[P-EM14] Study of coupling processes in solar-terrestrial system

[PEM14-07] Interaction between magnetic field topology and plasma dynamics of the solar wind-magnetosphere system in the northward IMF condition

*Shigeru Fujita¹, Masakazu Watanabe², Takashi Tanaka², DongSheng CAI³ (1.Research Organization of Information and Systems, Joint Support-Center for Data Science Research/The Institute of Statistical Mathematics, 2.International Research Center for Space and Planetary Environmental Science, Kyushu University, 3.University of Tsukuba)

Keywords:topology of magnetosphere, plasma dynamics, skeleton magnetic field

Fujita, et al. [2025] demonstrated that the quasi-steady magnetic field structure of the solar wind-magnetosphere system in the northward IMF condition is determined from the interaction between the ground-state magnetic field consisting of the superposition of the Earth’s dipole field and the uniform IMF and solar-wind plasmas. In addition, in this IMF condition, the 2 null - 2 separator structure (the torus-cylinder structure) is conserved when the solar wind plasmas deform the skeletal field structure. Following this research, we will discuss in detail the interaction between the magnetic field topology and the plasma dynamics. The following are the topics concerned;The plasma pressure distribution in the magnetotail is determined mainly by the obstruction of the solar-wind plasmas by the Earth, which in turn creates a plasma shadow on the night side in the typical solar wind condition with northward IMF.The mechanism by which the high-pressure plume structure that penetrates the lobe is generated is that the plasma is convected to the tail due to the slit structure of the magnetic field lines, and interchange instability creates a plasma structure that extends into the lobe.The plasma pressure in the plasma sheet is transported through the slit structure.The behavior of the magnetic field and plasma associated with the reconnection is not symmetric on the dayside and night side of the null point. On the dayside, the over-draping field appears in the region between the cylinder and the torus. Plasmas in the solar wind penetrate the magnetosphere across the cylinder. On the other hand, the over-draping field is created outside of the cylinder on the night side. Plasmas in the lobe are transported to the solar wind region (the magnetosheath) from the inside of the cylinder (the lobe).We will pick up one or two topics in the talk.
References
Fujita, et al. (2025), Fundamental physical processes of the steady solar wind-magnetosphere system in the northward IMF condition, to be submitted to EPS.