Dipole model of the Earth's magnetic field

About: Dipole model of the Earth's magnetic field is a research topic. Over the lifetime, 2756 publications have been published within this topic receiving 83021 citations.

Propagation of low energy solar electrons

Abstract: Two events are reported in which 2-10 keV electrons of solar energy have undergone significant adiabatic mirroring and pitch angle scattering in large scale magnetic structures in the interplanetary medium within a distance of about 0.5 AU from the earth. Electrons of 3 keV, typical of the energies measured, have a speed of about one-tenth of the speed of light, so that their travel time from the sun at 0 deg pitch angle would be about 100 minutes. Their cyclotron radius is about 20 km for a pitch angle of 30 deg, and a field of magnitude of 5 nT, and the cyclotron period is about 7.1 milliseconds. The electrons are scattered by spatial variations in the interplanetary magnetic field. When the spatial variations are convected past a stationary spacecraft by a 500 km/sec solar wind, they are seen as temporal fluctuations at a frequency of about 3 Hz.

A fundamental theory of the magnetism of massive rotating bodies

Abstract: A phenomenological theory, based on a relativistically covariant generalization of Maxwell's equations to include gravitational fields, is developed to account for the magnetic fields of massive rotating bodies. The equations yield the Wilson–Blackett expression for the magnetic moment of the earth and stars but give no magnetic field for mass-bodies moving without rotation in their own gravitational fields. They indicate that the magnetic field due to the motion of the earth in its orbit is negligibly small compared to the field due to its rotational motion, and they provide a possible explanation for the variable magnetic fields of light-variable stars.

Evidence of magnetic field line merging in the solar wind

Abstract: An analysis is presented of a few of the sector boundary crossings measured by the Pioneer 8 magnetometer. By using a variance matrix technique, evidence is obtained of some amount of magnetic line reconnection through the sector boundaries. The thicknesses of such structures are around 0.1–2 × 104 km and are therefore larger than typical ion Larmor radii, in contrast with the magnetic structures characteristic of the geomagnetic tail. A theoretical discussion is given of the possible physical causes of the observed reconnection process. In particular, the possible role of tearing instabilities is analyzed with reference to the results of the observations.

Forecasting the velocity of quasi-stationary solar wind and the intensity of geomagnetic disturbances produced by it

Abstract: A brief review is given of contemporary approaches to solving the problem of medium-term forecast of the velocity of quasi-stationary solar wind (SW) and of the intensity of geomagnetic disturbances caused by it. At the present time, two promising models of calculating the velocity of quasi-stationary SW at the Earth’s orbit are realized. One model is the semi-empirical model of Wang-Sheeley-Arge (WSA) which allows one to calculate the dependence V(t) of SW velocity at the Earth’s orbit using measured values of the photospheric magnetic field. This model is based on calculation of the local divergence f S of magnetic field lines. The second model is semi-empirical model by Eselevich-Fainshtein-Rudenko (EFR). It is based on calculation in a potential approximation of the area of foot points on the solar surface of open magnetic tubes (sources of fast quasistationary SW). The new Bd-technology is used in these calculations, allowing one to calculate instantaneous distributions of the magnetic field above the entire visible surface of the Sun. Using predicted V(t) profiles, one can in EFR model calculate also the intensity of geomagnetic disturbances caused by quasi-stationary SW. This intensity is expressed through the K p index. In this paper the EFR model is discussed in detail. Some examples of epignosis and real forecast of V(t) and K p (t) are discussed. A comparison of the results of applying these two models for the SW velocity forecasting is presented.

Validation study of the magnetically self-consistent inner magnetosphere model RAM-SCB

Abstract: [1] The validation of the magnetically self-consistent inner magnetospheric model RAM-SCB developed at Los Alamos National Laboratory is presented here. The model consists of two codes: a kinetic ring current–atmosphere interaction model (RAM) and a 3-D equilibrium magnetic field code (SCB). The validation is conducted by simulating two magnetic storm events and then comparing the model results against a variety of satellite in situ observations, including the magnetic field from Cluster and Polar spacecraft, ion differential flux from the Cluster/CODIF (Composition and Distribution Function) analyzer, and the ground-based SYM-H index. The model prediction of the magnetic field is in good agreement with observations, which indicates the model's capability of representing well the inner magnetospheric field configuration. This provides confidence for the RAM-SCB model to be utilized for field line and drift shell tracing, which are needed in radiation belt studies. While the SYM-H index, which reflects the total ring current energy content, is generally reasonably reproduced by the model using the Weimer electric field model, the modeled ion differential flux clearly depends on the electric field strength, local time, and magnetic activity level. A self-consistent electric field approach may be needed to improve the model performance in this regard.