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.

Modelling of three‐dimensional current systems associated with magnetospheric substorms

Abstract: Summary It is now well accepted that magnetic field perturbations associated with polar magnetic substorms can be modelled by a three-dimensional equivalent current loop involving an electrojet segment in the high-latitude ionosphere linked to the outer magnetosphere by currents flowing parallel to magnetic lines of force. In this paper we present techniques for quantitative evaluation of the magnetic field perturbation at any point in space outside of the region of current flow. The technique is developed using the Biot–Savart Law and analytical expressions for the three components (H, D, Z) of the magnetic perturbation at the Earth's surface are developed. Assuming the Earth to be represented by an infinitely conducting sphere covered by a perfect insulator to some arbitrary depth, the time independent induction problem is treated and analytical expressions for H, D, and Z corrected for Earth induction are developed. The modelling technique is applied to three substorm events and the results provide an accurate and comprehensive indicator of the character and spatial extent of the inducing current system associated with magnetospheric substorms.

Magnetic cloud field intensities and solar wind velocities

Abstract: For the sets of magnetic clouds studied in this work we have shown that there is a general relationship between their magnetic fields strength and velocities. With a clear tendency that the faster the speed of the cloud the higher the magnetic field.

Ring current modeling in a realistic magnetic field configuration

Abstract: A 3-dimensional kinetic model has been developed to study the dynamics of the storm time ring current in a dipole magnetic field. In this paper, the ring current model is extended to include a realistic, time-varying magnetic field model. The magnetic field is expressed as the cross product of the gradients of two Euler potentials and the bounce-averaged particle drifts are calculated in the Euler potential coordinates. A dipolarization event is modeled by collapsing a tail-like magnetosphere to a dipole-like configuration. Our model is able to simulate the sudden enhancements in the ring current ion fluxes and the corresponding ionospheric precipitation during the substorm expansion.

The interaction between the Moon and the solar wind

Abstract: We study the interaction between the Moon and the solar wind using a three-dimensional hybrid plasma solver. The proton fluxes and electromagnetical fields are presented for typical solar wind conditions with different magnetic field directions. We find two different wake structures for an interplanetary magnetic field that is perpendicular to the solar wind flow, and for one that is parallell to the flow. The wake for intermediate magnetic field directions will be a mix of these two extreme conditions. Several features are consistent with a fluid interaction, e.g., the presence of a rarefaction cone, and an increased magnetic field in the wake. There are however several kinetic features of the interaction. We find kinks in the magnetic field at the wake boundary. There are also density and magnetic field variations in the far wake, maybe from an ion beam instability related to the wake refill. The results are compared to observations by the WIND spacecraft during a wake crossing. The model magnetic field and ion velocities are in agreement with the measurements. The density and the electron temperature in the central wake are not as well captured by the model, probably from the lack of electron physics in the hybrid model.