Correlated ULF Waves, Whistler-mode Chorus and Pulsating Aurora Observed by the Van Allen Probes and Ground-based Systems

Allison N Jaynes1, Marc Lessard2, Kazue Takahashi3, Ashar Ali4, David Malaspina5, Craig Kletzing6, John R Wygant7, Eric Donovan8, J Bernard Blake9, Robert Michell10,11, Marilia Samara11 and Emma Spanswick8, (1)University of Iowa, Iowa City, IA, United States, (2)University of New Hampshire Main Campus, Durham, NH, United States, (3)Applied Physics Laboratory Johns Hopkins, Laurel, MD, United States, (4)University of Colorado at Boulder, Boulder, CO, United States, (5)University of Colorado, Astrophysical and Planetary Sciences Department, Boulder, United States, (6)University of Iowa, Physics and Astronomy, Iowa City, United States, (7)University of Minnesota Twin Cities, Minneapolis, MN, United States, (8)University of Calgary, Calgary, AB, Canada, (9)Aerospace Corporation Santa Monica, Santa Monica, CA, United States, (10)University of Maryland, College Park, MD, United States, (11)NASA Goddard Space Flight Center, Greenbelt, MD, United States

Contact First Author: Allison N Jaynes; allison-n-jaynes@uiowa.edu

Previously Published Material: Preliminary findings reported at LWS meeting (Oct 2014) and more analysis reported at AGU (Dec 2014). Final work is expected to be published before Joint Assembly in the Pulsating Aurora special issue of JGR.

Abstract ID#: 35354

 

English Abstract:
Theory and observations have linked equatorial VLF waves with pulsating aurora for decades, invoking the process of pitch-angle scattering of 10's keV electrons in the equatorial magnetosphere. Recent satellite studies have strengthened this argument, by showing strong correlation between pulsating auroral patches and (1) lower-band chorus observed by THEMIS and (2) 30-100 keV electron modulation in the vicinity of geosynchronous orbit observed by GOES. Additionally, a link has been made between Pc4-5 compressional pulsations and modulation of whistler-mode chorus using THEMIS. Here we present simultaneous in-situ observations of structured chorus waves and an apparent field line resonance as a result of a substorm injection, observed by Van Allen Probes, along with ground-based observations of pulsating aurora. We demonstrate the possible scenario being one of substorm-driven ULF pulsations modulating chorus waves, and thus providing the driver for pulsating particle precipitation into the Earth's atmosphere. We also show, for the first time, a particular 3-Hz modulation of individual chorus elements. Such modulation has been noticed as a high-frequency component in camera data of pulsating aurora for decades, and is possibly a result of nonlinear chorus wave interactions.
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