Observations of field line resonances, auroral arcs, and auroral vortex structures

1996 ◽  
Vol 101 (A8) ◽  
pp. 17373-17383 ◽  
Author(s):  
J. C. Samson ◽  
L. L. Cogger ◽  
Q. Pao
Keyword(s):  
Field Line ◽  
Vortex Structures ◽  
Field Line Resonances ◽  
Auroral Arcs

scholarly journals Discrete Auroral Arcs and Nonlinear Dispersive Field Line Resonances

1999 ◽  
Vol 26 (6) ◽  
pp. 663-666 ◽  
Author(s):  
R. Rankin ◽  
J. C. Samson ◽  
V. T. Tikhonchuk
Keyword(s):  
Field Line ◽  
Field Line Resonances ◽  
Auroral Arcs

scholarly journals Poleward moving auroral arcs observed at the South Pole Station and the interpretation by field line resonances

2012 ◽  
Vol 117 (A9) ◽  
pp. n/a-n/a ◽  
Author(s):  
Y.-M. Tanaka ◽  
Y. Ebihara ◽  
S. Saita ◽  
A. Yoshikawa ◽  
Y. Obana ◽  
...  
Keyword(s):  
Field Line ◽  
South Pole ◽  
The South ◽  
Field Line Resonances ◽  
Auroral Arcs

scholarly journals Optical signatures of auroral arcs produced by field line resonances: comparison with satellite observations and modeling

2003 ◽  
Vol 21 (4) ◽  
pp. 933-945 ◽  
Author(s):  
J. C. Samson ◽  
R. Rankin ◽  
V. T. Tikhonchuk
Keyword(s):  
Phase Shift ◽  
Field Line ◽  
Electric Fields ◽  
Low Frequency ◽  
Optical Data ◽  
Field Line Resonance ◽  
Field Line Resonances ◽  
Line Resonance ◽  
Field Lines ◽  
Auroral Arcs

Abstract. We show two examples from the CANOPUS array of the optical signatures of auroral arcs produced by field line resonances on the night of 31 January 1997. The first example occurs during local evening at about 18:00 MLT (Magnetic Local Time), where CANOPUS meridian scanning photometer data show all the classic features of field line resonances. There are two, near-monochromatic resonances (at approximately 2.0 and 2.5 mHz) and both show latitudinal peaks in amplitude with an approximately 180 degree latitudinal phase shift across the maximum. The second field line resonance event occurs closer to local midnight, between approximately 22:00 and 22:40 MLT. Magnetometer and optical data show that the field line resonance has a very low frequency, near 1.3 mHz. All-sky imager data from CANOPUS show that in this event the field line resonances produce auroral arcs with westward propagation, with arc widths of about 10 km. Electron energies are on the order of 1 keV. This event was also seen in data from the FAST satellite (Lotko et al., 1998), and we compare our observations with those of Lotko et al. (1998). A remarkable feature of this field line resonance is that the latitudinal phase shift was substantially greater than 180 degrees. In our discussion, we present a model of field line resonances which accounts for the dominant physical effects and which is in good agreement with the observations. We emphasize three points. First, the low frequency of the field line resonance in the second event is likely due to the stretched topology of the magnetotail field lines, with the field line resonance on field lines threading the earthward edge of the plasma sheet. Second, the latitudinal phase structure may indicate dispersive effects due to electron trapping or finite ion gyroradius. Third, we show that a nonlocal conductivity model can easily explain the parallel electric fields and the precipitating electron energies seen in the field line resonance.Key words. Magnetospheric physics (electric fields; energetic particles precipitating; current systems)

scholarly journals A Statistical Survey of the 630.0-nm Optical Signature of Periodic Auroral Arcs Resulting From Magnetospheric Field Line Resonances

