Premium
Spatial Extent and Temporal Correlation of Chorus and Hiss: Statistical Results From Multipoint THEMIS Observations
Author(s) -
Agapitov O.,
Mourenas D.,
Artemyev A.,
Mozer F. S.,
Bonnell J. W.,
Angelopoulos V.,
Shastun V.,
Krasnoselskikh V.
Publication year - 2018
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2018ja025725
Subject(s) - chorus , hiss , physics , van allen radiation belt , amplitude , van allen probes , geophysics , computational physics , magnetosphere , magnetic field , electron , optics , nuclear physics , art , literature , quantum mechanics
The spatial localization of whistler mode waves, determined by their generation process, propagation, and damping, is important for assessing the efficiency of wave‐particle interactions and the dynamics of the radiation belts. We use 11 years of multipoint wave measurements in 2007–2017 from five Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft covering L = 2–10 at low magnetic latitudes over all magnetic local times (MLTs) to characterize both the instantaneous spatial extent of chorus and hiss active regions and their wave amplitude distribution in the vicinity of their respective generation regions, making use of the time domain correlation technique. The correlation of lower band chorus wave power dynamics from two spacecraft measurements remains significant up to 250–800 km transverse to the background magnetic field, in agreement with the typical scale of a chorus element, with a shorter correlation length for higher peak wave power. Additionally, a coordinated analysis of average chorus amplitudes at separate locations shows that the radial extent of the chorus active region varies from 0.2 R E on the nightside to 1 R E on the dayside, with an azimuthal width of 1 MLT. The wave power correlation scale of hiss has no fine structure and is generally larger (1,500–3,000 km); its correlation remains nonnegligible up to 1.5 R E . Such observations are consistent with chorus generation by localized electron injections and subsequent hiss amplification at lower L shells from seed chorus waves having propagated and spread over a wider region inside the plasmasphere. The connection between hiss and chorus is further explored statistically through the correlation between their respective wave power variations, suggesting a significant link between them.