scholarly journals Magnetopause reconnection and energy conversion as influenced by the dipole tilt and the IMF B x

2014 ◽  
Vol 119 (6) ◽  
pp. 4484-4494 ◽  
Author(s):  
Sanni Hoilijoki ◽  
Vitor M. Souza ◽  
Brian M. Walsh ◽  
Pekka Janhunen ◽  
Minna Palmroth
Keyword(s):  
Energy Conversion ◽  
Dipole Tilt ◽  
Magnetopause Reconnection ◽  
The Imf

scholarly journals Dipole Tilt Effect on Magnetopause Reconnection and the Steady‐State Magnetosphere‐Ionosphere System: Global MHD Simulations

2020 ◽  
Vol 125 (7) ◽  
Author(s):  
J. W. B. Eggington ◽  
J. P. Eastwood ◽  
L. Mejnertsen ◽  
R. T. Desai ◽  
J. P. Chittenden
Keyword(s):  
Steady State ◽  
Mhd Simulations ◽  
Dipole Tilt ◽  
Magnetopause Reconnection

Quantifying the lobe reconnection rate during dominant IMF By periods

2021 ◽  
Author(s):  
Jone Peter Reistad ◽  
Karl Magnus Laundal ◽  
Anders Ohma ◽  
Nikolai Østgaard ◽  
Spencer Hatch ◽  
...  
Keyword(s):  
Transverse Component ◽  
Conceptual Level ◽  
Polar Cap ◽  
Reconnection Rate ◽  
Ionospheric Convection ◽  
Relative Contribution ◽  
Close Proximity ◽  
Lobe Reconnection ◽  
Dipole Tilt ◽  
The Imf

<p>Lobe reconnection is usually considered to play an important role in geospace dynamics only when the Interplanetary Magnetic Field (IMF) is mainly northward. This is because the most common signature of lobe reconnection is the strong sunward convection in the polar cap ionosphere observed during these conditions. During more typical conditions, when the IMF is mainly in a dawn-dusk direction, plasma flows initiated by dayside as well as lobe reconnection map to high latitude ionospheric locations in close proximity to each other. This has been emphasized in the literature earlier, mainly on a conceptual level, but quantifying the relative importance of lobe reconnection to the observed ionospheric convection is highly challenging during these IMF By dominated conditions, since one has to identify and distinguish these regions. By normalizing the ionospheric convection (observed by SuperDARN) to the polar cap boundary (inferred from simultaneous AMPERE observations), we are able to do this separation, allowing us to quantify the relative contribution of both lobe reconnection and dayside/nightisde reconnection to the ionospheric convection pattern. Using this segmentation technique we can get new quantitative insights into the importance of the various mechanisms that affect the lobe reconnection rate. In this presentation we will describe the technique and show results of analysis of periods when the IMF is mainly in the dawn-dusk direction. Our quantification of the average lobe reconnection rate during various conditions yields quantitative knowledge of the importance of the lobe reconnection process, which can act independently in the two hemispheres. We will specifically constrain the influence from parameters such as the dipole tilt angle and the product of IMF transverse component and solar wind velocity.</p>

Possible dipole tilt dependence of dayside magnetopause reconnection

2003 ◽  
Vol 30 (18) ◽  
Author(s):  
C. T. Russell ◽  
Y. L. Wang ◽  
J. Raeder
Keyword(s):  
Dayside Magnetopause ◽  
Dipole Tilt ◽  
Magnetopause Reconnection

scholarly journals SWMF simulation of field-aligned currents for a varying northward and duskward IMF with nonzero dipole tilt

2008 ◽  
Vol 26 (6) ◽  
pp. 1461-1477 ◽  
Author(s):  
H. Wang ◽  
A. J. Ridley ◽  
H. Lühr
Keyword(s):  
Open Field ◽  
Hemispheric Asymmetry ◽  
Closed Field ◽  
Polar Cap ◽  
Counterclockwise Rotation ◽  
Summer Hemisphere ◽  
Field Lines ◽  
Winter Hemisphere ◽  
Dipole Tilt ◽  
The Imf