2018 ◽  
Vol 45 (10) ◽  
pp. 4648-4655 ◽  
Author(s):  
D. Megan Gillies ◽  
David Knudsen ◽  
Robert Rankin ◽  
Stephen Milan ◽  
Eric Donovan
Keyword(s):  
Field Line ◽  
Field Line Resonances ◽  
Optical Signature ◽  
Statistical Survey ◽  
Auroral Arcs ◽  
Magnetospheric Field

scholarly journals Pc5 modulation of high energy electron precipitation: particle interaction regions and scattering efficiency

2005 ◽  
Vol 23 (5) ◽  
pp. 1533-1542 ◽  
Author(s):  
E. Spanswick ◽  
E. Donovan ◽  
G. Baker
Keyword(s):  
Field Line ◽  
Electron Flux ◽  
High Energy ◽  
Energy Electron ◽  
Electron Precipitation ◽  
Necessary Condition ◽  
High Energy Electron ◽  
Magnetic Pulsation ◽  
Field Line Resonances ◽  
Morning Sector

Abstract. Using the NORSTAR riometer and CANOPUS magnetometer arrays we have investigated the modulation of high energy electron precipitation by ULF waves in the Pc5 frequency band. We conducted two separate studies of Pc5 activity in the riometers. The first is an independent survey of three riometer stations in the Churchill line (one at each sub-auroral, auroral, and typical polar cap boundary latitudes) in which we identified all riometer Pc5-band pulsations over 11 years. All had a corresponding magnetometer pulsation implying that a magnetic pulsation, is a necessary condition for a riometer pulsation (in the Pc5 Band). We find seasonal and latitude dependencies in the occurrence of riometer pulsations. By a factor of two, there are more riometer pulsations occurring in the fall-winter than the spring-summer. At higher latitudes there is a tendency towards noon pulsations during the spring-summer, suggesting that the criteria for riometer pulsations is affected by the dipole tilt. Our second study was based on the previous magnetometer study of Baker et al. (2003). Using the database of Pc5 activity from that study we were able to select the riometer Pc5 pulsations which adhere to the strict Pc5 definition in the magnetometer. We find that roughly 95% of the riometer pulsations occurred in the morning sector compared to 70% in the magnetometer. Given a magnetometer pulsation at Gillam in the morning sector, there is a 70% chance of there being a corresponding riometer pulsation. The morning sector probabilities at Rankin (geomagnetic (PACE) latitude 74°) and Pinawa (61°) are 3% and 5%, respectively. These statistics suggest there is a localized region in the pre-noon magnetosphere where Pc5 band ULF activity can modulate high energy electron precipitation. We also find that riometer pulsations display a Kp selection towards mid (i.e. 3–4) activity levels which mimics the product of the Kp dependence of high-energy electron fluxes on the dawn side (from CRRES) and all magnetic Pc5 activity. A superposed epoch analysis revealed that the elevated electron flux needed to produce a riometer pulsation is most likely provided by substorm injections on the nightside. We also find that the amplitude of modulated precipitation correlates well with the product of the background absorption and the magnetic pulsation amplitude, again leading to the idea that a riometer pulsation needs both favorable magnetospheric electron flux conditions and large enough magnetic Pc5 wave activity. We further separate our pulsations into field line resonances (FLRs), and non-field line resonances (non-FLRs), as identified in the Baker et al. (2003) survey. We find that FLRs are more efficient at modulating particle precipitation, and non-FLRs display an amplitude cutoff below which they do not interact with the high energy electron population. We conclude that the high energy electron precipitation associated with Pc5 pulsations is caused by pitch angle scattering (diffusion) rather than parallel acceleration. We suggest two future studies that are natural extensions of this one. Keywords. Energetic Particles/Precipitating; Wave-Particle Interactions; Auroral Phenomena

scholarly journals Field Line Resonances in Jupiter's Magnetosphere

2020 ◽  
Vol 47 (18) ◽  
Author(s):  
R. L. Lysak ◽  
Y. Song
Keyword(s):  
Field Line ◽  
Field Line Resonances
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