Topic
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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TL;DR: In this paper, the correlation of a function of solar wind parameters with a geomagnetic index is examined to identify the most relevant coupling function among those hitherto proposed, and a new function, BsVP1/3, where P is the dynamic pressure of the solar wind, is proposed as the one that surpasses all of the other three functions in predicting Dst.
Abstract: Results of past studies on the correlation of a function of solar wind parameters with a geomagnetic index are reviewed and examined to identify the most relevant coupling function among those hitherto proposed. For the AL index, three functions, BsV, BsV², and Akasofu's e, are compared, where Bs is the southward component of the interplanetary magnetic field and V is the solar wind velocity, and the importance of BsV² is then confirmed by a new presentation of the prediction of each function and the AL index. For the Dst index, validities of the above three functions are also compared, but a new function, BsVP1/3, where P is the dynamic pressure of the solar wind, is proposed as the one that surpasses all of the other three functions in predicting Dst. Implications of the two coupling functions are discussed, and possible directions for future work on this problem are suggested.
111 citations
TL;DR: In this paper, it was found that the isolated 10min oscillation in solar wind plasma density produced magnetic field compression oscillations within the magnetosphere at the same frequency, thereby enhancing resonant oscillations at approximately twice the frequency which were already present.
Abstract: Transient ULF pulsations associated with variations in solar wind plasma density observed by the IMP 8 satellite are presently studied in light of observations obtained during a fortuitous alignment of the AMPTE and Viking satellites with respect to the EISCAT Magnetometer Cross. It is found that the isolated 10-min oscillation in solar wind plasma density produced magnetic field compression oscillations within the magnetosphere at the same frequency, thereby enhancing resonant oscillations at approximately twice the frequency which were already present. Support is seen for the periodic solar wind density variation's exciting of a tailward-traveling large-scale magnetosphere wave train which excites local field line resonant oscillations.
110 citations
TL;DR: In this paper, the assumption of steady motion provides formally unique solutions and is tested along with that of no upwelling, which is substantially worse than that of the steady motion hypothesis.
Abstract: Select models of the main geomagnetic field and its secular variation are extrapolated to the base of an insulating mantle and used to estimate the adjacent fluid motion of a perfectly conducting outer core. The assumption of steady motion provides formally unique solutions and is tested along with that of no upwelling. The hypothesis of no upwelling is found to be substantially worse than that of steady motion. Although the actual motion is not thought to be steady, the large-scale secular variation at the top of the core can be adequately described by a large-scale, combined toroidal-poloidal circulation which is steady for intervals of at least a decade or two. The derived flows include a bulk westward drift but are complicated by superimposed jets, gyres, and surface divergence indicative of vigorous vertical motion at depth. The circulation pattern and key global properties including rms speed, upwelling, and westward drift are found to be fairly insensitive to variations in modeling parameters.
110 citations
TL;DR: In this article, a real-time tomographic model of the ionosphere created using dual-frequency phase data simultaneously collected with the re- ceiversofanetworkofstations in the USA and Canada, with separation of 400-1000km, during a period of high geomagnetic activity (Kp=6).
Abstract: Theinfluenceoftheionospherecanbeoneofthe mainobstacles toGPScarrierphaseambiguityresolution in real-time,particularlyoverlongbaselines. Thisisimportant toallusersofGPSrequiringsub-decimeterpositioning, per- haps in real time, especially with high geomagnetic activity or close to the Solar Maximum. Therefore, it is desirable to have a precise estimation of the ionospheric delay in real- time, to correct the data. In this paper we asses a real-time tomographic model of the ionosphere created using dual- frequency phase data simultaneously collected with the re- ceiversofanetworkofstationsintheUSAandCanada,with separationsof400-1000km,duringaperiodofhighgeomag- netic activity (Kp=6). When the tomographic ionospheric correctionisincluded,theresolutionon-the-fly(OTF)ofthe widelanedouble-dierencedambiguitiesatthereferencesta- tions is nearly 100% successful for satellite elevations above 20 degrees, while theresolution of theL1,L2ambiguities at the rover is typically more than 80% successful.
110 citations
TL;DR: In this article, the authors constructed a high-resolution archaeointensity record of the Levant from the 11th century to the early 9th century BCE, a period over which the geomagnetic field reached its maximum intensity in Eurasia over the past 50,000 years.
110 citations