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ORIGINAL RESEARCH article
Front. Astron. Space Sci.
Sec. Space Physics
Volume 11 - 2024 |
doi: 10.3389/fspas.2024.1442009
This article is part of the Research Topic Particle Precipitation in the Earth and Other Planetary Systems: Sources and Impacts View all 8 articles
The Global Mapping of Electron Precipitation and Ionospheric Conductance from Whistler-Mode Chorus Waves
Provisionally accepted- 1 University of Alaska Fairbanks, Fairbanks, United States
- 2 Goddard Space Flight Center, National Aeronautics and Space Administration, Greenbelt, Maryland, United States
- 3 The University of Texas at Dallas, Richardson, Texas, United States
- 4 University of California, Los Angeles, Los Angeles, California, United States
- 5 Boston University, Boston, Massachusetts, United States
Auroral precipitation is the second major energy source after solar irradiation that ionizes the Earth's upper atmosphere. Diffuse electron aurora caused by wave-particle interaction in the inner magnetosphere (L<8) takes over 60% of total auroral energy flux, strongly contributing to the ionospheric conductance and thus to the ionosphere-thermosphere dynamics. This paper quantifies the impact of chorus waves on the diffuse aurora and the ionospheric conductance during quiet, medium, and strong geomagnetic activities, parameterized by AE <100, 100 < AE < 300, and AE > 300, respectively. Using chorus wave statistics and inner-magnetosphere plasma conditions from Timed History Events and Macroscale Interactions during Substorms (THEMIS) observations, we directly derive the energy spectrum of diffuse electron precipitation under quasi-linear theory. We then calculate the height-integrated conductance from the wavedriven aurora spectrum using the electron impact ionization model of Fang et al. (2010) and the MSIS atmosphere model. By utilizing Fang's ionization model, the US Naval Research Laboratory Mass Spectrometer and Incoherent Scattar Radar (NRLMSISE-00) model from 2000s for the neutral atmosphere components, and the University of California, Los Angeles (UCLA) Full Diffusion Code, we improve upon the standard generalization of Maxwellian diffuse electron precipitation patterns and their resulting ionosphere conductance. Our study of global auroral precipitation and ionospheric conductance from chorus wave statistics is the first statistical model of its kind. We show that the total electron flux and conductance pattern from our results agree with those of Ovation Prime model over the pre-midnight to post-dawn sector as geomagnetic activity increases. Our study examines the relative contributions of upper band chorus (UBC) and lower band chorus wave (LBC) driven conductance in the ionosphere. We found LBC waves drove diffuse electron precipitation significantly more than UBC waves, however it is possible that THEMIS data may have underestimated the upper chorus band wave observations for magnetic latitudes below 65°.
Keywords: Diffuse auroral precipitation, Chorus Wave Distributions, Ionospheric conductance, conductance, Wave driven precipitation, Diffuse Electron Aurora
Received: 01 Jun 2024; Accepted: 25 Sep 2024.
Copyright: © 2024 Gillespie, Connor, Zhang, Ma, Shen and Ozturk. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Dillon Gillespie, University of Alaska Fairbanks, Fairbanks, United States
Hyunju K. Connor, University of Alaska Fairbanks, Fairbanks, United States
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