Substorm Driven Chorus Waves: Decay Timescales and Implications for Pulsating Aurora

Riley N. Troyer; Allison N. Jaynes; David P. Hartley; Nigel P. Meredith; Man Hua; Jacob Bortnik

doi:10.1029/2023JA031883

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Substorm Driven Chorus Waves: Decay Timescales and Implications for Pulsating Aurora

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Substorm Driven Chorus Waves: Decay Timescales and Implications for Pulsating Aurora

Riley N. Troyer, Allison N. Jaynes, David P. Hartley, Nigel P. Meredith, Man Hua and Jacob Bortnik

Journal of geophysical research. Space physics, Vol.129(1), e2023JA031883

01/2024

DOI: 10.1029/2023JA031883

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Abstract

Energetic electron precipitation (EEP) associated with pulsating aurora can transfer greater than 30 keV electrons from the outer radiation belt region into the upper atmosphere and can deplete atmospheric ozone via collisions that produce NOx and HOx molecules. Our knowledge of exactly how EEP occurs is incomplete. Previous studies have shown that pitch angle scattering between electrons and lower‐band chorus waves can cause pulsating aurora associated with EEP and that substorms play an important role. In this work, we quantify the timescale of chorus wave decay following substorms and compare that to previously determined timescales. We find that the chorus decay e‐folding time varies based on magnetic local time (MLT), magnetic latitude, and wave frequency. The shortest timescales occur for lower‐band chorus in the 21 to 9 MLT region and compares, within uncertainty, to the energetic pulsating aurora timescale of Troyer et al. (2022, https://doi.org/10.3389/fspas.2022.1032552 ) for energetic pulsating aurora. We are able to further support this connection by modeling our findings in a quasi‐linear diffusion simulation. These results provide observations of how chorus waves behave after substorms and add additional statistical evidence linking energetic pulsating aurora to substorm driven lower‐band chorus waves. Key Points Chorus waves exponentially decay with a timescale on the order of an hour in the quiet period following substorms This decay timescale varies based on magnetic local time, magnetic latitude, and wave frequency Lower‐band chorus waves between 21 and 5 magnetic local time decay with a similar timescale to energetic pulsating aurora electrons after substorms

pulsating aurora

chorus wave

lower band chorus

substorm

decay timescale

energetic electron precipitation

UIOWA OA Agreement

Details

Title: Subtitle: Substorm Driven Chorus Waves: Decay Timescales and Implications for Pulsating Aurora
Creators: Riley N. Troyer - University of Iowa
Allison N. Jaynes - University of Iowa
David P. Hartley - University of Iowa
Nigel P. Meredith - British Antarctic Survey
Man Hua - University of California, Los Angeles
Jacob Bortnik - University of California, Los Angeles
Resource Type: Journal article
Publication Details: Journal of geophysical research. Space physics, Vol.129(1), e2023JA031883
DOI: 10.1029/2023JA031883
ISSN: 2169-9380
eISSN: 2169-9402
Publisher: Wiley
Grant note: Goddard Space Flight Center. Grant Number: 80NSSC20K1514 National Science Foundation. Grant Numbers: 2225613, 2247255 Natural Environment Research Council. Grant Numbers: NE/V00249X/1, NE/R016038/1 National Aeronautics and Space Administration. Grant Numbers: 2045016, 80NSSC20K1514 University of Iowa University of California, Los Angeles Office of Nuclear Energy
Language: English
Date published: 01/2024
Academic Unit: Physics and Astronomy; University College Courses
Record Identifier: 9984544955802771

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