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 article, the ion measurements from selected passes of the Charge Composition Explorer during low geomagnetic activity were used to study the quiet time magnetosphere using ion measurements covering energies from about 1 keV to about 4 MeV, and the radial profile of total plasma pressure exhibited a peak at L = 3-4 and decreased monotonically from L = 4 and L = 9.
Abstract: The quiet time magnetosphere is studied using ion measurements covering energies from about 1 keV to about 4 MeV from selected passes of the Charge Composition Explorer during low geomagnetic activity. The quiet time plasma pressure in the midnight sector was found to be comparable to that deduced by Spence et al. (1989) and Kan et al. (1992) from inverting the magnetic field models of Tsyganenko and Usmanov (1982) and Tsyganenko (1987). The radial profile of the total plasma pressure exhibited a peak at L = 3-4 and decreased monotonically from L = 4 and L = 9. Contrary to theoretical expectations for the magnetospheric closure of the region 2 field-aligned current system, no large-scale earthward decrease in plasma pressure was found to occur in these outer L shells.
191 citations
TL;DR: In this article, the average relationship of the tail lobe magnetic energy density to the north-south component of the interplanetary magnetic field (IMF) and substorm expansion phase is investigated by using a superposed epoch analysis method.
Abstract: The average relationship of the tail lobe magnetic energy density to the north-south component of the interplanetary magnetic field (IMF) and substorm expansion phase is investigated by using a superposed epoch analysis method. An enhanced average lobe energy density is observed to be associated with a southward component of the IMF prior to substorm breakup. Coincident with the expansion onset, the lobe field rapidly recovers, and the north-south component of the IMF turns northward. The average magnitude of the substorm-associated lobe field variation is measured to be ∼14%, a value sufficiently large to enable the lobes to serve as the source of the energy dissipated during substorms.
191 citations
TL;DR: In this article, the conditions of local gradient drift instability are not sufficient and one has to consider the integrated properties of each magnetic filed tube, which can be explained in terms of gravity waves with frequencies close to the Brunt-Vaisala frequency.
Abstract: Recent E region VHF backscatter echoes observed by the MU radar at mid-latitudes show quasi-periodic striations with a fairly constant range vs. time tilt in a RTI display. These features are explained in terms of gravity waves with frequencies close to the Brunt-Vaisala frequency which modulate the shape of sporadic E layers. The conditions of instability, when the magnetic field has a significant dip angle, is revised. Differing from previous work, we argue that conditions of local gradient drift instability are not sufficient and one has to consider the integrated properties of each magnetic filed tube. Stratified sporadic E layers are stable using this new criteria, unless they are distorted to produce unstable integrated gradients. Gravity waves with phase fronts parallel to the magnetic dip angle are capable of producing such distortion, imposing its own temporal and spatial periodicity on the echoes.
191 citations
TL;DR: In this article, the authors presented new data obtained from fired archeological structures found in two French sites (Loupiac and Aspiran) dated within the first millennium b.c.
190 citations
TL;DR: It is shown that three-axis control can be achieved with magnetorquers as sole actuators in a low Earth near polar orbit with time-varying, nonlinear system point of view and suggests controllers for three- axis stabilization.
190 citations