Faculty Profiles - SHIOKAWA, Kazuo

Multi-Event Conjugate Measurements of the SAR Arc Detachment From the Auroral Oval Using DMSP Satellites and an All-Sky Camera at Athabasca, Canada Reviewed

Other Link： https://link.springer.com/article/10.1186/s40623-023-01829-0/fulltext.html

Unsolved problems: Mesoscale polar cap flow channels' structure, propagation, and effects on space weather disturbances Reviewed Open Access

Lyons Larry. R. R., Nishimura Yukitoshi, Liu Jiang, Zou Ying, Bristow William. A. A., Yadav Sneha, Donovan Eric, Nishitani Nozomu, Shiokawa Kazuo, Hosokawa Keisuke

FRONTIERS IN ASTRONOMY AND SPACE SCIENCES Vol. 10 2023.4

Gololobov A., Shiokawa K., Baishev D., Inaba Y., Otsuka Y., Connors M.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 128 ( 4 ) 2023.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Geophysical Research: Space Physics

We report the first statistical study of stable auroral red (SAR) arcs detached from the main auroral oval during non-storm time, using multi-event conjugate measurements by the Defense Meteorological Satellite Program (DMSP) satellites (F13–F19) and a ground-based all-sky imager at Athabasca (Canada) (54.6°W, 246.36°Е, MLAT = 61.5°, MLON = 308.3°, L = 4.4). We found 63 events of detached SAR arc conjunctions with the DMSP satellites in the northern hemisphere and 18 events in the opposite southern hemisphere from 2006 to 2018. Measurements aboard DMSP satellites show that detached SAR arcs are in general associated with enhancements of electron temperature (60 cases) and electron density troughs (58 cases). Only 14 cases show strong horizontal flow associated with the detached SAR arcs, indicating that the strong plasma flow is not a necessary condition to cause the detached SAR arcs. The electron temperature measured by DMSP associated with detached SAR arcs positively correlates with F10.7 solar activity index. The measured emission intensities at 630.0 nm in the SAR arcs show a good correlation with the electron temperature. These results indicate that the detached SAR arcs during non-storm time are caused by heat flux from the magnetosphere associated with substorms, and their intensity depends on the background plasma condition in the ionosphere.

DOI： 10.1029/2022JA030544

Multi-Event Analysis of Magnetosphere-Ionosphere Coupling of Nighttime Medium-Scale Traveling Ionospheric Disturbances From the Ground and the Arase Satellite Reviewed Open Access

K. Kawai, K. Shiokawa, Y. Otsuka, S. Oyama, M. G. Connors, Y. Kasahara, Y. Kasaba, S. Nakamura, F. Tsuchiya, A. Kumamoto, A. Shinbori, A. Matsuoka, I. Shinohara, Y. Miyoshi

Journal of Geophysical Research: Space Physics Vol. 128 ( 2 ) 2023.2

Language：English Publishing type：Research paper (scientific journal)

Kawai et al. (2021) reported the first ground-satellite conjugate observation of nighttime medium-scale traveling ionospheric disturbances (MSTIDs), by analyzing measurements from an airglow imager at Gakona (geographic latitude: 62.39°N, geographic longitude: 214.78°E, magnetic latitude: 63.60°N) and the Arase satellite in the magnetosphere on 3 November 2018. The Arase satellite observed variations in both the polarization electric field and the electron density as the Arase footprint passed through the MSTID structures in the ionosphere. In this study, we investigated whether these electric field and density variations associated with MSTIDs at subauroral latitudes are always observed by Arase in the magnetosphere. We used three airglow imagers installed at Gakona, Athabasca (geographic latitude: 54.60°N, geographic longitude: 246.36°E, magnetic latitude: 61.10°N), and Kapuskasing (geographic latitude: 49.39°N, geographic longitude: 277.81°E, magnetic latitude: 58.70°N) and the Arase satellite. We found eight observations of MSTIDs conjugate with Arase. They indicate that electric field and density variations associated with MSTIDs are not always observed in the magnetosphere. These variations tend to be observed in the magnetosphere during geomagnetically quiet times and when the amplitude of the MSTID is large. We categorized the MSTIDs into those caused by plasma instabilities and gravity waves and found that the electric field and density variations can be observed in the magnetosphere for both types of MSTIDs.

