scholarly journals Substorm onset location and the equatorward boundary of the proton auroral oval

2002 ◽  
Vol 29 (24) ◽  
pp. 12-1-12-4 ◽  
Author(s):  
P. T. Jayachandran ◽  
J. W. MacDougall ◽  
D. R. Moorcroft ◽  
J.-P. St-Maurice ◽  
K. Liou ◽  
...  
Keyword(s):  
Auroral Oval ◽  
Substorm Onset ◽  
Equatorward Boundary ◽  
Onset Location

scholarly journals Correspondence between the ULF wave power spatial distribution and auroral oval boundaries

2016 ◽  
Vol 2 (2) ◽  
pp. 46-65 ◽  
Author(s):  
Ольга Козырева ◽  
Olga Kozyreva ◽  
Вячеслав Пилипенко ◽  
Vyacheslav Pilipenko ◽  
Марк Энгебретсон ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Spectral Power ◽  
Recovery Phase ◽  
Temporal Variations ◽  
Auroral Oval ◽  
Wave Power ◽  
Observational Result ◽  
Equatorward Boundary ◽  
Image Satellite ◽  
Magnetospheric Field

The world-wide spatial distribution of the wave power in the Pc5 band during magnetic storms has been compared with auroral oval boundaries. The poleward and equatorward auroral oval boundaries are estimated using either the British Antarctic Survey database containing IMAGE satellite UV observations of the aurora or the OVATION model based on the DMSP particle data. The “epicenter” of the spectral power of broadband Pc5 fluctuations during the storm growth phase is mapped inside the auroral oval. During the storm recovery phase, the spectral power of narrowband Pc5 waves, both in the dawn and dusk sectors, is mapped inside the auroral oval or around its equatorward boundary. This observational result confirms previously reported effects: the spatial/temporal variations of the Pc5 wave power in the morning/pre-noon sector are closely related to the dynamics of the auroral electrojet and magnetospheric field-aligned currents. At the same time, narrowband Pc5 waves demonstrate typical resonant features in the amplitude-phase latitudinal structure. Thus, the location of the auroral oval or its equatorward boundary is the preferred latitude for magnetospheric field-line Alfven resonator excitation. This effect is not taken into account by modern theories of ULF Pc5 waves, but it could be significant for the development of more adequate models.

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>

Testing Ionospheric influence on Substorm Onset Location

2021 ◽  
Author(s):  
Reham Elhawary ◽  
Karl Laundal ◽  
Jone Peter Reistad ◽  
Spencer Mark Hatch
Keyword(s):  
Substorm Onset ◽  
Onset Location

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.

scholarly journals Dayside cosmic noise absorption at the equatorward boundary of auroral oval as observed from Maitri, Antarctica ( L  = 5; CGM 62.45°S, 55.45°E)

2016 ◽  
Vol 121 (4) ◽  
pp. 3198-3211 ◽  
Author(s):  
Jayanta K. Behera ◽  
Ashwini K. Sinha ◽  
Geeta Vichare ◽  
Olga Kozyreva ◽  
Rahul Rawat ◽  
...  
Keyword(s):  
Auroral Oval ◽  
Noise Absorption ◽  
Equatorward Boundary ◽  
Cosmic Noise

scholarly journals Influences on the radius of the auroral oval

2009 ◽  
Vol 27 (7) ◽  
pp. 2913-2924 ◽  
Author(s):  
S. E. Milan ◽  
J. Hutchinson ◽  
P. D. Boakes ◽  
B. Hubert
Keyword(s):  
Solar Wind ◽  
Ring Current ◽  
Geomagnetic Storms ◽  
Auroral Oval ◽  
Substorm Onset ◽  
Polar Cap ◽  
H Index ◽  
Magnetic Perturbation

Abstract. We examine the variation in the radius of the auroral oval, as measured from auroral images gathered by the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft, in response to solar wind inputs measured by the Advanced Composition Explorer (ACE) spacecraft for the two year interval June 2000 to May 2002. Our main finding is that the oval radius increases when the ring current, as measured by the Sym-H index, is intensified during geomagnetic storms. We discuss our findings within the context of the expanding/contracting polar cap paradigm, in terms of a modification of substorm onset conditions by the magnetic perturbation associated with the ring current.

scholarly journals Identification of substorm onset location and preonset sequence using Reimei, THEMIS GBO, PFISR, and Geotail

2010 ◽  
Vol 115 (A12) ◽  
pp. n/a-n/a ◽  
Author(s):  
S. Zou ◽  
M. B. Moldwin ◽  
L. R. Lyons ◽  
Y. Nishimura ◽  
M. Hirahara ◽  
...  
Keyword(s):  
Substorm Onset ◽  
Onset Location

scholarly journals SuperDARN E-region backscatter boundary in the dusk-midnight sector – tracer of equatorward boundary of the auroral oval

2002 ◽  
Vol 20 (12) ◽  
pp. 1899-1904 ◽  
Author(s):  
P. T. Jayachandran ◽  
E. F. Donovan ◽  
J. W. MacDougall ◽  
D. R. Moorcroft ◽  
J.-P. St. Maurice ◽  
...  
Keyword(s):  
Energy Flux ◽  
Proton Energy ◽  
Auroral Oval ◽  
Ionospheric Irregularities ◽  
Auroral Ionosphere ◽  
Particle Precipitation ◽  
Equatorward Boundary ◽  
E Region ◽  
Proton Aurora

Abstract. We compare the locations of the equatorward boundaries of SuperDARN E-region backscatter and Hb  emissions, focusing on the dusk-midnight sector of the auroral oval where the proton aurora is statistically located equatorward of the discrete electron aurora. We show that, whenever both boundaries can be simultaneously identified, they are coincident. Our result complements earlier studies, which demonstrated the correspondence between the DMSP b2i boundary and both the equatorward boundary of the proton auroral oval (Donovan et al., 2002), and the equatorward boundary of SuperDARN E-region echoes (Jayachandran et al., 2002). Further, our result shows that, provided there is sufficient precipitating proton energy flux, the SuperDARN radars can be used to monitor the equatorward edge of the proton auroral oval.Key words. Ionosphere (auroral ionosphere; particle precipitation; ionospheric irregularities)

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