scholarly journals Causality and Information Transfer Between the Solar Wind and the Magnetosphere–Ionosphere System

Entropy ◽  
2021 ◽  
Vol 23 (4) ◽  
pp. 390
Author(s):  
Pouya Manshour ◽  
Georgios Balasis ◽  
Giuseppe Consolini ◽  
Constantinos Papadimitriou ◽  
Milan Paluš
Keyword(s):  
Solar Wind ◽  
Information Transfer ◽  
Linear Time ◽  
Vertical Component ◽  
Causal Link ◽  
Theoretic Approach ◽  
Geomagnetic Disturbances ◽  
Magnetospheric Substorms ◽  
Solar Wind Parameters ◽  
Information Theoretic Approach

An information-theoretic approach for detecting causality and information transfer is used to identify interactions of solar activity and interplanetary medium conditions with the Earth’s magnetosphere–ionosphere systems. A causal information transfer from the solar wind parameters to geomagnetic indices is detected. The vertical component of the interplanetary magnetic field (Bz) influences the auroral electrojet (AE) index with an information transfer delay of 10 min and the geomagnetic disturbances at mid-latitudes measured by the symmetric field in the H component (SYM-H) index with a delay of about 30 min. Using a properly conditioned causality measure, no causal link between AE and SYM-H, or between magnetospheric substorms and magnetic storms can be detected. The observed causal relations can be described as linear time-delayed information transfer.

Magnetic Reconnection in the Earth's Magnetotail

1985 ◽  
Vol 38 (6) ◽  
pp. 981 ◽  
Author(s):  
Edward W Hones Jr
Keyword(s):  
Solar Wind ◽  
Magnetic Reconnection ◽  
Plasma Sheet ◽  
Solar Flares ◽  
Reasonable Doubt ◽  
Physical Processes ◽  
Geomagnetic Disturbances ◽  
Magnetospheric Substorms ◽  
The Past ◽  
Fundamental Physical

Over the past few years satellite observations of the plasma sheet in the Earth's magnetotail during magnetospheric substorms have established beyond reasonable doubt that magnetic reconnection occurs in the magnetotail and that it plays a central role in the substorm process. The features seen at Earth by which substorms were originally identified (e.g. the auroras and geomagnetic disturbances) are simply superficial manifestations of a more fundamental physical process-the magnetosphere divesting itself of stored energy and plasma that was acquired earlier from the solar wind. It does so by shedding a part of its plasma sheet. This is accomplished by magnetic reconnection near the Earth that severs the plasma sheet, forming a plasmoid that flows out of the tail and that is lost to the solar wind. Recognition of the existence of plasmoids and our developing understanding of them have been important elements in confirming the occurrence of reconnection in the magnetosphere. In an analogous way, the best evidence for the occurrence of reconnection on the Sun has come from observations of closed magnetic configurations (plasmoids) in the solar wind and in the corona. But while magnetic reconnection is certainly the key ingredient in solar flares and substorms, analogies between them should not be carried too far, because there are basic differences in the environments in which they prevail and in the physical procesSes that lead to their occurrence.

scholarly journals Anomalous Forbush effects from sources far from Sun center

2008 ◽  
Vol 4 (S257) ◽  
pp. 451-456
Author(s):  
E. Eroshenko ◽  
A. Belov ◽  
H. Mavromichalaki ◽  
V. Oleneva ◽  
A. Papaioannou ◽  
...  
Keyword(s):  
Solar Wind ◽  
Cosmic Ray ◽  
The Sun ◽  
Geomagnetic Disturbances ◽  
Cosmic Ray Intensity ◽  
The Earth ◽  
The Common ◽  
Solar Wind Parameters ◽  
Significant Disturbance ◽  
Forbush Effect

AbstractThe Forbush effects associated with far western and eastern powerful sources on the Sun that occurred on the background of unsettled and moderate interplanetary and geomagnetic disturbances have been studied by data from neutron monitor networks and relevant measurements of the solar wind parameters. These Forbush effects may be referred to a special sub-class of events, with the characteristics like the event in July 2005, and incorporated by the common conditions: absence of a significant disturbance in the Earth vicinity; absence of a strong geomagnetic storm; slow decrease of cosmic ray intensity during the main phase of the Forbush effect. General features and separate properties in behavior of density and anisotropy of 10 GV cosmic rays for this subclass are investigated.

