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Magnetopause ripples going against the flow form azimuthally stationary surface waves
M O Archer1, M D Hartinger2, F Plaschke3
1Space and Atmospheric Physics Group, Department of Physics, Imperial College London, London, UK. m.archer10@imperial.ac.uk.
Nature Communications
|October 7, 2021
Summary
Magnetopause surface waves, crucial for plasma dynamics, were found to propagate against solar wind flow, challenging established tailward propagation models. This discovery impacts understanding of Earth's magnetosphere and associated phenomena.
Area of Science:
- Space Physics
- Plasma Physics
- Geophysics
Background:
- Surface waves are key drivers of plasma dynamics in various systems.
- The magnetopause is an accessible region for studying these waves.
- Existing paradigms suggest magnetopause surface waves propagate tailward with the solar wind.
Purpose of the Study:
- To investigate the propagation direction of low-frequency magnetopause surface waves.
- To challenge the established paradigm of tailward wave propagation.
- To understand the energy transfer mechanisms at the magnetopause.
Main Methods:
- Multi-spacecraft observations
- Global magnetohydrodynamic (MHD) simulations
- Analytic theory
Main Results:
- Lowest-frequency impulsively-excited magnetopause surface waves propagate against the solar wind flow.
- Wave Poynting flux balances advective effects, causing stationary structure across the magnetic field.
- Downstream, advection dominates, leading to tailward propagation and seeding Kelvin-Helmholtz instability.
Conclusions:
- The established paradigm of tailward propagation of magnetopause surface waves is challenged.
- Wave dynamics at the magnetopause have significant implications for radiation belts, ionosphere, and auroral dynamics.
- Findings offer potential applications for other dynamical plasma systems.
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