Physics – Plasma Physics
Scientific paper
Dec 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufmsm23c..07e&link_type=abstract
American Geophysical Union, Fall Meeting 2011, abstract #SM23C-07
Physics
Plasma Physics
[7845] Space Plasma Physics / Particle Acceleration, [7846] Space Plasma Physics / Plasma Energization, [7867] Space Plasma Physics / Wave/Particle Interactions, [7984] Space Weather / Space Radiation Environment
Scientific paper
Electromagnetic Ion Cyclotron (EMIC) waves result from temperature anisotropies in warm (keV) ions, and have been identified as a potentially important means of removing relativistic electrons from the radiation belts through pitch angle scattering into the drift or bounce loss cone. The temperature anisotropies that lead to EMIC wave growth may be broadly categorized as originating either through particle energization, whereby the ion energy distribution is preferentially increased in the direction perpendicular to the local magnetic field; or through non-energizing processes that change the relative distribution of energy between the parallel and perpendicular directions, without increasing or decreasing the energy of individual particles. An example of an energizing process that may lead temperature anisotropies is radial transport conserving the first adiabatic invariant, such that particles moving into regions of stronger magnetic field are preferentially accelerated in the perpendicular direction. Examples of non-energizing processes that lead to temperature anisotropies include the redistribution of energy that results from the violation of the second adiabatic invariant as particles drift into regions of dayside off-equatorial magnetic minima associated with Shabansky orbits, as well as the effects of drift shell splitting in an asymmetric magnetic field. In this work we examine the origins of EMIC waves observed during 29 June 2007 [Usanova et al., GRL 2008, doi:10.1029/2008GL034458]. The waves occurred over a broad range of dayside local times in association with a pressure impulse in the solar wind. McCollough et al. [JGR 2010, doi:10.1029/2010JA015393] investigated the effect of dayside Shabansky orbits in generating the anisotropy that lead to the waves during this event, and concluded that a non-energizing process associated with breaking of the second adiabatic invariant contributed to the anisotropies in the dayside regions. In this work we use global magnetohydrodynamic (MHD) simulations of the event, combined with test particle simulations of the warm ion populations in the inner magnetosphere and plasmasheet, to examine the contribution of the energizing anisotropies generated by the inward radial transport of ions from the outer reaches of the ring current and near-Earth tail. We calculate EMIC growth rates associated with this process, and contrast the spatiotemporal and spectral characteristics of these waves with those that arise from drift shell splitting and Shabansky orbits alone.
Elkington Scot R.
Mann Ian R.
McCollough J. P.
Usanova M.
No associations
LandOfFree
EMIC wave growth in the magnetosphere: Contrasting energizing and non-energizing sources of anisotropy in the ring current does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with EMIC wave growth in the magnetosphere: Contrasting energizing and non-energizing sources of anisotropy in the ring current, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and EMIC wave growth in the magnetosphere: Contrasting energizing and non-energizing sources of anisotropy in the ring current will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1890474