A5033483342- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Earthquake Detection and Analysis
- Geomagnetism and Paleomagnetism Studies
- Atmospheric Ozone and Climate
- GNSS positioning and interference
- Geophysics and Gravity Measurements
- Astro and Planetary Science
- Geophysics and Sensor Technology
- Ocular and Laser Science Research
- Planetary Science and Exploration
- Methane Hydrates and Related Phenomena
- Gyrotron and Vacuum Electronics Research
- Seismic Waves and Analysis
- Arctic and Russian Policy Studies
- Aerospace Engineering and Energy Systems
- Cryospheric studies and observations
- Arctic and Antarctic ice dynamics
- Advanced Fiber Optic Sensors
- Meteorological Phenomena and Simulations
- Astrophysics and Cosmic Phenomena
- Spacecraft and Cryogenic Technologies
- Atomic and Subatomic Physics Research
- Optical Systems and Laser Technology
- Particle accelerators and beam dynamics
National Institute of Polar Research
2010-2022
The Graduate University for Advanced Studies, SOKENDAI
2004-2015
Research Organization of Information and Systems
2005
Tohoku University
2003
Seoul National University
2003
Johns Hopkins University Applied Physics Laboratory
1992-2001
Keio University
1960-2001
Chiba University
1998
Tokai University
1992
The Aerospace Corporation
1992
In an attempt to place short‐lived, high‐speed magnetotail flows termed bursty bulk flow events (BBFs) in the context of substorm phenomenology we analyze one such event that took on April 11, 1985, using data from several spacecraft and many ground stations. The onset, which at 0127 UT, had a meridian 2 hours local time east AMPTE/IRM. satellite did not detect time. A high‐latitude (∼70° corrected geomagnetic) intensification 0202 UT centered ∼0.5 hour west AMPTE/IRM meridian. ISEE lobe...
We have carried out a direct comparison of pulsating auroras observed from the ground at Syowa Station in Antarctica and on board FAST satellite (∼3100 km altitude), with reference to simultaneous data obtained by Syowa‐Iceland conjugate pair observatories. The aurora appeared as east‐west aligned bands consisting two different types: poleward moving oscillation standing oscillation, each period ∼6 s. Spatial temporal variations downgoing high‐energy (>5 keV) electron flux showed...
Four Pi 2 magnetic pulsations, observed on the ground at L = 1.2–6.9 in interval from 2300 UT May 22 to 0300 23, 1985, provide new evidence of a global nature pulsations inner ( ≲ 7) region magnetosphere bounded by plasma sheet during quiet geomagnetic conditions. In present study, data have been collected stations distributed widely both local time and latitude, including conjugate stations, AMPTE/CCE spacecraft located magnetotail. On basis high resolution field data, following...
Abstract We report results from the analysis of a case conjugate polar cap arcs (PCAs) observed on 5 February 2006 in Northern Hemisphere by ground‐based Yellow River Station all‐sky imager (Svalbard) and both hemispheres space‐based DMSP/SSUSI TIMED/GUVI instruments. The PCA's motion dawn‐dusk direction shows clear dependence interplanetary magnetic field (IMF) B y component presents asymmetry between Southern Hemispheres, that is, formed duskside moving dusk to dawn vice versa other...
This paper reports the first comparison between comprehensive observations of equatorward moving traveling ionospheric disturbance at midlatitudes and thermospheric general circulation model with high‐latitude energy input based on data assimilation. A prominent (TID) was observed during major magnetic storm 31 March 2001. The TID propagated from north to south over Japan phase speeds 370–640 m/s. assimilative mapping electrodynamics (AMIE) technique used as...
We present a fine‐scale electrodynamic structure behind the auroral beads observed immediately before substorm onset, as inferred from high spatial and temporal resolution measurements of with an all‐sky TV camera (ATV) coherent frequency radar Super Dual Auroral Radar Network in Iceland. On night 24 September 2006, ATV eastward propagating initial brightening arc just prior to poleward expansion. During sequential passage across beams, detected large velocity flow shears whose magnitude was...
Fine examples of both conjugate and nonconjugate isolated auroral arcs were observed at two geomagnetically stations near L = 6, Syowa Station in Antarctica Husafell Iceland on September 12, 1988. These events exhibited some interesting characteristics. An loop structure that appeared hemispheres was ∼2.0 times larger the north‐south direction than Husafell. This scale difference is greater expected from geographic geomagnetic (IGRF) coordinates between points observation. However, temporal...
Both odd‐mode and even‐mode standing wave structures have been proposed for giant pulsations. Unless a conclusion is drawn on the field‐aligned mode structure, little progress can be made in understanding excitation mechanism of In order to determine mode, we systematic survey magnetic field data from AMPTE CCE spacecraft ground stations located near geomagnetic foot point CCE. We selected time intervals when was close equator also magnetically Syowa Iceland, either transverse or...
We show evidence to suggest that some auroral forms may be related the field‐aligned current structure associated with magnetohydrodynamic wave activity, specifically field line resonances. These auroras appear as a series of azimuthally spaced east‐west elongated arcs, inclined slightly from north south. Modeling shows this “braided” appearance reflects locations upward driven by wave. Moreover, more complicated structures can produced if several harmonically waves occur together. model...
