scholarly journals Observations of magnetic field dipolarization during auroral substorm onset

2000 ◽  
Vol 105 (A7) ◽  
pp. 15897-15912 ◽  
Author(s):  
L. A. Frank ◽  
W. R. Paterson ◽  
J. B. Sigwarth ◽  
S. Kokubun
Keyword(s):  
Magnetic Field ◽  
Substorm Onset ◽  
Auroral Substorm

scholarly journals Distinction between auroral substorm onset and traditional ground magnetic onset signatures

2013 ◽  
Vol 118 (7) ◽  
pp. 4080-4092 ◽  
Author(s):  
L. R. Lyons ◽  
Y. Nishimura ◽  
E. Donovan ◽  
V. Angelopoulos
Keyword(s):  
Substorm Onset ◽  
Auroral Substorm ◽  
Ground Magnetic

scholarly journals Simultaneous observation of auroral substorm onset in Polar satellite global images and ground-based all-sky images

2018 ◽  
Vol 70 (1) ◽  
Author(s):  
Akimasa Ieda ◽  
Kirsti Kauristie ◽  
Yukitoshi Nishimura ◽  
Yukinaga Miyashita ◽  
Harald U. Frey ◽  
...  
Keyword(s):  
Substorm Onset ◽  
Simultaneous Observation ◽  
Auroral Substorm ◽  
Polar Satellite

Parameters controlling the substorm onset location

2021 ◽  
Author(s):  
Reham Elhawary ◽  
Karl Laundal ◽  
Jone Reistad ◽  
Anders Ohma ◽  
Spencer Hatch ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Tilt Angle ◽  
Linear Regression Analysis ◽  
Substorm Onset ◽  
Azimuthal Component ◽  
Field Orientation ◽  
Hall Conductance ◽  
Onset Location ◽  
Dipole Tilt

<p>Substorm onset location varies over a range of magnetic local time (MLT) and magnetic latitudes (MLat). It is well known that about 5% of the variation in onset MLT can be explained by variations in interplanetary magnetic field orientation and dipole tilt angle. Both parameters introduce an azimuthal component in the magnetic field in the magnetosphere such that the projection of the onset MLT in the ionosphere is shifted. The MLT of the onset near the magnetopsheric equatorial plane is even less predictable. Recent studies have suggested that gradients in the ionospheric Hall conductance lead to a duskward shift of tail dynamics, which could also influence the location of substorm onset. Our goal is to test these ideas by quantifying the dependence of the spatial variation of the onset location on external and internal conditions. We focus on the correlation between the substorm onset location with conditions prior to the onset, such as the interplanetary magnetic field By component, dipole tilt angle, and estimates of the Hall conductance. Linear regression analysis is used to determine the substorm onset location dependence on the proposed variables.</p>

scholarly journals Correction to: Simultaneous observation of auroral substorm onset in Polar satellite global images and ground-based all-sky images

2019 ◽  
Vol 71 (1) ◽  
Author(s):  
Akimasa Ieda ◽  
Kirsti Kauristie ◽  
Yukitoshi Nishimura ◽  
Yukinaga Miyashita ◽  
Harald U. Frey ◽  
...  
Keyword(s):  
Substorm Onset ◽  
Simultaneous Observation ◽  
Auroral Substorm ◽  
Polar Satellite

scholarly journals Interhemispheric comparison of average substorm onset locations: evidence for deviation from conjugacy

2007 ◽  
Vol 25 (4) ◽  
pp. 989-999 ◽  
Author(s):  
H. Wang ◽  
H. Lühr ◽  
S. Y. Ma ◽  
H. U. Frey
Keyword(s):  
Magnetic Field ◽  
Significant Influence ◽  
Solar Zenith Angle ◽  
Statistical Study ◽  
Substorm Onset ◽  
Seasonal Effects ◽  
Linear Relationships ◽  
Substorm Onsets ◽  
Relationship Of ◽  
The Relationship

