A5041690054- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Geomagnetism and Paleomagnetism Studies
- Magnetic confinement fusion research
- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Solar Radiation and Photovoltaics
- Plasma Diagnostics and Applications
- Geophysics and Gravity Measurements
- Gas Dynamics and Kinetic Theory
- Atmospheric aerosols and clouds
- Dust and Plasma Wave Phenomena
- Earthquake Detection and Analysis
- Computational Fluid Dynamics and Aerodynamics
- Laser-induced spectroscopy and plasma
- Oil, Gas, and Environmental Issues
- Global Energy and Sustainability Research
- Space exploration and regulation
- Magnetic Field Sensors Techniques
- Fluid Dynamics and Turbulent Flows
- Computational Physics and Python Applications
- Atmospheric chemistry and aerosols
- Advanced Thermodynamics and Statistical Mechanics
- Complex Systems and Time Series Analysis
- Atmospheric Ozone and Climate
Nagoya University
2016-2025
Earth and Space Research
2016-2023
University of Tsukuba
2017-2021
Japan Science and Technology Agency
2020
The University of Tokyo
1987-2019
Institute for Cosmic Ray Research
2019
Japan Agency for Marine-Earth Science and Technology
2007-2016
Institute of Solar-Terrestrial Physics
2014-2015
Hiroshima University
1997-2014
Mie University
2004
A novel, particle based, probabilistic approach for the simulation of cloud microphysics is proposed, which named Super-Droplet Method (SDM). This method enables accurate with less demanding cost in computation. SDM applied to a warm-cloud system, incorporates sedimentation, condensation/evaporation, and stochastic coalescence. The methodology couple super-droplets non-hydrostatic model also developed. It confirmed that result our Monte Carlo scheme coalescence agrees fairly well solutions...
Abstract In 2024 May, the scientific community observed intense solar eruptions that resulted in a great geomagnetic storm and auroral extensions, highlighting need to document quantify these events. This study mainly focuses on their quantification. The source active region (AR; NOAA Active Region 13664) evolved from 113 2761 millionths of hemisphere between May 4 14. AR 13664’s magnetic free energy surpassed 10 33 erg 7, triggering 12 X-class flares 8–15. Multiple interplanetary coronal...
Solar flares and coronal mass ejections are associated with rapid changes in field connectivity powered by the partial dissipation of electrical currents solar atmosphere. A critical unanswered question is whether involved induced motion pre-existing atmospheric magnetic flux subject to surface plasma flows, or these emergence from within convective zone. We address this problem applying state-of-the-art nonlinear force-free (NLFFF) modeling highest resolution quality vector-magnetographic...
We develop a new methodology that can determine magnetic helicity flux as well Poynting across the photosphere based on magnetograph observation. By applying this method, we study injection mechanism of and free energy into solar corona. In order to derive fluxes, first velocity tangential surface is constructed by correlation tracking technique observation, second, component normal derived from condition evolution must be consistent with induction equation. Through procedure, fluxes...
Solar flares and coronal mass ejections (CMEs), the most catastrophic eruptions in our solar system, have been known to affect terrestrial environments infrastructure. However, because their triggering mechanism is still not sufficiently understood, capacity predict occurrence of forecast space weather substantially hindered. Even though various models proposed determine onset eruptions, types magnetic structures capable these are unclear. In this study, we solved problem by systematically...
A severe geomagnetic storm, and the largest in solar cycle 24, occurred on 17–18 March 2015 without significant precursor X- or M-type flares. Figure 1 shows (first to fourth panels) wind variables, auroral electrojets indices, Disturbance Storm Time (Dst) index associated with event, which was classified as a G4 (severe) level storm (http://www.swpc.noaa.gov/noaa-scales-explanation). Red auroras were seen even from northern part of Japan for first time during present cycle, attracting...
Predicting large solar flares The sudden release of magnetic energy on the Sun drives powerful flares, which are difficult to predict. Kusano et al. derived physics-based thresholds for onset and show how they can be predicted from routine observations (see Perspective by Veronig). They tested their method using 2008 2019. In most cases, correctly identifies regions will produce within next 20 hours, although there some false positives negatives. also provides exact location where each flare...
We have investigated the possibility that magnetic reconnection between oppositely sheared loops works as a trigger mechanism of solar flares, based on three-dimensional numerical simulations. The simulations were carried out by applying slow footpoint motion, which reverses preloaded shear, in vicinity neutral line. simulation results clearly indicated reversal shear can cause large-scale eruption arcade through series two different kinds reconnections. first is initiated resistive-tearing...
Recently, several methods that measure the velocity of magnetized plasma from time series photospheric vector magnetograms have been developed. Velocity fields derived using such techniques can be used both to determine fluxes magnetic energy and helicity into corona, which important consequences for understanding solar flares, coronal mass ejections, dynamo, drive time-dependent numerical models fields. To date, these not rigorously tested against realistic, simulated data sets, in field...
