scholarly journals Possible risk resulting from the recent decay of the dipolar component of the terrestrial magnetic field

2021 ◽  
Author(s):  
Agata Bury ◽  
Marek Lewandowski ◽  
Krzysztof Mizerski
Keyword(s):  
Magnetic Field ◽  
Data Center ◽  
Main Magnetic Field ◽  
The Earth ◽  
Observatory Data ◽  
Dipole Magnetic Field ◽  
Harmonic Decomposition ◽  
History Of ◽  
Spherical Harmonic Decomposition ◽  
Terrestrial Magnetic Field

AbstractIn this study, we investigated the geomagnetic ground observatory data from 1980 to 2011 collected from World Data Center from 134 stations. To analyze the data we have applied spherical harmonic decomposition to obtain components associated with the Earth’s main magnetic field and to calculate how the Earth’s dipole was varying in the aforementioned recent 31-year period. There is a visible ~ 2.3% decay of the dipole magnetic field of the Earth. We note that the present-day value of the magnetic dipole intensity is the lowest one in the history of modern civilization and that further drop of this value may pose a risk for different domains of our life.

The French network of magnetic observatories

2020 ◽  
Author(s):  
Vincent Lesur ◽  
Aude Chambodut
Keyword(s):  
Magnetic Field ◽  
Measurement Techniques ◽  
Main Magnetic Field ◽  
Magnetic Observatory ◽  
Environmental Constraints ◽  
The Earth ◽  
Different Types ◽  
New Challenges ◽  
Data Centres ◽  
Magnetic Observatories

<p>In magnetic observatories the Earth’s magnetic field is continuously recorded and the acquired data are calibrated so that the evolution of the field can be studied on time scales ranging from seconds to decades. The French network (the so called BCMT) includes 18 observatories around the world and the different types of data produced are freely accessible on several data centres. We will describe a typical infrastructure of a magnetic observatory, the measurement techniques, the instruments used, the general processing applied to obtain calibrated data and finally the environmental constraints that have to be respected in order to acquire suitable data. If magnetic observatories were originally set to monitor the slow variations of the Earth’s main magnetic field, they are more and more often used for space-weather monitoring and to study signal generated in the ionosphere and magnetosphere. This new range of applications implies an evolution of the network, of the acquisition and distribution techniques. The strategy we developed to respond to these new challenges will be also presented.</p>

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.

scholarly journals Study of Interplanetary and Geomagnetic Response of Filament Associated CMEs

2018 ◽  
Vol 13 (S340) ◽  
pp. 83-84
Author(s):  
Kunjal Dave ◽  
Wageesh Mishra ◽  
Nandita Srivastava ◽  
R. M. Jadhav
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Activity ◽  
Space Weather ◽  
Coronal Mass Ejections ◽  
The Sun ◽  
The Earth ◽  
Weather Events ◽  
Terrestrial Magnetic Field

AbstractIt has been established that Coronal Mass Ejections (CMEs) may have significant impact on terrestrial magnetic field and lead to space weather events. In the present study, we selected several CMEs which are associated with filament eruptions on the Sun. We attempt to identify the presence of filament material within ICME at 1AU. We discuss how different ICMEs associated with filaments lead to moderate or major geomagnetic activity on their arrival at the Earth. Our study also highlights the difficulties in identifying the filament material at 1AU within isolated and in interacting CMEs.

Thermoelectric model of the Earth's magnetic field

2021 ◽  
pp. 39-52
Author(s):  
A. N. Dmitriev ◽  
Yu. V. Pakharukov
Keyword(s):  
Magnetic Field ◽  
Inner Core ◽  
Inversion Process ◽  
Earth’S Magnetic Field ◽  
The Earth ◽  
Dipole Magnetic Field ◽  
Earth's Magnetic Field ◽  
Direction Of Movement ◽  
The Moment ◽  
Thermoelectric Model

A variant of the thermoelectric model of the Earth's dipole magnetic field is considered. It is based on geothermoelectric currents present in the planet's core. The currents cyclically change their direction, which leads over time either to warming on the Earth, if their movement is directed towards the Earth's crust, or to cooling, when moving towards the inner core. With each change in the direction of movement of the thermal currents, the poles of the Earth's magnetic field are inverted simultaneously. The inversion process is instantaneous (on the scale of planetary time) and is not the result of a gradual reversal on the 180° Earth's magnetic axis. At the moment of inversions of thermal currents in the core, the total geomagnetic field decreases to the level of 4.6∙10-6 T, which is constantly supported by thermal currents of semi-conducting rocks of the lower mantle. The considered version of the thermoelectric model of the Earth's magnetic field may be promising for studying the magnetic fields of planets in the Solar system.

Magnetic World: The Historiography of an Inherently Complex Science, Geomagnetism, in The 20th Century

2007 ◽  
Vol 26 (2) ◽  
pp. 281-299 ◽  
Author(s):  
Gregory Good
Keyword(s):  
Magnetic Field ◽  
20Th Century ◽  
Geomagnetic Field ◽  
Plate Tectonics ◽  
Radiation Belts ◽  
Problem Area ◽  
Early 20Th Century ◽  
The Earth ◽  
History Of ◽  
Field Lines

The 20th century witnessed a succession of remarkable developments in the history of geomagnetic research. After 1900, geomagnetic researchers increased their activity as they adopted theories by C. F. Gauss and J. C. Maxwell and developed means to bridge the gulf between these theories and masses of data of global phenomena. This paper outlines three main streams in 20th-century geomagnetic research: investigations of processes deep inside the Earth that produce the main geomagnetic field, examinations of crustal magnetism, and research into processes on the edge of space, where Earth's magnetic field interacts with the interplanetary environment. This discussion places these research streams in the historiographic context of disciplinary specialization and transformation. In the early 20th century, geomagnetic researchers thought of their domain as all of Earth's magnetic and electric phenomena. In mid-century, however, many researchers began to narrow their gaze to one problem area or another. This specialization contributed to a period of dramatic developments in the latter half of the century: geodynamo theory, paleomagnetic evidence of plate tectonics, computer modeling of magnetic reversals, and discovery of the solar wind, radiation belts, and magnetic substorms. But there was more to this period than simple specialization. As researchers gradually shifted their research programs, their methods, instruments, and theories moved from one program to another, researchers sometimes going with them. Chameleons and opportunists frequently left one research program for another, more promising one. This paper closes with a discussion of the possibility of "re-connection" among these specializations, as researchers have begun once again to communicate across inter-field lines.

scholarly journals Jets in the magnetosheath: IMF control of where they occur

2019 ◽  
Vol 37 (4) ◽  
pp. 689-697 ◽  
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 to 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 an 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, locations, and magnetopause impact rates of jets observed during different IMF orientations, allowing us to better forecast the formation of these jets and their impact on the magnetosphere.

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