How do Ultra‐Low Frequency waves access the inner magnetosphere during geomagnetic storms?

Jonathan Rae, Kyle Murphy, Clare Watt, Jasmine Sandhu, Marina Georgiou, Alex Degeling, Colin Forsyth, Sarah Bentley, Frances Staples, Quanqi Shi

Research output: Contribution to journalLetterpeer-review

21 Citations (Scopus)
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Wave‐particle interactions play a key role in radiation belt dynamics. Traditionally, ultra‐low frequency (ULF) wave‐particle interaction is parameterized statistically by a small number of controlling factors for given solar wind driving conditions or geomagnetic activity levels. Here we investigate solar wind driving of ULF wave power and the role of the magnetosphere in screening that power from penetrating deep into the inner magnetosphere. We demonstrate that during enhanced ring current intensity, the Alfvén continuum plummets, allowing lower frequency waves to penetrate deeper into the magnetosphere than during quiet periods. With this penetration, ULF wave power is able to accumulate closer to the Earth than characterized by statistical models. During periods of enhanced solar wind driving such as coronal mass ejection driven storms, where ring current intensities maximize, the observed penetration provides a simple physics‐based reason for why storm time ULF wave power is different compared to nonstorm time waves.
Original languageEnglish
Pages (from-to)10699-10709
Number of pages11
JournalGeophysical Research Letters
Issue number19
Early online date11 Oct 2019
Publication statusPublished - 16 Oct 2019
Externally publishedYes


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