Magnetic field and plasma properties associated with pressure pulses and magnetic reconnection at the dayside magnetopause

1995 ◽  
Vol 100 (A8) ◽  
pp. 14895 ◽  
Author(s):  
A. Otto ◽  
L. C. Lee ◽  
Z. W. Ma
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Plasma Properties ◽  
Dayside Magnetopause ◽  
Pressure Pulses

Hybrid-Vlasov modelling of three-dimensional dayside magnetopause reconnection

2021 ◽  
Author(s):  
Yann Pfau-Kempf ◽  
Minna Palmroth ◽  
Andreas Johlander ◽  
Lucile Turc ◽  
Markku Alho ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Three Dimensional ◽  
Meridional Plane ◽  
Kinetic Behavior ◽  
Dayside Magnetopause ◽  
Field Junction ◽  
First Time ◽  
Kinetic Instabilities ◽  
Magnetopause Reconnection

<p>Dayside magnetic reconnection at the magnetopause, which is a major driver of space weather, is studied for the first time in a three-dimensional (3D) realistic setup using the Vlasiator hybrid-Vlasov kinetic model. A noon–midnight meridional plane simulation is extended in the dawn–dusk direction to cover 7 Earth radii. The southward interplanetary magnetic field causes magnetic reconnection to occur at the subsolar magnetopause. Perturbations arising from kinetic instabilities in the magnetosheath appear to modulate the reconnection. Its characteristics are consistent with multiple, bursty, and patchy magnetopause reconnection. It is shown that the kinetic behavior of the plasma, as simulated by the model, has consequences on the applicability of methods such as the four-field junction to identify and analyse magnetic reconnection in 3D kinetic simulations.</p>

scholarly journals Concerning the occurrence pattern of flux transfer events on the dayside magnetopause

2009 ◽  
Vol 27 (2) ◽  
pp. 895-903 ◽  
Author(s):  
D. G. Sibeck
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Reconnection ◽  
Interplanetary Magnetic Field ◽  
Flux Transfer Events ◽  
Dayside Magnetopause ◽  
Two Factors ◽  
Flux Transfer ◽  
Occurrence Pattern ◽  
The Magnetic Field

Abstract. We present an analytical model for the magnetic field perturbations associated with flux transfer events (FTEs) on the dayside magnetopause as a function of the shear between the magnetosheath and magnetospheric magnetic fields and the ratio of their strengths. We assume that the events are produced by component reconnection along subsolar reconnection lines with tilts that depend upon the orientation of the interplanetary magnetic field (IMF), and show that the amplitudes of the perturbations generated during southward IMF greatly exceed those during northward IMF. As a result, even if the distributions of magnetic reconnection burst durations/event dimensions are identical during periods of northward and southward IMF orientation, events occurring for southward IMF orientations must predominate in surveys of dayside events. Two factors may restore the balance between events occurring for northward and southward IMF orientations on the flanks of the magnetosphere. Events generated on the dayside magnetopause during periods of southward IMF move poleward, while those generated during periods of northward IMF slip dawnward or duskward towards the flanks. Due to differing event and magnetospheric magnetic field orientations, events that produce weak signatures on the dayside magnetopause during intervals of northward IMF orientation may produce strong signatures on the flanks.

scholarly journals Global MHD Simulation of the Weak Southward IMF Condition for Different Time Resolutions

2021 ◽  
Vol 8 ◽  
Author(s):  
Kyung Sun Park
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Magnetic Reconnection ◽  
Three Dimensional ◽  
Slow Solar Wind ◽  
Polar Cap ◽  
Plasma Properties ◽  
Simulation Results ◽  
Field Lines ◽  
The Impact

We performed high-resolution three-dimensional global MHD simulations to determine the impact of weak southward interplanetary magnetic field (IMF) (Bz = −2 nT) and slow solar wind to the Earth’s magnetosphere and ionosphere. We considered two cases of differing, uniform time resolution with the same grid spacing simulation to find any possible differences in the simulation results. The simulation results show that dayside magnetic reconnection and tail reconnection continuously occur even during the weak and steady southward IMF conditions. A plasmoid is generated on closed plasma sheet field lines. Vortices are formed in the inner side of the magnetopause due to the viscous-like interaction, which is strengthened by dayside magnetic reconnection. We estimated the dayside magnetic reconnection which occurred in relation to the electric field at the magnetopause and confirmed that the enhanced electric field is caused by the reconnection and the twisted structure of the electric field is due to the vortex. The simulation results of the magnetic field and the plasma properties show quasi-periodic variations with a period of 9–11 min between the appearances of vortices. Also the peak values of the cross-polar cap potential are both approximately 50 kV, the occurrence time of dayside reconnections are the same, and the polar cap potential patterns are the same in both cases. Thus, there are no significant differences in outcome between the two cases.