Interhemispheric conjugate auroral features during a weak substorm interval were investigated using simultaneous all‐sky camera (ASC) measurements at the northern and southern geomagnetic points Tjörnes (TJO; 66.2°N, 342.9°E) in Iceland Syowa Station (SYO; 69.0°S, 39.6°E) Antarctica. Around postmidnight, just after onset, ASC field of view (FOV) TJO was first filled with dynamic activations; however, its counterpart not detected over zenith SYO that time. In contrast, late stage (about 20...
[1] We examined temporal variations of a dayside aurora and corresponding ionospheric plasma convection observed by an all-sky camera (ASC) the Super Dual Auroral Radar Network (SuperDARN) over Zhongshan (ZHS), located at −74.5° in magnetic latitude (MLAT) Antarctica, during geomagnetic sudden commencement (SC) event that occurred on 27 May 2001. Simultaneous ASC observations South Pole (SP, −74.3° MLAT) were also analyzed. During SC time, ZHS SP postnoon (1610 MLT) prenoon (1100 sectors,...
[1] Simultaneous observations of auroral kilometric radiation from the Northern and Southern Hemispheres showed some cases in which buildup field-aligned acceleration occurred only one hemisphere at substorm onset. This indicates that a does not always complete current system by connecting cross-tail with both northern southern ionospheric currents. Conjugate case, breakup was simultaneous; rather, they few minutes apart. time difference between two hemispheres suggests local ionosphere...
Using data from the polar orbiting Dynamic Explorer (DE) −1 and −2 satellites a ground‐based station, we investigated electron precipitation phenomena accompanying Pc 5 pulsations. DE‐2 observed oscillatory disturbances in magnetic electric fields upper ionosphere at geomagnetic footprint of high altitude region which transverse pulsations were detected by DE‐1. electrons precipitating into with energies several keV to tens keV. These accelerated direction ambient field. When H‐component...
We report on highly similar auroras that were simultaneously acquired with all‐sky TV cameras situated at two geomagnetically conjugate points, Tjornes in Iceland and Syowa Station Antarctica. During this event, meso‐scale discrete auroras, including both east‐west north‐south directed auroral forms, showed excellent similarity terms of shapes, movements luminosity variations observatories. Using these data we able to trace the temporal displacement Northern Southern Hemispheres a high...
[1] We provide in situ evidence for a twisted near-Earth tail configuration that is responsible the time sequence of conjugate auroral features associated with relative interhemispheric displacement during weak substorm, as reported by Motoba et al. (2010). analyzed magnetic field data observed using four Cluster satellites vicinity 11–14 RE central downtail, close conjunction Iceland-Syowa optical features. Interestingly, we found variations y component (By) at all correlated moderately...
We have made a direct comparison of pulsating aurora observed simultaneously from the ground at Syowa in Antarctica and onboard FAST satellite (∼3100 km altitude). The auroral form appeared as east‐west‐aligned bands consisting two different types: poleward moving pulsation standing mode pulsation, each with period ∼5 sec. occurs within region an inverted‐V structure lower energy (0.1–1 keV) electron precipitation. types are separated space by narrow gap potential structure. Spatial temporal...
Type 2 quasi‐periodic (QP) VLF emissions with fairly regular‐period pulsations sometimes show good coherency the H component of magnetic pulsations. From relative‐phase analysis between QP and pulsations, it is found that relative phases are independent pulsation periods. It suggested observed on ground generated in ionosphere. The precipitating electron fluxes induced by modify ionospheric conductivity. enhancement conductivity D E regions would S q p current flows ionosphere, resulting...
We have studied the response of large‐scale ionospheric convection to substorm expansion onsets on basis two weak substorms 1 May 2001, during which a large part dawn cell two‐cell pattern was monitored by SuperDARN radars. Ionospheric began enhance first in localized region equatorward ∼2 minutes before both and then enhanced entire successively. The persisted throughout their phase, possibly even near footprint plasma sheet without fast flows observed Geotail. These observations suggest...
A high correlation between a pulsating auroral patch and grouped chorus waves was observed on 17 April 2006 at Syowa Station in Antarctica. The spatial distribution of aurora–chorus coefficients is evaluated order to determine the source region. highest‐correlation pixel shows one‐to‐one correspondence with intensity variation waves, consisting successive rising‐tone elements duration spacing 2–3 s 20–30 s, respectively. generation region estimated from latitude longitude dependence...
Abstract The substorm onset process was studied on the basis of vertical evolution auroral acceleration regions derived from kilometric radiation (AKR) spectra and Pi pulsations ground. field‐aligned at demonstrated two distinct phases. Low‐altitude ( h ~3000–5000 km), which accompanied initial brightening, prebreakup Pi2, direct current ultralow frequency (DC‐ULF) pulsation were first activated played an important role (precondition) in subsequent expansion phase onset. Prebreakup Pi2 is...