiokawa

JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS Vol. 130 page： 151 - 158 2015.8

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

Equatorial ionosphere plasma bubbles over the South American continent were successfully observed by mapping the total electron content (TECMAP) using data provided by ground-based GNSS receiver networks. The TECMAP could cover almost all of the continent within 4000 km distance in longitude and latitude, monitoring TEC variability continuously with a time resolution of 10 min. Simultaneous observations of OI 630 nm all-sky image at Cachoeira Paulista (22.7 degrees S, 45.0 degrees W) and Cariri (7.4 degrees S, 36.5 degrees W) were used to compare the bubble structures. The spatial resolution of the TECMAP varied from 50 km to 1000 km, depending on the density of the observation sites. On the other hand, optical imaging has a spatial resolution better than 15 km, depicting the fine structure of the bubbles but covering a limited area (similar to 1600 km diameter). TECMAP has an advantage in its spatial coverage and the continuous monitoring (day and night) form. The initial phase of plasma depletion in the post-sunset equatorial ionization anomaly (PS-EIA) trough region, followed by development of plasma bubbles in the crest region, could be monitored in a progressive way over the magnetic equator. In December 2013 to January 2014, periodically spaced bubble structures were frequently observed. The longitudinal spacing between the bubbles was around 600-800 km depending on the day. The periodic form of plasma bubbles may suggest a seeding process related to the solar terminator passage in the ionosphere. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jastp.2015.06.003

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Van Allen probes, NOAA, GOES, and ground observations of an intense EMIC wave event extending over 12 h in magnetic local time Reviewed

M. J. Engebretson, J. L. Posch, J. R. Wygant, C. A. Kletzing, M. R. Lessard, C. -L. Huang, H. E. Spence, C. W. Smith, H. J. Singer, Y. Omura, R. B. Horne, G. D. Reeves, D. N. Baker, M. Gkioulidou, K. Oksavik, I. R. Mann, T. Raita, K. Shiokawa

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 120 ( 7 ) page： 5465 - 5488 2015.7

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

Although most studies of the effects of electromagnetic ion cyclotron (EMIC) waves on Earth's outer radiation belt have focused on events in the afternoon sector in the outer plasmasphere or plume region, strong magnetospheric compressions provide an additional stimulus for EMIC wave generation across a large range of local times and L shells. We present here observations of the effects of a wave event on 23 February 2014 that extended over 8h in UT and over 12h in local time, stimulated by a gradual 4h rise and subsequent sharp increases in solar wind pressure. Large-amplitude linearly polarized hydrogen band EMIC waves (up to 25nT p-p) appeared for over 4h at both Van Allen Probes, from late morning through local noon, when these spacecraft were outside the plasmapause, with densities similar to 5-20cm(-3). Waves were also observed by ground-based induction magnetometers in Antarctica (near dawn), Finland (near local noon), Russia (in the afternoon), and in Canada (from dusk to midnight). Ten passes of NOAA-POES and METOP satellites near the northern foot point of the Van Allen Probes observed 30-80keV subauroral proton precipitation, often over extended L shell ranges; other passes identified a narrow L shell region of precipitation over Canada. Observations of relativistic electrons by the Van Allen Probes showed that the fluxes of more field-aligned and more energetic radiation belt electrons were reduced in response to both the emission over Canada and the more spatially extended emission associated with the compression, confirming the effectiveness of EMIC-induced loss processes for this event.

DOI： 10.1002/2015JA021227

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Resonance structure and mode transition of quarter-wave ULF pulsations around the dawn terminator Reviewed

Obana Yuki, Waters Colin L., Sciffer Murray D., Menk Frederick W., Lysak Robert L., Shiokawa Kazuo, Hurst Anthony W., Petersen Tanja

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 120 ( 6 ) page： 4194-4212 2015.6

Three different types of electric field disturbances affecting equatorial ionosphere during a long-duration prompt penetration event Reviewed

D. Chakrabarty, Diptiranjan Rout, R. Sekar, R. Narayanan, G. D. Reeves, Tarun K. Pant, B. Veenadhari, K. Shiokawa

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 120 ( 6 ) page： 4993 - 5008 2015.6

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

Coordinated digisonde and OI 630.0nm airglow observations from Thumba (TVM), an Indian dip equatorial station, in conjunction with magnetic and geosynchronous particle flux measurements, reveal three different types of electric field disturbances in the equatorial ionosphere-thermosphere system (ITS) occurring in succession over a period of 6h on a single night (22-23 January,2012; A(p) = 24). These include (1) westward electric field perturbations owing to a pseudo-breakup and a substorm event, each lasting for about 30min; (2) eastward electric field perturbations continuing for about an hour, owing to the southward excursion of Z component of interplanetary magnetic field (B-z); and (3) DP2-type fluctuating (period approximate to 40min) electric field perturbation sustaining for about 4h. The pseudo-breakup and the fully grown substorm events are found to be longitudinally localized and different in terms of response in the westward auroral electrojet index (AL) as well as geosynchronous electron/proton injections. The polarity of the prompt penetration of interplanetary electric field that affects the equatorial ionosphere is observed to be eastward during 2100-2200 IST (Indian Standard Time) which is observationally sparse but consistent with modeling studies. Interestingly, on the same night, DP2-type electric field fluctuations with approximate to 40min periodicity and occasional eastward polarity (akin to daytime) are also found to affect the equatorial ITS for about 4h (2200-0200 IST). The case study, thus, brings out different processes that constitute a long duration prompt penetration event which, otherwise, would have been categorized as a single event.

DOI： 10.1002/2014JA020759

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Localized polar cap flow enhancement tracing using airglow patches: Statistical properties, IMF dependence, and contribution to polar cap convection Reviewed

Zou Ying, Nishimura Yukitoshi, Lyons Larry R., Shiokawa Kazuo, Donovan Eric F., Ruohoniemi J. Michael, McWilliams Kathryn A., Nishitani Nozomu

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 120 ( 5 ) page： 4064-4078 2015.5

Airglow-imaging observation of plasma bubble disappearance at geomagnetically conjugate points Reviewed

Shiokawa Kazuo, Otsuka Yuichi, Lynn Kenneth J. W., Wilkinson Philip, Tsugawa Takuya

EARTH PLANETS AND SPACE Vol. 67 ( 43 ) page： 1-12 2015.3

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Papers - SHIOKAWA, Kazuo