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Baek S, Sohn SI. Motion of a current-vortex sheet in the magnetic Kelvin-Helmholtz instability. Phys Rev E 2023; 108:035107. [PMID: 37849202 DOI: 10.1103/physreve.108.035107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 08/30/2023] [Indexed: 10/19/2023]
Abstract
In this paper, we consider the Kelvin-Helmholtz instability in the magnetohydrodynamic flow. The motion of the interface is described by a current-vortex sheet. We examine the linear stability of the current-vortex sheet model and determine the growth rate of the interface. The interface is linearly stable for M_{A}<2 where M_{A} represents the Alfvén Mach number. It is found that the interface is linearly unstable in the limit of the critical Alfvén Mach number M_{A}=2, due to resonance of eigenvalues. We perform numerical simulations for the current-vortex sheet for both regimes of M_{A}<2 and M_{A}>2. The numerical results show the stabilizing effects of the magnetic field on the evolution of the current-vortex sheet when the magnetic field is sufficiently large. For the regime M_{A}<2, the sheet oscillates both longitudinally and transversely and the transverse surface wave is pronounced for a large M_{A}. Remarkably, the interface is nonlinearly unstable for M_{A}≈2, for M_{A}<2, which may be due to the propagation of surface waves. For the regime M_{A}>2, the roll-up of the spiral is weakened and the spiral is more pinched and stretched for smaller M_{A}. A comparison of the unstable evolutions of large and small values of M_{A} shows significant differences of the magnetic field and vortex sheet strength.
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Affiliation(s)
- Seunghyeon Baek
- Department of Applied Mathematical Sciences, Korea University, Sejong 30019, South Korea
| | - Sung-Ik Sohn
- Department of Mathematics, Gangneung-Wonju National University, Gangneung 25457, South Korea
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2
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Li Z, Wang XQ, Xu Y, Liu HF, Huang J. Nonlinear interaction between double tearing mode and Kelvin-Helmholtz instability with different shear flows. Sci Rep 2023; 13:13559. [PMID: 37604840 PMCID: PMC10442345 DOI: 10.1038/s41598-023-40920-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 08/18/2023] [Indexed: 08/23/2023] Open
Abstract
The nonlinear interaction between the double tearing mode (DTM) and Kelvin-Helmholtz (KH) instabilities with different shear flow profiles has been numerically investigated via the use of a compressible magnetohydrodynamics (MHD) model. We focus on KH instabilities in weak and reversed magnetic shear plasmas with strong stabilizing effect of field line bending. Results show that KH instabilities coupled with DTMs occur in these plasmas and the KH mode dominates the instability dynamics, suggesting the crucial role of weak magnetic shear in the formation of high-mode harmonics. For symmetric flows, an asymmetric forced magnetic reconnection configuration is maintained during the growth phase, leading to interlocking of the modes. Additionally, this investigation of the DTM-KH instability interaction contributes to our understanding of the nonlinear reconnection mechanism in the regime of weak and reversed magnetic shear plasmas, which is relevant for astrophysical and fusion studies.
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Affiliation(s)
- Z Li
- Institute of Fusion Science, School of Physical Science and Technology Southwest, Jiaotong University, Chengdu, 610031, China
| | - X Q Wang
- Institute of Fusion Science, School of Physical Science and Technology Southwest, Jiaotong University, Chengdu, 610031, China.
| | - Y Xu
- Institute of Fusion Science, School of Physical Science and Technology Southwest, Jiaotong University, Chengdu, 610031, China
| | - H F Liu
- Institute of Fusion Science, School of Physical Science and Technology Southwest, Jiaotong University, Chengdu, 610031, China
| | - J Huang
- Institute of Fusion Science, School of Physical Science and Technology Southwest, Jiaotong University, Chengdu, 610031, China
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3
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Zhang HX, Lu JY, Wang M. Energy transfer across magnetopause under dawn-dusk IMFs. Sci Rep 2023; 13:7409. [PMID: 37150770 PMCID: PMC10164745 DOI: 10.1038/s41598-023-34082-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 04/24/2023] [Indexed: 05/09/2023] Open
Abstract
A parametric study on the energy transfer of the solar wind across the magnetopause entering the magnetosphere is conducted using a global magnetohydrodynamic numerical simulation. The characteristics of the mechanical and electromagnetic energy distribution under the dawn-dusk interplanetary magnetic fields (IMFs) are investigated by analyzing magnetic reconnection and viscous effect, and compared with the radial and north-south IMFs. It is shown that (1) the interactions at the magnetopause and the transfer of energy across this boundary move in relation to the IMF orientation. (2) For the duskward IMF, the mechanical energy flow clearly enters the equatorial and low-latitude regions on the dayside, and the electromagnetic energy flow has a small inflow on the equatorial and low latitudes of the dayside. A significant energy inflow appears on the dawn side in the northern hemisphere and the dusk side in the southern hemisphere near the polar cusp. (3) The energy distribution characteristics across the magnetopause under dawn-dusk IMFs are mirror symmetric about the [Formula: see text] plane. (4) For a magnetic field of 5 nT, the electromagnetic energy input under the dawn-dusk IMFs is twice as large as the mechanical energy and the electromagnetic energy under the radial IMF, which is five times as large as the electromagnetic energy during the pure northward IMF, but only half as large as the electromagnetic energy under the pure southward IMF. The mechanical energy input under dawn-dusk IMFs has the same magnitude as that under radial and north-south IMFs. The magnitude of the energy transfer rate for the dawn IMF and dusk IMF (about 3.5%) is between 1.71% for the northward IMF and 4.95% for the southward IMF, but higher than 2.22% for the radial IMF. The Akasofu-type energy-coupling formula, [Formula: see text], underestimates the energy input from the solar wind under [Formula: see text] dominated IMF.
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Affiliation(s)
- H X Zhang
- Institute of Space Weather, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing, 210044, China
| | - J Y Lu
- Institute of Space Weather, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing, 210044, China.
| | - M Wang
- Institute of Space Weather, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing, 210044, China.
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Kavosi S, Raeder J, Johnson JR, Nykyri K, Farrugia CJ. Seasonal and diurnal variations of Kelvin-Helmholtz Instability at terrestrial magnetopause. Nat Commun 2023; 14:2513. [PMID: 37142596 PMCID: PMC10160038 DOI: 10.1038/s41467-023-37485-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 03/16/2023] [Indexed: 05/06/2023] Open
Abstract
Kelvin-Helmholtz Instability is ubiquitous at Earth's magnetopause and plays an important role in plasma entry into the magnetosphere during northward interplanetary magnetic fields. Here, using one solar cycle of data from NASA THEMIS (Time History of Events and Macro scale Interactions during Substorms) and MMS (Magnetospheric Multiscale) missions, we found that KHI occurrence rates show seasonal and diurnal variations with the rate being high near the equinoxes and low near the solstices. The instability depends directly on the Earth's dipole tilt angle. The tilt toward or away from the Sun explains most of the seasonal and diurnal variations, while the tilt in the plane perpendicular to the Earth-Sun line explains the difference between the equinoxes. The results reveal the critical role of dipole tilt in modulating KHI across the magnetopause as a function of time, highlighting the importance of Sun-Earth geometry for solar wind-magnetosphere interaction and for space weather.
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Affiliation(s)
- S Kavosi
- Embry-Riddle Aeronautical University, Daytona Beach, FL, USA.
| | - J Raeder
- University of New Hampshire, Institute for the Study of Earth, Oceans and Space, Durham, NH, USA
| | - J R Johnson
- Andrews University, Berrien Springs, MI, USA
| | - K Nykyri
- Embry-Riddle Aeronautical University, Daytona Beach, FL, USA
| | - C J Farrugia
- University of New Hampshire, Institute for the Study of Earth, Oceans and Space, Durham, NH, USA
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Zilli Vieira CL, Chen K, Garshick E, Liu M, Vokonas P, Ljungman P, Schwartz J, Koutrakis P. Geomagnetic disturbances reduce heart rate variability in the Normative Aging Study. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 839:156235. [PMID: 35644403 PMCID: PMC9233046 DOI: 10.1016/j.scitotenv.2022.156235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 05/20/2022] [Accepted: 05/22/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Solar and geomagnetic activity (GA) have been linked to increased cardiovascular (CVD) events. We hypothesize that heart rate variability (HRV) may be the biological mechanism between increased CVD risk and intense geomagnetic disturbances (GMD). METHODS To evaluate the impact of GA and intense GMD on HRV in 809 elderly men [age mean 74.5 (SD = 6.8)] enrolled in the Normative Aging Study (Greater Boston Area), we performed repeated-measures using mixed-effects regression models. We evaluated two HRV outcomes: the square root of the mean squared differences of successive normal-to-normal intervals (r-MSSD) and the standard deviation of normal-to-normal heartbeat intervals (SDNN) in milliseconds (ms). We also compared the associations between Kp and HRV in patients with and without comorbidities such as diabetes and coronary heart diseases (CHD). We used data on global planetary K-Index (Kp) from middle latitudes as a GA and GMD (>75th Kp) parameters from the National Oceanic and Atmospheric Agency's Space Weather Prediction Center. RESULTS We found a near immediate effect of continuous and higher Kp on reduced HRV for exposures up to 24 h prior to electrocardiogram recording. A 75th percentile increase in 15-hour Kp prior the examination was associated with a -14.7 ms change in r-MSSD (95 CI: -23.1, -6.3, p-value = 0.0007) and a -8.2 ms change in SDNN (95 CI: -13.9, -2.5, p-value = 0.006). The associations remained similar after adjusting the models for air pollutants over the exposure window prior to the event. In periods of intense GMD, the associations were stronger in patients with CHD and non-diabetes. CONCLUSIONS This is the first study to demonstrate the potential adverse effects of geomagnetic activity on reduced heart rate variability in a large epidemiologic cohort over an extended period, which may have important clinical implications among different populations.
