Observations of chorus at sun-synchronous orbit
Abstract
Using the data of the DEMTER satellite during the magnetic storm on 14 April 2006, we study the storm time VLF electromagnetic waves, and find the first observational evidence of chorus waves propagating to high latitude and entering the plasmasphere. During this geomagnetic storm, ';banded' emissions of a few hertz to 20 kHz are observed to be intensified and to be organized in the frequency range of 0.1-0.5fce (equatorial electron cyclotron frequency) in high latitude region of magnetic latitude between ~40°to ~60°. The signatures in the wave power spectra suggest these emissions are likely lower-band chorus. We also investigate the spatial coverage and temporal variation of the observed high-latitude chorus emissions and their relation to plasmapause locations. It is convincing that the plasmapause location obtained from the observations by DEMETER and the one from the empirical model are consistent. The observed chorus waves are generally outside the plasmasphere. However, interestingly, these waves are frequently observed inside the plasmasphere at regions with low L value during the main phase and early recover phase, which has never been reported in previous studies of chorus in low latitude regions. The present study gives observational supports for the theory and simulations suggesting that chorus waves propagate into the plasmasphere and evolve into hiss waves.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMSM41A2214Z
- Keywords:
-
- 2431 IONOSPHERE Ionosphere/magnetosphere interactions;
- 2736 MAGNETOSPHERIC PHYSICS Magnetosphere/ionosphere interactions;
- 2772 MAGNETOSPHERIC PHYSICS Plasma waves and instabilities;
- 2774 MAGNETOSPHERIC PHYSICS Radiation belts