Article
Physics, Multidisciplinary
Akash Biswas, Bidya Binay Karak, Robert Cameron
Summary: A striking feature of the solar cycle is the migration of sunspots from midlatitudes to the equator over time. The level of activity and width of sunspot belts increase rapidly and then decline, while in the late stages of the cycle, the statistical properties remain the same regardless of the cycle's strength during its rise and maximum phases.
PHYSICAL REVIEW LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Junjie Chen, Binzheng Zhang, Dong Lin, Peter A. Delamere, Zhonghua Yao, Oliver Brambles, Kareem A. Sorathia, Viacheslav G. Merkin, John G. Lyon
Summary: Using physics-based global simulations, we have demonstrated the possible presence of a significant axial asymmetry in the reconnection separator at the Jovian magnetopause. Reconnection occurs at the southern-dusk and northern magnetopause under eastward interplanetary magnetic field (IMF) conditions, and switches to the northern-dusk and southern magnetopause when driven by the westward IMF. The different reconnection positions are associated with the interaction of the IMF with the nearly-dipolar background fields and the dawn-dusk asymmetric, helical, closed lobe magnetic fields.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Multidisciplinary Sciences
S. D. Bale, J. F. Drake, M. D. McManus, M. I. Desai, S. T. Badman, D. E. Larson, M. Swisdak, T. S. Horbury, N. E. Raouafi, T. Phan, M. Velli, D. J. McComas, C. M. S. Cohen, D. Mitchell, O. Panasenco, J. C. Kasper
Summary: The fast solar wind that fills the heliosphere originates from coronal holes on the Sun and is believed to be accelerated by magnetic reconnection mechanisms such as wave heating and interchange reconnection. Measurements from the Parker Solar Probe provide strong evidence for the interchange reconnection mechanism, showing imprints of supergranulation structure in the solar wind and the presence of magnetic switchbacks and bursty wind streams. Computer simulations support these observations and suggest that the reconnection is collisionless and drives the fast wind through both plasma pressure and radial Alfvenic flow bursts.
Article
Geosciences, Multidisciplinary
H. Gurram, J. Egedal, W. Daughton
Summary: This study found that shear Alfven waves (SAWs) can efficiently transport wave energy during magnetic reconnection in the magnetotail, greatly enhancing the energy input for the Aurora Borealis compared to previous estimates.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Geosciences, Multidisciplinary
K. Jiang, S. Y. Huang, Z. G. Yuan, Q. Y. Xiong, Y. Y. Wei
Summary: With high-resolution data from the MMS mission, a tilted ion-scale flux rope is observed in the tailward outflow of a magnetic reconnection in the terrestrial magnetotail, indicating the extension of the X-line in the dawn-dusk direction. The observed electron vortex embedded in the flux rope generates an induced magnetic field with the same direction as the axial component, contributing to the enhancement of the magnetic flux carried by the flux rope.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Z. H. Zhong, M. Zhou, X. H. Deng, L. J. Song, D. B. Graham, R. X. Tang, H. Y. Man, Y. Pang, Yu V. Khotyaintsev, B. L. Giles
Summary: The two-dimensional Hall reconnection model can explain the rapid release of magnetic energy, but the effects of the three-dimensional evolution on reconnection remain poorly understood. Recent numerical simulations have shown that reconnection in three dimensions is more complex than in two dimensions, possibly occurring in multiple sites not in the primary neutral current sheet. The first observational evidence of localized secondary reconnection at the separatrix surface of a magnetic flux rope has been presented, facilitating energy conversion at electron scales.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Astronomy & Astrophysics
A. Masters, W. R. Dunn, T. S. Stallard, H. Manners, J. Stawarz
Summary: Auroral emissions have been extensively observed at the Earth, Jupiter, and Saturn, with Jupiter's polar auroras being brighter and more dynamic. The stronger magnetic field of Jupiter may trigger magnetic reconnection and generate high-energy electron beams, explaining some of the mysterious features of Jupiter's polar auroras.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Geosciences, Multidisciplinary
Z. Z. Chen, H. S. Fu, Z. Wang, Z. Z. Guo, Y. Xu, C. M. Liu
Summary: This study presents the first observation of a magnetic flux rope (MFR) inside an electron diffusion region (EDR), confirming its crucial role in magnetic reconnection. By observing and analyzing the structure and energy dissipation of MFR, it helps to understand the modulation of the electric field in EDR by MFR.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Physics, Multidisciplinary
Hengqiang Feng, Yan Zhao, Jiemin Wang, Qiang Liu, Guoqing Zhao
Summary: This paper examines the evolution of closed magnetic flux ropes in interplanetary space using data collected by the Wind spacecraft in 1997. The study finds that interchange reconnection and disconnection are important mechanisms that change the magnetic topology of flux ropes during their propagation.
