Role of ULF waves in Energetic Particle Transport and Ring Current Dynamics
Thursday, 4 September 2014
Regency Ballroom (Hyatt Regency)
Kyle R Murphy1, Ian Robert Mann2, Jonathan Rae1,3, David G Sibeck4 and Louis Ozeke1,5, (1)University of Alberta, Edmonton, AB, Canada, (2)Univ Alberta, Edmonton, AB, Canada, (3)University College London, Mullard Space Science Laboratory, Dorking, United Kingdom, (4)NASA Goddard Space Flight Center, NASA, Greenbelt, MD, United States, (5)university of alberta, Edmonton, AB, Canada
Abstract:
ULF waves are recognised as playing an important role in the transport of energetic electrons into the outer radiation belt through ULF wave driven radial diffusion. Since the drift frequency of energetic particles is controlled by particle energy and is independent of mass (neglecting any relativistic correction) a similar diffusive transport via ULF wave energisation is also possible for energetic ions. Although the energies of ions and specifically those in the ring current are typically less than those characteristic of electrons in the outer radiation belt, whenever the ULF wave-energetic particle drift resonance condition is satisfied for ring current ions, ULF wave diffusive transport of ions should be expected to be important. Here we examine the correlation between ULF wave power observed inside of the magnetosphere and the response of the ring current as characterised by Dst. We use both standard rank order correlations as well as analyses of the probability distributions for ULF waves and Dst. Our observations show that there is a clear and definitive correlation between ULF wave power and Dst. Significantly, the correlation peaks on the day prior to the Dst response such that the ULF waves precede the response of the ring current. We suggest that this correlation and the enhancements in Dst are the a result of enhanced radial transport and energisation of ring current ions through drift resonance and ULF wave radial diffusion during periods of increased ULF wave activity.
