Hybrid simulations of the cusp and dayside magnetosheath dynamics under \ quasi-radial interplanetary magnetic fields

TL;DR

This study uses 3D hybrid simulations to explore how quasi-radial IMF affects Earth's magnetosheath and cusps, revealing different plasma behaviors under northward and southward IMF conditions.

Contribution

It provides new insights into the magnetosheath and cusp dynamics under quasi-radial IMF using detailed hybrid simulations, highlighting the effects of foreshock turbulence.

Findings

Plasma depletion layer forms outside the northern cusp under northward IMF.

Southward IMF causes density enhancements in the cusp due to turbulence and reconnection.

Magnetic field configurations vary significantly between IMF orientations.

Abstract

Under quasi-radial interplanetary magnetic fields (IMF), foreshock turbulence can have an impact on the magnetosheath and cusps depending on the location of the quasi-parallel shock. We perform three-dimensional simulations of Earth's dayside magnetosphere using the hybrid code HYPERS, and compare northward and southward quasi-radial IMF configurations. We study the magnetic field configuration, fluctuations in the magnetosheath and the plasma in the regions around the northern cusp. Under northward IMF with Earthward $B_x$, there is a time-varying plasma depletion layer immediately outside the northern cusp. In the southward IMF case, the impact of foreshock turbulence and high-speed jets, together with magnetopause reconnection, can lead to strong density enhancements in the cusp.