scholarly journals On the longitudinal extent of magnetopause reconnection pulses

1996 ◽  
Vol 14 (9) ◽  
pp. 865-878 ◽  
Author(s):  
M. Lockwood ◽  
C. J. Davis
Keyword(s):  
Magnetic Reconnection ◽  
Local Time ◽  
Magnetic Local Time ◽  
Dispersion Characteristics ◽  
Low Latitude ◽  
Ion Injection ◽  
Reconnection Region ◽  
Transient Events ◽  
Magnetopause Reconnection

Abstract. The open magnetosphere model of cusp ion injection, acceleration and precipitation is used to predict the dispersion characteristics for fully pulsed magnetic reconnection at a low-latitude magnetopause X-line. The resulting steps, as would be seen by a satellite moving meridionally and normal to the ionospheric projection of the X-line, are compared with those seen by satellites moving longitudinally, along the open/closed boundary. It is shown that two observed cases can be explained by similar magnetosheath and reconnection characteristics, and that the major differences between them are well explained by the different satellite paths through the events. Both cases were observed in association with poleward-moving transient events seen by ground-based radar, as also predicted by the theory. The results show that the reconnection is pulsed but strongly imply it cannot also be spatially patchy, in the sense of isolated X-lines which independently are intermittently active. Furthermore they show that the reconnection pulses responsible for the poleward-moving events and the cusp ion steps, must cover at least 3 h of magnetic local time, although propagation of the active reconnection region may mean that it does not extend this far at any one instant of time.

scholarly journals Local time extent of magnetopause reconnection X-lines using space–ground coordination

2018 ◽  
Author(s):  
Ying Zou ◽  
Brian M. Walsh ◽  
Yukitoshi Nishimura ◽  
Vassilis Angelopoulos ◽  
J. Michael Ruohoniemi ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Field Line ◽  
Local Time ◽  
Closed Field ◽  
Lack Of Information ◽  
Closed Field Line ◽  
Reliable Interpretation ◽  
Magnetopause Reconnection

Abstract. Magnetic reconnection X-lines can vary considerably in length. At the Earth's magnetopause, the length generally corresponds to the extent in local time. The extent has been probed by multi-spacecraft crossing the magnetopause, but the estimates have large uncertainties because of the assumption of a continuous X-line between spacecraft and the lack of information beyond areas of spacecraft coverage. The extent has also been inferred by radars as fast ionospheric flows moving anti-sunward across the open-closed field line boundary, but whether a particular ionospheric flow results from reconnection needs to be confirmed. To achieve a reliable interpretation, we compare X-line extents probed by multi-spacecraft and radars for three conjunction events. We find that when reconnection is active at only one spacecraft, only the ionosphere conjugate to this spacecraft shows a channel of fast anti-sunward flow. When reconnection is active at two spacecraft and the spacecraft are separated by  10 Re) are possible forms of reconnection at the magnetopause. Interestingly, the extended reconnection develops from a localized patch via spreading across local time. Potential effects of IMF Bx and By on the X-line extent are discussed.

scholarly journals Simultaneous observations of fluctuating cusp aurora and low-latitude magnetopause reconnection

2007 ◽  
Vol 112 (A11) ◽  
pp. n/a-n/a ◽  
Author(s):  
S. A. Fuselier ◽  
S. M. Petrinec ◽  
K. J. Trattner ◽  
M. Fujimoto ◽  
H. Hasegawa
Keyword(s):  
Low Latitude ◽  
Magnetopause Reconnection

scholarly journals Electron flat-top distributions around the magnetic reconnection region

2008 ◽  
Vol 113 (A1) ◽  
pp. n/a-n/a ◽  
Author(s):  
Y. Asano ◽  
R. Nakamura ◽  
I. Shinohara ◽  
M. Fujimoto ◽  
T. Takada ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Reconnection Region

Suppression of Magnetic Reconnection at Saturn's Low‐Latitude Magnetopause

2020 ◽  
Vol 125 (5) ◽  
Author(s):  
S. A. Fuselier ◽  
S. M. Petrinec ◽  
R. P. Sawyer ◽  
J. Mukherjee ◽  
A. Masters
Keyword(s):  
Magnetic Reconnection ◽  
Low Latitude

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 A study of geomagnetic field variations along the 80° S geomagnetic parallel

