scholarly journals The mechanical advantage of the magnetosphere: solar-wind-related forces in the magnetosphere-ionosphere-Earth system

2007 ◽  
Vol 25 (1) ◽  
pp. 255-269 ◽  
Author(s):  
V. M. Vasyliūnas
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Lorentz Force ◽  
Linear Momentum ◽  
Neutral Atmosphere ◽  
Earth System ◽  
Mechanical Advantage ◽  
The Earth ◽  
Earth’S Interior ◽  
Earth's Interior

Abstract. Magnetosphere-ionosphere interactions involve electric currents that circulate between the two regions; the associated Lorentz forces, existing in both regions as matched opposite pairs, are generally viewed as the primary mechanism by which linear momentum, derived ultimately from solar wind flow, is transferred from the magnetosphere to the ionosphere, where it is further transferred by collisions to the neutral atmosphere. For a given total amount of current, however, the total force is proportional to ℒB and in general, since ℒ2B~ constant by flux conservation, is much larger in the ionosphere than in the magnetosphere (ℒ = effective length, B = magnetic field). The magnetosphere may be described as possesing a mechanical advantage: the Lorentz force in it is coupled with a Lorentz force in the ionosphere that has been amplified by a factor given approximately by the square root of magnetic field magnitude ratio (~20 to 40 on field lines connected to the outer magnetosphere). The linear momentum transferred to the ionosphere (and thence to the atmosphere) as the result of magnetic stresses applied by the magnetosphere can thus be much larger than the momentum supplied by the solar wind through tangential stress. The added linear momentum comes from within the Earth, extracted by the Lorentz force on currents that arise as a consequence of magnetic perturbation fields from the ionosphere (specifically, the shielding currents within the Earth that keep out the time-varying external fields). This implies at once that Fukushima's theorem on the vanishing of ground-level magnetic perturbations cannot be fully applicable, a conclusion confirmed by re-examining the assumptions from which the theorem is derived. To balance the inferred Lorentz force within the Earth's interior, there must exist an antisunward mechanical stress there, only a small part of which is the acceleration of the entire Earth system by the net force exerted on it by the solar wind. The solar-wind interaction can thus give rise to internal forces, significantly larger than the force exerted by the solar wind itself, between the ionosphere and the neutral atmosphere as well as within the current-carrying regions of the Earth's interior.

scholarly journals Geosystemics View of Earthquakes

Entropy ◽  
2019 ◽  
Vol 21 (4) ◽  
pp. 412 ◽  
Author(s):  
Angelo De Santis ◽  
Cristoforo Abbattista ◽  
Lucilla Alfonsi ◽  
Leonardo Amoruso ◽  
Saioa A. Campuzano ◽  
...  
Keyword(s):  
Solid Earth ◽  
Point Of View ◽  
Satellite Observations ◽  
Earth System ◽  
Seismic Sequences ◽  
The Earth ◽  
Earth’S Interior ◽  
Earth's Interior ◽  
Physical Quantities

Earthquakes are the most energetic phenomena in the lithosphere: their study and comprehension are greatly worth doing because of the obvious importance for society. Geosystemics intends to study the Earth system as a whole, looking at the possible couplings among the different geo-layers, i.e., from the earth’s interior to the above atmosphere. It uses specific universal tools to integrate different methods that can be applied to multi-parameter data, often taken on different platforms (e.g., ground, marine or satellite observations). Its main objective is to understand the particular phenomenon of interest from a holistic point of view. Central is the use of entropy, together with other physical quantities that will be introduced case by case. In this paper, we will deal with earthquakes, as final part of a long-term chain of processes involving, not only the interaction between different components of the Earth’s interior but also the coupling of the solid earth with the above neutral or ionized atmosphere, and finally culminating with the main rupture along the fault of concern. Particular emphasis will be given to some Italian seismic sequences.

