Van Allen Probes and Arase measurements of whistler mode waves in the Earth’s radiation belts

0504791 - ÚFA 2020 BE eng A - Abstract
Santolík, Ondřej - Hospodarsky, G. B. - Kasahara, Y. - Kurth, W. S. - Miyoshi, Y. - Kletzing, C. A.
Van Allen Probes and Arase measurements of whistler mode waves in the Earth’s radiation belts.
URSI AP-RASC 2019 Proceedings. Gent: URSI, 2019.
[URSI Asia Pacific Radio Science Conference (AT-RASC). 09.03.2019-15.03.2019, New Delhi]
Institutional support: RVO:68378289
Keywords : whistler mode waves * radiation belts * Van Allen Probes * hiss * chorus
OECD category: Fluids and plasma physics (including surface physics)
http://www.ursi.org/proceedings/procAP19/papers2019/URSIAPRASCAbstractsantolik.pdf

Natural emissions of whistler-mode electromagnetic waves, especially chorus and hiss, can influence the
dynamics of the Van Allen radiation belts via quasilinear or nonlinear wave particle interactions. They can play
a role in complex processes of the energy transfer between different electron populations. Average intensities of
chorus and hiss emissions have been found to increase with increasing levels of geomagnetic activity but their
random variations in individual spacecraft measurements are usually stronger than these large-scale temporal
effects. To separate temporal and spatial variations of wave characteristics, measurements at different points in
space are necessary.
We use two-point measurements of the Waves instruments of the Electric and Magnetic Field Instrument Suite
and Integrated Science (EMFISIS) to investigate whistler-mode emissions in the Earth’s radiation belts.
Identical instruments are carried onboard two Van Allen Probes. We systematically analyze their large data sets
which have been collected since 2012 over a range of separation vectors of the two spacecraft. We investigate
similar variations of the whistler-mode wave power occurring at the same time at different places.
The Waves survey data give good orbital coverage in L, latitude, and magnetic local time (MLT) for whistlermode plasmaspheric hiss and chorus. The results show that average and/or median wave power exhibits a flat
peak at MLT ≈ 8-17h and L ≈ 2-4 and that these characteristic values generally increase with geomagnetic
activity while observed random variations are still comparable to the effects of systematic trends.
We also use measurements of the onboard two Van Allen Probes to analyze these waves during conjunctions of
one of the Van Allen Probes spacecraft with the Arase spacecraft at close separations.
Permanent Link: http://hdl.handle.net/11104/0296348