This paper explores the characteristics of 42 solar X-class flares that were observed between February 2011 and November 2014, with data from Solar Dynamics Observatory (SDO) other sources. flare list includes nine had no associated CMEs. In particular our aim was to determine whether a clear signature could be identified differentiate powerful have coronal mass ejections (CMEs) those do not. Part motivation for this study is characterization paradigm flare/CME occurrence as possible guide...
Abstract Solar eruptions are well-known drivers of extreme space weather, which can greatly disturb the Earth’s magnetosphere and ionosphere. The triggering process initial dynamics these still an area intense study. Here we perform a magnetohydrodynamic simulation taking into account observed photospheric magnetic field to reveal solar eruption in real environment. In our simulation, confirmed that tether-cutting reconnection occurring locally above polarity inversion line creates twisted...
We analyze the simulation result shown in Hotta & Kusano, 2021 which solar-like differential rotation is reproduced. The Sun rotating differentially with fast equator and slow pole. It widely thought that thermal convection maintains rotation, but recent high-resolution simulations tend to fail reproduce equator. This fact an aspect of one biggest problems solar physics called convective conundrum. succeed reproducing without using any manipulation unprecedentedly simulation. In this study,...
Twist and connectivity of magnetic field lines in the flare-productive active region NOAA 10930 are investigated terms vector magnetograms observed by Solar Optical Telescope on board Hinode satellite nonlinear force-free (NLFFF) extrapolation. First, we show that footpoints reconstructed NLFFF correspond well to conjugate pair highly sheared flare ribbons Ca ii images, which were as an X3.4 class 2006 December 13. This demonstrates extrapolation may be used analyze connectivity. Second,...
A 3‐D magnetohydrodynamic (MHD) simulation is performed to reconstruct the interplanetary propagation of a coronal mass ejection (CME) that occurred on 13 December 2006. spheromak‐type magnetic field superposed realistic ambient solar wind reproduce large‐scale (IMF) associated with CME. Here we show westward and southward directed spheromak CME reasonable geometric, dynamic, parameters reproduces cloud, shock, sheath profiles as observed by in situ spacecraft. We suggest simple model...
Aims. We report the small temporal variation of axial dipole moment near solar minimum and its application to cycle prediction by surface flux transport (SFT) model. Methods. measure using photospheric synoptic magnetogram observed Wilcox Solar Observatory (WSO), ESA/NASA Heliospheric Michelson Doppler Imager (MDI), NASA Dynamics Helioseismic Magnetic (HMI). also use model for interpretation moment. Results. find that becomes approximately constant during period several years before each...
The stability of the magnetic field in solar corona is important for understanding causes eruptions. Although various scenarios have been suggested to date, tether-cutting reconnection scenario proposed by Moore et al.(2001) one widely accepted models explain onset process that sigmoidal formed internal pre-eruptive state, has not yet investigated quantitatively. In this paper, order elucidate problem we developed a simple numerical analysis, which modeled double arc electric current loop...
We performed a magnetohydrodynamic simulation of formation process coronal mass ejections (CMEs), focusing on the interaction (reconnection) between an ejecting flux rope and its ambient field. examined three cases with different fields: one had no field, while other two dipole fields opposite directions, parallel anti-parallel to that surface. found disappears in case, ropes can evolve CMEs show amounts rotation. The results imply field is important for determining CME orientation, also...
We report a detailed event analysis on the M6.6-class flare in active region (AR) NOAA 11158 2011 February 13. AR 11158, which consisted of two major emerging bipoles, showed prominent activities including one X- and several M-class flares. In order to investigate magnetic structures related M6.6 event, particularly formation process flare-triggering region, we analyzed multiple spacecraft observations numerical results simulation. observed that, center this quadrupolar AR, highly sheared...
We develop a nonlinear force-free field (NLFFF) extrapolation code based on the magnetohydrodynamic (MHD) relaxation method. extend classical MHD method in two important ways. First, we introduce an algorithm initially proposed by cite{2002JCoPh.175..645D} to effectively clean numerical errors associated with $nabla cdot vec{B}$. Second, multi-grid type is implemented our NLFFF perform direct analysis of high-resolution magnetogram data. As result these implementations, successfully...
Solar flares are extremely energetic phenomena in our System. Their impulsive, often drastic radiative increases, particular at short wavelengths, bring immediate impacts that motivate solar physics and space weather research to understand the point of being able forecast them. As data algorithms improve dramatically, questions must be asked concerning how well forecasting performs; crucially, we ask rigorously measure performance order critically gauge any improvements. Building upon...
One comprehensive calculation covers the whole solar convection zone.