2017 ◽  
Vol 35 (1) ◽  
pp. 139-146 ◽  
Author(s):  
Stefania Lepidi ◽  
Lili Cafarella ◽  
Patrizia Francia ◽  
Andrea Piancatelli ◽  
Manuela Pietrolungo ◽  
...  
Keyword(s):  
Local Time ◽  
Geomagnetic Field ◽  
Daily Variation ◽  
Low Frequency ◽  
Magnetic Local Time ◽  
The Other ◽  
Ionospheric Currents ◽  
Wave Propagation Direction ◽  
Predominant Effect ◽  
Local Noon

Abstract. The availability of measurements of the geomagnetic field variations in Antarctica at three sites along the 80° S geomagnetic parallel, separated by approximately 1 h in magnetic local time, allows us to study the longitudinal dependence of the observed variations. In particular, using 1 min data from Mario Zucchelli Station, Scott Base and Talos Dome, a temporary installation during 2007–2008 Antarctic campaign, we investigated the diurnal variation and the low-frequency fluctuations (approximately in the Pc5 range, ∼ 1–7 mHz). We found that the daily variation is clearly ordered by local time, suggesting a predominant effect of the polar extension of midlatitude ionospheric currents. On the other hand, the pulsation power is dependent on magnetic local time maximizing around magnetic local noon, when the stations are closer to the polar cusp, while the highest coherence between pairs of stations is observed in the magnetic local nighttime sector. The wave propagation direction observed during selected events, one around local magnetic noon and the other around local magnetic midnight, is consistent with a solar-wind-driven source in the daytime and with substorm-associated processes in the nighttime.

scholarly journals Comparison of the magnetic equivalent convection direction and ionospheric convection observed by the SuperDARN radars

2006 ◽  
Vol 24 (11) ◽  
pp. 2981-2990 ◽  
Author(s):  
L. V. Benkevitch ◽  
A. V. Koustov ◽  
J. Liang ◽  
J. F. Watermann
Keyword(s):  
Local Time ◽  
High Latitude ◽  
Early Morning ◽  
Auroral Oval ◽  
Magnetic Local Time ◽  
Ionospheric Convection ◽  
Morning Sector ◽  
Magnetometer Data ◽  
Different Seasons

Abstract. SuperDARN radar and high-latitude magnetometer observations are used to statistically investigate quality of the convection direction estimates from magnetometer data if assumption is made that the magnetic equivalent convection vector (MEC) corresponds to the convection direction. The statistics includes five full days, ~75 000 of joint individual measurements for different seasons. It is demonstrated that the best (worst) agreement between the MEC and ionospheric convection occurs for the sunlit, summer (dark, winter) ionosphere. Overall, the MEC direction is reasonable (deviates less than 45° from the SuperDARN direction) in at least ~55% of points and it is better for the latitudes of the auroral oval. In terms of the magnetic local time, the agreement is the best (worst) in the dusk (early morning) sector. Possible reasons for differences between the MEC and ionospheric convection directions are discussed.

scholarly journals Magnetic local time dependence of geomagnetic disturbances contributing to the AU and AL indices

2011 ◽  
Vol 29 (4) ◽  
pp. 673-678 ◽  
Author(s):  
S. Tomita ◽  
M. Nosé ◽  
T. Iyemori ◽  
H. Toh ◽  
M. Takeda ◽  
...  
Keyword(s):  
Local Time ◽  
Geomagnetic Field ◽  
Field Data ◽  
Geomagnetic Latitude ◽  
Magnetic Activity ◽  
Auroral Zone ◽  
Magnetic Local Time ◽  
Geomagnetic Disturbances ◽  
Current Systems ◽  
Local Time Dependence

Abstract. The Auroral Electrojet (AE) indices, which are composed of four indices (AU, AL, AE, and AO), are calculated from the geomagnetic field data obtained at 12 geomagnetic observatories that are located in geomagnetic latitude (GMLAT) of 61.7°–70°. The indices have been widely used to study magnetic activity in the auroral zone. In the present study, we examine magnetic local time (MLT) dependence of geomagnetic field variations contributing to the AU and AL indices. We use 1-min geomagnetic field data obtained in 2003. It is found that both AU and AL indices have two ranges of MLT (AU: 15:00–22:00 MLT, ~06:00 MLT; and AL: ~02:00 MLT, 09:00–12:00 MLT) contributing to the index during quiet periods and one MLT range (AU: 15:00–20:00 MLT, and AL: 00:00–06:00 MLT) during disturbed periods. These results are interpreted in terms of various ionospheric current systems, such as, Sqp, Sq, and DP2.

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