DOI： 10.1029/2022JA030542

A Statistical Study of Longitudinal Extent of Pc1 Pulsations Using Seven PWING Ground Stations at Subauroral Latitudes Reviewed Open Access

Jie Liu, Kazuo Shiokawa, Shin‐Ichiro Oyama, Yuichi Otsuka, Chae‐Woo Jun, Masahito Nosé, Tsutomu Nagatsuma, Kaori Sakaguchi, Akira Kadokura, Mitsunori Ozaki, Martin Connors, Dmitry Baishev, Nozomu Nishitani, Alexey Oinats, Vladimir Kurkin, Tero Raita

Journal of Geophysical Research: Space Physics Vol. 128 ( 1 ) 2023.1

Ionospheric Modulation by EMIC Wave-Driven Proton Precipitation: Observations and Simulations Reviewed Open Access

Tian X., Yu Y., Gong F., Ma L., Cao J., Solomon S.C., Shreedevi P.R., Shiokawa K., Otsuka Y., Oyama S.i., Miyoshi Y.

Journal of Geophysical Research Space Physics Vol. 128 ( 1 ) 2023.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Geophysical Research Space Physics

Protons of tens of keV can be resonantly scattered by electromagnetic ion cyclotron (EMIC) waves excited in the magnetosphere, resulting in proton precipitation down to the upper atmosphere. In this study, we report for the first time the ionospheric height-dependent ionization in response to EMIC-associated isolated proton aurora (IPA) using simultaneous space-borne and ground-based measurements. On 06 March 2019, the Polar Orbiting Environmental Satellites observed significant proton precipitation in the dusk sector (MLT ∼ 19), while ground-based magnetometers detected a clear signature of EMIC waves. Meanwhile, the conjugated all sky imager captured an IPA and the nearby Poker Flat incoherent scatter radar (PFISR) showed enhanced electron density in the E region, suggesting a potential consequence of the EMIC wave-driven proton precipitation. The Global Airglow model simulations confirmed the dominant impact of proton precipitation on the ionosphere and agreed well with PFISR observations. This study confirmed physical links from the magnetosphere to the ionosphere through EMIC-driven proton precipitation.

DOI： 10.1029/2022JA030983

ELECTROMAGNETIC ULF/ELF OSCILLATIONS CAUSED BY THE ERUPTION OF THE TONGA VOLCANO Reviewed Open Access

Martines-Bedenko V. A., Pilipenko V. A., Shiokawa K., Akbashev R. R.

SOLAR-TERRESTRIAL PHYSICS Vol. 9 ( 1 ) page： 47 - 55 2023

Language：English Publishing type：Research paper (scientific journal) Publisher：Solar-Terrestrial Physics

The eruption of the Tonga volcano on January 13 and 15, 2022 and related intense lightning activity led to the excitation of a number of specific electromagnetic oscillations in different frequency ranges. We examine properties of these oscillations, using data from magnetometers of various types located in Kamchatka and in the Pacific region. We confirmed that there might have been a geomagnetic response to the formation of an acoustic resonance between the Earth surface and the ionosphere: localized harmonic oscillations with a frequency 3.5-4.0 mHz, which lasted for ~1.5 hr, were detected ~15 min after the beginning of the eruption at distance of ~800 km. An increase was observed in the intensity of the Schumann resonance at stations in the Far East. Broadband emission stimulated by intense volcanic lightning was detected to occur in the Pc1 range (2-5 Hz). The emission presumably results from the excitation of the magnetosonic waveguide in the upper ionosphere by lightning activity.