An information-theoretic approach to study fluid–structure interactions

2018 ◽  
Vol 848 ◽  
pp. 968-986 ◽  
Author(s):  
Peng Zhang ◽  
Maxwell Rosen ◽  
Sean D. Peterson ◽  
Maurizio Porfiri
Keyword(s):  
Information Transfer ◽  
Transfer Entropy ◽  
The Other ◽  
Theoretic Approach ◽  
Fluid Structure Interactions ◽  
Fluid Medium ◽  
Fluid Structure ◽  
Information Theoretic ◽  
Model Free ◽  
Information Theoretic Approach

The question of causality is pervasive to fluid–structure interactions, where it finds its most alluring instance in the study of fish swimming in coordination. How and why fish align their bodies, synchronize their motion, and position in crystallized formations are yet to be fully understood. Here, we posit a model-free approach to infer causality in fluid–structure interactions through the information-theoretic notion of transfer entropy. Given two dynamical units, transfer entropy quantifies the reduction of uncertainty in predicting the future state of one of them due to additional knowledge about the past of the other. We demonstrate our approach on a system of two tandem airfoils in a uniform flow, where the pitch angle of one airfoil is actively controlled while the other is allowed to passively rotate. Through transfer entropy, we seek to unveil causal relationships between the airfoils from information transfer conducted by the fluid medium.

scholarly journals The effect of nonlinear ionospheric conductivity enhancement on magnetospheric substorms

2013 ◽  
Vol 20 (3) ◽  
pp. 429-435 ◽  
Author(s):  
E. Spencer ◽  
S. Patra
Keyword(s):  
Solar Wind ◽  
Onset Time ◽  
Recovery Phase ◽  
Model Parameters ◽  
Magnetospheric Substorms ◽  
Ionospheric Conductivity ◽  
Conductivity Enhancement ◽  
Solar Wind Parameters ◽  
Enhanced Conductivity

Abstract. We introduce the effect of enhanced ionospheric conductivity into a low-order, physics-based nonlinear model of the nightside magnetosphere called WINDMI. The model uses solar wind and interplanetary magnetic field (IMF) parameters from the ACE satellite located at the L1 point to predict substorm growth, onset, expansion and recovery measured by the AL index roughly 50–60 min in advance. The dynamics introduced by the conductivity enhancement into the model behavior is described, and illustrated through using synthetically constructed solar wind parameters as input. We use the new model to analyze two well-documented isolated substorms: one that occurred on 31 July 1997 from Aksnes et al. (2002), and another on 13 April 2000 from Huang et al. (2004). These two substorms have a common feature in that the solar wind driver sharply decreases in the early part of the recovery phase, and that neither of them are triggered by northward turning of the IMF Bz. By controlling the model parameters such that the onset time of the substorm is closely adhered to, the westward auroral electrojet peaks during substorm expansion are qualitatively reproduced. Furthermore, the electrojet recovers more slowly with enhanced conductivity playing a role, which explains the data more accurately.

scholarly journals Variation of Solar Wind Parameters Along With the Understanding of Energy Dynamics Within the Magnetospheric System During Geomagnetic Disturbances

2019 ◽  
Vol 6 (2) ◽  
pp. 276-293
Author(s):  
Prashant Poudel ◽  
Sunil Simkhada ◽  
Binod Adhikari ◽  
Deepak Sharma ◽  
Jeevan Jyoti Nakarmi
Keyword(s):  
Solar Wind ◽  
Geomagnetic Disturbances ◽  
Energy Dynamics ◽  
Solar Wind Parameters

scholarly journals Cross-Scale Causality and Information Transfer in Simulated Epileptic Seizures

Entropy ◽  
2021 ◽  
Vol 23 (5) ◽  
pp. 526
Author(s):  
Kajari Gupta ◽  
Milan Paluš
Keyword(s):  
Time Series ◽  
Wavelet Transform ◽  
Time Scales ◽  
Information Transfer ◽  
Epileptic Seizures ◽  
Surrogate Data ◽  
Theoretic Approach ◽  
Phase Amplitude ◽  
Information Theoretic Approach ◽  
Different Time Scales

An information-theoretic approach for detecting causality and information transfer was applied to phases and amplitudes of oscillatory components related to different time scales and obtained using the wavelet transform from a time series generated by the Epileptor model. Three main time scales and their causal interactions were identified in the simulated epileptic seizures, in agreement with the interactions of the model variables. An approach consisting of wavelet transform, conditional mutual information estimation, and surrogate data testing applied to a single time series generated by the model was demonstrated to be successful in the identification of all directional (causal) interactions between the three different time scales described in the model. Thus, the methodology was prepared for the identification of causal cross-frequency phase–phase and phase–amplitude interactions in experimental and clinical neural data.

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