scholarly journals Observation of drift compressional waves with a mid-latitude decameter coherent radar

2016 ◽  
Vol 2 (2) ◽  
pp. 46-56 ◽  
Author(s):  
Максим Челпанов ◽  
Maksim Chelpanov ◽  
Павел Магер ◽  
Pavel Mager ◽  
Дмитрий Климушкин ◽  
...  
Keyword(s):  
Ionospheric Plasma ◽  
Wave Number ◽  
Frequency Increase ◽  
Compressional Waves ◽  
Absolute Value ◽  
Compressional Mode ◽  
Existence Conditions ◽  
Cross Wavelet Analysis ◽  
Coherent Radar ◽  
Cross Wavelet

Magnetospheric Pc5 pulsations observed on December 26, 2014 are analyzed. They were recorded in the nightside magnetosphere with a mid-latitude coherent decameter radar located near Ekaterinburg. It registers velocity variations in electric drift of ionospheric plasma caused by ULF waves in the magnetosphere. The westward direction of azimuthal propagation of wave coincides with the direction of magnetic drift of protons. A cross-wavelet analysis reveals that the frequency of oscillations depends on the wave number m, and the correlation between them is 0.90. The frequency increase from 2.5 to 5 mHz was followed by an increase in the absolute value m from 20 to 80. These features of the wave under study testify that it should be classified as a drift compressional mode which is typical for the ULF mode in kinetics. Existence conditions for it are the terminal pressure of plasma and its inhomogeneity across magnetic shells.

scholarly journals Wavelet analysis of the magnetotail response to solar wind fluctuations during HILDCAA events

2019 ◽  
Vol 37 (5) ◽  
pp. 919-929
Author(s):  
Adriane Marques de Souza Franco ◽  
Ezequiel Echer ◽  
Mauricio José Alves Bolzan
Keyword(s):  
Solar Wind ◽  
Wavelet Transform ◽  
Wavelet Analysis ◽  
Geomagnetic Field ◽  
Field Component ◽  
Long Duration ◽  
Analysis Technique ◽  
Spacecraft Mission ◽  
Cross Wavelet Analysis ◽  
Cross Wavelet

Abstract. In this work a study of the effects of the high-intensity long-duration continuous AE activity (HILDCAAs) events in the magnetotail was conducted. The aim of this study was to search the main frequencies during HILDCAAs in the Bx component of the geomagnetic field in the magnetotail, as well as the main frequencies, at which the magnetotail responds to the solar wind during these events. In order to conduct this analysis the wavelet transform was employed during nine HILDCAA events that coincided with Cluster spacecraft mission crossing through the tail of the magnetosphere from 2003 to 2007. The most energetic periods for each event were identified. It was found that 76 % of them have periods ≤4 h. With the aim to search the periods that have the highest correlation between the IMF Bz (OMNI) component and the Cluster Bx geomagnetic field component, the cross wavelet analysis technique was also used in this study. The majority of correlation periods between the Bz (IMF) and Bx component of the geomagnetic field observed also were ≤4 h, with 62.9 % of the periods. Thus the magnetotail responds stronger to IMF fluctuations during HILDCCAS at 2–4 h scales, which are typical substorm periods. The results obtained in this work show that these scales are the ones on which the coupling of energy is stronger, as well as the modulation of the magnetotail by the solar wind during HILDCAA events.

Study of Pc5 compressional waves by MMS observations

2021 ◽  
Author(s):  
Anmin Tian
Keyword(s):  
Wave Structure ◽  
Tetrahedral Configuration ◽  
Compressional Waves ◽  
Structure And Motion ◽  
Time Period ◽  
Spatial Coverage ◽  
Compressional Mode ◽  
Mirror Mode ◽  
Motion Characteristics ◽  
Magnetic Bottle

<p>Pc5 compressional waves are frequently observed in the outer magnetosphere with mirror mode features. Due to the limited spatial coverage of spacecraft, their overall structure is still poorly understood. In this work, the wave structure and motion characteristics are statistically investigated based on the MMS data from September to October 2015. During this time period, the apogees of the MMS spacecraft were located in the outer dusk magnetosphere, and the spacecraft has regular tetrahedral configuration that facilitates the application of multi-spacecraft analysis techniques. The magnetic trough boundaries are identified, and their normal direction, current density and velocity of these boundaries are calculated. We found that the magnetic trough has a magnetic bottle topology along the field line. In the r-a plane, the two boundaries has an open angle toward the radial direction.The boundaries mainly move sunward in the GSE XY plane with average speed of ~26km/s. The poloidal Alfven mode is found to be coupling with the compressional mode oscillation. It suggests that our observations could be explained by the theory of drift Alfven ballooning mirror instability.</p>

scholarly journals MULTIFRACTAL CROSS WAVELET ANALYSIS

Fractals ◽  
2017 ◽  
Vol 25 (06) ◽  
pp. 1750054 ◽  
Author(s):  
ZHI-QIANG JIANG ◽  
XING-LU GAO ◽  
WEI-XING ZHOU ◽  
H. EUGENE STANLEY
Keyword(s):  
Wavelet Analysis ◽  
Long Range ◽  
Cross Correlation ◽  
Multifractal Spectrum ◽  
Theoretical Formula ◽  
Cross Correlations ◽  
The Cross ◽  
Cross Wavelet Analysis ◽  
Multifractal Behavior ◽  
Cross Wavelet

Complex systems are composed of mutually interacting components and the output values of these components usually exhibit long-range cross-correlations. Using wavelet analysis, we propose a method of characterizing the joint multifractal nature of these long-range cross correlations, a method we call multifractal cross wavelet analysis (MFXWT). We assess the performance of the MFXWT method by performing extensive numerical experiments on the dual binomial measures with multifractal cross correlations and the bivariate fractional Brownian motions (bFBMs) with monofractal cross correlations. For binomial multifractal measures, we find the empirical joint multifractality of MFXWT to be in approximate agreement with the theoretical formula. For bFBMs, MFXWT may provide spurious multifractality because of the wide spanning range of the multifractal spectrum. We also apply the MFXWT method to stock market indices, and in pairs of index returns and volatilities we find an intriguing joint multifractal behavior. The tests on surrogate series also reveal that the cross correlation behavior, particularly the cross correlation with zero lag, is the main origin of cross multifractality.

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