DOI： 10.12737/stp-91202306

Ultra Low Frequency Modulation of Energetic Electron Precipitation in the D-Region Ionosphere in a Magnetically Quiet Time Using OCTAVE Very Low Frequency and Low Frequency (VLF/LF) Observations Reviewed

Kentaro Tanaka, Hiroyo Ohya, Fuminori Tsuchiya, Kenro Nozaki, Mariko Teramoto, Kazuo Shiokawa, Yoshizumi Miyoshi, Martin Connors, Hiroyuki Nakata

URSI Radio Science Letters Vol. 4 2023

SEARCH FOR PULSED ULTRALOW-FREQUENCY ELECTROMAGNETIC EARTHQUAKE PRECURSORS Reviewed Open Access

Martines-Bedenko V.A., Pilipenko V.A., Shiokawa K., Kasimova V.A.

Geophysical Research Vol. 24 ( 2 ) page： 5 - 24 2023

Language：English Publishing type：Research paper (scientific journal) Publisher：Geophysical Research

Numerous publications have appeared in the literature describing a new seismo-electromagnetic effect – the appearance of magnetic pulses with a duration of 1–40 s, which are detected at distances up to ten thousand km several minutes before earthquakes of even low magnitude. An assumption was made about the universality of the processes of impulse precursor generation and the fundamental possibility of a short-term (several minutes) warning of an approaching earthquake. In the presented article, the possibility of the appearance of ultra-low-frequency pulses that precede seismic events with magnitudes M>5.0, according to the data of a network of induction magnetometers in the Far East, is investigated. In the records of these highly sensitive magnetometers, impulse disturbances are constantly encountered, some of which are observed synchronously at several stations, which eliminates the influence of local noise. The spectral maximum of about 7–8 Hz of the oscillatory structure, which manifests itself in many pulses, corresponds to the fundamental frequency of the Schumann resonator. A comparison of magnetic observations with data from the WWLLN (World Wide Lightning Location Network) showed that some of the pulses were caused by lightning discharges in the 650 km vicinity of magnetic station. Despite the fact that some of the impulses are observed immediately before earthquakes, it is impossible to speak with confidence about their connection with seismic activity. The calculation of the number of impulses in the 5-min interval before and after the seismic shock shows that they are randomly distributed relative to the moment of the earthquake. Apparently, the pulses are predominantly due to the ionospheric response to a far lightning discharge.

DOI： 10.21455/gr2023.2-1

Relationship between geomagnetic storms and occurrence of ionospheric irregularities in the west sector of Africa during the peak of the 24th solar cycle Reviewed Open Access

Ondede George Ochieng, Rabiu A. B., Okoh Daniel, Baki Paul, Olwendo Joseph, Shiokawa Kazuo, Otsuka Yuichi

FRONTIERS IN ASTRONOMY AND SPACE SCIENCES Vol. 9 2022.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Frontiers in Astronomy and Space Sciences

The study of ionospheric irregularities is important since many technological systems might be influenced by the ionosphere. In this work, we use data from the Global Navigation Satellite Systems (GNSS) receiver installed in Abuja, Nigeria, GPS Scintillation Network Decision Aid (SCINDA) TEC data from the Air Force Research Laboratory (AFRL) data archive, and the geomagnetic data from the World Data Center (WDC) in Kyoto, Japan, to investigate the relationship between geomagnetic storm and ionospheric irregularity occurrences using the rate of change of total electron content (TEC) index (ROTI), with a validation using the S4 indices, during the peak of the 24th solar cycle. The occurrences of irregularities were investigated on day-to-day and seasonal bases. The nighttime ionospheric irregularities, which are attributed to ionospheric plasma irregularities in the equatorial ionospheric F-region, were found to be prevalent. To investigate the relationship between the strength of ionospheric irregularities (ROTI) and the geomagnetic storm (Dst), the periodogram power spectral density (PSD) and regression analysis were used. The results showed that there was no correlation, cc = 0.073, between the Dst and ROTI, implying that the strengths of ionospheric irregularities occurring during geomagnetic storms are not strictly decided by the magnitudes of the storms; this was also confirmed using the S4 index. The impact of geomagnetic storms caused enhanced development or inhibition of ionospheric irregularities. We observed that the bulk of the storms occurring during the period of this study is not associated with ionospheric irregularities. Finally, the investigation showed that the correlation between the ROTI and Dst observed during the coronal mass ejection (CME)-driven geomagnetic storms was higher than that during the corotating interaction region (CIR)-driven geomagnetic storms, during the peak of the 24th solar cycle. The results of this work confirm the findings by other researchers.

