SM039-0011
When Pulsating Aurorae and Chorus Waves Don’t Align: Comparing Simultaneous Observations by Gakona All Sky Camera and the Van Allen Probes

Tuesday, 15 December 2020
Poster
Shannon Hill, University of Michigan Ann Arbor, Climate and Space Sciences and Engineering, Ann Arbor, MI, United States, Robert Michell, NASA Goddard Space Flight Center, Geospace Physics Laboratory, Greenbelt, MD, United States, Marilia Samara, NASA Goddard Space Flight Center, Greenbelt, MD, United States, Tuija I Pulkkinen, University of Michigan, Department of Climate and Space Sciences and Engineering, Ann Arbor, United States, Oleksiy V Agapitov, Space Science Laboratory, UCB, Berkeley, CA, United States, Aaron W Breneman, The University of Minnesota, Minneapolis, MN, United States and Sheng Tian, University of Minnesota Twin Cities, School of Physics and Astronomy, Minneapolis, MN, United States
Abstract:
Pulsating aurorae are patches of diffuse auroral emission with pulsation frequencies thought to be connected to the bursts of electron precipitation from lower band chorus waves in the inner magnetosphere. During three nights in Oct 2016, a high time resolution (3 FPS) green-line (557.7 nm) all sky camera was operated at Gakona, AK observed pulsating aurora events during the time when the Van Allen Probe magnetic footpoint crosses the camera’s field of view. The VAP were in waveform burst mode during the crossover events, which enables high time resolution waveform analysis of chorus wave activity. We compare simultaneous observations of pulsating aurora and chorus waves and find that the pulsating aurora events are broadly associated with chorus waves, but the high-resolution emissions in the chorus waves do not correspond with the high frequency pulsations of the aurora. We investigate the lack of correlation between the observed chorus waves and pulsating aurora intensity fluctuations by examining the accuracy of the magnetic field mapping, and by analysis of the Poynting flux directed toward the ionosphere. The magnetic footpoint of the Probes was mapped using the Tsyganenko 89 magnetic field line model for Kp 1, 3, and 5 and the Tsyganenko 96 magnetic field line model using observed solar wind parameters. We then extract the optical intensity fluctuations from the all sky camera at each mapped footpoint and compare to the simultaneous chorus wave emissions. Finally, we use the waveform data to compute the chorus wave Poynting flux magnitude and direction with respect to the ionosphere. We seek to identify particular chorus wave electron resonance conditions that lead to the relationship between chorus waves and pulsating aurorae.
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