Resonance maps for 3D Alfvén waves in a compressed dipole field
Abstract
Resonance Maps depict the possible locations and polarisations of resonant Alfvén waves (Field Line Resonances – FLRs) for a given equilibrium and driving frequency. Previously the use of Resonance Maps has been developed for gaining insight into the behavior of Alfvén waves in basic potential magnetic fields that allow the use of an orthogonal field aligned coordinate system. In more general magnetic fields these coordinates do not exist. In this paper we explore the application of Resonance Maps to such equilibria. A number of simulations of resonant Alfvén waves are presented and interpreted using the Maps. We find that Resonance Maps remain useful when some of the constructions used previously are generalised to accommodate the properties of more general magnetic fields. For example, Resonance Maps are able to predict the location and polarisation of Alfvén waves which are driven strongly by fast mode waves using a “tangential alignment condition”. Unusual properties, such as Alfvén waves crossing flux surfaces persist in the more general magnetic fields we consider.
Citation
Wright , A , Degeling , A & Elsden , T 2022 , ' Resonance maps for 3D Alfvén waves in a compressed dipole field ' , Journal of Geophysical Research: Space Physics , vol. 127 , no. 4 , e2022JA030294 . https://doi.org/10.1029/2022JA030294
Publication
Journal of Geophysical Research: Space Physics
Status
Peer reviewed
ISSN
2169-9402Type
Journal article
Description
Funding: Science and Technology Facilities Council (Grant Number(s): ST/N000609/1); National Natural Science Foundation of China (Grant Number(s): 41774172); Leverhulme Trust (Grant Number(s): ECF-2019-155).Collections
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