DOI： 10.3389/fspas.2022.969235

Observation of source plasma and field variations of a substorm brightening aurora at L ∼ 6 by a ground‐based camera and the Arase satellite on 12 October 2017 Reviewed

L. Chen, K. Shiokawa, Y. Miyoshi, S. Oyama, C‐W. Jun, Y. Ogawa, K. Hosokawa, Y. Inaba, Y. Kazama, S. Y. Wang, S. W. Y. Tam, T. F. Chang, B. J. Wang, K. Asamura, S. Kasahara, S. Yokota, T. Hori, K. Keika, Y. Kasaba, A. Kumamoto, F. Tsuchiya, M. Shoji, Y. Kasahara, A. Matsuoka, I. Shinohara, S. Imajo, S. Nakamura, M. Kitahara

Journal of Geophysical Research: Space Physics Vol. 127 ( 11 ) 2022.11

Thermospheric wind response to a sudden ionospheric variation in the trough: Event at a pseudo breakup during geomagnetically quiet conditions Reviewed Open Access

S.-i. Oyama, H. Vanhamäki, L. Cai, A. Aikio, M. Rietveld, Y. Ogawa, T. Raita, M. Kellinsalmi, K. Kauristie, B. Kozelov, A. Shinbori, K. Shiokawa, T. T. Tsuda, T. Sakanoi

Earth Planets Space Vol. 74 ( 1 ) page： 154 2022.10

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

The thermospheric wind response to a sudden westward turning of the ion velocity at a high latitude was studied by analyzing data obtained with a Fabry-Perot interferometer (FPI; 630 nm), Dynasonde, and Swarm A & C satellites during a conjunction event. The event occurred during a geomagnetically quiet period (Kp= 0+) through the night, but some auroral activity occurred in the north. The collocated FPI and Dynasonde measured the thermospheric wind (U) and ionospheric plasma velocity (V), respectively, in the F region at the equatorward trough edge. A notable scientific message from this study is the possible role of thermospheric wind in the energy dissipation process at F-region altitude. The FPI thermospheric wind did not instantly follow a sudden V change due to thermospheric inertia in the F region. At a pseudo-breakup during the event, V suddenly changed direction from eastward to westward within 10 min. U was concurrently accelerated westward, but its development was more gradual than that of V, with U remaining eastward for a while after the pseudo-breakup. The delay of U is attributed to the thermospheric inertia. During this transition interval, U.V was negative, which would result in more efficient generation of frictional heating than the positive U.V case. The sign of U.V, which is related to the relative directions of the neutral wind and plasma drift, is important because of its direct impact on ion-neutral energy exchange during collisions. This becomes especially important during substorm events, where rapid plasma velocity changes are common. The sign of U.V may be used as an indicator to find the times and locations where thermospheric inertia plays a role in the energy dissipation process.

DOI： 10.1186/s40623-022-01710-6

Three-Dimensional Fourier Analysis of Atmospheric Gravity Waves and Medium-Scale Traveling Ionospheric Disturbances Observed in Airglow Images in Hawaii Over Three Years Reviewed

Localized mesospheric ozone destruction corresponding to isolated proton aurora coming from Earth's radiation belt. Reviewed International journal Open Access

Mitsunori Ozaki, Kazuo Shiokawa, Ryuho Kataoka, Martin Mlynczak, Larry Paxton, Martin Connors, Satoshi Yagitani, Shion Hashimoto, Yuichi Otsuka, Satoshi Nakahira, Ian Mann

Scientific reports Vol. 12 ( 1 ) page： 16300 - 16300 2022.10

Language：English Publishing type：Research paper (scientific journal)