FRONTIERS IN PHYSICS
(2021)
Article
Geosciences, Multidisciplinary
R. L. Guo, Z. H. Yao, D. Grodent, B. Bonfond, G. Clark, W. R. Dunn, B. Palmaerts, B. H. Mauk, M. F. Vogt, Q. Q. Shi, Y. Wei, J. E. P. Connerney, S. J. Bolton
Summary: By analyzing observations from the Hubble Space Telescope and the Juno spacecraft, this study demonstrates the evolution of a double-auroral arc on the dawnside of Jupiter and suggests that this evolution is likely a result of the non-steady progress of magnetic reconnection.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Astronomy & Astrophysics
Marissa F. Vogt, Matthew Rutala, Bertrand Bonfond, John T. Clarke, Luke Moore, Jonathan D. Nichols
Summary: Hubble Space Telescope images of Jupiter's UV aurora show that the main emission occasionally contracts or expands, shifting toward or away from the magnetic pole by several degrees in response to changes in the solar wind dynamic pressure and Io's volcanic activity. The study analyzes HST images from the Galileo era (1996-2003) and compares the latitudinal shifts of the Ganymede footprint and the main auroral emission. The research finds that the Ganymede footprint and main auroral emission typically, but not always, move together and their movements are weakly linked to changes in the current sheet strength measured by Galileo.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Xiangning Chu, Robert McPherron, Tung-Shin Hsu, Vassilis Angelopoulos, James M. Weygand, Jiang Liu, Jacob Bortnik
Summary: This study investigates the relationships between the development of the substorm current wedge (SCW) and reconnection-generated earthward flows, magnetic field dipolarizations, and auroral expansions. By using an SCW inversion technique to model FAC locations and determine connections between magnetospheric and ionospheric phenomena, it was found that the accumulated magnetic flux is positively correlated with the generation of SCW, causing magnetic dipolarization and auroral poleward expansion.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Geosciences, Multidisciplinary
R. J. He, H. S. Fu, Y. Y. Liu, Z. Wang, C. M. Liu
Summary: This study presents the first observation of a subion-scale MFR nested in an ion-scale MFR, revealing that the subion-scale MFR exhibits more intense plasma activity than the ion-scale MFR, potentially due to 3D magnetic reconnection. These findings may provide new insights into understanding energy cascade in space plasmas.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Geosciences, Multidisciplinary
E. Dubinin, M. Fraenz, M. Paetzold, S. Tellmann, G. DiBraccio, J. McFadden
Summary: We report on observations of the Mars Atmosphere and Volatile EvolutioN spacecraft in the ion plume region on Mars. We found that under certain conditions, the interaction between oxygen ions and solar wind protons leads to the formation of mini induced magnetospheres with typical features observed at Mars or Venus. These observations provide insights into the mechanism behind induced magnetosphere formation.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Xinmin Li, Rongsheng Wang, Quanming Lu
Summary: Using high-resolution data from the MMS mission, researchers have observed an intense current layer in the center of a flux rope in the magnetotail. This current layer is caused by the compression of ion bulk flows and is different from the previously reported interlaced flux tubes at the magnetopause. The observed current layer is identified as an electron diffusion region of magnetic reconnection, which leads to the crater-shaped structure of the flux rope.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Astronomy & Astrophysics
K. Nykyri, X. Ma, B. Burkholder, R. Rice, J. R. Johnson, E-K Kim, P. Delamere, A. Michael, K. Sorathia, D. Lin, S. Merkin, S. Fuselier, J. Broll, O. Le Contel, D. Gershman, I Cohen, B. Giles, R. J. Strangeway, C. T. Russell, J. L. Burch
Summary: This study utilized observations from the Magnetosphere Multiscale (MMS) mission to reveal the low-frequency wave phenomena occurring in the energy transport and plasma heating processes at the dawn-side boundary layer of the Earth's magnetosphere, identifying phenomena related to Kelvin-Helmholtz instability.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Jay R. Johnson, Simon Wing, Peter Delamere, Steven Petrinec, Shiva Kavosi
Summary: Research indicates that auroral bright spots are possibly linked to the Kelvin-Helmholtz instability, with studies using a model to explore the relationship between current structure and boundary layer parameters. Findings show that vortex-induced currents and shear-flow-induced currents exhibit comparable maximum strengths but different structures, with the current structure dependent on the size of the vortex for the former, and the larger of Delta or L for the latter.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Geosciences, Multidisciplinary