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Affiliation(s)
- Carolina L Zilli Vieira
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA.
| | - Kelly Chen
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Eric Garshick
- Pulmonary, Allergy, Sleep and Critical Care Medicine Section, Veterans Affairs Boston Healthcare System, Boston, MA, USA; Harvard Medical School, Boston, MA, USA; Channing Division of Network Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Man Liu
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Pantel Vokonas
- VA Normative Aging Study, Veterans Affairs Boston Healthcare System and the Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Petter Ljungman
- Institute of Environmental Medicine, Karolinska Institute, Sweden; Department of Cardiology, Danderyd University Hospital, Stockholm, Sweden
| | - Joel Schwartz
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Channing Division of Network Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Petros Koutrakis
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
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Zhang H, Zong Q, Connor H, Delamere P, Facskó G, Han D, Hasegawa H, Kallio E, Kis Á, Le G, Lembège B, Lin Y, Liu T, Oksavik K, Omidi N, Otto A, Ren J, Shi Q, Sibeck D, Yao S. Dayside Transient Phenomena and Their Impact on the Magnetosphere and Ionosphere. SPACE SCIENCE REVIEWS 2022; 218:40. [PMID: 35784192 PMCID: PMC9239986 DOI: 10.1007/s11214-021-00865-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Accepted: 11/11/2021] [Indexed: 06/15/2023]
Abstract
Dayside transients, such as hot flow anomalies, foreshock bubbles, magnetosheath jets, flux transfer events, and surface waves, are frequently observed upstream from the bow shock, in the magnetosheath, and at the magnetopause. They play a significant role in the solar wind-magnetosphere-ionosphere coupling. Foreshock transient phenomena, associated with variations in the solar wind dynamic pressure, deform the magnetopause, and in turn generates field-aligned currents (FACs) connected to the auroral ionosphere. Solar wind dynamic pressure variations and transient phenomena at the dayside magnetopause drive magnetospheric ultra low frequency (ULF) waves, which can play an important role in the dynamics of Earth's radiation belts. These transient phenomena and their geoeffects have been investigated using coordinated in-situ spacecraft observations, spacecraft-borne imagers, ground-based observations, and numerical simulations. Cluster, THEMIS, Geotail, and MMS multi-mission observations allow us to track the motion and time evolution of transient phenomena at different spatial and temporal scales in detail, whereas ground-based experiments can observe the ionospheric projections of transient magnetopause phenomena such as waves on the magnetopause driven by hot flow anomalies or flux transfer events produced by bursty reconnection across their full longitudinal and latitudinal extent. Magnetohydrodynamics (MHD), hybrid, and particle-in-cell (PIC) simulations are powerful tools to simulate the dayside transient phenomena. This paper provides a comprehensive review of the present understanding of dayside transient phenomena at Earth and other planets, their geoeffects, and outstanding questions.
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Affiliation(s)
- Hui Zhang
- Physics Department & Geophysical Institute, University of Alaska Fairbanks, 2156 Koyukuk Drive, Fairbanks, AK 99775 USA
- Shandong University, Weihai, China
| | - Qiugang Zong
- Institute of Space Physics and Applied Technology, Peking University, Beijing, 100871 China
- Polar Research Institute of China, Shanghai, 200136 China
| | - Hyunju Connor
- Physics Department & Geophysical Institute, University of Alaska Fairbanks, 2156 Koyukuk Drive, Fairbanks, AK 99775 USA
- NASA Goddard Space Flight Center, Greenbelt, MD 20771 USA
| | - Peter Delamere
- Physics Department & Geophysical Institute, University of Alaska Fairbanks, 2156 Koyukuk Drive, Fairbanks, AK 99775 USA
| | - Gábor Facskó
- Department of Informatics, Milton Friedman University, 1039 Budapest, Hungary
- Wigner Research Centre for Physics, Konkoly-Thege Miklós út 29-33, 1121 Budapest, Hungary
| | | | - Hiroshi Hasegawa
- Institute of Space and Astronautical Science, JAXA, Sagamihara, Japan
| | | | - Árpád Kis
- Institute of Earth Physics and Space Science (ELKH EPSS), Sopron, Hungary
| | - Guan Le
- NASA Goddard Space Flight Center, Greenbelt, MD 20771 USA
| | - Bertrand Lembège
- LATMOS (Laboratoire Atmosphères, Milieux, Observations Spatiales), IPSL/CNRS/UVSQ, 11 Bd d’Alembert, Guyancourt, 78280 France
| | - Yu Lin
- Auburn University, Auburn, USA
| | - Terry Liu
- Physics Department & Geophysical Institute, University of Alaska Fairbanks, 2156 Koyukuk Drive, Fairbanks, AK 99775 USA
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, Los Angeles, USA
| | - Kjellmar Oksavik
- Birkeland Centre for Space Science, Department of Physics and Technology, University of Bergen, Bergen, Norway
- Arctic Geophysics, The University Centre in Svalbard, Longyearbyen, Norway
| | | | - Antonius Otto
- Physics Department & Geophysical Institute, University of Alaska Fairbanks, 2156 Koyukuk Drive, Fairbanks, AK 99775 USA
| | - Jie Ren
- Institute of Space Physics and Applied Technology, Peking University, Beijing, 100871 China
| | | | - David Sibeck
- NASA Goddard Space Flight Center, Greenbelt, MD 20771 USA
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Jin Y, Kotova D, Xiong C, Brask SM, Clausen LBN, Kervalishvili G, Stolle C, Miloch WJ. Ionospheric Plasma IRregularities - IPIR - Data Product Based on Data From the Swarm Satellites. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2022; 127:e2021JA030183. [PMID: 35866071 PMCID: PMC9285927 DOI: 10.1029/2021ja030183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 02/21/2022] [Accepted: 03/07/2022] [Indexed: 06/15/2023]
Abstract
Ionospheric plasma irregularities can be successfully studied with the Swarm satellites. Parameters derived from the in-situ plasma measurements and from the topside ionosphere total electron content provide a comprehensive dataset for characterizing plasma structuring along the orbits of the Swarm satellites. The Ionospheric Plasma IRregularities (IPIR) data product summarizes these parameters and allows for systematic studies of ionospheric irregularities. IPIR has already been used in investigations of structuring and variability of ionospheric plasma. This report provides a detailed description of algorithms behind the IPIR data product and demonstrates its use for ionospheric studies.
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Affiliation(s)
- Yaqi Jin
- Department of PhysicsUniversity of OsloOsloNorway
| | - Daria Kotova
- Department of PhysicsUniversity of OsloOsloNorway
| | - Chao Xiong
- Helmholtz Centre PotsdamGFZ German Research Centre for GeosciencesPotsdamGermany
- Now at Department of Space PhysicsElectronic Information SchoolWuhan UniversityWuhanChina
| | | | | | - Guram Kervalishvili
- Helmholtz Centre PotsdamGFZ German Research Centre for GeosciencesPotsdamGermany
| | - Claudia Stolle
- Helmholtz Centre PotsdamGFZ German Research Centre for GeosciencesPotsdamGermany
- Now at Leibniz Institute of Atmospheric Physics e.V. at the University of RostockKühlungsbornGermany
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Kelvin–Helmholtz Waves on the Magnetopause at the Lunar Distances under Southward IMF: ARTEMIS Observations. UNIVERSE 2022. [DOI: 10.3390/universe8040209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The Kelvin–Helmholtz (KH) instability, a common phenomenon widely observed at the magnetopause, plays an important role in plasma transport while reconnection at low latitude is less efficient during the northward interplanetary magnetic field (IMF). In this study, we analyze the magnetic field and plasma observations obtained by the Acceleration, Reconnection, Turbulence, and Electrodynamics of Moon’s Interaction with the Sun (ARTEMIS) spacecraft located near the lunar orbit and find KH waves under the southward IMF at the lunar-orbit magnetopause. We also calculate the dominant period, phase velocity, and wavelength of the KH waves and further compare this event with the KH waves seen at the flank magnetopause under the southward IMF, which indicates that the wavelength increases as the distance from the subsolar point increases. The observations also show that the KH waves at lunar distance under the southward IMF are characterized by irregularity and intermittence.
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9
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Michael AT, Sorathia KA, Merkin VG, Nykyri K, Burkholder B, Ma X, Ukhorskiy AY, Garretson J. Modeling Kelvin-Helmholtz Instability at the High-Latitude Boundary Layer in a Global Magnetosphere Simulation. GEOPHYSICAL RESEARCH LETTERS 2021; 48:e2021GL094002. [PMID: 35846947 PMCID: PMC9285077 DOI: 10.1029/2021gl094002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 09/08/2021] [Accepted: 09/14/2021] [Indexed: 06/15/2023]
Abstract
The Kelvin-Helmholtz instability at the magnetospheric boundary plays a crucial role in solar wind-magnetosphere-ionosphere coupling, particle entry, and energization. The full extent of its impact has remained an open question due, in part, to global models without sufficient resolution to capture waves at higher latitudes. Using global magnetohydrodynamic simulations, we investigate an event when the Magnetospheric Multiscale (MMS) mission observed periodic low-frequency waves at the dawn-flank, high-latitude boundary layer. We show the layer to be unstable, even though the slow solar wind with the draped interplanetary magnetic field is seemingly unfavorable for wave generation. The simulated velocity shear at the boundary is thin ( ∼ 0.65 R E ) and requires commensurately high spatial resolution. These results, together with MMS observations, confirm for the first time in fully three-dimensional global geometry that KH waves can grow in this region and thus can be an important process for energetic particle acceleration, dynamics, and transport.
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Affiliation(s)
- A. T. Michael
- The Johns Hopkins University Applied Physics LaboratoryLaurelMDUSA
| | - K. A. Sorathia
- The Johns Hopkins University Applied Physics LaboratoryLaurelMDUSA
| | - V. G. Merkin
- The Johns Hopkins University Applied Physics LaboratoryLaurelMDUSA
| | - K. Nykyri
- Department of Physical Sciences and Center for Space and Atmospheric Research (CSAR)Embry‐Riddle Aeronautical UniversityDaytona BeachFLUSA
| | - B. Burkholder
- Department of Physical Sciences and Center for Space and Atmospheric Research (CSAR)Embry‐Riddle Aeronautical UniversityDaytona BeachFLUSA
| | - X. Ma
- Department of Physical Sciences and Center for Space and Atmospheric Research (CSAR)Embry‐Riddle Aeronautical UniversityDaytona BeachFLUSA
| | - A. Y. Ukhorskiy
- The Johns Hopkins University Applied Physics LaboratoryLaurelMDUSA
| | - J. Garretson
- The Johns Hopkins University Applied Physics LaboratoryLaurelMDUSA
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10
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Abstract
In the last few decades, solar activity has been diminishing, and so space weather studies need to be revisited with more attention. The physical processes involved in dealing with various space weather parameters have presented a challenge to the scientific community, with a threat of having a serious impact on modern society and humankind. In the present paper, we have reviewed various aspects of space weather and its present understanding. The Sun and the Earth are the two major elements of space weather, so the solar and the terrestrial perspectives are discussed in detail. A variety of space weather effects and their societal as well as anthropogenic aspects are discussed. The impact of space weather on the terrestrial climate is discussed briefly. A few tools (models) to explain the dynamical space environment and its effects, incorporating real-time data for forecasting space weather, are also summarized. The physical relation of the Earth’s changing climate with various long-term changes in the space environment have provided clues to the short-term/long-term changes. A summary and some unanswered questions are presented in the final section.
