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Examination of Radiation Belt Dynamics During Substorm Clusters: Magnetic Local Time Variation and Intensity of Precipitating Fluxes.

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Title: Examination of Radiation Belt Dynamics During Substorm Clusters: Magnetic Local Time Variation and Intensity of Precipitating Fluxes.
Authors: Rodger, Craig J.1 (AUTHOR) craig.rodger@otago.ac.nz, Clilverd, Mark A.2 (AUTHOR), Hendry, Aaron T.1 (AUTHOR), Forsyth, Colin3 (AUTHOR)
Source: Journal of Geophysical Research. Space Physics. Dec2022, Vol. 127 Issue 12, p1-24. 24p.
Subject Terms: *Geomagnetism, Radiation belts, Low earth orbit satellites, Magnetic declination
Abstract: Substorms are short‐lived but significant reconfigurations of the geomagnetic field during which energetic particles are injected into the inner magnetosphere close to magnetic midnight. There is currently a need to quantify substorm‐driven energetic electron precipitation (EEP) to better understand its role in radiation belt dynamics and to quantify its impact on the atmosphere. As substorm injections trigger chorus waves, which have strong MLT, AE, and L‐shell dependence, we investigate the dependence of EEP in terms of these variables. We utilize many decades of low Earth orbit satellite observations to examine the typical statistical variability around substorm events identified by the Substorm Onsets and Phases from Indices of the Electrojet (SOPHIE) algorithm. In contrast to trapped flux enhancements, enhanced EEP is found to occur even for the quietest AE range of those considered (AE ≤ 100 nT, 100 nT < AE ≤ 300 nT, AE ≥ 300 nT). The MLT‐dependent analysis for all AE‐ranges shows a well‐defined variation in >30 keV EEP magnitude, with a distinct and deep minimum in the late afternoon sector (15–18 MLT), and maxima in the mid to late morning sector (6–12 MLT). The patterns show similarities to previously published whistler‐mode lower band chorus distributions with MLT. Clusters of substorms reliably produce enhancements in electron precipitation for >30 keV and >300 keV, with steadily increasing peak precipitation magnitudes with increasing AE. The peak precipitation flux L‐shell also moves inwards with increasing AE, in a similar way for the two energy ranges. Key Points: Magnetospheric substorm clusters produces energetic electron precipitation peaking in flux ∼2 hr after onsetThe precipitation of >30 keV electrons has a well‐defined pattern in Magnetic Local Time and L‐shell, peaking in the morning sectorIncreasing AE geomagnetic disturbance is found to be a good proxy of both >30 and > 300 keV peak precipitation flux for these events [ABSTRACT FROM AUTHOR]
Copyright of Journal of Geophysical Research. Space Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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  Data: Examination of Radiation Belt Dynamics During Substorm Clusters: Magnetic Local Time Variation and Intensity of Precipitating Fluxes.
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  Data: &lt;searchLink fieldCode=&quot;AR&quot; term=&quot;%22Rodger%2C+Craig+J%2E%22&quot;&gt;Rodger, Craig J.&lt;/searchLink&gt;&lt;relatesTo&gt;1&lt;/relatesTo&gt; (AUTHOR)&lt;i&gt; craig.rodger@otago.ac.nz&lt;/i&gt;&lt;br /&gt;&lt;searchLink fieldCode=&quot;AR&quot; term=&quot;%22Clilverd%2C+Mark+A%2E%22&quot;&gt;Clilverd, Mark A.&lt;/searchLink&gt;&lt;relatesTo&gt;2&lt;/relatesTo&gt; (AUTHOR)&lt;br /&gt;&lt;searchLink fieldCode=&quot;AR&quot; term=&quot;%22Hendry%2C+Aaron+T%2E%22&quot;&gt;Hendry, Aaron T.&lt;/searchLink&gt;&lt;relatesTo&gt;1&lt;/relatesTo&gt; (AUTHOR)&lt;br /&gt;&lt;searchLink fieldCode=&quot;AR&quot; term=&quot;%22Forsyth%2C+Colin%22&quot;&gt;Forsyth, Colin&lt;/searchLink&gt;&lt;relatesTo&gt;3&lt;/relatesTo&gt; (AUTHOR)
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  Data: *&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Geomagnetism%22&quot;&gt;Geomagnetism&lt;/searchLink&gt;&lt;br /&gt;&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Radiation+belts%22&quot;&gt;Radiation belts&lt;/searchLink&gt;&lt;br /&gt;&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Low+earth+orbit+satellites%22&quot;&gt;Low earth orbit satellites&lt;/searchLink&gt;&lt;br /&gt;&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Magnetic+declination%22&quot;&gt;Magnetic declination&lt;/searchLink&gt;
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: Substorms are short‐lived but significant reconfigurations of the geomagnetic field during which energetic particles are injected into the inner magnetosphere close to magnetic midnight. There is currently a need to quantify substorm‐driven energetic electron precipitation (EEP) to better understand its role in radiation belt dynamics and to quantify its impact on the atmosphere. As substorm injections trigger chorus waves, which have strong MLT, AE, and L‐shell dependence, we investigate the dependence of EEP in terms of these variables. We utilize many decades of low Earth orbit satellite observations to examine the typical statistical variability around substorm events identified by the Substorm Onsets and Phases from Indices of the Electrojet (SOPHIE) algorithm. In contrast to trapped flux enhancements, enhanced EEP is found to occur even for the quietest AE range of those considered (AE ≤ 100 nT, 100 nT &lt; AE ≤ 300 nT, AE ≥ 300 nT). The MLT‐dependent analysis for all AE‐ranges shows a well‐defined variation in &gt;30 keV EEP magnitude, with a distinct and deep minimum in the late afternoon sector (15–18 MLT), and maxima in the mid to late morning sector (6–12 MLT). The patterns show similarities to previously published whistler‐mode lower band chorus distributions with MLT. Clusters of substorms reliably produce enhancements in electron precipitation for &gt;30 keV and &gt;300 keV, with steadily increasing peak precipitation magnitudes with increasing AE. The peak precipitation flux L‐shell also moves inwards with increasing AE, in a similar way for the two energy ranges. Key Points: Magnetospheric substorm clusters produces energetic electron precipitation peaking in flux ∼2 hr after onsetThe precipitation of &gt;30 keV electrons has a well‐defined pattern in Magnetic Local Time and L‐shell, peaking in the morning sectorIncreasing AE geomagnetic disturbance is found to be a good proxy of both &gt;30 and &gt; 300 keV peak precipitation flux for these events [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
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  Data: &lt;i&gt;Copyright of Journal of Geophysical Research. Space Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder&#39;s express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.&lt;/i&gt; (Copyright applies to all Abstracts.)
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        Value: 10.1029/2022JA030750
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      – Code: eng
        Text: English
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        PageCount: 24
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    Subjects:
      – SubjectFull: Geomagnetism
        Type: general
      – SubjectFull: Radiation belts
        Type: general
      – SubjectFull: Low earth orbit satellites
        Type: general
      – SubjectFull: Magnetic declination
        Type: general
    Titles:
      – TitleFull: Examination of Radiation Belt Dynamics During Substorm Clusters: Magnetic Local Time Variation and Intensity of Precipitating Fluxes.
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            NameFull: Clilverd, Mark A.
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            – D: 01
              M: 12
              Text: Dec2022
              Type: published
              Y: 2022
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              Value: 127
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