The fine structure of the subsolar MPB current layer from MAVEN observations: Implications for the Lorentz force

2020 ◽  
Author(s):  
Gabriela Boscoboinik ◽  
Cesar Bertucci ◽  
Daniel Gomez ◽  
Laura Morales ◽  
Christian Mazelle ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Fine Structure ◽  
Lorentz Force ◽  
Current Density ◽  
Current System ◽  
Minimum Variance ◽  
Current Layer ◽  
The Earth ◽  
Steady Current

<p>We report on the local structure of the Martian subsolar Magnetic Pileup Boundary (MPB) from minimum variance analysis of the magnetic field measured by the MAVEN spacecraft for six orbits. In particular, we detect a well defined current layer within the MPB’s fine structure and<br>provide a local estimate of its current density and compare these results with the current density obtained by multi-fluid simulations.<br>This current is of the order of hundreds of nAm<sup>-2</sup> which results in a sunward Lorentz force of the order of 10<sup>-14</sup> Nm<sup>-3</sup>. We compare these results with multifluid numerical simulations.<br>This force is associated with the gradient of the magnetic pressure, it accounts for the deflection of the solar wind ions near the MPB and for the acceleration of solar wind electrons which carry the interplanetary magnetic field through the MPB into the MPR. We also find that the<br>thickness of the MPB current layer is of the order of both the upstream (magnetosheath) solar wind proton inertial length and convective gyroradius. The former is consistent with the demagnetization of the ions due to the Hall electric field, an effect observed recently at the Earth magnetopause, while the latter would imply kinetic processes are important at the MPB.<br>This study supports recent results that report the presence of a steady current system around Mars in a similar way to the Earth.</p>

scholarly journals Geosystemics and Earthquakes

2018 ◽  
Author(s):  
Angelo De Santis ◽  
Gianfranco Cianchini ◽  
Rita Di Giovambattista ◽  
Cristoforo Abbattista ◽  
Lucilla Alfonsi ◽  
...  
Keyword(s):  
Dynamical System ◽  
Solid Earth ◽  
Case Studies ◽  
Central Italy ◽  
Point Of View ◽  
Earth System ◽  
Complex Dynamical System ◽  
The Earth ◽  
Earth’S Interior

Abstract. Geosystemics (De Santis 2009, 2014) studies the Earth system as a whole focusing on the possible coupling among the Earth layers (the so called geo-layers), and using universal tools to integrate different methods that can be applied to multi-parameter data, often taken on different platforms. Its main objective is to understand the particular phenomenon of interest from a holistic point of view. In this paper we will deal with earthquakes, considered as a long term chain of processes involving, not only the interaction between different components of the Earth’s interior, but also the coupling of the solid earth with the above neutral and ionized atmosphere, and finally culminating with the main rupture along the fault of concern (De Santis et al., 2015a). Some case studies (particular emphasis is given to recent central Italy earthquakes) will be discussed in the frame of the geosystemic approach for better understanding the physics of the underlying complex dynamical system.

scholarly journals Cellular automata model of magnetospheric-ionospheric coupling

2003 ◽  
Vol 21 (9) ◽  
pp. 1931-1938 ◽  
Author(s):  
B. V. Kozelov ◽  
T. V. Kozelova
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Cellular Automata ◽  
Interplanetary Magnetic Field ◽  
Control Parameter ◽  
Energy Content ◽  
Nonlinear Phenomena ◽  
Cellular Automata Model ◽  
The Earth ◽  
Magnetospheric Tail

Abstract. We propose a cellular automata model (CAM) to describe the substorm activity of the magnetospheric-ionospheric system. The state of each cell in the model is described by two numbers that correspond to the energy content in a region of the current sheet in the magnetospheric tail and to the conductivity of the ionospheric domain that is magnetically connected with this region. The driving force of the system is supposed to be provided by the solar wind that is convected along the two boundaries of the system. The energy flux inside is ensured by the penetration of the energy from the solar wind into the array of cells (magnetospheric tail) with a finite velocity. The third boundary (near to the Earth) is closed and the fourth boundary is opened, thereby modeling the flux far away from the tail. The energy dissipation in the system is quite similar to other CAM models, when the energy in a particular cell exceeds some pre-defined threshold, and the part of the energy excess is redistributed between the neighbouring cells. The second number attributed to each cell mimics ionospheric conductivity that can allow for a part of the energy to be shed on field-aligned currents. The feedback between "ionosphere" and "magnetospheric tail" is provided by the change in a part of the energy, which is redistributed in the tail when the threshold is surpassed. The control parameter of the model is the z-component of the interplanetary magnetic field (Bz IMF), "frozen" into the solar wind. To study the internal dynamics of the system at the beginning, this control parameter is taken to be constant. The dynamics of the system undergoes several bifurcations, when the constant varies from - 0.6 to - 6.0. The Bz IMF input results in the periodic transients (activation regions) and the inter-transient period decreases with the decrease of Bz. At the same time the onset of activations in the array shifts towards the "Earth". When the modulus of the Bz IMF exceeds some threshold value, the transition takes place from periodic to chaotic dynamics. In the second part of the work we have chosen as the source the real values of the z-component of the interplanetary magnetic field taken from satellite observations. We have shown that in this case the statistical properties of the transients reproduce the characteristic features observed by Lui et al. (2000).Key words. Magnetospheric physics (magnetosphere-ionosphere interactions) – Space plasma physics (nonlinear phenomena)