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11
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Cael BB, Mashayek A. Log-Skew-Normality of Ocean Turbulence. PHYSICAL REVIEW LETTERS 2021; 126:224502. [PMID: 34152160 DOI: 10.1103/physrevlett.126.224502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 01/12/2021] [Accepted: 03/16/2021] [Indexed: 06/13/2023]
Abstract
The statistics of intermittent ocean turbulence is the key link between physical understanding of turbulence and its global implications. The log-normal distribution is the standard but imperfect assumed distribution for the turbulent kinetic energy dissipation rate. We argue that as turbulence is often generated by multiple changing sources, a log-skew-normal (LSN) distribution is more appropriate. We show the LSN distribution agrees excellently and robustly with observations. The heavy tail of the LSN distribution has important implications for sampling of turbulence in terrestrial and extraterrestrial analogous systems.
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Affiliation(s)
- B B Cael
- National Oceanography Centre, Cael SO14 3ZH, Southampton, United Kingdom
| | - Ali Mashayek
- Imperial College, Mashayek SW7 2BB, London, United Kingdom
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12
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Zhang QH, Zhang YL, Wang C, Oksavik K, Lyons LR, Lockwood M, Yang HG, Tang BB, Moen JI, Xing ZY, Ma YZ, Wang XY, Ning YF, Xia LD. A space hurricane over the Earth's polar ionosphere. Nat Commun 2021; 12:1207. [PMID: 33619284 PMCID: PMC7900228 DOI: 10.1038/s41467-021-21459-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 01/28/2021] [Indexed: 11/08/2022] Open
Abstract
In Earth's low atmosphere, hurricanes are destructive due to their great size, strong spiral winds with shears, and intense rain/precipitation. However, disturbances resembling hurricanes have not been detected in Earth's upper atmosphere. Here, we report a long-lasting space hurricane in the polar ionosphere and magnetosphere during low solar and otherwise low geomagnetic activity. This hurricane shows strong circular horizontal plasma flow with shears, a nearly zero-flow center, and a coincident cyclone-shaped aurora caused by strong electron precipitation associated with intense upward magnetic field-aligned currents. Near the center, precipitating electrons were substantially accelerated to ~10 keV. The hurricane imparted large energy and momentum deposition into the ionosphere despite otherwise extremely quiet conditions. The observations and simulations reveal that the space hurricane is generated by steady high-latitude lobe magnetic reconnection and current continuity during a several hour period of northward interplanetary magnetic field and very low solar wind density and speed.
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Affiliation(s)
- Qing-He Zhang
- Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, Shandong, PR China.
| | - Yong-Liang Zhang
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - Chi Wang
- State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing, PR China
| | - Kjellmar Oksavik
- Birkeland Centre for Space Science, Department of Physics and Technology, University of Bergen, Bergen, Norway
- The University Centre in Svalbard, Longyearbyen, Norway
| | - Larry R Lyons
- Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA, USA
| | | | - Hui-Gen Yang
- Ministry of Natural Resources Key Laboratory of Polar Science, Polar Research Institute of China, Shanghai, PR China
| | - Bin-Bin Tang
- State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing, PR China
| | - Jøran Idar Moen
- The University Centre in Svalbard, Longyearbyen, Norway
- Department of Physics, University of Oslo, Blindern, Oslo, Norway
| | - Zan-Yang Xing
- Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, Shandong, PR China
| | - Yu-Zhang Ma
- Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, Shandong, PR China
| | - Xiang-Yu Wang
- Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, Shandong, PR China
| | - Ya-Fei Ning
- School of Microelectronic, Shandong University, Jinan, Shandong, PR China
| | - Li-Dong Xia
- Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, Shandong, PR China
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Nakamura TKM, Plaschke F, Hasegawa H, Liu Y, Hwang K, Blasl KA, Nakamura R. Decay of Kelvin-Helmholtz Vortices at the Earth's Magnetopause Under Pure Southward IMF Conditions. GEOPHYSICAL RESEARCH LETTERS 2020; 47:e2020GL087574. [PMID: 32999512 PMCID: PMC7507125 DOI: 10.1029/2020gl087574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 05/20/2020] [Accepted: 06/05/2020] [Indexed: 06/11/2023]
Abstract
At the Earth's low-latitude magnetopause, clear signatures of the Kelvin-Helmholtz (KH) waves have been frequently observed during periods of the northward interplanetary magnetic field (IMF), whereas these signatures have been much less frequently observed during the southward IMF. Here, we performed the first 3-D fully kinetic simulation of the magnetopause KH instability under the southward IMF condition. The simulation demonstrates that fast magnetic reconnection is induced at multiple locations along the vortex edge in an early nonlinear growth phase of the instability. The reconnection outflow jets significantly disrupt the flow of the nonlinear KH vortex, while the disrupted turbulent flow strongly bends and twists the reconnected field lines. The resulting coupling of the complex field and flow patterns within the magnetopause boundary layer leads to a quick decay of the vortex structure, which may explain the difference in the observation probability of KH waves between northward and southward IMF conditions.
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Affiliation(s)
| | - F. Plaschke
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - H. Hasegawa
- Institute of Space and Astronautical ScienceJapan Aerospace Exploration AgencySagamiharaJapan
| | - Y.‐H. Liu
- Department of Physics and AstronomyDartmouth CollegeHanoverNHUSA
| | - K.‐J. Hwang
- Southwest Research InstituteSan AntonioTXUSA
| | - K. A. Blasl
- Space Research InstituteAustrian Academy of SciencesGrazAustria
- Institute of PhysicsUniversity of GrazGrazAustria
| | - R. Nakamura
- Space Research InstituteAustrian Academy of SciencesGrazAustria
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14
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Zhang QH, Zhang YL, Wang C, Lockwood M, Yang HG, Tang BB, Xing ZY, Oksavik K, Lyons LR, Ma YZ, Zong QG, Moen JI, Xia LD. Multiple transpolar auroral arcs reveal insight about coupling processes in the Earth's magnetotail. Proc Natl Acad Sci U S A 2020; 117:16193-16198. [PMID: 32601186 PMCID: PMC7368316 DOI: 10.1073/pnas.2000614117] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A distinct class of aurora, called transpolar auroral arc (TPA) (in some cases called "theta" aurora), appears in the extremely high-latitude ionosphere of the Earth when interplanetary magnetic field (IMF) is northward. The formation and evolution of TPA offers clues about processes transferring energy and momentum from the solar wind to the magnetosphere and ionosphere during a northward IMF. However, their formation mechanisms remain poorly understood and controversial. We report a mechanism identified from multiple-instrument observations of unusually bright, multiple TPAs and simulations from a high-resolution three-dimensional (3D) global MagnetoHydroDynamics (MHD) model. The observations and simulations show an excellent agreement and reveal that these multiple TPAs are generated by precipitating energetic magnetospheric electrons within field-aligned current (FAC) sheets. These FAC sheets are generated by multiple-flow shear sheets in both the magnetospheric boundary produced by Kelvin-Helmholtz instability between supersonic solar wind flow and magnetosphere plasma, and the plasma sheet generated by the interactions between the enhanced earthward plasma flows from the distant tail (less than -100 RE) and the enhanced tailward flows from the near tail (about -20 RE). The study offers insight into the complex solar wind-magnetosphere-ionosphere coupling processes under a northward IMF condition, and it challenges existing paradigms of the dynamics of the Earth's magnetosphere.
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Affiliation(s)
- Qing-He Zhang
- Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, Shandong, 264209, China;
| | - Yong-Liang Zhang
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723
| | - Chi Wang
- State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing, 100190, China
| | - Michael Lockwood
- Department of Meteorology, University of Reading, Reading, RG6 6BB, United Kingdom
| | - Hui-Gen Yang
- Ministry of Natural Resources Key Laboratory of Polar Science, Polar Research Institute of China, Shanghai, 200136, China
| | - Bin-Bin Tang
- State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing, 100190, China
| | - Zan-Yang Xing
- Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, Shandong, 264209, China
| | - Kjellmar Oksavik
- Department of Physics and Technology, Birkeland Centre for Space Science, University of Bergen, Bergen, N-5020, Norway
- Arctic Geophysics Department, The University Centre in Svalbard, Longyearbyen, N-9171, Norway
| | - Larry R Lyons
- Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095
| | - Yu-Zhang Ma
- Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, Shandong, 264209, China
| | - Qiu-Gang Zong
- School of Earth and Space Sciences, Peking University, Beijing, 100871, China
| | - Jøran Idar Moen
- Department of Physics, University of Oslo, Blindern, Oslo 0371, Norway
- Arctic Geophysics Department, The University Centre in Svalbard, Longyearbyen, N-9171, Norway
| | - Li-Dong Xia
- Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, Shandong, 264209, China
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15
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Hwang K, Dokgo K, Choi E, Burch JL, Sibeck DG, Giles BL, Hasegawa H, Fu HS, Liu Y, Wang Z, Nakamura TKM, Ma X, Fear RC, Khotyaintsev Y, Graham DB, Shi QQ, Escoubet CP, Gershman DJ, Paterson WR, Pollock CJ, Ergun RE, Torbert RB, Dorelli JC, Avanov L, Russell CT, Strangeway RJ. Magnetic Reconnection Inside a Flux Rope Induced by Kelvin-Helmholtz Vortices. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2020; 125:e2019JA027665. [PMID: 32714734 PMCID: PMC7375157 DOI: 10.1029/2019ja027665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 01/29/2020] [Accepted: 03/03/2020] [Indexed: 06/11/2023]
Abstract
On 5 May 2017, MMS observed a crater-type flux rope on the dawnside tailward magnetopause with fluctuations. The boundary-normal analysis shows that the fluctuations can be attributed to nonlinear Kelvin-Helmholtz (KH) waves. Reconnection signatures such as flow reversals and Joule dissipation were identified at the leading and trailing edges of the flux rope. In particular, strong northward electron jets observed at the trailing edge indicated midlatitude reconnection associated with the 3-D structure of the KH vortex. The scale size of the flux rope, together with reconnection signatures, strongly supports the interpretation that the flux rope was generated locally by KH vortex-induced reconnection. The center of the flux rope also displayed signatures of guide-field reconnection (out-of-plane electron jets, parallel electron heating, and Joule dissipation). These signatures indicate that an interface between two interlinked flux tubes was undergoing interaction, causing a local magnetic depression, resulting in an M-shaped crater flux rope, as supported by reconstruction.
