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Earth's magnetic field

About: Earth's magnetic field is a research topic. Over the lifetime, 20360 publications have been published within this topic receiving 446747 citations. The topic is also known as: magnetic field of Earth & geomagnetic field.


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Journal ArticleDOI
TL;DR: In this article, a study of electron density and total electron content in tubes of force near the knee in magnetospheric ionization was made, based on whistler observations made at Eights, Antarctica, in July and August 1963, under conditions of steady, moderate geomagnetic agitation (Kp = 2-4).
Abstract: A study has been made of electron density and total electron content in tubes of force near the knee in magnetospheric ionization. It was based on whistler observations made at Eights, Antarctica, in July and August 1963, under conditions of steady, moderate geomagnetic agitation (Kp = 2–4). During the period 0100–0400 LT, the electron density near the equatorial plane at a geocentric distance of 4 RE drops a factor of 30–100 within a distance of less than 0.15 RE. The corresponding change in tube content above 1 cm2 at 1000 km is a factor of about 10 within less than a degree of latitude. The afternoon profiles are generally similar to the postmidnight results. In the afternoon the profiles are often well defined outside the knee, falling smoothly to about 1 el/cm3 at 7 RE. Both the equatorial and tube content profiles show a definite repeatability between observations at a given local time and under conditions of moderate, steady geomagnetic agitation. Diurnal effects are evident, with amplitude differing from point to point on the profiles. The problem of the field-line distribution of ionization has been studied with a view to minimizing error in the profiles. Experimental and theoretical support has been found for using a diffusive-equilibrium distribution along the field lines inside the knee and a ‘collisionless’ model, behaving approximately as Ne ∝ R−4, along the field lines outside the knee. A study of error shows that the uncertainty in individual points on the knee profiles is everywhere less than a factor of ±2, and on the content profiles less than a factor of ±1.5.

256 citations

Journal ArticleDOI
TL;DR: The NCAR Whole Atmosphere Community Climate Model, version 3 (WACCM3) is used to study the atmospheric response from the surface to the lower thermosphere to changes in solar and geomagnetic forcing over the 11-year solar cycle as mentioned in this paper.
Abstract: The NCAR Whole Atmosphere Community Climate Model, version 3 (WACCM3), is used to study the atmospheric response from the surface to the lower thermosphere to changes in solar and geomagnetic forcing over the 11-year solar cycle. WACCM3 is a general circulation model that incorporates interactive chemistry that solves for both neutral and ion species. Energy inputs include solar radiation and energetic particles, which vary significantly over the solar cycle. This paper presents a comparison of simulations for solar cycle maximum and solar cycle minimum conditions. Changes in composition and dynamical variables are clearly seen in the middle and upper atmosphere, and these in turn affect terms in the energy budget. Generally good agreement is found between the model response and that derived from satellite observations, although significant differences remain. A small but statistically significant response is predicted in tropospheric winds and temperatures which is consistent with signals observed in reanalysis data sets.

255 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that the ratio of the IEF to the Earth's magnetic field in the equatorial ionosphere for periods less than about two hours is 15:1, which corresponds to the ratio between the size of the magnetosphere to the length of the connection line between the Interplanetary Magnetic Field (IMF) and the Earth magnetic field.
Abstract: [1] On April 17, 2002 an intense, long duration electric field penetration event was captured by the Jicamarca incoherent scatter radar. Other radars in the U. S. chain detected the event as well, although not with as much clarity. The Interplanetary Electric Field (IEF) is available from the ACE satellite as well. The ratio of the dawn-to-dusk component of the IEF to the dawn-to-dusk electric field in the equatorial ionosphere for periods less than about two hours is 15:1. We suggest that this corresponds to the ratio of the size of the magnetosphere to the length of the connection line between the Interplanetary Magnetic Field (IMF) and the Earth's magnetic field. Simultaneous magnetic field measurements at Piura (off the magnetic equator) and at Jicamarca (under the magnetic equator) in Peru, reveal the same high frequency components and suggest that a chain of stations or an equatorial fleet of satellites in low earth orbit could be used to monitor the connection length continuously.

254 citations

Journal ArticleDOI
TL;DR: In this article, an updated analysis and interpretation of the magnetic field observations obtained during the Mariner 10 encounter with the planet Mercury on March 29, 1974 is presented, which leads to the conclusion that an internal planetary magnetic field exists with dipole moment approximately 5.1 × 1022 G cm³.
Abstract: An updated analysis and interpretation are presented of the magnetic field observations obtained during the Mariner 10 encounter with the planet Mercury on March 29, 1974. The combination of data relating to position of the detached bow shock wave and magnetopause and the geometry and magnitude of the magnetic field within the magnetospherelike region surrounding Mercury lead to the conclusion that an internal planetary field exists with dipole moment approximately 5.1 × 1022 G cm³. The limited data set precludes quantitative determination of an intrinsic field more complex than a centered dipole. The dipole axis has a polarity sense similar to that of earth and is tilted 7° from the normal to Mercury's orbital plane. The magnetic field observations reveal a significant distortion of the modest Hermean field (350 γ at the equator) by the solar wind flow and the formation of a magnetic tail and neutral sheet which begins close to the planet on the night side. Presently, an active dynamo mechanism in the planetary interior appears to be favored in the interpretation of the field origin, although fossil remanent magnetization cannot be excluded. The composite data set is not consistent with a complex induction process driven by the solar wind flow.

252 citations

Journal ArticleDOI
TL;DR: In this article, the authors found that most large geomagnetic storms during the interval surrounding the last solar maximum (August 1978 - October 1982) were associated with earth-passage of interplanetary disturbances in which the earth encountered both a shock and the CME driving the shock.
Abstract: Previous work indicates that coronal mass ejection (CME) events in the solar wind at 1 AU can be identified by the presence of a flux of counterstreaming solar wind halo electrons (above about 80 eV). Using this technique to identify CMEs in 1 AU plasma data, it is found that most large geomagnetic storms during the interval surrounding the last solar maximum (August 1978 - October 1982) were associated with earth-passage of interplanetary disturbances in which the earth encountered both a shock and the CME driving the shock. However, only about one CME in six encountered by earth was effective in causing a large geomagnetic storm. Slow CMEs which did not interact strongly with the ambient solar wind ahead were particularly ineffective in a geomagnetic sense.

251 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023657
20221,202
2021477
2020553
2019604
2018581