Abstract. This study concentrates on the FACs distribution for the varying northward and duskward interplanetary magnetic field (IMF) conditions when the dipole tilt is nonzero. A global MHD simulation (the Space Weather Modeling Framework, SWMF) has been used to perform this study. Hemispheric asymmetry of the time evolution of northward IMF Bz (NBZ) FACs is found. As the IMF changes from strictly northward to duskward, NBZ FACs shift counterclockwise in both summer and winter hemispheres. However, in the winter hemisphere, the counterclockwise rotation prohibits the duskward NBZ FACs from evolving into the midday R1 FACs. The midday R1 FACs seem to be an intrusion of dawnside R1 FACs. In the summer hemisphere, the NBZ FACs can evolve into the DPY FACs, consisting of the midday R0 and R1 FACs, after the counterclockwise rotation. The hemispheric asymmetry is due to the fact that the dipole tilt favors more reconnection between the IMF and the summer magnetosphere. When mapping the NBZ and DPY FACs into the magnetosphere it is found that the NBZ currents are located on both open and closed field lines, irrespective of the IMF direction. For the DPY FACs the hemispheric asymmetry emerges: the midday R1 FACs and a small part of R0 FACs are on closed field lines in the winter hemisphere, while a small part of the midday R1 FACs and all the R0 FACs are on open field lines in the summer hemisphere. Both IMF By and dipole tilt cause the polar cap hemispheric and local time asymmetric. When the IMF is northward, the summer polar cap is closed on the nightside while the winter polar cap is open. The polar cap boundary tends to move equatorward as the IMF rotates from northward to duskward, except in the summer hemisphere, the polar cap on the dawnside shifts poleward when the clock angle is less than 10°. The further poleward displacement of the polar cap boundary on one oval side is caused by the twist of the tail plasma sheet, which is in accordance with the changing open field lines topology in the magnetotail.

scholarly journals Plasma depletion layer: its dependence on solar wind conditions and the Earth dipole tilt

2004 ◽  
Vol 22 (12) ◽  
pp. 4273-4290 ◽  
Author(s):  
Y. L. Wang ◽  
J. Raeder ◽  
C. T. Russell
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Outer Boundary ◽  
Strong Dependence ◽  
Depletion Layer ◽  
Slow Mode ◽  
The Earth ◽  
Plasma Depletion ◽  
Dipole Tilt ◽  
The Imf

Abstract. The plasma depletion layer (PDL) is a layer on the sunward side of the magnetopause with lower plasma density and higher magnetic field compared to their corresponding upstream magnetosheath values. It is believed that the PDL is controlled jointly by conditions in the solar wind plasma and the (IMF). In this study, we extend our former model PDL studies by systematically investigating the dependence of the PDL and the slow mode front on solar wind conditions using global MHD simulations. We first point out the difficulties for the depletion factor method and the plasma β method for defining the outer boundary of the plasma depletion layer. We propose to use the N/B ratio to define the PDL outer boundary, which can give the best description of flux tube depletion. We find a strong dependence of the magnetosheath environment on the solar wind magnetosonic Mach number. A difference between the stagnation point and the magnetopause derived from the open-closed magnetic field boundary is found. We also find a strong and complex dependence of the PDL and the slow mode front on the IMF Bz. A density structure right inside the subsolar magnetopause for higher IMF Bz;might be responsible for some of this dependence. Both the IMF tilt and clock angles are found to have little influence on the magnetosheath and the PDL structures. However, the IMF geometry has a much stronger influence on the slow mode fronts in the magnetosheath. Finally, the Earth dipole tilt is found to play a minor role for the magnetosheath geometry and the PDL along the Sun-Earth line. A complex slow mode front geometry is found for cases with different Earth dipole tilts. Comparisons between our results with those from some former studies are conducted, and consistencies and inconsistencies are found. Key words. Magnetospheric physics (magnetosheath, solar wind-magnetosphere interactions) – Space plasma physics (numerical simulation studies)

scholarly journals Energy Conversion and Electron Acceleration in the Magnetopause Reconnection Diffusion Region

2019 ◽  
Vol 46 (17-18) ◽  
pp. 10274-10282 ◽  
Author(s):  
K. R. Pritchard ◽  
J. L. Burch ◽  
S. A. Fuselier ◽  
J. M. Webster ◽  
R. B. Torbert ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Electron Acceleration ◽  
Diffusion Region ◽  
Magnetopause Reconnection

Magnetopause Reconnection as Influenced by the Dipole Tilt Under Southward IMF Conditions: Hybrid Simulation and MMS Observation

2020 ◽  
Vol 125 (9) ◽  
Author(s):  
Zhifang Guo ◽  
Yu Lin ◽  
Xueyi Wang ◽  
Sarah K. Vines ◽  
S. H. Lee ◽  
...  
Keyword(s):  
Hybrid Simulation ◽  
Dipole Tilt ◽  
Magnetopause Reconnection

