scholarly journals Relationship between low-frequency electric-field fluctuations and ion conics around the cusp/cleft region

2006 ◽  
Vol 24 (2) ◽  
pp. 667-677
Author(s):  
W. Miyake ◽  
A. Matsuoka ◽  
T. Mukai
Keyword(s):  
Electric Field ◽  
Low Frequency ◽  
Low Energy ◽  
Integration Time ◽  
Field Fluctuations ◽  
The Difference ◽  
Field Lines ◽  
Local Intensity ◽  
The Relationship ◽  
Ion Conics

Abstract. We investigated the relationship between low-frequency (0.2-4.0 Hz) electric-field fluctuations (LEFs) and ion conics around the dayside cusp/cleft region in the altitude range from 5000 to 10000km from observations made by the Akebono satellite. Ion conics were generally associated with intense LEFs. We found a significant correlation between the power spectral density of LEFs at any frequency and the energy of simultaneously observed ion conics. Ion conics with a conic angle near 90 deg and those more aligned with magnetic field lines both had an equivalent correlation with the local intensity of the LEFs. The LEFs associated with near-perpendicular ion conics were, however, generally more intense than those associated with folded conics. The difference was clearer for low-energy conics. These results are in agreement with a scenario of height-integrated heating of ions and energization of ions by electromagnetic energy supplied by local LEFs. Ions generally stay in the energization region during their upward motion along the field line, so that more folded ion conics with weak energization reach the same energy level as near-perpendicular conics with strong energization, due to the difference in integration time. The limit on residence time in the intense heating region causes the clearer difference for low-energy conics. We set up a simple model to examine the relationship between the energization rate and the evolution of ion conics along the field lines, and obtained good agreement with the observation results.

A review of the October 21, 1989 red aurora seen in Japan and from the AKEBONO (EXOS-D) satellite

1992 ◽  
Vol 70 (7) ◽  
pp. 488-499 ◽  
Author(s):  
T. Oguti
Keyword(s):  
Electric Field ◽  
Magnetic Storm ◽  
Auroral Oval ◽  
Low Latitude ◽  
Terrestrial Environment ◽  
Acceleration Mechanism ◽  
Auroral Substorm ◽  
Field Fluctuations ◽  
The Difference ◽  
Auroral Expansion

Observations of the October 21, 1989 red aurora from the ground and AKEBONO satellite are reviewed mainly on the topics presented at the workshop on the aurora, held in Solar Terrestrial Environment Laboratory on January 17–18, 1991. Electric-field fluctuations associated with the auroral oval during the observation, together with auroral green-rayed structures embedded in the red veil strongly suggest that some electron acceleration mechanism was operative in the particle precipitation. Therefore this was not a typical stable auroral red (SAR) arc. This red aurora was most likely located at a low-latitude portion of an expansion aurora during an auroral substorm. The geomagnetic conditions at the time of the aurora were quite similar to those during the occurrence of a SAR arc. It occurred during a susbtorm that broke out at the maximum Dst (disturbance with storm time) phase of a magnetic storm, with an auroral expansion initiated from low latitude on a well-expanded auroral oval. The difference in conditions between a typical SAR arc and this red aurora with green-ray structures is to be studied further.

scholarly journals <i>Letter to the Editor</i> Low-frequency electric field fluctuations and field-aligned electron beams around the edge of an auroral acceleration region

2001 ◽  
Vol 19 (3) ◽  
pp. 389-393 ◽  
Author(s):  
W. Miyake ◽  
R. Yoshioka ◽  
A. Matsuoka ◽  
T. Mukai ◽  
T. Nagatsuma
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Electron Beams ◽  
Low Frequency ◽  
Static Field ◽  
Acceleration Region ◽  
Auroral Acceleration Region ◽  
Field Fluctuations ◽  
Current Region ◽  
Frequency Electric Field