Relativistic electron precipitation (REP) from the Earth's radiation belt plays an important role in mesospheric ozone loss as a connection between space weather and the climate system. However, the rapid (tens of minutes) destruction of mesospheric ozone directly caused by REP has remained poorly understood due to the difficulty of recognizing its location and duration. Here we show a compelling rapid correspondence between localized REP and ozone destruction during a specific auroral phenomenon, the called an isolated proton aurora (IPA). The IPA from the Earth's radiation belt becomes an important spatial and temporal proxy of REP, distinct from other auroral phenomena, and allowing visualizing micro-ozone holes. We found ozone destruction of as much as 10-60% within 1.5 h of the initiation of IPA. Electromagnetic ion cyclotron waves in the oxygen ion band observed as the driver of REP likely affect through resonance with mainly ultra-relativistic (> 2 mega-electron-volts) energy electrons. The rapid REP impact demonstrates its crucial role and direct effect on regulating the atmospheric chemical balance.

DOI： 10.1038/s41598-022-20548-2

Hideto Naito, Kazuo Shiokawa, Yuichi Otsuka, Hatsuki Fujinami, Takuma Tsuboi, Takeshi Sakanoi, Akinori Saito, Takuji Nakamura

Journal of Geophysical Research: Space Physics Vol. 127 ( 10 ) 2022.10

Language：English Publishing type：Research paper (scientific journal)

Three-dimensional Fourier spectral analysis of airglow images is a useful technique to provide propagation characteristics of atmospheric gravity waves (AGWs) in the mesopause region and medium-scale traveling ionospheric disturbances (MSTIDs) in the thermosphere observed at emission wavelengths of 557.7 nm (altitudes: 90–100 km for AGWs) and 630.0 nm (200–300 km for MSTIDs). However, a statistical study of spectral analysis of airglow images over years has not been done yet at Hawaii. Here, we report the first spectral analysis of AGWs and MSTIDs using airglow images obtained at Haleakala (20.71°N, 203.74°E), Hawaii, during the three years from 2013 to 2016. The power spectral density (PSD) of AGWs tends to be larger toward north to northeast in summer and from north to west and southward in winter. The eastward (summer) and westward (winter) preferences are consistent with a wind-filtering mechanism of AGWs by a mesospheric jet. Some correspondence is found between the locations of tropospheric convection activities and AGW propagation directions, suggesting that these mesospheric AGWs are originated from the troposphere. The PSDs of MSTIDs are larger in solstice than in equinox. This PSD enhancement in solstice is consistent with a sporadic-E (Es) layer occurrence in either northern or southern hemisphere, suggesting that the MSTIDs over Hawaii could be caused by a coupling process between the Perkins and Es layer instabilities. A small correlation was found between the PSDs of AGWs in the mesopause region and the PSDs of MSTIDs, suggesting that the MSTIDs are partly caused by AGWs from the mesopause region.

DOI： 10.1029/2022JA030346

Multi-Event Study of Simultaneous Observations of Isolated Proton Auroras at Subauroral Latitudes Using Ground All-Sky Imagers and the Van Allen Probes Reviewed

Nakamura Kohki, Shiokawa Kazuo, Nose Masahito, Nagatsuma Tsutomu, Sakaguchi Kaori, Spence Harlan, Reeves Geoff, Funsten Herbert O., MacDowall Robert, Smith Charles, Wygant John, Bonnell John, Mann Ian R.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 127 ( 9 ) 2022.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Geophysical Research: Space Physics