scholarly journals A case study of dayside reconnection under extremely low solar wind density conditions

2008 ◽  
Vol 26 (11) ◽  
pp. 3571-3583
Author(s):  
R. Maggiolo ◽  
J. A. Sauvaud ◽  
I. Dandouras ◽  
E. Luceck ◽  
H. Rème
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
High Speed ◽  
Radial Distance ◽  
Plasma Jets ◽  
Solar Wind Density ◽  
Ion Distribution ◽  
Dayside Magnetopause ◽  
Field Lines

Abstract. From 15 February 2004, 20:00 UT to 18 February 2004, 01:00 UT, the solar wind density dropped to extremely low values (about 0.35 cm−3). On 17 February, between 17:45 UT and 18:10 UT, the CLUSTER spacecraft cross the dayside magnetopause several times at a large radial distance of about 16 RE. During each of these crossings, the spacecraft detect high speed plasma jets in the dayside magnetopause and boundary layer. These observations are made during a period of southward and dawnward Interplanetary Magnetic Field (IMF). The magnetic shear across the local magnetopause is ~90° and the magnetosheath beta is very low (~0.15). We evidence the presence of a magnetic field of a few nT along the magnetopause normal. We also show that the plasma jets, accelerated up to 600 km/s, satisfy the tangential stress balance. These findings strongly suggest that the accelerated jets are due to magnetic reconnection between interplanetary and terrestrial magnetic field lines northward of the satellites. This is confirmed by the analysis of the ion distribution function that exhibits the presence of D shaped distributions and of a reflected ion population as predicted by theory. A quantitative analysis of the reflected ion population reveals that the reconnection process lasts about 30 min in a reconnection site located at a very large distance of several tens RE from the Cluster spacecraft. We also estimate the magnetopause motion and thickness during this event. This paper gives the first experimental study of magnetic reconnection during such rare periods of very low solar wind density. The results are discussed in the frame of magnetospheric response to extremely low solar wind density conditions.

scholarly journals On the location of dayside magnetic reconnection during an interval of duskward oriented IMF

2007 ◽  
Vol 25 (1) ◽  
pp. 219-238 ◽  
Author(s):  
J. A. Wild ◽  
S. E. Milan ◽  
J. A. Davies ◽  
M. W. Dunlop ◽  
D. M. Wright ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
Local Magnetic Field ◽  
High Latitudes ◽  
Reconnection Rate ◽  
Flux Tubes ◽  
Dayside Magnetopause ◽  
Line Passing ◽  
Open Flux

Abstract. We present space- and ground-based observations of the signatures of magnetic reconnection during an interval of duskward-oriented interplanetary magnetic field on 25 March 2004. In situ field and plasma measurements are drawn from the Double Star and Cluster satellites during traversals of the pre-noon sector dayside magnetopause at low and high latitudes, respectively. These reveal the typical signatures of flux transfer events (FTEs), namely bipolar perturbations in the magnetic field component normal to the local magnetopause, enhancements in the local magnetic field strength and mixing of magnetospheric and magnetosheath plasmas. Further evidence of magnetic reconnection is inferred from the ground-based signatures of pulsed ionospheric flow observed over an extended interval. In order to ascertain the location of the reconnection site responsible for the FTEs, a simple model of open flux tube motion over the surface of the magnetopause is employed. A comparison of the modelled and observed motion of open flux tubes (i.e. FTEs) and plasma flow in the magnetopause boundary layer indicates that the FTEs observed at both low and high latitudes were consistence with the existence of a tilted X-line passing through the sub-solar region, as suggested by the component reconnection paradigm. While a high latitude X-line (as predicted by the anti-parallel description of reconnection) may have been present, we find it unlikely that it could have been responsible for the FTEs observed in the pre-noon sector under the observed IMF conditions. Finally, we note that throughout the interval, the magnetosphere was bathed in ULF oscillations within the solar wind electric field. While no one-to-one correspondence with the pulsed reconnection rate suggested by the ground-based observation of pulsed ionospheric flow has been demonstrated, we note that similar periodicity oscillations were observed throughout the solar wind-magnetosphere-ionosphere system. These findings are consistent with previously proposed mechanisms of solar wind modulation of the dayside reconnection rate.