Interhemispheric conjugacy of transpolar arcs

2020 ◽  
Author(s):  
Anita Kullen ◽  
Simon Thor ◽  
Lei Cai
Keyword(s):  
Solar Wind ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Observational Studies ◽  
The Earth ◽  
Time Period ◽  
Statistical Effect ◽  
Small Influence ◽  
Dipole Tilt ◽  
The Imf

<p>Most models predict that transpolar arcs (TPAs) occur simultaneously in both hemispheres. Conjugate TPAs are expected to appear in the northern and southern hemisphere on opposite oval sides. However, several observational studies have shown that this is not always the cases. It has been suggested that IMF Bx and/or the Earth dipole tilt may be responsible for non-conjugate TPAs. During strongly negative IMF Bx and/or positive Earth dipole tilt a TPA is expected to occur only in the northern hemisphere (for positive Bx and/or negative dipole tilt only in the southern hemisphere).</p><p>In the present work we revisit this question by investigating three previously published and one new TPA dataset regarding the influence of IMF Bx and Earth dipole tilt on interhemispheric TPA occurrence. The results show, the Earth dipole tilt has no statistical effect on TPA conjugacy while IMF Bx may have a small influence. However, this influence is much smaller than previously reported, when normalizing the IMF Bx distribution during TPAs with the average IMF Bx distribution in the solar wind during the time period covered by the respective dataset.</p><p>In the second part of this study we present results from the new TPA dataset, which is based on three months of SUSSI DMSP images. Arc location and IMF conditions during conjugate and non-conjugate TPAs are discussed in detail and possible reasons for non-conjugate TPA events are discussed.</p>

scholarly journals Motion of the dayside polar cap boundary during substorm cycles: I. Observations of pulses in the magnetopause reconnection rate

2005 ◽  
Vol 23 (11) ◽  
pp. 3495-3511 ◽  
Author(s):  
M. Lockwood ◽  
J. Moen ◽  
A. P. van Eyken ◽  
J. A. Davies ◽  
K. Oksavik ◽  
...  
Keyword(s):  
Field Line ◽  
Rate Variation ◽  
Closed Field ◽  
Reconnection Rate ◽  
Vhf Radar ◽  
Closed Field Line ◽  
Using Data ◽  
Open Flux ◽  
Magnetopause Reconnection ◽  
The Imf

Abstract. Using data from the EISCAT (European Incoherent Scatter) VHF radar and DMSP (Defense Meteorological Satellite Program) spacecraft passes, we study the motion of the dayside open-closed field line boundary during two substorm cycles. The satellite data show that the motions of ion and electron temperature boundaries in EISCAT data, as reported by Moen et al. (2004), are not localised around the radar; rather, they reflect motions of the open-closed field line boundary at all MLT throughout the dayside auroral ionosphere. The boundary is shown to erode equatorward when the IMF points southward, consistent with the effect of magnetopause reconnection. During the substorm expansion and recovery phases, the dayside boundary returns poleward, whether the IMF points northward or southward. However, the poleward retreat was much faster during the substorm for which the IMF had returned to northward than for the substorm for which the IMF remained southward - even though the former substorm is much the weaker of the two. These poleward retreats are consistent with the destruction of open flux at the tail current sheet. Application of a new analysis of the peak ion energies at the equatorward edge of the cleft/cusp/mantle dispersion seen by the DMSP satellites identifies the dayside reconnection merging gap to extend in MLT from about 9.5 to 15.5 h for most of the interval. Analysis of the boundary motion, and of the convection velocities seen near the boundary by EISCAT, allows calculation of the reconnection rate (mapped down to the ionosphere) from the flow component normal to the boundary in its own rest frame. This reconnection rate is not, in general, significantly different from zero before 06:45 UT (MLT<9.5 h) - indicating that the X line footprint expands over the EISCAT field-of-view to earlier MLT only occasionally and briefly. Between 06:45 UT and 12:45 UT (9.5<MLT<15.5 h) reconnection is continuously observed by EISCAT, confirming the (large) MLT extent of the reconnection footprint deduced from the DMSP passes. As well as direct control by the IMF on longer timescales, the derived reconnection rate variation shows considerable pulsing on timescales of 2-20 min during periods of steady southward IMF.

scholarly journals Dependence of the IMF sector structure on the solar dipole tilt angle

2008 ◽  
Vol 113 (A7) ◽  
pp. n/a-n/a ◽  
Author(s):  
A. M. Du ◽  
W. Y. Xu ◽  
X. S. Feng
Keyword(s):  
Tilt Angle ◽  
Sector Structure ◽  
Dipole Tilt ◽  
The Imf
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