Van Allen probes, NOAA, GOES, and ground observations of an intense EMIC wave event extending over 12 h in magnetic local time

Engebretson, M. J.; Posch, J. L.; Wygant, J. R.; Kletzing, C. A.; Lessard, M. R.; Huang, C.-L.; Spence, H. E.; Smith, C. W.; Singer, H. J.; Omura, Y.; Horne, R. B. ORCID: https://orcid.org/0000-0002-0412-6407; Reeves, G. D.; Baker, D. N.; Gkioulidou, M.; Oksavik, K.; Mann, I. R.; Raita, T .; Shiokawa, K.. 2015 Van Allen probes, NOAA, GOES, and ground observations of an intense EMIC wave event extending over 12 h in magnetic local time. Journal of Geophysical Research: Space Physics, 120 (7). 5465-5488. https://doi.org/10.1002/2015JA021227

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Abstract/Summary

Although most studies of the effects of EMIC waves on Earth's outer radiation belt have focused on events in the afternoon sector in the outer plasmasphere or plume region, strong magnetospheric compressions provide an additional stimulus for EMIC wave generation across a large range of local times and L shells. We present here observations of the effects of a wave event on February 23, 2014 that extended over 8 hours in UT and over 12 hours in local time, stimulated by a gradual 4-hour rise and subsequent sharp increases in solar wind pressure. Large-amplitude linearly polarized hydrogen band EMIC waves (up to 25 nT p-p) appeared for over 4 hours at both Van Allen Probes, from late morning through local noon, when these spacecraft were outside the plasmapause, with densities ~5-20 cm-3. Waves were also observed by ground-based induction magnetometers in Antarctica (near dawn), Finland (near local noon), Russia (in the afternoon), and in Canada (from dusk to midnight). Ten passes of NOAA-POES and METOP satellites near the northern footpoint of the Van Allen Probes observed 30-80 keV subauroral proton precipitation, often over extended L shell ranges; other passes identified a narrow L-shell region of precipitation over Canada. Observations of relativistic electrons by the Van Allen Probes showed that the fluxes of more field-aligned and more energetic radiation belt electrons were reduced in response to both the emission over Canada and the more spatially extended emission associated with the compression, confirming the effectiveness of EMIC-induced loss processes for this event.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1002/2015JA021227
Programmes:	BAS Programmes > BAS Programmes 2015 > Space Weather and Atmosphere
ISSN:	21699380
Additional Keywords:	EMIC waves, radiation belts, magnetospheric compressions
Date made live:	01 Jul 2015 10:54 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/511210

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