A5082693247- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Stellar, planetary, and galactic studies
- Earthquake Detection and Analysis
- Solar Radiation and Photovoltaics
- Atmospheric Ozone and Climate
- Monetary Policy and Economic Impact
- CO2 Sequestration and Geologic Interactions
- Geotechnical Engineering and Underground Structures
- Astrophysics and Cosmic Phenomena
- Geophysics and Gravity Measurements
- Financial Markets and Investment Strategies
- Seismic Waves and Analysis
- Statistical and numerical algorithms
- Phase-change materials and chalcogenides
Indian Institute of Astrophysics
2021-2024
Nagoya University
2023
Max Planck Institute for Solar System Research
2019-2021
University of Science and Technology of China
2015-2020
Center for Excellence in Molecular Cell Science
2019
Physical Research Laboratory
2013-2015
Udaipur Solar Observatory
2013-2015
The arrival of a series coronal mass ejections (CMEs) at the Earth resulted in great geomagnetic storm on 10 May 2024, strongest last two decades. We investigated kinematic and thermal evolution successive CMEs to understand their interaction en route Earth. attempted find dynamic, thermodynamic, magnetic field signatures CME-CME interactions. Our focus was compare state near Sun post-interaction phase 1 AU. 3D kinematics six identified Earth-directed were determined using graduated...
The ISWAT (International Space Weather Action Teams) heliosphere clusters H1 and H2 have a focus on interplanetary space its characteristics, especially the large-scale co-rotating transient structures impacting Earth. Solar wind stream interaction regions, generated by between high-speed solar originating in open coronal magnetic fields slower from closed fields, are regions of compressed plasma field followed streams that recur at ∼27 day rotation period. Short-term reconfigurations lower...
The prediction of the arrival time and transit speed CMEs near Earth is one key problems in understanding solar terrestrial relationship. Although, STEREO observations now provide a multiple view heliosphere, true speeds derived from stereoscopic reconstruction SECCHI coronagraph data are not quite sufficient accurate forecasting majority at Earth. This due to many factors which change CME kinematics, like interaction two or more with pervading wind. In order understand propagation CMEs, we...
We have studied two Coronal Mass Ejections (CMEs) that occurred on September 25 and 28, 2012 interacted near the Earth. By fitting Graduated Cylindrical Shell (GCS) model SECCHI/COR2 images applying Stereoscopic Self-Similar Expansion (SSSE) method SECCHI/HI images, initial direction of both CMEs is estimated to be west Sun-Earth line. Further, three-dimensional (3D) heliospheric kinematics these been using (SSE) reconstruction method. show use SSE with different values angular extent CMEs,...
A study of the kinematics and arrival times coronal mass ejections (CMEs) at Earth, derived from time-elongation maps (J-maps) constructed STEREO/heliospheric imager (HI) observations, provides an opportunity to understand heliospheric evolution CMEs in general. We implement various reconstruction techniques, based on use profiles propagating viewed single or multiple vantage points, estimate dynamics three geo-effective CMEs. kinematic properties, analysis elongation profiles, as inputs...
ABSTRACT Coronal mass ejections (CMEs) and Stream Interaction Regions (SIRs) are the main drivers of intense geomagnetic storms. We study distribution storms associated with different during solar cycles 23 24 (1996–2019). Although annual occurrence rate in both tracks sunspot cycle, second peak storm activity lags peak. SIRs contribute significantly to numbers cycles, particularly for moderate stronger-than-moderate note semiannual peaks much closer equinoxes storms, slightly shifted from...
Abstract Studies for inferring the global characteristics of coronal mass ejections (CMEs) from multipoint local in situ observations have been undertaken previously, but limited studies utilized measurements multiple spacecraft with sufficiently small radial and angular separations. In present study, we investigate a magnetic cloud (MC) region CME observed during 2023 September 24–26 by STEREO-A Wind near 1 au, which had separations 0.03 au 3 <mml:math...
Abstract As solar coronal mass ejections (CMEs) propagate through the heliosphere, they expend energy in heating protons to compensate for cooling that occurs due expansion. CME propagation models usually treat dissipation implicitly via a polytropic index (δ). Here we calculate power implied by given δ and compare it with available turbulent velocity fluctuations. We make this comparison using near-Earth in-situ observations of 27 most geoeffective CMEs (Dst &lt; −75 nT) cycle 24. For =...
Similar to the Sun, other stars shed mass and magnetic flux via ubiquitous quasi-steady wind episodic stellar coronal ejections (CMEs). We investigate loss rate solar CMEs as a function of variability represented in terms sunspot number X-ray background luminosity. estimate contribution total ecliptic beyond, its variation over different phases activity cycles. The study exploits sunspots observed, coronagraphic observations near Sun by SOHO/LASCO, situ at 1 AU WIND, GOES during cycle 23 24....