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Affiliation(s)
- K.‐J. Hwang
- Southwest Research InstituteSan AntonioTXUSA
| | - K. Dokgo
- Southwest Research InstituteSan AntonioTXUSA
| | - E. Choi
- Southwest Research InstituteSan AntonioTXUSA
| | - J. L. Burch
- Southwest Research InstituteSan AntonioTXUSA
| | | | - B. L. Giles
- NASA Goddard Space Flight CenterGreenbeltMDUSA
| | - H. Hasegawa
- Institute of Space and Astronautical ScienceJapan Aerospace Exploration AgencySagamiharaJapan
| | - H. S. Fu
- School of Science and EnvironmentBeihang UniversityBeijingChina
| | - Y. Liu
- School of Science and EnvironmentBeihang UniversityBeijingChina
| | - Z. Wang
- School of Science and EnvironmentBeihang UniversityBeijingChina
| | | | - X. Ma
- Physical Sciences DepartmentEmbry‐Riddle Aeronautical UniversityDaytona BeachFLUSA
| | - R. C. Fear
- School of Physics and AstronomyUniversity of SouthamptonSouthamptonUK
| | | | | | - Q. Q. Shi
- School of Earth and Space SciencesPeking UniversityPekingChina
| | - C. P. Escoubet
- European Space Research and Technology CentreNoordwijkthe Netherlands
| | | | | | | | - R. E. Ergun
- Laboratory for Atmospheric and Space PhysicsUniversity of Colorado at BoulderBoulderCOUSA
| | - R. B. Torbert
- Space Science CenterUniversity of New HampshireDurhamNHUSA
| | | | - L. Avanov
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- The Goddard Planetary Heliophysics InstituteUniversity of Maryland, Baltimore CountyBaltimoreMDUSA
| | - C. T. Russell
- Institute of Geophysics and Planetary PhysicsUniversity of California, Los AngelesLos AngelesCAUSA
| | - R. J. Strangeway
- Institute of Geophysics and Planetary PhysicsUniversity of California, Los AngelesLos AngelesCAUSA
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16
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Abstract
By means of the formation of vortices in the nonlinear phase, the Kelvin Helmholtz instability is able to redistribute the flux of energy of the solar wind that flows parallel to the magnetopause. The energy transport associated with the Kelvin Helmholtz instability contributes significantly to the magnetosphere and magnetosheath dynamics, in particular at the flanks of the magnetopause where the presence of a magnetic field perpendicular to the velocity flow does not inhibit the instability development. By means of a 2D two-fluid simulation code, the behavior of the Kelvin Helmholtz instability is investigated in the presence of typical conditions observed at the magnetopause. In particular, the energy penetration in the magnetosphere is studied as a function of an important parameter such as the solar wind velocity. The influence of the density jump at the magnetopause is also discussed.
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17
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Hogan JA, Nytch CJ, Bithorn JE, Zimmerman JK. Proposing the solar-wind energy flux hypothesis as a driver of inter-annual variation in tropical tree reproductive effort. AMERICAN JOURNAL OF BOTANY 2019; 106:1519-1525. [PMID: 31664731 DOI: 10.1002/ajb2.1380] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 09/11/2019] [Indexed: 06/10/2023]
Abstract
PREMISE The El Niño Southern Oscillation (ENSO) affects tropical environmental conditions, potentially altering ecosystem function as El Niño events interact with longer-term climate change. Anomalously warm equatorial Pacific Ocean temperatures affect rainfall and temperature throughout the tropics and coincide with altered leaf flush phenology and increased fruit production in wet tropical forests; however, the understanding of mechanisms underlying this pattern is limited. There is evidence that increases in tropical tree reproduction anticipate El Niño onset, motivating the continued search for a global driver of tropical angiosperm reproduction. We present the solar-wind energy flux hypothesis: that physical energy influx to the Earth's upper atmosphere and magnetosphere, generated by a positive anomaly in the solar wind preceding El Niño development, cues tropical trees to increase resource allocation to reproduction. METHODS We test this hypothesis using 19 years of data from Luquillo, Puerto Rico, correlating them with measures of solar-wind energy. RESULTS From 1994 to 2013, the solar-wind energy flux into Earth's magnetosphere (Ein ) was more strongly correlated with the number of species fruiting and flowering than the Niño 3.4 climate index, despite Niño 3.4 being previously identified as a driver of interannual increases in reproduction. CONCLUSIONS Changes in the global magnetosphere and thermosphere conditions from increased solar-wind energy affect global atmospheric pressure and circulation patterns, principally by weakening the Walker circulation. We discuss the idea that these changes cue interannual increases in tropical tree reproduction and act through an unidentified mechanism that anticipates and synchronizes the reproductive output of the tropical trees with El Niño.
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Affiliation(s)
- J Aaron Hogan
- International Center for Tropical Botany, Department of Biological Sciences, Florida International University, Miami, FL, 33175, USA
| | - Christopher J Nytch
- Department of Environmental Sciences, University of Puerto Rico-Río Piedras, San Juan, PR, 00925, USA
| | - John E Bithorn
- Department of Environmental Sciences, University of Puerto Rico-Río Piedras, San Juan, PR, 00925, USA
| | - Jess K Zimmerman
- Department of Environmental Sciences, University of Puerto Rico-Río Piedras, San Juan, PR, 00925, USA
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18
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Evolution of Turbulence in the Kelvin–Helmholtz Instability in the Terrestrial Magnetopause. ATMOSPHERE 2019. [DOI: 10.3390/atmos10090561] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The dynamics occurring at the terrestrial magnetopause are investigated by using Geotail and THEMIS spacecraft data of magnetopause crossings during ongoing Kelvin–Helmholtz instability. Properties of plasma turbulence and intermittency are presented, with the aim of understanding the evolution of the turbulence as a result of the development of Kelvin–Helmholtz instability. The data have been tested against standard diagnostics for intermittent turbulence, such as the autocorrelation function, the spectral analysis and the scale-dependent statistics of the magnetic field increments. A quasi-periodic modulation of different scaling exponents may exist along the direction of propagation of the Kelvin–Helmholtz waves along the Geocentric Solar Magnetosphere coordinate system (GSM), and it is visible as a quasi-periodic modulation of the scaling exponents we have studied. The wave period associated with such oscillation was estimated to be approximately 6.4 Earth Radii ( R E ). Furthermore, the amplitude of such modulation seems to decrease as the measurements are taken further away from the Earth along the magnetopause, in particular after X ( G S M ) ≲ − 15 R E . The observed modulation seems to persist for most of the parameters considered in this analysis. This suggests that a kind of signature related to the development of the Kelvin–Helmholtz instabilities could be present in the statistical properties of the magnetic turbulence.
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19
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Samanta T, Tian H, Nakariakov VM. Evidence for Vortex Shedding in the Sun's Hot Corona. PHYSICAL REVIEW LETTERS 2019; 123:035102. [PMID: 31386484 DOI: 10.1103/physrevlett.123.035102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 06/21/2019] [Indexed: 06/10/2023]
Abstract
Vortex shedding is an oscillating flow that is commonly observed in fluids due to the presence of a blunt body in a flowing medium. Numerical simulations have shown that the phenomenon of vortex shedding could also develop in the magnetohydrodynamic (MHD) domain. The dimensionless Strouhal number, the ratio of the blunt body diameter to the product of the period of vortex shedding and the speed of a flowing medium, is a robust indicator for vortex shedding, and, generally of the order of 0.2 for a wide range of Reynolds number. Using an observation from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, we report a wavelike or oscillating plasma flow propagating upward against the Sun's gravitational force. A newly formed shrinking loop in the postflare region possibly generates the oscillation of the upflow in the wake of the hot and dense loop through vortex shedding. The computed Strouhal number is consistent with the prediction from previous MHD simulations. Our observation suggests the possibility of vortex shedding in the solar corona.
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Affiliation(s)
- Tanmoy Samanta
- School of Earth and Space Sciences, Peking University, Beijing 100871, China
| | - Hui Tian
- School of Earth and Space Sciences, Peking University, Beijing 100871, China
| | - Valery M Nakariakov
- Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV47AL, United Kingdom
- St. Petersburg Branch, Special Astrophysical Observatory, Russian Academy of Sciences, 196140 St. Petersburg, Russia
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20
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Murphy KR, Inglis AR, Sibeck DG, Rae IJ, Watt CEJ, Silveira M, Plaschke F, Claudepierre SG, Nakamura R. Determining the Mode, Frequency, and Azimuthal Wave Number of ULF Waves During a HSS and Moderate Geomagnetic Storm. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2018; 123:6457-6477. [PMID: 31681521 PMCID: PMC6813628 DOI: 10.1029/2017ja024877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 05/15/2018] [Accepted: 05/17/2018] [Indexed: 06/10/2023]
Abstract
Ultralow frequency (ULF) waves play a fundamental role in the dynamics of the inner magnetosphere and outer radiation belt during geomagnetic storms. Broadband ULF wave power can transport energetic electrons via radial diffusion, and discrete ULF wave power can energize electrons through a resonant interaction. Using observations from the Magnetospheric Multiscale mission, we characterize the evolution of ULF waves during a high-speed solar wind stream (HSS) and moderate geomagnetic storm while there is an enhancement of the outer radiation belt. The Automated Flare Inference of Oscillations code is used to distinguish discrete ULF wave power from broadband wave power during the HSS. During periods of discrete wave power and utilizing the close separation of the Magnetospheric Multiscale spacecraft, we estimate the toroidal mode ULF azimuthal wave number throughout the geomagnetic storm. We concentrate on the toroidal mode as the HSS compresses the dayside magnetosphere resulting in an asymmetric magnetic field topology where toroidal mode waves can interact with energetic electrons. Analysis of the mode structure and wave numbers demonstrates that the generation of the observed ULF waves is a combination of externally driven waves, via the Kelvin-Helmholtz instability, and internally driven waves, via unstable ion distributions. Further analysis of the periods and toroidal azimuthal wave numbers suggests that these waves can couple with the core electron radiation belt population via the drift resonance during the storm. The azimuthal wave number and structure of ULF wave power (broadband or discrete) have important implications for the inner magnetospheric and radiation belt dynamics.
