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

Rae, I. J., Murphy, K. R., Watt, C. E. J., Sandhu, J. K., Georgiou, M., Degeling, A. W., Forsyth, C., Bentley, S., Staples, F. A. and Shi, Q. (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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To link to this item DOI: 10.1029/2019gl082395


Wave‐particle interactions play a key role in radiation belt dynamics. Traditionally, Ultra‐Low Frequency (ULF) wave‐particle interaction is parameterised 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 ultra‐low frequency (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 characterised by statistical models. During periods of enhanced solar wind driving such as coronal mass ejection driven storms, where ring current intensities maximise, the observed penetration provides a simple physics‐based reason for why storm‐time ULF wave power is different compared to non‐storm time waves.

Item Type:Article
Divisions:Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
ID Code:84081
Publisher:American Geophysical Union


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