Coherently modulated whistler mode waves simultaneously observed over unexpectedly large spatial scales

Jinxing Li; Jacob Bortnik; Wen Li; Richard M Thorne; Qianli Ma; Xiangning Chu; Lunjin Chen; Craig A Kletzing; William S Kurth; George B Hospodarsky; John Wygant; Aaron Breneman; Scott Thaller

doi:10.1002/2016JA023706

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Coherently modulated whistler mode waves simultaneously observed over unexpectedly large spatial scales

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Coherently modulated whistler mode waves simultaneously observed over unexpectedly large spatial scales

Jinxing Li, Jacob Bortnik, Wen Li, Richard M Thorne, Qianli Ma, Xiangning Chu, Lunjin Chen, Craig A Kletzing, William S Kurth, George B Hospodarsky, …

Journal of geophysical research. Space physics, Vol.122(2), pp.1871-1882

02/2017

DOI: 10.1002/2016JA023706

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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

coherent waves

multisatellite

periodic rising tone

whistler mode

Details

Title: Subtitle: Coherently modulated whistler mode waves simultaneously observed over unexpectedly large spatial scales
Creators: Jinxing Li - University of California, Los Angeles
Jacob Bortnik - University of California, Los Angeles
Wen Li - Boston University
Richard M Thorne - University of California, Los Angeles
Qianli Ma - University of California, Los Angeles
Xiangning Chu - University of California, Los Angeles
Lunjin Chen - University of Texas at Dallas
Craig A Kletzing - University of Iowa
William S Kurth - University of Iowa
George B Hospodarsky - University of Iowa
John Wygant - University of Minnesota
Aaron Breneman - University of Minnesota
Scott 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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