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Affiliation(s)
- Kyle R. Murphy
- Department of AstronomyUniversity of MarylandCollege ParkMDUSA
| | | | - David G. Sibeck
- NASA Goddard Space Flight Center, Space Weather Laboratory (674)GreenbeltMDUSA
| | - I. Jonathan Rae
- Department of Space and Climate Physics, Mullard Space Science LaboratoryUniversity College LondonLondonUK
| | | | | | | | | | - Rumi Nakamura
- Space Research InstituteAustrian Academy of SciencesGrazAustria
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21
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Malara F, Pezzi O, Valentini F. Exact hybrid Vlasov equilibria for sheared plasmas with in-plane and out-of-plane magnetic field. Phys Rev E 2018; 97:053212. [PMID: 29906964 DOI: 10.1103/physreve.97.053212] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Indexed: 11/07/2022]
Abstract
The hybrid Vlasov-Maxwell system of equations is suitable to describe a magnetized plasma at scales on the order of or larger than proton kinetic scales. An exact stationary solution is presented by revisiting previous results with a uniform-density shear flow, directed either parallel or perpendicular to a uniform magnetic field, and by adapting the solution to the hybrid Vlasov-Maxwell model. A quantitative characterization of the equilibrium distribution function is provided by studying both analytically and numerically the temperature anisotropy and gyrotropy and the heat flux. In both cases, in the shear region, the velocity distribution significantly departs from local thermodynamical equilibrium. A comparison between the time behavior of the usual "fluidlike" equilibrium shifted Maxwellian and the exact stationary solutions is carried out by means of numerical simulations of the hybrid Vlasov-Maxwell equations. These hybrid equilibria can be employed as unperturbed states for numerous problems which involve sheared flows, such as the wave propagation in an inhomogeneous background and the onset of the Kelvin-Helmholtz instability.
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Affiliation(s)
- F Malara
- Dipartimento di Fisica, Università della Calabria, 87036, Rende (Cosenza), Italy
| | - O Pezzi
- Dipartimento di Fisica, Università della Calabria, 87036, Rende (Cosenza), Italy
| | - F Valentini
- Dipartimento di Fisica, Università della Calabria, 87036, Rende (Cosenza), Italy
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22
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Li X, Zhang J, Yang S, Hou Y, Erdélyi R. Observing Kelvin-Helmholtz instability in solar blowout jet. Sci Rep 2018; 8:8136. [PMID: 29802364 PMCID: PMC5970241 DOI: 10.1038/s41598-018-26581-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 05/15/2018] [Indexed: 11/09/2022] Open
Abstract
Kelvin-Helmholtz instability (KHI) is a basic physical process in fluids and magnetized plasmas, with applications successfully modelling e.g. exponentially growing instabilities observed at magnetospheric and heliospheric boundaries, in the solar or Earth's atmosphere and within astrophysical jets. Here, we report the discovery of the KHI in solar blowout jets and analyse the detailed evolution by employing high-resolution data from the Interface Region Imaging Spectrograph (IRIS) satellite launched in 2013. The particular jet we focus on is rooted in the surrounding penumbra of the main negative polarity sunspot of Active Region 12365, where the main body of the jet is a super-penumbral structure. At its maximum, the jet has a length of 90 Mm, a width of 19.7 Mm, and its density is about 40 times higher than its surroundings. During the evolution of the jet, a cavity appears near the base of the jet, and bi-directional flows originated from the top and bottom of the cavity start to develop, indicating that magnetic reconnection takes place around the cavity. Two upward flows pass along the left boundary of the jet successively. Next, KHI develops due to a strong velocity shear (∼204 km s-1) between these two flows, and subsequently the smooth left boundary exhibits a sawtooth pattern, evidencing the onset of the instability.
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Affiliation(s)
- Xiaohong Li
- CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100101, China. .,School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Jun Zhang
- CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100101, China. .,School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Shuhong Yang
- CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100101, China.,School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yijun Hou
- CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100101, China.,School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Robert Erdélyi
- Solar Physics and Space Plasma Research Centre, School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH, UK.,Department of Astronomy, Eötvös Lorand University, Pázmány Péter sétány 1/A, Budapest, H-1117, Hungary
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23
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Nakamura TKM, Hasegawa H, Daughton W, Eriksson S, Li WY, Nakamura R. Turbulent mass transfer caused by vortex induced reconnection in collisionless magnetospheric plasmas. Nat Commun 2017; 8:1582. [PMID: 29150662 PMCID: PMC5693928 DOI: 10.1038/s41467-017-01579-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 10/01/2017] [Indexed: 11/09/2022] Open
Abstract
Magnetic reconnection is believed to be the main driver to transport solar wind into the Earth's magnetosphere when the magnetopause features a large magnetic shear. However, even when the magnetic shear is too small for spontaneous reconnection, the Kelvin-Helmholtz instability driven by a super-Alfvénic velocity shear is expected to facilitate the transport. Although previous kinetic simulations have demonstrated that the non-linear vortex flows from the Kelvin-Helmholtz instability gives rise to vortex-induced reconnection and resulting plasma transport, the system sizes of these simulations were too small to allow the reconnection to evolve much beyond the electron scale as recently observed by the Magnetospheric Multiscale (MMS) spacecraft. Here, based on a large-scale kinetic simulation and its comparison with MMS observations, we show for the first time that ion-scale jets from vortex-induced reconnection rapidly decay through self-generated turbulence, leading to a mass transfer rate nearly one order higher than previous expectations for the Kelvin-Helmholtz instability.
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Affiliation(s)
- T K M Nakamura
- Space Research Institute, Austrian Academy of Sciences, 8010, Graz, Austria.
| | - H Hasegawa
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, 252-5210, Japan
| | - W Daughton
- Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - S Eriksson
- Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, CO, 80303, USA
| | - W Y Li
- Swedish Institute of Space Physics, SE751-21, Uppsala, Sweden.,State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing, 100190, China
| | - R Nakamura
- Space Research Institute, Austrian Academy of Sciences, 8010, Graz, Austria
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24
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Dimmock AP, Nykyri K, Osmane A, Karimabadi H, Pulkkinen TI. Dawn-Dusk Asymmetries of the Earth's Dayside Magnetosheath in the Magnetosheath Interplanetary Medium Reference Frame. ACTA ACUST UNITED AC 2017. [DOI: 10.1002/9781119216346.ch5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Affiliation(s)
- A. P. Dimmock
- School of Electrical Engineering; Aalto University; Espoo Finland
| | - K. Nykyri
- Department of Physical Sciences; Embry-Riddle Aeronautical University; Daytona Beach Florida USA
| | - A. Osmane
- School of Electrical Engineering; Aalto University; Espoo Finland
| | - H. Karimabadi
- University of California; San Diego, La Jolla California
- SciberQuest, Inc.; Del Mar California USA
| | - T. I. Pulkkinen
- School of Electrical Engineering; Aalto University; Espoo Finland
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25
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On the Existence of the Kolmogorov Inertial Range in the Terrestrial Magnetosheath Turbulence. ACTA ACUST UNITED AC 2017. [DOI: 10.3847/2041-8213/836/1/l10] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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26
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Karimi M, Girimaji SS. Suppression mechanism of Kelvin-Helmholtz instability in compressible fluid flows. Phys Rev E 2016; 93:041102. [PMID: 27176246 DOI: 10.1103/physreve.93.041102] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Indexed: 11/07/2022]
Abstract
The transformative influence of compressibility on the Kelvin-Helmholtz instability (KHI) at the interface between two fluid streams of different velocities is explicated. When the velocity difference is small (subsonic), shear effects dominate the interface flow dynamics causing monotonic roll-up of vorticity and mixing between the two streams leading to the KHI. We find that at supersonic speed differentials, compressibility forces the dominance of dilatational (acoustic) rather than shear dynamics at the interface. Within this dilatational interface layer, traveling pressure waves cause the velocity perturbations to become oscillatory. We demonstrate that the oscillatory fluid motion reverses vortex roll-up and segregates the two streams leading to KHI suppression. Analysis and illustrations of the compressibility-induced suppression mechanism are presented.
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Affiliation(s)
- Mona Karimi
- Department of Mathematics, Texas A&M University, College Station, Texas 77843, USA.,Aerospace Engineering Department, Texas A&M University, College Station, Texas 77843, USA
| | - Sharath S Girimaji
- Aerospace Engineering Department, Texas A&M University, College Station, Texas 77843, USA
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27
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Xu Z, Qiao B, Chang HX, Yao WP, Wu SZ, Yan XQ, Zhou CT, Wang XG, He XT. Characterization of magnetic reconnection in the high-energy-density regime. Phys Rev E 2016; 93:033206. [PMID: 27078474 DOI: 10.1103/physreve.93.033206] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Indexed: 11/07/2022]
Abstract
The dynamics of magnetic reconnection (MR) in the high-energy-density (HED) regime, where the plasma inflow is strongly driven and the thermal pressure is larger than the magnetic pressure (β>1), is reexamined theoretically and by particle-in-cell simulations. Interactions of two colliding laser-produced plasma bubbles with self-generated poloidal magnetic fields of, respectively, antiparallel and parallel field lines are considered. Through comparison, it is found that the quadrupole magnetic field, bipolar poloidal electric field, plasma heating, and even the out-of-plane electric field can appear in both cases due to the mere plasma bubble collision, which may not be individually recognized as evidences of MR in the HED regime separately. The Lorentz-invariant scalar quantity D(e) ≃ γ(e)j · (E + v(e) × B) (γ(e) = [1-(v(e)/c)(2)](-1/2)) in the electron dissipation region is proposed as the key sign of MR occurrence in this regime.