scholarly journals Nutation in Space and Diurnal Nutation in the Case of an Elastic Earth

1979 ◽  
Vol 82 ◽  
pp. 169-174 ◽  
Author(s):  
Nicole Capitaine
Keyword(s):  
Rotation Axis ◽  
Liquid Core ◽  
Elastic Earth ◽  
The Earth ◽  
Earth’S Interior ◽  
Earth's Interior

In order to improve the representation of nutation, the effect of elasticity of the Earth on the nutation in space and diurnal nutation of the terrestrial rotation axis is considered and its amplitude is evaluated for the principal terms. The choice between several methods taking this effect into account is discussed. A comparison with the effect induced on nutation by the existence of a liquid core in the Earth's interior shows that the consideration of elasticity alone cannot give any amelioration in the representation of nutation.

scholarly journals Region-1 field aligned currents in experiments on laser-produced plasma interacting with magnetic dipole

2010 ◽  
Vol 6 (S274) ◽  
pp. 40-43
Author(s):  
I. F. Shaikhislamov ◽  
Yu. P. Zakharov ◽  
V. G. Posukh ◽  
E. L. Boyarintsev ◽  
A. V. Melekhov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Solar Wind ◽  
Experimental Evidence ◽  
Magnetic Dipole ◽  
Present Report ◽  
Low Latitude ◽  
The Earth ◽  
Field Aligned Current ◽  
Low Latitude Boundary Layer

AbstractIn previous experiments by the authors a generation of intense field aligned current (FAC) system on Terrella poles was observed. In the present report a question of these currents origin in a low latitude boundary layer of magnetosphere is investigated. Experimental evidence of such a link was obtained by measurements of magnetic field generated by tangential sheared drag. Results suggest that compressional and Alfven waves are responsible for FAC generation. The study is most relevant to FAC generation in the Earth and Hermean magnetospheres following pressure jumps in Solar Wind.

XXII. Researches in terrestrial physics.-Part II

1851 ◽  
Vol 141 ◽  
pp. 511-547
Keyword(s):  
Physical Properties ◽  
Crystalline State ◽  
Fundamental Importance ◽  
Interior Structure ◽  
Geological History ◽  
Experimental Knowledge ◽  
Physical Evidence ◽  
The Earth ◽  
Earth’S Interior ◽  
Earth's Interior

In the first part of these researches, I have endeavoured, by generalizing the hypothesis on which is usually founded the theory of the earth’s figure, not only to improve that theory, but also to establish a secure basis for researches into the changes which may have taken place within and at the surface of the earth during the epochs of its geological history. Although I stated that no precise physical evidence could be adduced for the examination of the assumption that the molecules of the primitive fluid, supposed to have constituted the earth, retained their positions after solidification, it yet appears that such evidence exists, if we may be permitted to draw any conclusions relative to the physical properties of substances in the earth’s interior, from the observed physical properties of substances at its surface. Professor Bischof of Bonn, has shown that Granite contracts in volume in passing from the fluid to the solid crystalline state, from 1 to ⋅7481, Trachyte from 1 to ⋅8187, and Basalt from 1 to ⋅8960. The first of these rocks appears, as far as can be observed, to constitute the greater part of the earth; hence the assumption alluded to must be considered not only as superfluous, but as erroneous. In this Part it is my object to discover relations between the interior structure of the earth and phenomena observed at its surface, and also the effects of the reaction of the fluid nucleus, described in Article 6, Part I., upon the solid crust. I divide this Part into sections, each containing a distinct investigation, the order of arrangement of these sections being determined according to their fundamental importance. The statement of the geological results capable of being deduced from these investigations is, for greater clearness, reserved for the end. Such of these results as chiefly depend on the validity of the reasonings used in Section III. are presented with some diffidence, owing to the imperfect experimental knowledge we possess respecting the subjects discussed in that section. The diminution of the earth’s mean radius by refrigeration is neglected all through, except where the contrary is specially mentioned.

