scholarly journals Modeling the wave normal distribution of chorus waves

2013 ◽  
Vol 118 (3) ◽  
pp. 1074-1088 ◽  
Author(s):  
Lunjin Chen ◽  
Richard M. Thorne ◽  
Wen Li ◽  
Jacob Bortnik
Keyword(s):  
Normal Distribution ◽  
Chorus Waves ◽  
Wave Normal

Global distribution of wave amplitudes and wave normal angles of chorus waves using THEMIS wave observations

2011 ◽  
Vol 116 (A12) ◽  
pp. n/a-n/a ◽  
Author(s):  
W. Li ◽  
J. Bortnik ◽  
R. M. Thorne ◽  
V. Angelopoulos
Keyword(s):  
Global Distribution ◽  
Chorus Waves ◽  
Wave Normal

scholarly journals Electron Microbursts Induced by Nonducted Chorus Waves

2021 ◽  
Vol 8 ◽  
Author(s):  
Lunjin Chen ◽  
Xiao-Jia Zhang ◽  
Anton Artemyev ◽  
Liheng Zheng ◽  
Zhiyang Xia ◽  
...  
Keyword(s):  
Field Line ◽  
Particle Simulation ◽  
Electron Precipitation ◽  
Outer Radiation Belt ◽  
Energetic Electrons ◽  
Chorus Waves ◽  
Wave Normal ◽  
Intense Electron ◽  
The Magnetic Field ◽  
Normal Angle

Microbursts, short-lived but intense electron precipitation observed by low-Earth-orbiting satellites, may contribute significantly to the losses of energetic electrons in the outer radiation belt. Their origin is likely due to whistler mode chorus waves, as evidenced by a strong overlap in spatial correlation of the two. Despite previous efforts on modeling bursty electron precipitation induced by chorus waves, most, if not all, rely on the assumption that chorus waves are ducted along the field line with zero wave normal angle. Such ducting is limited to cases when fine-scale plasma density irregularities are present. In contrast, chorus waves propagate in a nonducted way in plasmas with smoothly varying density, allowing wave normals to gradually refract away from the magnetic field line. In this study, the interaction of ducted and nonducted chorus waves with energetic electrons is investigated using test particle simulation. Substantial differences in electron transport are found between the two different scenarios, and resultant electron precipitation patterns are compared. Such a comparison is valuable for interpreting low Earth-orbiting satellite observations of electron flux variation in response to the interaction with magnetospheric chorus waves.

scholarly journals Magnetospherically reflected chorus waves revealed by ray tracing with CLUSTER data

2003 ◽  
Vol 21 (5) ◽  
pp. 1111-1120 ◽  
Author(s):  
M. Parrot ◽  
O. Santolík ◽  
N. Cornilleau-Wehrlin ◽  
M. Maksimovic ◽  
C. Harvey
Keyword(s):  
Ray Tracing ◽  
Source Area ◽  
Lower Hybrid ◽  
Magnetospheric Physics ◽  
Lower Intensity ◽  
Spectral Matrix ◽  
Radio Science ◽  
Chorus Waves ◽  
Wave Normal ◽  
The Waves

Abstract. This paper is related to the propagation characteristics of a chorus emission recorded simultaneously by the 4 satellites of the CLUSTER mission on 29 October 2001 between 01:00 and 05:00 UT. During this day, the spacecraft (SC) 1, 2, and 4 are relatively close to each other but SC3 has been delayed by half an hour. We use the data recorded aboard CLUSTER by the STAFF spectrum analyser. This instrument provides the cross spectral matrix of three magnetic and two electric field components. Dedicated software processes this spectral matrix in order to determine the wave normal directions relative to the Earth’s magnetic field. This calculation is done for the 4 satellites at different times and different frequencies and allows us to check the directions of these waves. Measurements around the magnetic equator show that the parallel component of the Poynting vector changes its sign when the satellites cross the equator region. It indicates that the chorus waves propagate away from this region which is considered as the source area of these emissions. This is valid for the most intense waves observed on the magnetic and electric power spectrograms. But it is also observed on SC1, SC2, and SC4 that lower intensity waves propagate toward the equator simultaneously with the SC3 intense chorus waves propagating away from the equator. Both waves are at the same frequency. Using the wave normal directions of these waves, a ray tracing study shows that the waves observed by SC1, SC2, and SC4 cross the equatorial plane at the same location as the waves observed by SC3. SC3 which is 30 minutes late observes the waves that originate first from the equator; meanwhile, SC1, SC2, and SC4 observe the same waves that have suffered a Lower Hybrid Resonance (LHR) reflection at low altitudes (based on the ray tracing analysis) and now return to the equator at a different location with a lower intensity. Similar phenomenon is observed when all SC are on the other side of the equator. The intensity ratio between magnetic waves coming directly from the equator and waves returning to the equator is between 0.005 and 0.01, which is in agreement with previously published theoretical calculation of the growth rates with the particle distribution seen by GEOS.Key words. Magnetospheric physics (plasma waves and instabilities) – Ionosphere (wave propagation) – Radio science (magnetospheric physics)

scholarly journals Source location of chorus emissions observed by Cluster

2003 ◽  
Vol 21 (2) ◽  
pp. 473-480 ◽  
Author(s):  
M. Parrot ◽  
O. Santolík ◽  
N. Cornilleau-Wehrlin ◽  
M. Maksimovic ◽  
C. C. Harvey
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Waves ◽  
Plasma Waves ◽  
Magnetic Activity ◽  
Spectral Matrix ◽  
Chorus Waves ◽  
Storms And Substorms ◽  
Wave Normal ◽  
The Magnetic Field ◽  
Different Levels