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Affiliation(s)
- Z Xu
- Center for Applied Physics and Technology, HEDPS, and State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - B Qiao
- Center for Applied Physics and Technology, HEDPS, and State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, People's Republic of China.,Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, People's Republic of China
| | - H X Chang
- Center for Applied Physics and Technology, HEDPS, and State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - W P Yao
- Center for Applied Physics and Technology, HEDPS, and State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - S Z Wu
- Institute of Applied Physics and Computational Mathematics, Beijing 100094, People's Republic of China
| | - X Q Yan
- Center for Applied Physics and Technology, HEDPS, and State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - C T Zhou
- Center for Applied Physics and Technology, HEDPS, and State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, People's Republic of China.,Institute of Applied Physics and Computational Mathematics, Beijing 100094, People's Republic of China
| | - X G Wang
- Center for Applied Physics and Technology, HEDPS, and State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - X T He
- Center for Applied Physics and Technology, HEDPS, and State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, People's Republic of China.,Institute of Applied Physics and Computational Mathematics, Beijing 100094, People's Republic of China
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28
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Dunn WR, Branduardi-Raymont G, Elsner RF, Vogt MF, Lamy L, Ford PG, Coates AJ, Gladstone GR, Jackman CM, Nichols JD, Rae IJ, Varsani A, Kimura T, Hansen KC, Jasinski JM. The impact of an ICME on the Jovian X-ray aurora. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2016; 121:2274-2307. [PMID: 27867794 PMCID: PMC5111422 DOI: 10.1002/2015ja021888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 01/11/2016] [Accepted: 01/27/2016] [Indexed: 06/06/2023]
Abstract
We report the first Jupiter X-ray observations planned to coincide with an interplanetary coronal mass ejection (ICME). At the predicted ICME arrival time, we observed a factor of ∼8 enhancement in Jupiter's X-ray aurora. Within 1.5 h of this enhancement, intense bursts of non-Io decametric radio emission occurred. Spatial, spectral, and temporal characteristics also varied between ICME arrival and another X-ray observation two days later. Gladstone et al. (2002) discovered the polar X-ray hot spot and found it pulsed with 45 min quasiperiodicity. During the ICME arrival, the hot spot expanded and exhibited two periods: 26 min periodicity from sulfur ions and 12 min periodicity from a mixture of carbon/sulfur and oxygen ions. After the ICME, the dominant period became 42 min. By comparing Vogt et al. (2011) Jovian mapping models with spectral analysis, we found that during ICME arrival at least two distinct ion populations, from Jupiter's dayside, produced the X-ray aurora. Auroras mapping to magnetospheric field lines between 50 and 70 RJ were dominated by emission from precipitating sulfur ions (S7+,…,14+). Emissions mapping to closed field lines between 70 and 120 RJ and to open field lines were generated by a mixture of precipitating oxygen (O7+,8+) and sulfur/carbon ions, possibly implying some solar wind precipitation. We suggest that the best explanation for the X-ray hot spot is pulsed dayside reconnection perturbing magnetospheric downward currents, as proposed by Bunce et al. (2004). The auroral enhancement has different spectral, spatial, and temporal characteristics to the hot spot. By analyzing these characteristics and coincident radio emissions, we propose that the enhancement is driven directly by the ICME through Jovian magnetosphere compression and/or a large-scale dayside reconnection event.
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Affiliation(s)
- William R Dunn
- Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK; Centre for Planetary Science UCL/Birkbeck London UK
| | | | - Ronald F Elsner
- ZP12, NASA Marshall Space Flight Center Huntsville Alabama USA
| | - Marissa F Vogt
- Center for Space Physics Boston University Boston Massachusetts USA
| | - Laurent Lamy
- LESIA, Observatoire de Paris, CNRS, UPMC Université Paris Diderot Meudon France
| | - Peter G Ford
- Kavli Institute for Astrophysics and Space Research MIT Cambridge Massachusetts USA
| | - Andrew J Coates
- Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK; Centre for Planetary Science UCL/Birkbeck London UK
| | - G Randall Gladstone
- Space Science and Engineering Division Southwest Research Institute San Antonio Texas USA
| | - Caitriona M Jackman
- Department of Physics and Astronomy University of Southampton Southampton UK
| | - Jonathan D Nichols
- Department of Physics and Astronomy University of Leicester Leicester UK
| | - I Jonathan Rae
- Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK
| | - Ali Varsani
- Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK; Space Research Institute Austrian Academy of Sciences Graz Austria
| | - Tomoki Kimura
- Institute of Space and Astronautical Science Japan Aerospace Exploration Agency Sagamihara Japan; Nishina Center for Accelerator-Based Science RIKEN Wako Japan
| | - Kenneth C Hansen
- Department of Atmospheric, Oceanic and Space Sciences University of Michigan Ann Arbor Michigan USA
| | - Jamie M Jasinski
- Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK; Centre for Planetary Science UCL/Birkbeck London UK; Department of Atmospheric, Oceanic and Space Sciences University of Michigan Ann Arbor Michigan USA
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29
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Inagaki S, Kobayashi T, Kosuga Y, Itoh SI, Mitsuzono T, Nagashima Y, Arakawa H, Yamada T, Miwa Y, Kasuya N, Sasaki M, Lesur M, Fujisawa A, Itoh K. A Concept of Cross-Ferroic Plasma Turbulence. Sci Rep 2016; 6:22189. [PMID: 26917218 PMCID: PMC4768185 DOI: 10.1038/srep22189] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 02/08/2016] [Indexed: 11/18/2022] Open
Abstract
The variety of scalar and vector fields in laboratory and nature plasmas is formed by plasma turbulence. Drift-wave fluctuations, driven by density gradients in magnetized plasmas, are known to relax the density gradient while they can generate flows. On the other hand, the sheared flow in the direction of magnetic fields causes Kelvin-Helmholtz type instabilities, which mix particle and momentum. These different types of fluctuations coexist in laboratory and nature, so that the multiple mechanisms for structural formation exist in extremely non-equilibrium plasmas. Here we report the discovery of a new order in plasma turbulence, in which chained structure formation is realized by cross-interaction between inhomogeneities of scalar and vector fields. The concept of cross-ferroic turbulence is developed, and the causal relation in the multiple mechanisms behind structural formation is identified, by measuring the relaxation rate and dissipation power caused by the complex turbulence-driven flux.
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Affiliation(s)
- S Inagaki
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan.,Research Center for Plasma Turbulence, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580 Japan
| | - T Kobayashi
- National Institute for Fusion Science, 322-6 Oroshi-cho, Toki-city, Gifu 509-5292, Japan
| | - Y Kosuga
- Institute for Advanced Study, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, 812-8581, Fukuoka Japan
| | - S-I Itoh
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan.,Research Center for Plasma Turbulence, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580 Japan
| | - T Mitsuzono
- Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan
| | - Y Nagashima
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan.,Research Center for Plasma Turbulence, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580 Japan
| | - H Arakawa
- Teikyo University, 6-22 Misaki-machi, Omuta-city, Fukuoka 836-8505, Japan
| | - T Yamada
- Faculty of Arts and Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Y Miwa
- Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan
| | - N Kasuya
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan.,Research Center for Plasma Turbulence, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580 Japan
| | - M Sasaki
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan.,Research Center for Plasma Turbulence, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580 Japan
| | - M Lesur
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan
| | - A Fujisawa
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan.,Research Center for Plasma Turbulence, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580 Japan
| | - K Itoh
- Research Center for Plasma Turbulence, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580 Japan.,National Institute for Fusion Science, 322-6 Oroshi-cho, Toki-city, Gifu 509-5292, Japan
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30
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Kavosi S, Raeder J. Ubiquity of Kelvin-Helmholtz waves at Earth's magnetopause. Nat Commun 2015; 6:7019. [PMID: 25960122 PMCID: PMC4432594 DOI: 10.1038/ncomms8019] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 03/24/2015] [Indexed: 11/09/2022] Open
Abstract
Magnetic reconnection is believed to be the dominant process by which solar wind plasma enters the magnetosphere. However, for periods of northward interplanetary magnetic field (IMF) reconnection is less likely at the dayside magnetopause, and Kelvin-Helmholtz waves (KHWs) may be important agents for plasma entry and for the excitation of ultra-low-frequency (ULF) waves. The relative importance of KHWs is controversial because no statistical data on their occurrence frequency exist. Here we survey 7 years of in situ data from the NASA THEMIS (Time History of Events and Macro scale Interactions during Substorms) mission and find that KHWs occur at the magnetopause ∼19% of the time. The rate increases with solar wind speed, Alfven Mach number and number density, but is mostly independent of IMF magnitude. KHWs may thus be more important for plasma transport across the magnetopause than previously thought, and frequently drive magnetospheric ULF waves.
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Affiliation(s)
- Shiva Kavosi
- Department of Physics and Space Science Center, University of New Hampshire, 8 College Road, Durham, New Hampshire 03824, USA
| | - Joachim Raeder
- Department of Physics and Space Science Center, University of New Hampshire, 8 College Road, Durham, New Hampshire 03824, USA
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31
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Banerjee R, Kanjilal S. Influence of surface tension on two fluids shearing instability. PAPERS IN PHYSICS 2014. [DOI: 10.4279/pip.060006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Using extended Layzer's potential flow model, we investigate the effects of surface tension on the growth of the bubble and spike in combined Rayleigh-Taylor and Kelvin-Helmholtz instability. The nonlinear asymptotic solutions are obtained analytically for the velocity and curvature of the bubble and spike tip. We find that the surface tension decreases the velocity but does not affect the curvature, provided surface tension is greater than a critical value. For a certain condition, we observe that surface tension stabilizes the motion. Any perturbation, whatever its magnitude, results stable with nonlinear oscillations. The nonlinear oscillations depend on surface tension and relative velocity shear of the two fluids. Received: 20 March 2014, Accepted: 7 August 2014; Edited by: A. Marti; DOI:http://dx.doi.org/10.4279/PIP.060006Cite as: R Banerjee, S Kanjilal, Papers in Physics 6, 060006 (2014)
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32
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Feng Y, Goree J, Liu B, Intrator TP, Murillo MS. Superdiffusion of two-dimensional Yukawa liquids due to a perpendicular magnetic field. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:013105. [PMID: 25122399 DOI: 10.1103/physreve.90.013105] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Indexed: 06/03/2023]
Abstract
Stochastic transport of a two-dimensional (2D) dusty plasma liquid with a perpendicular magnetic field is studied. Superdiffusion is found to occur especially at higher magnetic fields with β of order unity. Here, β = ω(c)/ω(pd) is the ratio of the cyclotron and plasma frequencies for dust particles. The mean-square displacement MSD = 4D(α)t(α) is found to have an exponent α > 1, indicating superdiffusion, with α increasing monotonically to 1.1 as β increases to unity. The 2D Langevin molecular dynamics simulation used here also reveals that another indicator of random particle motion, the velocity autocorrelation function, has a dominant peak frequency ω(peak) that empirically obeys ω(peak)(2) = ω(c)(2) + ω(pd)(2)/4.
