scholarly journals Detection of Hertz Frequency Multi‐Harmonic Field Line Resonances at Low‐L ( L =1.1 to 1.5) during Van Allen Probe Perigee Passes

2020 ◽  
Author(s):  
F. R. Lena ◽  
L. G. Ozeke ◽  
J. R. Wygant ◽  
S. Tian ◽  
A. W. Breneman ◽  
...  
Keyword(s):  
Field Line ◽  
Harmonic Field ◽  
Field Line Resonances

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

Fine structure in the spectra of low latitude field line resonances

1995 ◽  
Vol 22 (16) ◽  
pp. 2111-2114 ◽  
Author(s):  
J. C. Samson ◽  
C. L. Waters ◽  
F. W. Menk ◽  
B. J. Fraser
Keyword(s):  
Fine Structure ◽  
Field Line ◽  
Low Latitude ◽  
Field Line Resonances

scholarly journals Statistical study of geomagnetic field line resonances observed by CHAMP and on the ground

2013 ◽  
Vol 118 (5) ◽  
pp. 1934-1947 ◽  
Author(s):  
B. Heilig ◽  
P. R. Sutcliffe ◽  
D. C. Ndiitwani ◽  
A. B. Collier
Keyword(s):  
Field Line ◽  
Geomagnetic Field ◽  
Statistical Study ◽  
Geomagnetic Field Line ◽  
Field Line Resonances

Field-line resonances in a time-varying magnetosphere

2014 ◽  
Vol 64 (2) ◽  
pp. 249-253
Author(s):  
D. H. Lee ◽  
K. H. Kim ◽  
E. S. Lee ◽  
H. Jin ◽  
J. Seon
Keyword(s):  
Field Line ◽  
Time Varying ◽  
Field Line Resonances
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