Journal article
Coherently modulated whistler mode waves simultaneously observed over unexpectedly large spatial scales
Journal of geophysical research. Space physics, Vol.122(2), pp.1871-1882
02/2017
DOI: 10.1002/2016JA023706
Abstract
Utilizing simultaneous twin Van Allen Probes observations of whistler mode waves at variable separations, we are able to distinguish the temporal variations from spatial variations, determine the coherence spatial scale, and suggest the possible mechanism of wave modulation. The two probes observed coherently modulated whistler mode waves simultaneously at an unexpectedly large distance up to ~4.3 RE over 3 h during a relatively quiet period. The modulation of 150–500 Hz plasmaspheric hiss was correlated with whistler mode waves measured outside the plasmasphere across 3 h in magnetic local time and 3 L shells, revealing that the modulation was temporal in nature. We suggest that the coherent modulation of whistler mode waves was associated with the coherent ULF waves measured over a large scale, which modulate the plasmaspheric density and result in the modulation of hiss waves via local amplification. In a later period, the 500–1500 Hz periodic rising‐tone whistler mode waves were strongly correlated when the two probes traversed large spatial regions and even across the plasmapause. These periodic rising‐tone emissions recurred with roughly the same period as the ULF wave, but there was no one‐to‐one correspondence, and a cross‐correlation analysis suggests that they possibly originated from large L shells although the actual cause needs further investigation.
Key Points
Coherently modulated whistler mode waves are continuously observed over unexpectedly large spatial scales up to 4.3 RE
Wave coherence depends on frequency and changes with different spacecraft spatial configurations
The sources of coherently modulated waves in each phase are investigated by cross correlations and electron anisotropy
Details
- Title: Subtitle
- Coherently modulated whistler mode waves simultaneously observed over unexpectedly large spatial scales
- Creators
- Jinxing Li - University of California, Los AngelesJacob Bortnik - University of California, Los AngelesWen Li - Boston UniversityRichard M Thorne - University of California, Los AngelesQianli Ma - University of California, Los AngelesXiangning Chu - University of California, Los AngelesLunjin Chen - University of Texas at DallasCraig A Kletzing - University of IowaWilliam S Kurth - University of IowaGeorge B Hospodarsky - University of IowaJohn Wygant - University of MinnesotaAaron Breneman - University of MinnesotaScott Thaller - University of Minnesota
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.122(2), pp.1871-1882
- DOI
- 10.1002/2016JA023706
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Number of pages
- 12
- Grant note
- ECT (13‐041; 967399; 921647) NSF Geospace Environment Modeling (AGS‐1723342) JHU/APL NASA (NNX13AI61G; NNX14AN85G; NNX11AR64G; NNX17AD15G; NNX15AI96G) EMFISIS (1001057397:01)
- Language
- English
- Date published
- 02/2017
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984199719102771
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