How Do Ultra‐Low Frequency Waves Access the Inner Magnetosphere During Geomagnetic Storms?

Rae, Jonathan, Murphy, Kyle R., Watt, Clare, Sandhu, Jasmine K., Georgiou, Marina, Degeling, Alex W., Forsyth, Colin, Bentley, Sarah, Staples, Frances A. and Shi, Quanqi (2019) How Do Ultra‐Low Frequency Waves Access the Inner Magnetosphere During Geomagnetic Storms? Geophysical Research Letters, 46 (19). pp. 10699-10709. ISSN 0094-8276

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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.

Item Type: Article
Uncontrolled Keywords: ULF waves, storm time, radiation belt, wave penetration
Subjects: F500 Astronomy
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: John Coen
Date Deposited: 05 Oct 2020 14:01
Last Modified: 31 Jul 2021 13:00

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