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.

Recent satellite measurements of the morphology and dynamics of the plasmasphere

Abstract: The characteristic morphology and dynamics of the plasmasphere vary with local time and with geomagnetic conditions. On the nightside the plasmapause position changes predictably with changing magnetic activity. Once established at a specific L-shell value, the steep density gradient on the nightside corotates into the dayside, where filling from the ionosphere takes place. In the duskside bulge region the characteristic density profile inside the plasmapause displays a smooth decrease proportional to 1/R to the fourth power where R is radial distance. Plasmasphere morphology and dynamics can be understood in terms of a time-varying convection electric-field model of the magnetosphere that includes the bulge region as part of the main circulation pattern of the plasmasphere.

Magnetospheric convection induced by the positive and negative Z components of the interplanetary magnetic field: Quantitative analysis using polar cap magnetic records

Abstract: The dependence of the polar cap magnetic disturbance on the polarity and magnitude of the Z component of the interplanetary magnetic field is investigated by regression analysis using hourly values The Svalgaard-Mansurov effect has been eliminated by assuming a linear dependence on the Y component of the interplanetary field It is shown that as the northward component of the interplanetary magnetic field increases, a characteristic current system appears in the polar cap This current system is composed of two current vortices in the day side polar cap: one in the prenoon sector and the other in the afternoon sector The current direction is antisunward in the central polar cap, suggesting that sunward plasma convection is induced in the polar cap Current intensity is strongest at фM ∼ 84° around the noon meridian We propose that the tail field lines are reconnected with the northward interplanetary field on the polar side of the day side polar cusp and, as a result, that plasma convection is induced which is closed within the high-latitude magnetosphere On the other hand, when the interplanetary magnetic field is directed southward, a transpolar current sheet appears, covering the whole polar cap (фM ≥ 775°) The characteristics of this transpolar current sheet are as follows: (1) On the day side, especially around noon, the direction of the current is roughly consistent with the Hall current direction expected from the dawn-to-dusk electric field, while on the night side the direction of the current is considerably skewed from the noon-midnight meridian Skewing of the current direction can be explained by the effect of the currents external to the ionosphere (2) The strength of the current is almost linearly dependent on Bz when the interplanetary magnetic field is directed southward (θ < −45°) However, the current intensity is also a function of the magnitude of By, this being apparent when Bz ∼ 0 This indicates that the day side reconnection rate is a function of |By| as well as of Bz, and information is derived about the applicability of the three-dimensional reconnection model in the presence of finite |By|

Motions in the magnetosphere of the Earth

Abstract: The conditions determining the dynamical behavior of the ionized gas in the outer atmosphere of the earth are discussed. It is proposed to call this region in which the magnetic field of the earth dominates the ‘magnetosphere.’ Observations by Van Allen and others indicate that this zone reaches out to between 5 and 10 earth radii, depending on the degree of magnetic disturbance. It is shown that the existence of an insulating layer at the base of this region, namely the non-ionized atmosphere, completely changes the type of control exerted by the magnetic field, allowing a class of motions to occur freely without the need to overcome any magnetic forces. The extent to which such motions may occur is discussed, and some of the indications from airglow and magnetic observations are mentioned. The theory predicts that, at the level of the F2 layer and above, most motions will show strict symmetry between the two base points of a magnetic line of force.

Dayside global ionospheric response to the major interplanetary events of October 29-30, 2003 Halloween Storms : Violent sun-earth connection events of October-November 2003

Abstract: We demonstrate extreme ionospheric response to the large interplanetary electric fields during the Halloween storms that occurred on October 29 and 30, 2003 Within a few (2-5) hours of the time when the enhanced interplanetary electric field impinged on the magnetopause, dayside total electron content increases of ∼40% and ∼250% are observed for the October 29 and 30 events, respectively During the Oct 30 event, ∼900% increases in electron content above the CHAMP satellite (∼400 km altitude) were observed at mid-latitudes (±30 degrees geomagnetic) The geomagnetic storm-time phenomenon of prompt penetration electric fields is a possible contributing cause of these electron content increases, producing dayside ionospheric uplift combined with equatorial plasma diffusion along magnetic field lines to higher latitudes, creating a daytime super-fountain effect