Possible solar cycle dependence of hydromagnetic waves in the earth's magnetosphere

1991 ◽  
Vol 39 (6) ◽  
pp. 879-883 ◽  
Author(s):  
L.J. Lanzerotti
Keyword(s):  
Solar Cycle ◽  
Earth’S Magnetosphere ◽  
Earth's Magnetosphere ◽  
Hydromagnetic Waves ◽  
Cycle Dependence

Influence of seasonal changes on the mid-latitude trough properties

2020 ◽  
Author(s):  
Barbara Matyjasiak ◽  
Dorota Przepiórka ◽  
Hanna Rothkaehl
Keyword(s):  
Solar Cycle ◽  
Coordinate System ◽  
Seasonal Changes ◽  
Time Of Day ◽  
Auroral Region ◽  
Earth’S Magnetosphere ◽  
Annual Variations ◽  
Earth’S Atmosphere ◽  
Main Ionospheric Trough ◽  
Earth's Magnetosphere

<pre>The sub-auroral region of the main ionospheric trough is a very unique area strongly affected by different type of instabilities coming from both the bottom (Earth's atmosphere) and the top (Earth's magnetosphere) neighbouring regions. The main ionospheric trough’s general characteristics as well as the detailed features change accordingly to the time of day, season, solar cycle and many others. The location of MIT in the latitude-longitude coordinate system throughout the year reflects seasonal changes. Annual variations are observed also in the shape and intensity of the structure. Despite the representation of the structure in the geomagnetic coordinate system, northern and southern trough are not symmetric in the same local season. However some similarities have also been observed. In particular for both hemispheres the structure appears the deepest and well developed during local winter, whereas during local summer the structure becomes hardly visible. Observations show that the MIT tends to shift equatorward for some longitudes in both hemispheres. MIT properties for this study have been derived from DEMETER and COSMIC/FORMOSAT-3 observations.</pre> <p> </p>

scholarly journals Hydromagnetic waves in a compressed-dipole field via field-aligned Klein–Gordon equations

2016 ◽  
Vol 34 (4) ◽  
pp. 473-484 ◽  
Author(s):  
Jinlei Zheng ◽  
Qiang Hu ◽  
Gary M. Webb ◽  
James F. McKenzie
Keyword(s):  
Magnetic Field ◽  
Amplitude Ratio ◽  
Low Frequency ◽  
Alfven Wave ◽  
Earth’S Magnetosphere ◽  
Background Magnetic Field ◽  
Earth's Magnetosphere ◽  
Klein Gordon ◽  
Field Lines ◽  
Hydromagnetic Waves

Abstract. Hydromagnetic waves, especially those of frequencies in the range of a few millihertz to a few hertz observed in the Earth's magnetosphere, are categorized as ultra low-frequency (ULF) waves or pulsations. They have been extensively studied due to their importance in the interaction with radiation belt particles and in probing the structures of the magnetosphere. We developed an approach to examining the toroidal standing Aflvén waves in a background magnetic field by recasting the wave equation into a Klein–Gordon (KG) form along individual field lines. The eigenvalue solutions to the system are characteristic of a propagation type when the corresponding eigenfrequency is greater than a critical frequency and a decaying type otherwise. We apply the approach to a compressed-dipole magnetic field model of the inner magnetosphere and obtain the spatial profiles of relevant parameters and the spatial wave forms of harmonic oscillations. We further extend the approach to poloidal-mode standing Alfvén waves along field lines. In particular, we present a quantitative comparison with a recent spacecraft observation of a poloidal standing Alfvén wave in the Earth's magnetosphere. Our analysis based on the KG equation yields consistent results which agree with the spacecraft measurements of the wave period and the amplitude ratio between the magnetic field and electric field perturbations.

scholarly journals Current Systems in the Earth's Magnetosphere

2018 ◽  
Vol 56 (2) ◽  
pp. 309-332 ◽  
Author(s):  
N. Yu. Ganushkina ◽  
M. W. Liemohn ◽  
S. Dubyagin
Keyword(s):  
Earth’S Magnetosphere ◽  
Earth's Magnetosphere ◽  
Current Systems
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