C. S. Ng, B. R. Neupane, P. A. Delamere, P. A. Damiano
Summary: By combining diffusion and advection effects, the turbulent heating model can explain the temperature increase of ions in the magnetospheres of Jupiter and Saturn.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
J. R. Szalay, H. T. Smith, E. J. Zirnstein, D. J. McComas, L. J. Begley, F. Bagenal, P. A. Delamere, R. J. Wilson, P. W. Valek, A. R. Poppe, Q. Nenon, F. Allegrini, R. W. Ebert, S. J. Bolton
Summary: Water-group gas continuously escapes from Jupiter's icy moons, forming co-orbiting populations of particles or neutral toroidal clouds. These clouds provide valuable information about their source moons, alter the composition of the local plasma, and act as sources and sinks for magnetospheric particles. The first observations of H-2(+) pickup ions in Jupiter's magnetosphere confirm the presence of a neutral H-2 toroidal cloud and provide insight into Europa's neutral loss rate.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Astronomy & Astrophysics
C. T. S. Lorch, L. C. Ray, R. J. Wilson, F. Bagenal, F. Crary, P. A. Delamere, P. A. Damiano, C. E. J. Watt, F. Allegrini
Summary: By using Juno magnetometer and plasma data, we have discovered evidence of Alfvenic turbulence in the mid-to-high latitude magnetosphere of Jupiter, which has sufficient conditions to trigger auroral particle acceleration. These turbulence events are found to be dissipative at the electron inertial scale and generate significant Poynting flux in the ionospheric altitudes, leading to auroral emissions. These findings highlight the important role of turbulence in driving particle acceleration in the mid-to-high latitudes of Jupiter's magnetosphere.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Drew Coffin, Peter Damiano, Peter Delamere, Jay Johnson, Chung-Sang Ng
Summary: This study investigates the origin of electron energization at high latitudes of Jupiter through simulating the propagation of dispersive Alfven waves, and quantifies the impact of these waves on electron energization. It successfully generates electron populations consistent with observations, shedding light on the energy budget of the torus and Io-related auroral emissions.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Geosciences, Multidisciplinary
Enhao Feng, Binzheng Zhang, Zhonghua Yao, Peter A. Delamere, Zhiqi Zheng, Oliver J. Brambles, Sheng-Yi Ye, Kareem A. Sorathia
Summary: This study investigates the response of proxies of auroral emissions to enhanced solar wind ram pressure using three-dimensional global simulations. The results reveal that during solar wind compression, both field-aligned current and Alfvenic power exhibit an up-down-up trend, which potentially explains various observations.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Astronomy & Astrophysics
X. Ma, P. A. Delamere, A. Schok, S. Wing, J. R. Johnson, Yu-Lun Liou
Summary: The interaction between the solar wind and giant magnetospheres is crucial for magnetospheric physics, with the Kelvin-Helmholtz instability playing a significant role in the low-latitude dawn side flank region of Jupiter. The occurrence of this instability can modify the magnetopause boundary layer, as confirmed by the observations from Juno's mission.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Andrew Vu, Terry Z. Z. Liu, Hui Zhang, Peter Delamere
Summary: This study uses 2-D local hybrid simulations to investigate the effects of different foreshock ion distributions and properties on the growth of tangential discontinuity-driven foreshock bubbles (FBs). It is found that for a gyrophase-bunched distribution, where the initial phase is on the other side of the tangential discontinuity, more foreshock ions cross the discontinuity, leading to a faster expansion compared to a Maxwellian distribution. A ring distribution also results in higher expansion speeds due to greater projected velocity. For Maxwellian distributions, there are positive and linear correlations between the FB expansion speeds and initial foreshock ion densities, thermal speeds, parallel speeds, and sine of the tangential discontinuity magnetic shear angles. These parameter dependencies become stronger as the structures evolve with time. Foreshock ion distributions and properties that generate stronger currents produce more significant magnetic field variations and higher expansion speeds.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Geosciences, Multidisciplinary
P. A. Damiano, P. A. Delamere, E. -H. Kim, J. R. Johnson, C. S. Ng