scholarly journals On the magnetic characteristics of magnetic holes in the solar wind between Mercury and Earth

2019 ◽  
Author(s):  
Martin Volwerk ◽  
Charlotte Goetz ◽  
Ferdinand Plaschke ◽  
Tomas Karlsson ◽  
Daniel Heyner
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Occurrence Rate ◽  
Magnetic Characteristics ◽  
The Earth ◽  
The Magnetic Field

Abstract. The occurrence rate of linear and pseudo magnetic holes has been determined during MESSENGER's cruise phase starting from Earth (2005) and arriving at Mercury (2011). It is shown that the occurrence rate of linear magnetic holes, defined as a maximum of 10° rotation of the magnetic field over the hole, slowly decreases from Mercury to Earth. The pseudo magnetic holes, defined as a rotation between 10° and 45° over the hole, have mostly a constant occurrence rate, with a slight increase in front of the Earth and a decrease around the Earth. The width and depth of these structures seem to strongly differ depending on whether they are inside or outside of Venus's orbit.

scholarly journals Jets in the Magnetosheath: IMF Control of Where They Occur

2019 ◽  
Author(s):  
Laura Vuorinen ◽  
Heli Hietala ◽  
Ferdinand Plaschke
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Spatial Distribution ◽  
Interplanetary Magnetic Field ◽  
Cone Angle ◽  
Time History ◽  
Bow Shock ◽  
The Earth ◽  
Parallel Side ◽  
History Of

Abstract. Magnetosheath jets are localized regions of plasma that move faster towards the Earth than the surrounding magnetosheath plasma. Due to their high velocities, they can cause indentations when colliding into the magnetopause and trigger processes such as magnetic reconnection and magnetopause surface waves. We statistically study the occurrence of these jets in the subsolar magnetosheath using measurements from the five Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft and OMNI solar wind data from 2008–2011. We present the observations in the BIMF-vSW plane and study the spatial distribution of jets during different interplanetary magnetic field (IMF) orientations. Jets occur downstream of the quasi-parallel bow shock approximately 9 times as often as downstream of the quasi-perpendicular shock, suggesting that foreshock processes are responsible for most jets. For oblique IMF, with 30°–60° cone angle, the occurrence increases monotonically from the quasi-perpendicular side to the quasi-parallel side. This study offers predictability for the numbers and locations of jets observed during different IMF orientations allowing us to better forecast the formation of these jets and their impact on the magnetosphere.

L'interpretation petrographique des donnees geophysiques sur la structure de l'ecorce terrestre

1960 ◽  
Vol S7-II (6) ◽  
pp. 801-820
Author(s):  
G. D. Afanasev
Keyword(s):  
Wave Propagation ◽  
Elastic Wave ◽  
Oceanic Crust ◽  
Physical State ◽  
Elastic Wave Propagation ◽  
Seismic Velocities ◽  
Petrographic Composition ◽  
The Earth ◽  
Earth’S Interior ◽  
Earth's Interior

Abstract The results of recent studies of elastic wave propagation within the earth are reviewed and different interpretations of the earth's interior which have been proposed, particularly in recent American works, are outlined. The results of these studies and of oceanographic work are incompatible with certain classic theories. The main facts are the differences between the continental and oceanic crust and the relatively recent (Tertiary and Quaternary) age of the great zones of continental subsidence, where a transformation from a continental to an oceanic-type crust is implied. The concept of permanent ocean basins is rejected. Differences between the continental and oceanic crust are considered essentially a function of physical state rather than petrographic composition. Continental zones that have subsided are characterized by greater seismic velocities because of the extra pressure to which they have been subjected in the course of the ages.

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