Abstract. Electron beams narrowly collimated to the magnetic field line were observed continuously from a down-ward current region to an auroral acceleration region (i.e., upward current region). They were well correlated with low-frequency electric field fluctuations in the auroral acceleration region as well as in the adjacent downward current region. Magnetic field fluctuations were found only in the downward current region. The analysis suggests that static field-aligned electric fields are not fully responsible for the filed-aligned electron acceleration; the ac electric field, presumably associated with Alfvenic fluctuations, should also be involved in the acceleration of ionospheric electrons.Key words. Ionosphere (particle acceleration) – Magnetospheric physics (auroral phenomena; magnetosphere-ionosphere interactions)

Low-frequency electric field fluctuations excited by ring current protons

1996 ◽  
Vol 74 (3) ◽  
pp. 231-242
Author(s):  
S. V. Singh ◽  
G. S. Lakhina ◽  
R. Bharuthram
Keyword(s):  
Electric Field ◽  
Ring Current ◽  
Low Frequency ◽  
Field Fluctuations ◽  
Frequency Electric Field

On the upward acceleration of electrons and ions by low-frequency electric field fluctuations observed by Viking

1991 ◽  
Vol 96 (A7) ◽  
pp. 11609 ◽  
Author(s):  
Bengt Hultqvist ◽  
Hien Vo ◽  
Rickard Lundin ◽  
Bruno Aparicio ◽  
Per-Arne Lindqvist ◽  
...  
Keyword(s):  
Electric Field ◽  
Low Frequency ◽  
Electrons And Ions ◽  
Field Fluctuations ◽  
Frequency Electric Field

scholarly journals Alfvén waves in the near-PSBL lobe: Cluster observations

2006 ◽  
Vol 24 (3) ◽  
pp. 1001-1013 ◽  
Author(s):  
T. Takada ◽  
R. Nakamura ◽  
W. Baumjohann ◽  
K. Seki ◽  
Z. Vörös ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Ion Beam ◽  
Low Frequency ◽  
Poynting Flux ◽  
Field Fluctuations ◽  
The Rich ◽  
Field Lines ◽  
The Waves ◽  
The Magnetic Field ◽  
Low Frequency Waves

Abstract. Electromagnetic low-frequency waves in the magnetotail lobe close to the PSBL (Plasma Sheet Boundary Layer) are studied using the Cluster spacecraft. The lobe waves show Alfvénic properties and transport their wave energy (Poynting flux) on average toward the Earth along magnetic field lines. Most of the wave events are rich with oxygen (O+) ion plasma. The rich O+ plasma can serve to enhance the magnetic field fluctuations, resulting in a greater likelihood of observation, but it does not appear to be necessary for the generation of the waves. Taking into account the fact that all events are associated with auroral electrojet enhancements, the source of the lobe waves might be a substorm-associated instability, i.e. some instability near the reconnection site, or an ion beam-related instability in the PSBL.

Comparison of the low-frequency variations of the vertical and horizontal components of the electric background field at the sea bottom

Geophysics ◽  
2012 ◽  
Vol 77 (6) ◽  
pp. E391-E396 ◽  
Author(s):  
Eirik G. Flekkøy ◽  
Endre Håland ◽  
Knut Jørgen Måløy
Keyword(s):  
Electric Field ◽  
Power Spectra ◽  
Low Frequency ◽  
Background Field ◽  
Sea Bottom ◽  
Vertical Electric Field ◽  
The Difference ◽  
Natural Electric Field ◽  
Frequency Variations ◽  
Averaging Techniques

Natural electric field variations are measured at the sea bottom over long periods of time by means of stationary, vertical, and horizontal galvanic antennas. We compare the power spectra of the vertical and horizontal field components and the extent to which they may be reduced by standard averaging techniques. Although the raw spectra of the vertical and horizontal components do not differ greatly, the difference in the spectra after averaging is significantly greater. Most significantly, in the frequency range between 0.0005 and 0.03 Hz, this averaging scheme suppresses the vertical electric field component more strongly than the horizontal component.

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