Magnetic Curvature Analysis on Reconnection Related Structures at Earth’s Magnetopause

2020 ◽  
Author(s):  
Yi Qi ◽  
Christopher T. Russell ◽  
Robert J. Strangeway ◽  
Yingdong Jia ◽  
Roy B. Torbert ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
Solar Wind Plasma ◽  
Radius Of Curvature ◽  
Plasma Properties ◽  
Magnetospheric Multiscale ◽  
Reconnection Site ◽  
Field Lines ◽  
The Magnetic Field

<p>Magnetic reconnection is a mechanism that allows rapid and explosive energy transfer from the magnetic field to the plasma. The magnetopause is the interface between the shocked solar wind plasma and Earth’s magnetosphere. Reconnection enables the transport of momentum from the solar wind into Earth’s magnetosphere. Because of its importance in this regard, magnetic reconnection has been extensively studied in the past and is the primary goal of the ongoing Magnetospheric Multiscale (MMS) mission. During magnetic reconnection, the originally anti-parallel fields annihilate and reconnect in a thinned current sheet. In the vicinity of a reconnection site, a prominently increased curvature of the magnetic field (and smaller radius of curvature) marks the region where the particles start to deviate from their regular gyro-motion and become available for energy conversion. Before MMS, there were no closely separated multi-spacecraft missions capable of resolving these micro-scale curvature features, nor examining particle dynamics with sufficiently fast cadence.</p><p>In this study, we use measurements from the four MMS spacecraft to determine the curvature of the field lines and the plasma properties near the reconnection site. We use this method to study FTEs (flux ropes) on the magnetopause, and the interaction between co-existing FTEs. Our study not only improves our understanding of magnetic reconnection, but also resolves the relationship between FTEs and structures on the magnetopause.</p>

scholarly journals Mass and energy supply of a cool coronal loop near its apex

2018 ◽  
Vol 611 ◽  
pp. A49 ◽  
Author(s):  
Limei Yan ◽  
Hardi Peter ◽  
Jiansen He ◽  
Lidong Xia ◽  
Linghua Wang
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Magnetic Reconnection ◽  
Transition Region ◽  
Doppler Velocity ◽  
Small Scale ◽  
Solar Dynamics Observatory ◽  
Plasma Properties ◽  
Flux Tubes ◽  
Magnetic Flux Tubes

Context. Different models for the heating of solar corona assume or predict different locations of the energy input: concentrated at the footpoints, at the apex, or uniformly distributed. The brightening of a loop could be due to the increase in electron density ne, the temperature T, or a mixture of both.Aim. We investigate possible reasons for the brightening of a cool loop at transition region temperatures through imaging and spectral observation.Methods. We observed a loop with the Interface Region Imaging Spectrograph (IRIS) and used the slit-jaw images together with spectra taken at a fixed slit position to study the evolution of plasma properties in and below the loop. We used spectra of Si iv, which forms at around 80 000 K in equilibrium, to identify plasma motions and derive electron densities from the ratio of inter-combination lines of O IV. Additional observations from the Solar Dynamics Observatory (SDO) were employed to study the response at coronal temperatures (Atmospheric Imaging Assembly, AIA) and to investigate the surface magnetic field below the loop (Helioseismic and Magnetic Imager, HMI).Results. The loop first appears at transition region temperatures and later also at coronal temperatures, indicating a heating of the plasma in the loop. The appearance of hot plasma in the loop coincides with a possible accelerating upflow seen in Si IV, with the Doppler velocity shifting continuously from ~−70 km s−1 to ~−265 km s−1. The 3D magnetic field lines extrapolated from the HMI magnetogram indicate possible magnetic reconnection between small-scale magnetic flux tubes below or near the loop apex. At the same time, an additional intensity enhancement near the loop apex is visible in the IRIS slit-jaw images at 1400 Å. These observations suggest that the loop is probably heated by the interaction between the loop and the upflows, which are accelerated by the magnetic reconnection between small-scale magnetic flux tubes at lower altitudes. Before and after the possible heating phase, the intensity changes in the optically thin (Si IV) and optical thick line (C II) are mainly contributed by the density variation without significant heating.Conclusions. We therefore provide evidence for the heating of an envelope loop that is affected by accelerating upflows, which are probably launched by magnetic reconnection between small-scale magnetic flux tubes underneath the envelope loop. This study emphasizes that in the complex upper atmosphere of the Sun, the dynamics of the 3D coupled magnetic field and flow field plays a key role in thermalizing 1D structures such as coronal loops.

