Seminars

Lecturer: Dr Yasuhide Hobara (IRF-Kiruna)
Date: 2005-06-02 10:00
Place: Aniara

High altitude oxygen outflow and subsequent low frequency wave activities: A case study

Cluster satellites observe the significant energized outflowing oxygen ions (mean energy up to 6 keV) around the high-altitude poleward dayside cusp, so-called oxygen outflow burst. These high energy burst oxygen ions are accompanied by the large broadband low frequency electric field activity and rotation of ambient magnetic field vector.

In this study, the scenario explaining the observed high altitude oxygen ion bursts is presented. According to the data analysis (ions and fields) and simple particle simulation, even at the high altitude the wave-article interaction is found to play the important role on the formation of the observed oxygen burst as shown below:

(1)The burst oxygen ions are transversely heated by low frequency waves through the ion cyclotron resonance up to high altitude (7 Re) at the poleward cusp.
(2)Observed mean energy and temperature ratio of the burst oxygen ions (~1) are explained by co-existence of ion cyclotron heating by the low frequency waves, convection drift, and mirror holding. (3)Triggering of the oxygen outflow burst may be related to the solar wind pressure pulse and/or IMF southward turning ~6 minutes before the onset time of the burst.

Created 2005-04-01 13:36:59 by Rick McGregor
Last changed 2005-05-31 15:59:33 by Rick McGregor