Abstract. Based on 2760 well-defined substorm onsets in the Northern Hemisphere and 1432 in the Southern Hemisphere observed by the FUV Imager on board the IMAGE spacecraft, a detailed statistical study is performed including both auroral regions. This study focuses on the hemispheric comparisons. Southward pointing interplanetary magnetic field (IMF) is favorable for substorm to occur, but still 30% of the events are preceded by northward IMF. The magnetic latitude (MLat) of substorm onset depends mainly on the merging electric field (Em) with a relationship of |dMLat|= −5.2 Em0.5, where dMLat is the deviation from onset MLat. In addition, seasonal effects on onset MLat are also detected, with about 2 degrees higher latitudes during solstices than equinoxes. Both IMF By and solar illumination have a significant influence on the magnetic local time (MLT) of onsets. An average relation, dMLT=0.25 By between IMF By and the deviation from onset MLT, was found. The By dependence varies slightly with the onset latitude. At lower latitudes (higher activity) it is reduced. After removal of the relationship with IMF By a linear relationships remains between the solar zenith angle and onset MLT with dMLT=1 min/deg. Therefore, both solar illumination and IMF By can contribute to hemispheric longitudinal displacements of substorm onset locations from conjugacy. No indications for systematic latitudinal displacements between the hemispheres have been found.

scholarly journals Substorm onset location and dipole tilt angle

2006 ◽  
Vol 24 (2) ◽  
pp. 577-588 ◽  
Author(s):  
J. Wanliss
Keyword(s):  
Magnetic Field ◽  
Tilt Angle ◽  
Source Region ◽  
Radial Distance ◽  
Substorm Onset ◽  
Magnetospheric Substorms ◽  
Data Set ◽  
Current Disruption ◽  
Onset Location ◽  
Dipole Tilt

Abstract. From an initial data set of over 200 substorms we have studied a subset of 30 magnetospheric substorms close to magnetic midnight to investigate, in a statistical fashion, the source region of the auroral arc that brightens at the onset of expansive phase. This arc is usually identified as the ionospheric signature of the expansive phase onset that occurs in the magnetotail. All the substorm onsets were identified via ground-based magnetometer and photometer data from the CANOPUS array. Various Tsyganenko global magnetic field models were used to map magnetic field lines from the location of the onset arc out to its greatest radial distance in the magnetotail. The results appear to favour the current disruption model of substorms since the average onset location has an average of 14.1 Earth radii (RE) and is therefore more consistent with theories that place the onset location in the inner magnetotail. For the narrow range of tilts available our modeling indicates the parameter that appears to strongly influence the location of the substorm onset is the dipole tilt angle; as tilt becomes less negative onsets occur further downtail.

Observation of IMF and seasonal effects in the location of auroral substorm onset

2001 ◽  
Vol 106 (A4) ◽  
pp. 5799-5810 ◽  
Author(s):  
K. Liou ◽  
P. T. Newell ◽  
D. G. Sibeck ◽  
C.-I Meng ◽  
M. Brittnacher ◽  
...  
Keyword(s):  
Substorm Onset ◽  
Seasonal Effects ◽  
Auroral Substorm

Interhemispherical asymmetry of substorm onset locations and the interplanetary magnetic field

2011 ◽  
Vol 38 (8) ◽  
pp. n/a-n/a ◽  
Author(s):  
N. Østgaard ◽  
K. M. Laundal ◽  
L. Juusola ◽  
A. Åsnes ◽  
S. E. Håland ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Substorm Onset

Relation of auroral substorm onset to local AL index and dispersionless particle injections

2008 ◽  
Vol 70 (18) ◽  
pp. 2336-2345 ◽  
Author(s):  
James M. Weygand ◽  
R.L McPherron ◽  
K. Kauristie ◽  
H.U. Frey ◽  
T.-S. Hsu
Keyword(s):  
Substorm Onset ◽  
Auroral Substorm
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