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Affiliation(s)
- Yan Feng
- Los Alamos National Laboratory, Mail Stop E526, Los Alamos, New Mexico 87545, USA
| | - J Goree
- Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Bin Liu
- Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242, USA
| | - T P Intrator
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - M S Murillo
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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33
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Thomas K, Herminghaus S, Porada H, Goehring L. Formation of Kinneyia via shear-induced instabilities in microbial mats. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2013; 371:20120362. [PMID: 24191114 DOI: 10.1098/rsta.2012.0362] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Kinneyia are a class of microbially mediated sedimentary fossils. Characterized by clearly defined ripple structures, Kinneyia are generally found in areas that were formally littoral habitats and covered by microbial mats. To date, there has been no conclusive explanation of the processes involved in the formation of these fossils. Microbial mats behave like viscoelastic fluids. We propose that the key mechanism involved in the formation of Kinneyia is a Kelvin-Helmholtz-type instability induced in a viscoelastic film under flowing water. A ripple corrugation is spontaneously induced in the film and grows in amplitude over time. Theoretical predictions show that the ripple instability has a wavelength proportional to the thickness of the film. Experiments carried out using viscoelastic films confirm this prediction. The ripple pattern that forms has a wavelength roughly three times the thickness of the film. This behaviour is independent of the viscosity of the film and the flow conditions. Laboratory-analogue Kinneyia were formed via the sedimentation of glass beads, which preferentially deposit in the troughs of the ripples. Well-ordered patterns form, with both honeycomb-like and parallel ridges being observed, depending on the flow speed. These patterns correspond well with those found in Kinneyia, with similar morphologies, wavelengths and amplitudes being observed.
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Affiliation(s)
- Katherine Thomas
- Max Planck Institute for Dynamics and Self-Organization, , Am Fassberg 17, 37077 Göttingen, Germany
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34
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Paral J, Rankin R. Dawn–dusk asymmetry in the Kelvin–Helmholtz instability at Mercury. Nat Commun 2013; 4:1645. [DOI: 10.1038/ncomms2676] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2012] [Accepted: 03/01/2013] [Indexed: 11/09/2022] Open
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35
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Solar wind entry into the high-latitude terrestrial magnetosphere during geomagnetically quiet times. Nat Commun 2013; 4:1466. [PMID: 23403567 DOI: 10.1038/ncomms2476] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 01/11/2013] [Indexed: 11/08/2022] Open
Abstract
An understanding of the transport of solar wind plasma into and throughout the terrestrial magnetosphere is crucial to space science and space weather. For non-active periods, there is little agreement on where and how plasma entry into the magnetosphere might occur. Moreover, behaviour in the high-latitude region behind the magnetospheric cusps, for example, the lobes, is poorly understood, partly because of lack of coverage by previous space missions. Here, using Cluster multi-spacecraft data, we report an unexpected discovery of regions of solar wind entry into the Earth's high-latitude magnetosphere tailward of the cusps. From statistical observational facts and simulation analysis we suggest that these regions are most likely produced by magnetic reconnection at the high-latitude magnetopause, although other processes, such as impulsive penetration, may not be ruled out entirely. We find that the degree of entry can be significant for solar wind transport into the magnetosphere during such quiet times.
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36
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Brachet ME, Bustamante MD, Krstulovic G, Mininni PD, Pouquet A, Rosenberg D. Ideal evolution of magnetohydrodynamic turbulence when imposing Taylor-Green symmetries. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:013110. [PMID: 23410449 DOI: 10.1103/physreve.87.013110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Indexed: 06/01/2023]
Abstract
We investigate the ideal and incompressible magnetohydrodynamic (MHD) equations in three space dimensions for the development of potentially singular structures. The methodology consists in implementing the fourfold symmetries of the Taylor-Green vortex generalized to MHD, leading to substantial computer time and memory savings at a given resolution; we also use a regridding method that allows for lower-resolution runs at early times, with no loss of spectral accuracy. One magnetic configuration is examined at an equivalent resolution of 6144(3) points and three different configurations on grids of 4096(3) points. At the highest resolution, two different current and vorticity sheet systems are found to collide, producing two successive accelerations in the development of small scales. At the latest time, a convergence of magnetic field lines to the location of maximum current is probably leading locally to a strong bending and directional variability of such lines. A novel analytical method, based on sharp analysis inequalities, is used to assess the validity of the finite-time singularity scenario. This method allows one to rule out spurious singularities by evaluating the rate at which the logarithmic decrement of the analyticity-strip method goes to zero. The result is that the finite-time singularity scenario cannot be ruled out, and the singularity time could be somewhere between t=2.33 and t=2.70. More robust conclusions will require higher resolution runs and grid-point interpolation measurements of maximum current and vorticity.
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Affiliation(s)
- M E Brachet
- Laboratoire de Physique Statistique de l'École Normale Supérieure, associé au CNRS et aux Universités ParisVI et VII, 24 Rue Lhomond, 75231 Paris, France
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37
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Tu W, Elkington SR, Li X, Liu W, Bonnell J. Quantifying radial diffusion coefficients of radiation belt electrons based on global MHD simulation and spacecraft measurements. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2012ja017901] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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38
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Stawarz JE, Pouquet A, Brachet ME. Long-time properties of magnetohydrodynamic turbulence and the role of symmetries. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:036307. [PMID: 23031013 DOI: 10.1103/physreve.86.036307] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Indexed: 06/01/2023]
Abstract
Using direct numerical simulations with grids of up to 512(3) points, we investigate long-time properties of three-dimensional magnetohydrodynamic turbulence in the absence of forcing and examine in particular the roles played by the quadratic invariants of the system and the symmetries of the initial configurations. We observe that when sufficient accuracy is used, initial conditions with a high degree of symmetries, as in the absence of helicity, do not travel through parameter space over time, whereas by perturbing these solutions either explicitly or implicitly using, for example, single precision for long times, the flows depart from their original behavior and can either become strongly helical or have a strong alignment between the velocity and the magnetic field. When the symmetries are broken, the flows evolve towards different end states, as already predicted by statistical arguments for nondissipative systems with the addition of an energy minimization principle. Increasing the Reynolds number by an order of magnitude when using grids of 64(3)-512(3) points does not alter these conclusions. Furthermore, the alignment properties of these flows, between velocity, vorticity, magnetic potential, induction, and current, correspond to the dominance of two main regimes, one helically dominated and one in quasiequipartition of kinetic and magnetic energies. We also contrast the scaling of the ratio of magnetic energy to kinetic energy as a function of wave number to the ratio of eddy turnover time to Alfvén time as a function of wave number. We find that the former ratio is constant with an approximate equipartition for scales smaller than the largest scale of the flow, whereas the ratio of time scales increases with increasing wave number.
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Affiliation(s)
- Julia E Stawarz
- Geophysical Turbulence Program, Computational and Information Systems Laboratory, National Center for Atmospheric Research, P.O. Box 3000, Boulder Colorado 80307, USA
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39
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Desroche M, Bagenal F, Delamere PA, Erkaev N. Conditions at the expanded Jovian magnetopause and implications for the solar wind interaction. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2012ja017621] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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40
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Rae IJ, Mann IR, Murphy KR, Ozeke LG, Milling DK, Chan AA, Elkington SR, Honary F. Ground-based magnetometer determination of in situ Pc4-5 ULF electric field wave spectra as a function of solar wind speed. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011ja017335] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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41
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Gan Y, Xu A, Zhang G, Li Y. Lattice Boltzmann study on Kelvin-Helmholtz instability: roles of velocity and density gradients. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:056704. [PMID: 21728690 DOI: 10.1103/physreve.83.056704] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 01/26/2011] [Indexed: 05/31/2023]
Abstract
A two-dimensional lattice Boltzmann model with 19 discrete velocities for compressible fluids is proposed. The fifth-order weighted essentially nonoscillatory (5th-WENO) finite difference scheme is employed to calculate the convection term of the lattice Boltzmann equation. The validity of the model is verified by comparing simulation results of the Sod shock tube with its corresponding analytical solutions [G. A. Sod, J. Comput. Phys. 27, 1 (1978).]. The velocity and density gradient effects on the Kelvin-Helmholtz instability (KHI) are investigated using the proposed model. Sharp density contours are obtained in our simulations. It is found that the linear growth rate γ for the KHI decreases by increasing the width of velocity transition layer D(v) but increases by increasing the width of density transition layer D(ρ). After the initial transient period and before the vortex has been well formed, the linear growth rates γ(v) and γ(ρ), vary with D(v) and D(ρ) approximately in the following way, lnγ(v)=a-bD(v) and γ(ρ)=c+elnD(ρ)(D(ρ)<D(ρ)(E)), where a, b, c, and e are fitting parameters and D(ρ)(E) is the effective interaction width of the density transition layer. When D(ρ)>D(ρ)(E) the linear growth rate γ(ρ) does not vary significantly any more. One can use the hybrid effects of velocity and density transition layers to stabilize the KHI. Our numerical simulation results are in general agreement with the analytical results [L. F. Wang et al., Phys. Plasma 17, 042103 (2010)].
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Affiliation(s)
- Yanbiao Gan
- State Key Laboratory for GeoMechanics and Deep Underground Engineering, SMCE, China University of Mining and Technology (Beijing), Beijing 100083, PR China
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42
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Zong Q, Wang Y, Yuan C, Yang B, Wang C, Zhang X. Fast acceleration of “killer” electrons and energetic ions by interplanetary shock stimulated ULF waves in the inner magnetosphere. CHINESE SCIENCE BULLETIN-CHINESE 2011. [DOI: 10.1007/s11434-010-4308-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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43
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Takeuchi H, Ishino S, Tsubota M. Binary quantum turbulence arising from countersuperflow instability in two-component Bose-Einstein condensates. PHYSICAL REVIEW LETTERS 2010; 105:205301. [PMID: 21231243 DOI: 10.1103/physrevlett.105.205301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Revised: 10/06/2010] [Indexed: 05/30/2023]
Abstract
We theoretically study the development of quantum turbulence from two counter-propagating superfluids of miscible Bose-Einstein condensates by numerically solving the coupled Gross-Pitaevskii equations. When the relative velocity exceeds a critical value, the countersuperflow becomes unstable and quantized vortices are nucleated, which leads to isotropic quantum turbulence consisting of two superflows. It is shown that the binary turbulence can be realized experimentally in a trapped system.