scholarly journals Cluster observation of continuous reconnection at dayside magnetopause in the vicinity of cusp

2005 ◽  
Vol 23 (6) ◽  
pp. 2199-2215 ◽  
Author(s):  
Y. Zheng ◽  
G. Le ◽  
J. A. Slavin ◽  
M. L. Goldstein ◽  
C. Cattell ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Electric Fields ◽  
Minimum Variance ◽  
Current Layer ◽  
Normal Surface ◽  
Reconnection Process ◽  
Dayside Magnetopause ◽  
Plasma Measurements

Abstract. In this paper, we present a case study of continuous reconnection at the dayside magnetopause observed by the Cluster spacecraft. On 1 April 2003, the four Cluster spacecraft experienced multiple encounters with the Earth's dayside magnetopause under a fairly stable southwestward interplanetary magnetic field (IMF). Accelerated plasma flows, whose magnitude and direction are consistent with the predictions of the reconnection theory (the Walén relation), were observed at and around the magnetopause current layer for a prolonged interval of ~3 h at two types of magnetopause crossings, one with small magnetic shears and the other one with large magnetic shears. Reversals in the Y component of ion bulk flow between the magnetosheath and magnetopause current layer and acceleration of magnetosheath electrons were also observed. Kinetic signatures using electron and ion velocity distributions corroborate the interpretation of continuous magnetic reconnection. This event provides strong in-situ evidence that magnetic reconnection at the dayside magnetopause can be continuous for many hours. However, the reconnection process appeared to be very dynamic rather than steady, despite the steady nature of the IMF. Detailed analysis using multi-spacecraft magnetic field and plasma measurements shows that the dynamics and structure of the magnetopause current layer/boundary can be very complex. For example, highly variable magnetic and electric fields were observed in the magnetopause current layer. Minimum variance analysis shows that the magnetopause normal deviates from the model normal. Surface waves resulting from the reconnection process may be involved in the oscillation of the magnetopause. Keywords. Magnetospheric physics (Magnetopause, cusp and boundary layers; Solar wind-magnetosphere interactions) – Space plasma physics (magnetic reconnection)

The location of Component Reconnection at the Earth’s Magnetopause During Dominant IMF By and Large Dipole Tilt Conditions

2020 ◽  
Author(s):  
Karlheinz Trattner ◽  
Stephen Fuselier ◽  
Steven Petrinec ◽  
James Burch ◽  
Paul Cassak ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Magnetic Energy ◽  
Magnetic Shear ◽  
The Earth ◽  
Laboratory Plasmas ◽  
Reconnection Region ◽  
Dayside Magnetopause ◽  
Field Lines ◽  
Dipole Tilt

<p>The interplanetary magnetic field (IMF) convected with the solar wind drapes around the region of space dominated by Earth’s geomagnetic field and undergoes a process called magnetic reconnection at the magnetopause; the boundary layer that separates these two distinct regimes. Magnetic reconnection changes the topology of magnetic field lines and is known to convert magnetic energy into kinetic energy and heat. This fundamental process occurs in many environments, spanning from laboratory plasmas to the heliosphere, the solar atmosphere, and to astrophysical phenomena. Magnetic reconnection at the Earth’s magnetopause has been observed at various times and places as either anti-parallel and/or component reconnection. A model known as the Maximum Magnetic Shear Model combines these two scenarios, creating long reconnection lines crossing the dayside magnetopause along a ridge of maximum magnetic shear. <br>The connection points between the anti-parallel and the component reconnection segments of the reconnection line are known as ‘Knee’ regions. Using observations from the MMS satellites, it was shown that the location of the Knee region depends strongly on the local draping conditions of the IMF across the magnetopause, with certain draping conditions causing a deflection of the location along the anti-parallel reconnection region. This study discusses an event that shows that the entire component reconnection X-line crossing the dayside magnetopause can be affected by this deflection. This result emphasizes the importance of anti-parallel reconnection that seems to control where component reconnection is occurring. </p>

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