Abstract. One of the objectives of the Cluster mission is to study sources of various electromagnetic waves using the four satellites. This paper describes the methods we have applied to data recorded from the STAFF spectrum analyser. This instrument provides the cross spectral matrix of three magnetic and two electric field components. This spectral matrix is analysed to determine, for each satellite, the direction of the wave normal relative to the Earth’s magnetic field as a function of frequency and of time. Due to the Cluster orbit, chorus emissions are often observed close to perigee, and the data analysis determines the direction of these waves. Three events observed during different levels of magnetic activity are reported. It is shown that the component of the Poynting vector parallel to the magnetic field changes its sense when the satellites cross the magnetic equator, which indicates that the chorus waves propagate away from the equator. Detailed analysis indicates that the source is located in close vicinity of the plane of the geomagnetic equator. Key words. Magnetospheric physics (plasma waves and instabilities; storms and substorms); Space plasma physics (waves and instabilities)

scholarly journals VLF emission triggering by a highly anisotropic energetic electron plasma

2003 ◽  
Vol 21 (2) ◽  
pp. 481-492 ◽  
Author(s):  
D. Nunn ◽  
A. Demekhov ◽  
V. Trakhtengerts ◽  
M. J. Rycroft
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Waves ◽  
Energetic Electron ◽  
Magnetic Activity ◽  
Spectral Matrix ◽  
Chorus Waves ◽  
Storms And Substorms ◽  
Wave Normal ◽  
The Magnetic Field ◽  
Different Levels

Abstract. One of the objectives of the Cluster mission is to study sources of various electromagnetic waves using the four satellites. This paper describes the methods we have applied to data recorded from the STAFF spectrum analyser. This instrument provides the cross spectral matrix of three magnetic and two electric field components. This spectral matrix is analysed to determine, for each satellite, the direction of the wave normal relative to the Earth’s magnetic field as a function of frequency and of time. Due to the Cluster orbit, chorus emissions are often observed close to perigee, and the data analysis determines the direction of these waves. Three events observed during different levels of magnetic activity are reported. It is shown that the component of the Poynting vector parallel to the magnetic field changes its sense when the satellites cross the magnetic equator, which indicates that the chorus waves propagate away from the equator. Detailed analysis indicates that the source is located in close vicinity of the plane of the geomagnetic equator. Key words. Magnetospheric physics (plasma waves and instabilities; storms and substorms); Space plasma physics (waves and instabilities)

scholarly journals Characteristics of magnetospherically reflected chorus waves observed by CLUSTER

2004 ◽  
Vol 22 (7) ◽  
pp. 2597-2606 ◽  
Author(s):  
M. Parrot ◽  
O. Santolík ◽  
D. A. Gurnett ◽  
J. S. Pickett ◽  
N. Cornilleau-Wehrlin
Keyword(s):  
Source Area ◽  
Propagation Characteristic ◽  
Degree Of Polarization ◽  
Lower Hybrid ◽  
Lower Intensity ◽  
Spectral Matrix ◽  
Chorus Waves ◽  
High Degree ◽  
Wave Normal ◽  
The Waves

Abstract. Chorus emissions are often observed by the STAFF spectrum analyser on board the 4 satellites of CLUSTER. This instrument provides the cross spectral matrix of three magnetic and two electric field components. Dedicated software processes this spectral matrix in order to determine the propagation characteristic of these chorus waves. Measurements of the parallel component of the Poynting vector around the magnetic equator indicate that the chorus waves propagate away from this region which is considered as the source area of these emissions. This is valid for the most intense waves observed on the magnetic and electric power spectrograms. But it has also been observed that lower intensity waves propagate toward the equator at the same frequency. Using the wave normal directions of these waves, a ray tracing study has shown that the waves have suffered a Lower Hybrid Resonance (LHR) reflection at low altitudes and now return to the equator at a different location with a lower intensity. The paper presents other similar events when WBD data are simultaneously recorded. The WBD experiment provides a much better time resolution and allows one to check the structure of the returning waves. It is observed that these waves have still a high degree of polarization, even if they started to lose the coherent structure of the chorus elements. They reach the equator with a small wave normal angle which is more efficient for a further amplification. It is explained that these emissions could be a source of hiss.

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