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Affiliation(s)
- Hiromitsu Takeuchi
- Department of Physics, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan
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44
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Uritsky VM, Pouquet A, Rosenberg D, Mininni PD, Donovan EF. Structures in magnetohydrodynamic turbulence: detection and scaling. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:056326. [PMID: 21230595 DOI: 10.1103/physreve.82.056326] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 09/29/2010] [Indexed: 05/30/2023]
Abstract
We present a systematic analysis of statistical properties of turbulent current and vorticity structures at a given time using cluster analysis. The data stem from numerical simulations of decaying three-dimensional magnetohydrodynamic turbulence in the absence of an imposed uniform magnetic field; the magnetic Prandtl number is taken equal to unity, and we use a periodic box with grids of up to 1536³ points and with Taylor Reynolds numbers up to 1100. The initial conditions are either an X -point configuration embedded in three dimensions, the so-called Orszag-Tang vortex, or an Arn'old-Beltrami-Childress configuration with a fully helical velocity and magnetic field. In each case two snapshots are analyzed, separated by one turn-over time, starting just after the peak of dissipation. We show that the algorithm is able to select a large number of structures (in excess of 8000) for each snapshot and that the statistical properties of these clusters are remarkably similar for the two snapshots as well as for the two flows under study in terms of scaling laws for the cluster characteristics, with the structures in the vorticity and in the current behaving in the same way. We also study the effect of Reynolds number on cluster statistics, and we finally analyze the properties of these clusters in terms of their velocity-magnetic-field correlation. Self-organized criticality features have been identified in the dissipative range of scales. A different scaling arises in the inertial range, which cannot be identified for the moment with a known self-organized criticality class consistent with magnetohydrodynamics. We suggest that this range can be governed by turbulence dynamics as opposed to criticality and propose an interpretation of intermittency in terms of propagation of local instabilities.
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Affiliation(s)
- V M Uritsky
- Physics and Astronomy Department, University of Calgary, Calgary, Alberta T2N1N4, Canada
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45
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Masters A, Achilleos N, Kivelson MG, Sergis N, Dougherty MK, Thomsen MF, Arridge CS, Krimigis SM, McAndrews HJ, Kanani SJ, Krupp N, Coates AJ. Cassini observations of a Kelvin-Helmholtz vortex in Saturn's outer magnetosphere. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010ja015351] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- A. Masters
- Space and Atmospheric Physics Group, Blackett Laboratory; Imperial College London; London UK
- Mullard Space Science Laboratory, Department of Space and Climate Physics; University College London; Dorking UK
- Center for Planetary Sciences; University College London; London UK
| | - N. Achilleos
- Center for Planetary Sciences; University College London; London UK
- Atmospheric Physics Laboratory, Department of Physics and Astronomy; University College London; London UK
| | - M. G. Kivelson
- Institute of Geophysics and Planetary Physics; University of California; Los Angeles California USA
| | - N. Sergis
- Office of Space Research and Technology; Academy of Athens; Athens Greece
| | - M. K. Dougherty
- Space and Atmospheric Physics Group, Blackett Laboratory; Imperial College London; London UK
| | - M. F. Thomsen
- Space Science and Applications; Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - C. S. Arridge
- Mullard Space Science Laboratory, Department of Space and Climate Physics; University College London; Dorking UK
- Center for Planetary Sciences; University College London; London UK
| | - S. M. Krimigis
- Johns Hopkins University Applied Physics Laboratory; Laurel Maryland USA
| | - H. J. McAndrews
- Space Science and Applications; Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - S. J. Kanani
- Mullard Space Science Laboratory, Department of Space and Climate Physics; University College London; Dorking UK
- Center for Planetary Sciences; University College London; London UK
| | - N. Krupp
- Max-Planck-Institut für Sonnensystemforschung; Katlenburg-Lindau Germany
| | - A. J. Coates
- Mullard Space Science Laboratory, Department of Space and Climate Physics; University College London; Dorking UK
- Center for Planetary Sciences; University College London; London UK
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46
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Slavin JA, Anderson BJ, Baker DN, Benna M, Boardsen SA, Gloeckler G, Gold RE, Ho GC, Korth H, Krimigis SM, McNutt RL, Nittler LR, Raines JM, Sarantos M, Schriver D, Solomon SC, Starr RD, Trávnícek PM, Zurbuchen TH. MESSENGER observations of extreme loading and unloading of Mercury's magnetic tail. Science 2010; 329:665-8. [PMID: 20647422 DOI: 10.1126/science.1188067] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
During MESSENGER's third flyby of Mercury, the magnetic field in the planet's magnetic tail increased by factors of 2 to 3.5 over intervals of 2 to 3 minutes. Magnetospheric substorms at Earth are powered by similar tail loading, but the amplitude is lower by a factor of approximately 10 and typical durations are approximately 1 hour. The extreme tail loading observed at Mercury implies that the relative intensity of substorms must be much larger than at Earth. The correspondence between the duration of tail field enhancements and the characteristic time for the Dungey cycle, which describes plasma circulation through Mercury's magnetosphere, suggests that such circulation determines the substorm time scale. A key aspect of tail unloading during terrestrial substorms is the acceleration of energetic charged particles, but no acceleration signatures were seen during the MESSENGER flyby.
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Affiliation(s)
- James A Slavin
- Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
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47
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Nakamura TKM, Hasegawa H, Shinohara I. Kinetic effects on the Kelvin-Helmholtz instability in ion-to-magnetohydrodynamic scale transverse velocity shear layers: Particle simulations. PHYSICS OF PLASMAS 2010; 17:042119. [PMID: 20838425 PMCID: PMC2931600 DOI: 10.1063/1.3385445] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Accepted: 03/18/2010] [Indexed: 05/29/2023]
Abstract
Ion-to-magnetohydrodynamic scale physics of the transverse velocity shear layer and associated Kelvin-Helmholtz instability (KHI) in a homogeneous, collisionless plasma are investigated by means of full particle simulations. The shear layer is broadened to reach a kinetic equilibrium when its initial thickness is close to the gyrodiameter of ions crossing the layer, namely, of ion-kinetic scale. The broadened thickness is larger in B⋅Ω<0 case than in B⋅Ω>0 case, where Ω is the vorticity at the layer. This is because the convective electric field, which points out of (into) the layer for B⋅Ω<0 (B⋅Ω>0), extends (reduces) the gyrodiameters. Since the kinetic equilibrium is established before the KHI onset, the KHI growth rate depends on the broadened thickness. In the saturation phase of the KHI, the ion vortex flow is strengthened (weakened) for B⋅Ω<0 (B⋅Ω>0), due to ion centrifugal drift along the rotational plasma flow. In ion inertial scale vortices, this drift effect is crucial in altering the ion vortex size. These results indicate that the KHI at Mercury-like ion-scale magnetospheric boundaries could show clear dawn-dusk asymmetries in both its linear and nonlinear growth.
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Affiliation(s)
- T K M Nakamura
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Kanagawa 229-8510, Japan
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48
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Nakamura TKM, Fujimoto M. Magnetic effects on the coalescence of Kelvin-Helmholtz vortices. PHYSICAL REVIEW LETTERS 2008; 101:165002. [PMID: 18999678 DOI: 10.1103/physrevlett.101.165002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2008] [Indexed: 05/27/2023]
Abstract
We simulate the coalescence process of MHD-scale Kelvin-Helmholtz vortices with the electron inertial effects taken into account. Reconnection of highly stretched magnetic field lines within a rolled-up vortex destroys the vortex itself and the coalescence process, which is well known in ordinary fluid dynamics, is seen to be inhibited. When the magnetic field is initially antiparallel across the shear layer, on the other hand, multiple vortices are seen to coalesce continuously because another type of magnetic reconnection prevents the vortex decay. This type of reconnection at the hyperbolic point also changes the field line connectivity and thus leads to large-scale plasma mixing across the shear layer.
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Affiliation(s)
- T K M Nakamura
- Japan Aerospace Exploration Agency/Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Kanagawa, Japan.
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49
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Faganello M, Califano F, Pegoraro F. Numerical evidence of undriven, fast reconnection in the solar-wind interaction with earth's magnetosphere: formation of electromagnetic coherent structures. PHYSICAL REVIEW LETTERS 2008; 101:105001. [PMID: 18851219 DOI: 10.1103/physrevlett.101.105001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2008] [Indexed: 05/26/2023]
Abstract
We give evidence for the first time of the onset of undriven fast, collisionless magnetic reconnection during the evolution of an initially homogeneous magnetic field advected in a sheared velocity field. We consider the interaction of the solar wind with the magnetospheric plasma at low latitude and show that reconnection takes place in the layer between adjacent vortices generated by the Kelvin-Helmholtz instability. This process generates coherent magnetic structures with a size comparable to the ion inertial scale, much smaller than the system dimensions but much larger than the electron inertial scale. These magnetic structures are further advected in the plasma in a complex pattern but remain stable over a time interval much longer than their formation time. These results can be crucial for the interpretation of satellite data showing coherent magnetic structures in the Earth's magnetosheath or the magnetotail.
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Affiliation(s)
- M Faganello
- Physics Department, University of Pisa, Pisa, Italy
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50
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Faganello M, Califano F, Pegoraro F. Competing mechanisms of plasma transport in inhomogeneous configurations with velocity shear: the solar-wind interaction with earth's magnetosphere. PHYSICAL REVIEW LETTERS 2008; 100:015001. [PMID: 18232777 DOI: 10.1103/physrevlett.100.015001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Indexed: 05/25/2023]
Abstract
Two-dimensional simulations of the Kelvin-Helmholtz instability in an inhomogeneous compressible plasma with a density gradient show that, in a transverse magnetic field configuration, the vortex pairing process and the Rayleigh-Taylor secondary instability compete during the nonlinear evolution of the vortices. Two different regimes exist depending on the value of the density jump across the velocity shear layer. These regimes have different physical signatures that can be crucial for the interpretation of satellite data of the interaction of the solar wind with the magnetospheric plasma.
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Affiliation(s)
- M Faganello
- Physics Department, University of Pisa, Pisa, Italy
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