Abstract Coronal mass ejections (CMEs) are primary drivers of space weather, and studying their evolution in the inner heliosphere is vital to prepare for a timely response. Solar wind streams, acting as background, influence propagation associated geomagnetic storm activity. This study introduces SWASTi-CME, newly developed MHD-based CME model integrated into Space Weather Adaptive SimulaTion (SWASTi) framework. It incorporates nonmagnetized elliptic cone magnetized flux rope model. To...
We present an investigation of eruption event a coronal mass ejection (CME) magnetic flux rope (MFR) from the source active region (AR) NOAA 11719 on 2013 April 11 utilizing observations Solar Dynamic Observatory, Terrestrial Relations and Heliospheric WIND spacecraft. The AR consists pre-existing sigmoidal structure stacked over filament channel which is regarded as MFR system. EUV low corona suggest further development this system by added axial through tether-cutting reconnection loops at...
During 2011 February 13 to 15, three Earth-directed CMEs launched in successively were recorded as limb by coronagraphs (COR) of STEREO. These provided an opportunity study their geometrical and kinematic evolution from multiple vantage points. In this paper, we examine the differences slow fast speed during propagation heliosphere. We also interaction collision using STEREO/SECCHI COR Heliospheric Imager (HI) observations. have found evidence between 15 14 COR2 HI1 FOV, respectively, while...
Abstract A Forbush decrease is a sudden in cosmic-ray intensity caused by transient interplanetary disturbances. The substructure of an counterpart coronal mass ejection (ICME) such as shock sheath and/or magnetic cloud independently contributes to decrease, which evident two-step decrease. Our earlier work has shown multistep and recovery within the ICME-driven shock-sheath region. Further, we have suggested that presence small-scale flux rope region causes steady/gradual intensity. Here,...
Our study attempts to understand the collision characteristics of two coronal mass ejections (CMEs) launched successively from Sun on 2013 October 25. The estimated kinematics, three-dimensional (3D) reconstruction techniques applied observations CMEs by SECCHI/Coronagraphic (COR) and Heliospheric Imagers (HIs), reveal their around 37 $R_\sun$ Sun. In analysis, we take into account propagation expansion speeds, impact direction, angular size as well masses CMEs. These parameters are derived...
Abstract There have been several attempts in the past to understand nature of collision individual cases interacting coronal mass ejections (CMEs). We selected eight CMEs and estimated their propagation expansion speeds, direction impact masses, by exploiting coronagraphic heliospheric imaging observations. Using these estimates while ignoring errors therein, we find that collisions is perfectly inelastic for two (i.e., 2012 March November), June 2011 August), elastic one case 2013 October),...
ABSTRACT Generally, interplanetary coronal mass ejection (ICME) triggers intense and strong geomagnetic storms. It has been established that the ICME sheath-moulded planar magnetic structure enhances amplitude of Alfvén waves embedded in clouds or high solar streams including corotating interacting regions (CIRs) turn extend recovery phase storm. Here, we investigate a storm with very complex temporal profile multiple decreasing phases. We examine role (PMS) various phases find fast decrease...
Abstract In 2023 April, a low-latitude aurora observed by the all-sky camera at Hanle, Ladakh, India (33°14’N geographic latitude), generated significant interest. This was first such recorded from Indian region in space era and occurred during moderate solar storm. study explores this auroral sighting, which happened sheath-region passage of an interplanetary coronal mass ejection. We analyze situ multispacecraft particle measurements geomagnetic field observations both ground-based...
In the context of Sun-Earth connection coronal mass ejections and magnetic flux ropes (MFRs), we studied solar active region (AR) properties cloud (MC) event during April 14-15, 2013. We use in-situ observations from Advanced Composition Explorer source AR measurements Solar Dynamic Observatory. The MCs structure is reconstructed Grad-Shafranov method which reveals a northern component axial field with left-handed helicity. MC invariant axis highly inclined to ecliptic plane pointing...
ABSTRACT Planar magnetic structures (PMS) are often observed in sheath regions driven by interplanetary coronal mass ejections (ICMEs) and corotating interaction (CIRs). Here, we study plasma properties statistically within planar non-planar ICME using situ data from the Advanced Composition Explore (ACE) spacecraft. The includes 420 ICME-driven sheaths 1998–2017. We found that 146 ($\sim 35{{\ \rm per\ cent}}$) planar, whereas 274 65{{\ non-planar. This average temperature, density, speed,...
Earlier studies on Coronal Mass Ejections (CMEs), using remote sensing and in situ observations, have attempted to determine some of the internal properties CMEs, which were limited a certain position or time. For understanding evolution thermodynamic state CMEs during their heliospheric propagation, we improve self-similar flux rope (FRIS) model, is constrained by measured propagation expansion speed profiles CME. We implement model CME erupted 2008 December 12 probe It found that...