Summary: Juno satellite observations have shown significant levels of electron energization, reaching up to 10⁵-10⁶ eV. To explain these observations, a hybrid gyrofluid kinetic-electron model is used in an untilted dipolar topology, illustrating high energization in weak current conditions through inertial Alfven waves close to the Jupiter ionosphere. This is achieved with ambient plasma densities and magnetic field perturbations inferred from Juno satellite data. The key factor enabling the high energization is the extremely low densities observed, requiring the acceleration of electrons to very high velocities to carry the field-aligned current.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Junjie Chen, Binzheng Zhang, Dong Lin, Peter A. Delamere, Zhonghua Yao, Oliver Brambles, Kareem A. Sorathia, Viacheslav G. Merkin, John G. Lyon
Summary: Using physics-based global simulations, we have demonstrated the possible presence of a significant axial asymmetry in the reconnection separator at the Jovian magnetopause. Reconnection occurs at the southern-dusk and northern magnetopause under eastward interplanetary magnetic field (IMF) conditions, and switches to the northern-dusk and southern magnetopause when driven by the westward IMF. The different reconnection positions are associated with the interaction of the IMF with the nearly-dipolar background fields and the dawn-dusk asymmetric, helical, closed lobe magnetic fields.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Enhao Feng, Binzheng Zhang, Zhonghua Yao, Peter A. Delamere, Zhiqi Zheng, William R. Dunn, Sheng-Yi Ye
Summary: It is found that the location of Jupiter's magnetopause is not only influenced by the solar wind and interplanetary magnetic field, but also by internal driving factors such as magnetodisc dynamics. Simulation experiments show that even under constant solar wind/IMF conditions, the magnetopause of Jupiter can exhibit dynamic variations, with a predicted range of up to 50 Jupiter radii. The study reveals that interchange structures in the Jovian magnetodisc can generate significant radial dynamic pressure, leading to significant variations in the magnetopause location. These findings provide important new insights into the understanding of magnetopause location and dynamics, with implications for other systems with internal mass loading and/or rapid rotation.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geochemistry & Geophysics
W. D. Gu, Z. H. Yao, D. X. Pan, Y. Xu, B. Zhang, P. A. Delamere, S. Y. Fu, L. Xie, S. Y. Ye, Y. N. Chen, W. R. Dunn, Y. Wei
Summary: Periodic variations in the Jovian system are influenced by solar wind conditions, planetary rotation, and Io's volcanic activity. In this study, we focus on the multihour variations of ultralow-frequency (ULF) waves, which are difficult to identify within the magnetosphere due to rapid planetary rotation modulation. Using magnetic field observations from Juno and Galileo, we found multiple significant multihour periodicities, ranging from 2 to 10 hr, with the most common periodicities occurring between 3 and 5 hr on both the dawn and dusk sides of Jupiter.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Geochemistry & Geophysics
A. A. Schok, P. A. Delamere, B. Mino, P. A. Damiano, B. Zhang, A. Sciola, K. Sorathia, S. Wing, J. R. Johnson, X. Ma, Z. Yao, O. Brambles
Summary: By analyzing the magnetic field and particle data from the Juno spacecraft, researchers have discovered a highly structured plasmadisc within Jupiter's magnetosphere, which is magnetically connected to the high-latitude polar region. This finding is crucial for understanding the overall structure and dynamics of Jupiter.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Geosciences, Multidisciplinary
Y. Xu, Z. H. Yao, B. Zhang, P. A. Delamere, L. C. Ray, W. R. Dunn, S. V. Badman, E. H. Feng, Z. Q. Zheng, S. J. Bolton, D. Grodent, B. Bonfond, Y. Wei
Summary: By using joint observations from Juno and the Hubble Space Telescope, this study statistically investigates the relationship between auroral power and current sheet variations under different solar wind conditions. The researchers found that during global main auroral brightening events, which are closely connected to solar wind compressions, the dawn side current sheet becomes substantially thinner compared to times when a quiet auroral morphology is present. Furthermore, the total current intensity in the current sheet increases under solar wind compression conditions. These findings provide important observational evidence on how magnetospheric dynamics driven by solar wind behavior affect auroral activity, deepening our understanding of the coupling between Jupiter's magnetosphere and ionosphere.
GEOPHYSICAL RESEARCH LETTERS
(2023)