EMIC wave spatial and coherence scales as determined from multipoint Van Allen Probe measurements

L. W Blum; O Agapitov; J. W Bonnell; C Kletzing; J Wygant

doi:10.1002/2016GL068799

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EMIC wave spatial and coherence scales as determined from multipoint Van Allen Probe measurements

Journal article

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EMIC wave spatial and coherence scales as determined from multipoint Van Allen Probe measurements

L. W Blum, O Agapitov, J. W Bonnell, C Kletzing and J Wygant

Geophysical research letters, Vol.43(10), pp.4799-4807

05/28/2016

DOI: 10.1002/2016GL068799

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Abstract

Electromagnetic ion cyclotron (EMIC) waves can provide a strong source of energetic electron pitch angle scattering. These waves are often quite localized, thus their spatial extent can have a large effect on their overall scattering efficiency. Using measurements from the dual Van Allen Probes, we examine four EMIC wave events observed simultaneously on the two probes at varying spacecraft separations. Correlation of both the wave amplitude and phase observed at both spacecraft is examined to estimate the active region and coherence scales of the waves. We find well‐correlated wave amplitude and amplitude modulation across distances spanning hundreds to thousands of kilometers. Phase coherence persisting 30–60 s is observable during close conjunction events but is lost as spacecraft separations exceed ~1 Earth Radii. Key Points Multipoint Van Allen Probe measurements are used to investigate EMIC wave amplitude and phase correlation at varying spacecraft separations EMIC wave active regions can span Earth radii and persist for hours Phase coherence scales of these waves break down somewhere between a few 100 to few 1000 km

coherence scales

EMIC waves

multipoint measurements

Details

Title: Subtitle: EMIC wave spatial and coherence scales as determined from multipoint Van Allen Probe measurements
Creators: L. W Blum - University of California, Berkeley
O Agapitov - University of California, Berkeley
J. W Bonnell - University of California, Berkeley
C Kletzing - University of Iowa
J Wygant - University of Minnesota
Resource Type: Journal article
Publication Details: Geophysical research letters, Vol.43(10), pp.4799-4807
DOI: 10.1002/2016GL068799
ISSN: 0094-8276
eISSN: 1944-8007
Number of pages: 9
Grant note: NSF Atmospheric and Geospace Sciences (AGS) Postdoctoral Fellowship JHU/APL (922613)
Language: English
Date published: 05/28/2016
Academic Unit: Physics and Astronomy
Record Identifier: 9984199857102771

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