Isolated proton auroras (IPAs) appearing at subauroral latitudes are generated by energetic protons precipitating from the magnetosphere through interaction with electromagnetic ion cyclotron (EMIC) waves. Thus, an IPA is the ionospheric projection of the spatial and temporal variation of wave-particle interaction regions in the magnetosphere. In this study, we conducted unique multi-event analysis of simultaneous observations of IPAs and their source regions on 22 April, 7 September, and 22 March 2018, using all-sky imagers at subauroral latitudes and the Van Allen Probes. When the satellite footprint passed over the IPAs associated with ground Pc1 geomagnetic pulsations, locally generated He+-band EMIC waves with the same frequencies as the ground Pc1 pulsations were observed in all events. The IPAs and EMIC waves had comparable narrow widths in the latitudinal direction. The EMIC waves appeared during the rapid enhancement of the ring current proton flux at energy range of ∼10–50 keV, while they disappeared at the rapid decrease of the electron density. From these results, we conclude that the boundaries of the localized IPAs and EMIC waves were determined by the overlap region of energetic proton enhancement and the plasmasphere. This overlap of ring-current protons and plasmasphere is a favorable condition for the pitch-angle scattering of protons by the EMIC waves. Characteristic magnetic and electric field variations with the IPAs were not observed by the satellite, indicating that the IPAs were not accompanied by field-aligned currents comparable to that of oval auroral arcs.

DOI： 10.1029/2022JA030455

Statistical Study of Subauroral Arc Detachment at Athabasca, Canada: New Insights on STEVE Reviewed

Yadav Sneha, Shiokawa Kazuo, Otsuka Yuichi, Connors Martin

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 127 ( 9 ) 2022.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Geophysical Research: Space Physics

We present the first comparative statistical study of subauroral arc detachment from the main auroral oval at Athabasca (magnetic latitude = 61.5°N), Canada, for three different types of subauroral arcs: pure red arc, red arc with simultaneous emission in green-line (red + green arc), and STEVE (strong thermal emission velocity enhancement). Based on 15-years (2006–2020) of all-sky imaging observations, this study not only uncovers the occurrence characteristics of different arcs but also provides important insights into the specific geomagnetic conditions under which STEVE develops. Red arc was the most common subauroral arc (139 events), followed by red + green arc (42 events), and STEVE (26 events) was a rare phenomenon. The detachment rate of red and red + green arcs exhibits dependence on both the solar flux and geomagnetic activity. The detachment rate of STEVE was higher during premidnight, whereas that of red and red + green arcs was higher around the midnight sector. The geomagnetic activity was relatively higher for STEVE, the decrease in the AL index and local X-component magnetic variations being ∼2–3 times higher for STEVE as compared to other arcs. STEVE shows a strong association with asymmetric ring current in terms of prominent bay-like enhancement in ASY-H index prior to its detachment. Such bay-like enhancement was ∼4 times higher for STEVE as compared to other arcs. STEVE events were accompanied by dispersionless injection for both electron and proton flux at geosynchronous orbit. These results unambiguously suggest that STEVE develops after substorm associated energy injection and significant intensification of the asymmetric ring current.

DOI： 10.1029/2021JA029856

Quantifying the Size and Duration of a Microburst‐Producing Chorus Region on 5 December 2017 Reviewed Open Access

S. S. Elliott, A. W. Breneman, C. Colpitts, J. M. Pettit, C. A. Cattell, A. J. Halford, M. Shumko, J. Sample, A. T. Johnson, Y. Miyoshi, Y. Kasahara, C. M. Cully, S. Nakamura, T. Mitani, T. Hori, I. Shinohara, K. Shiokawa, S. Matsuda, M. Connors, M. Ozaki, J. Manninen

Geophysical Research Letters Vol. 49 ( 15 ) page： e2022GL099655 2022.8

A Story of Developing the Idea of Plasma-Sheet Flow Braking Reviewed Open Access

Shiokawa Kazuo

FRONTIERS IN ASTRONOMY AND SPACE SCIENCES Vol. 9 2022.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Frontiers in Astronomy and Space Sciences

This paper reports a story of developing the idea of Earthward ion flow braking in the near-Earth plasma sheet and its relationship with substorm onset processes. This idea and the data that support it are the basis for today’s two competing models for substorms: the near-Earth neutral-line model and the current disruption model. The idea was developed when the author was staying at the Max Planck Institute for Extraterrestrial Physics (MPE) from July 1996 to June 1997. The story addresses the colleagues and mentors who had contributed to the development of this idea. The lessons learned from this story are also summarized for students and early-career scientists for their development of new scientific ideas.

DOI： 10.3389/fspas.2022.957776