Multi-point observations of VLF quasi-periodic emissions: Results from Arase, PWING and Van Allen Probes.
Abstract
Extremely Low (ELF) and Very Low Frequency (VLF) emissions are naturally occurring magnetospheric plasma waves with frequencies between 3 Hz and 30 kHz. They help regulate the electron population in the radiation belts through wave-particle interactions. VLF emissions with a fairly regular periodic modulation of their wave intensity are known as quasi-periodic (QP). We report a unique study on the characteristics of QP emissions at subauroral latitudes and the properties of their source region based on multi-point observations on the ground and in space. We used the observation timings from two ground stations on the dayside, Kapuskasing (KAP, MLAT=58.7N, L=3.7) and Athabasca (ATH, MLAT=61.2N, L=4.3) with that of Kannushleto (KAN, 67.74°N 26.27°E, MLAT=64.4°N, L=5.3) in the post-midnight sector, to study the spatial extent of the QP emissions and locate their source(s). We combine ground based measurements with satellite data provided by Arase/ERG, in conjunction with KAN, and Van Allen Probes A and B, located between KAP and KAN, at the time of the observations. This event is characterized by a large amount of space and ground-based data as it is the first time that QP emissions have been simultaneously monitored by several longitudinally-separated ground stations and spacecrafts. We investigated interesting spectral features observed by the ground-stations and satellites. Ground-based magnetometer data will be applied to determine the correlation with geomagnetic pulsations. Comparing ground and space measurements, we identified whether the characteristic periodicity of the waves is related to their propagation or to generation effects at their source. Using in-situ satellite data, we discuss the properties of the source region and investigate the influence of longitudinal density variations on wave generation and propagation.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFMSM51B2431M
- Keywords:
-
- 7829 Kinetic waves and instabilities;
- SPACE PLASMA PHYSICS;
- 7836 MHD waves and instabilities;
- SPACE PLASMA PHYSICS;
- 7867 Wave/particle interactions;
- SPACE PLASMA PHYSICS;
- 7954 Magnetic storms;
- SPACE WEATHER