Waves in planetary dynamos

TL;DR

This paper reviews MHD waves, especially torsional Alfvén and magnetic Rossby waves, in planetary dynamos, highlighting their role in understanding planetary magnetic fields and interior dynamics.

Contribution

It provides a comprehensive overview of wave dynamics in planetary dynamos, emphasizing recent advances and open questions in the study of MHD waves in planetary interiors.

Findings

Evidence of wave excitation in the geodynamo

Potential wave activity in Jupiter's interior

Current understanding of wave dynamics in planetary cores

Abstract

This Special Topic focuses on magnetohydrodynamic (MHD) processes in deep interiors of planets, in which their fluid dynamos are in operation. The dynamo-generated, global, magnetic fields provide a background for our solar-terrestrial environment. Probing the processes within the dynamos is a significant theoretical and computational challenge and any window into interior dynamics greatly increases our understanding. Such a window is provided by exploring rapid dynamics, particularly MHD waves about the dynamo-defined basic state. This field is the subject of current attention as geophysical observations and numerical modellings advance. We give here particular attention to torsional Alfv\'{e}n waves/oscillations and magnetic Rossby waves, which may be regarded as typical axisymmetric and nonaxisymmetric modes, respectively, amongst a wide variety of wave classes of the rapidly-rotating MHD fluids. The excitation of those waves is being evidenced for the geodynamo, whilst also being suggested for Jupiter. We shall overview their dynamics, summarise our current understanding, and give open questions for future perspectives.