A5079579082- Ionosphere and magnetosphere dynamics
- Earthquake Detection and Analysis
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- GNSS positioning and interference
- Atmospheric and Environmental Gas Dynamics
- Atmospheric Ozone and Climate
- Seismic Waves and Analysis
- Space Exploration and Technology
- Astro and Planetary Science
- Plasma Diagnostics and Applications
- Spacecraft Design and Technology
- Atomic and Subatomic Physics Research
- Underwater Acoustics Research
- Methane Hydrates and Related Phenomena
- Lightning and Electromagnetic Phenomena
- Infrared Target Detection Methodologies
- Underwater Vehicles and Communication Systems
- Currency Recognition and Detection
National Institute of Polar Research
2022-2024
Tohoku University
2018-2022
Planetary Science Institute
2018-2020
Abstract Pulsating auroras (PsAs) are thought to be generated by precipitating electrons scattered lower‐band chorus (LBC) waves near the magnetic equator. One‐to‐one correlation between LBC intensity and PsA has been reported. Electrostatic electron cyclotron harmonic (ECH) can also scatter electrons. However, direct ECH not reported yet. In this study, using a coordinated Exploration of energization Radiation in Geospace (Arase) satellite ground‐based imager observation, we report that...
Abstract. We studied the effects of geomagnetic mirror force on electron density enhancements in polar atmosphere due to energetic precipitation. Using pitch angle and energy distribution electrons observed by low-altitude Electron Losses Fields INvestigation (ELFIN) satellites as initial conditions, caused precipitating was calculated a simulation with two different methods: traditional method that does not include effect recently developed includes effect. From simultaneous observation...
Abstract We report on the relationship between a pulsating aurora and relativistic electron microburst using simultaneous observations of ground‐based fast auroral imagers with FIREBIRD‐Ⅱ CubeSat for first time. conducted detailed analysis an event October 8, 2018 found that occurrence internal modulations corresponds to flux enhancement electrons energy ranging from ∼220 keV >1 MeV detected Flight Unit 4, one FIREBIRD's CubeSat, time delay ∼585 ms. Combining this result flight model, we...
Abstract Inner magnetospheric electrons are precipitated in the ionosphere via pitch‐angle (PA) scattering by lower band chorus (LBC), upper (UBC), and electrostatic electron cyclotron harmonic (ECH) waves. However, PA efficiency of low‐energy (0.1–10 keV) has not been investigated situ observations because difficulties flux measurements within loss cones at magnetosphere. In this study, we demonstrate that LBC, UBC, ECH waves contribute to different energy ranges using Arase (ERG) satellite...
Abstract Electrostatic electron cyclotron harmonic (ECH) waves are generally excited in the magnetic equator region, sector from nightside to dayside during geomagnetically active conditions, and cause pitch angle scattering by resonance. The scattered electrons precipitate into Earth's atmosphere auroral emission. However, there is no observational evidence that ECH actually scatter loss cone magnetosphere. In this study, simultaneous wave particle observation data obtained Arase satellite...
Abstract We present the first and direct comparison between magnetospheric plasma waves polar mesosphere winter echoes (PMWE) simultaneously observed by conjugate observation with Arase satellite high‐power atmospheric radars in both hemispheres, namely, Program of Antarctic Syowa Mesosphere, Stratosphere, Troposphere/Incoherent Scatter Radar at Station (SYO; −69.00°S, 39.58°E), Antarctica, Middle Atmosphere Alomar System Andøya (AND; 69.30°N, 16.04°E), Norway. The PMWE were during 03–07 UT...
Abstract. In recent years, aurora observation networks using high-sensitivity cameras have been developed in the polar regions. These allow dimmer auroras, such as pulsating auroras (PsAs), to be observed with a high signal-to-noise ratio. We reconstructed horizontal distribution of precipitating electrons computed tomography monochromatic PsA images obtained from three points. The three-dimensional volume emission rate (VER) was also reconstructed. characteristic energy electron flux ranged...
Abstract An energy spectrum of electrons from 180 to 550 keV precipitating into the dayside polar ionosphere was observed under a geomagnetically quiet condition (AE ≤ 100 nT, Kp = 1‐). The observation carried out at 73–184 km altitudes by HEP instrument onboard RockSat‐XN sounding rocket that has been launched Andøya, Norway. follows power law −4.9 ± 0.4 and electron flux does not vary much over period (∼274.4 s). A nearby ground‐based VLF receiver Lovozero, Russia shows presence...
We conducted a feasibility study to estimate the horizontal ion velocity field in ionospheric F region from velocities observed by EISCAT_3D radar. assumed 27-beam configuration with minimum elevation angle of 30 degrees. The observation data 200 km 500 altitude were projected altitude, assuming ions above follow E x B drift. Then, we reconstructed vectors for ±250 east-west direction and ±500 north-south at altitude. resolution directions was 25 km. reconstruction...
Abstract Pulsating Aurora (PsA) is one of the major classes diffuse aurora associated with precipitation a few to tens keV electrons from magnetosphere. Recent studies suggested that, during PsA, more energetic (i.e., sub‐relativistic/relativistic) precipitate into ionosphere at same time. Those are considered be scattered higher latitude part magnetosphere by whistler‐mode chorus waves propagating away magnetic equator. However, there have been no actual cases simultaneous observations...
Abstract Pulsating auroras (PsAs) are considered to be caused by energetic (>a few keV) electron precipitation. Additionally, soft precipitation (<a has often been observed in PsAs. This enhances the density ionospheric F region. However, date, relationship between PsAs and not well understood. In this study, using data taken European incoherent scatter radar auroral all‐sky imager at Tromsø, we conducted two case studies investigate, detail, height profile type of aurora. statistical...
Abstract Whistler mode chorus waves scatter magnetospheric electrons and cause precipitation into the Earth's atmosphere. Previous measurements showed that nightside are indeed responsible for diffuse/pulsating aurora. Although electron have also been detected on dayside, their link has not illustrated (or demonstrated) in detail compared to observations. Conventional low‐altitude satellite observations do well resolve energy range of 10–100 keV, hampering verification resonance condition...
Earth and Space Science Open Archive This work has been accepted for publication in Science. Version of RecordESSOAr is a venue early communication or feedback before peer review. Data may be preliminary. Learn more about preprints. preprintOpen AccessYou are viewing the latest version by default [v1]Simultaneous pulsating aurora microburst observations with ground-based fast auroral imagers CubeSat...
Abstract. Pulsating auroras (PsAs) appear over a wide area within the aurora oval from midnight sector to noon sector. In previous studies, observations by magnetometers onboard satellites have reported presence of field-aligned currents (FACs) near edges and interiors pulsating patches. PsAs are thus key research target for understanding magnetosphere–ionosphere coupling process. However, three-dimensional (3-D) structure electric has yet be clarified, since each satellite observation is...
Abstract. Pulsating auroras (PsAs) appear over a wide area within the aurora oval in midnight–morning–noon sector. In previous studies, observations by magnetometers on board satellites have reported presence of field-aligned currents (FACs) near edges and interiors pulsating patches. PsAs are thus key research target for understanding magnetosphere–ionosphere coupling process. However, three-dimensional (3-D) structure electric has yet to be clarified, since each satellite observation is...