View in EDS

Comparing Influences of Solar Wind, ULF Waves, and Substorms on 20 eV–2 MeV Electron Flux (RBSP) Using ARMAX Models.

Saved in:
Bibliographic Details
Title: Comparing Influences of Solar Wind, ULF Waves, and Substorms on 20 eV–2 MeV Electron Flux (RBSP) Using ARMAX Models.
Authors: Simms, L. E.1,2 (AUTHOR) laurasim@umich.edu, Ganushkina, N. Y.1,3 (AUTHOR), Dubyagin, S.3 (AUTHOR)
Source: Journal of Geophysical Research. Space Physics. Jun2024, Vol. 129 Issue 6, p1-18. 18p.
Subject Terms: *Magnetic storms, Solar wind, Time series analysis, Electrons, Wind pressure, Radiation belts
Abstract: Electron fluxes (20 eV–2 MeV, RBSP‐A satellite) show reasonable simple correlation with a variety of parameters (solar wind, IMF, substorms, ultralow frequency (ULF) waves, geomagnetic indices) over L‐shells 2–6. Removing correlation‐inflating common cycles and trends (using autoregressive and moving average terms in an ARMAX analysis) results in a 10 times reduction in apparent association between drivers and electron flux, although many are still statistically significant (p < 0.05). Corrected influences are highest in the 20 eV–1 keV and 1–2 MeV electrons, more modest in the midrange (2–40 keV). Solar wind velocity and pressure (but not number density), IMF magnitude (with lower influence of Bz), SME (a substorm measure), a ULF wave index, and geomagnetic indices Kp and SymH all show statistically significant associations with electron flux in the corrected individual ARMAX analyses. We postulate that only pressure, ULF waves, and substorms are direct drivers of electron flux and compare their influences in a combined analysis. SME is the strongest influence of these three, mainly in the eV and MeV electrons. ULF is most influential on the MeV electrons. Pressure shows a smaller positive influence and some indication of either magnetopause shadowing or simply compression on the eV electrons. While strictly predictive models may improve forecasting ability by including indirect driver and proxy parameters, and while these models may be made more parsimonious by choosing not to explicitly model time series behavior, our present analyses include time series variables in order to draw valid conclusions about the physical influences of exogenous parameters. Plain Language Summary: High levels of satellite‐damaging electrons (both high and low energy) in the radiation belts appear to be driven by substorms and ultralow frequency waves. There is a positive association between these variables and electron levels even when the cycling behavior of satellite‐derived data is corrected. Solar wind pressure, thought to reduce electron levels either temporarily (by compressing the magnetosphere below the level of the nominal L‐shell) or permanently (via magnetopause shadowing), shows only a small influence on lower energy electrons. Other solar wind and magnetosphere parameters do show correlations with electron levels even if autocorrelation and cycling behavior is accounted for, but these are not postulated to be direct drivers. Key Points: Substorms are the predominant driver of eV and MeV electron flux, with less influence on keV fluxUltralow frequency waves also influence MeV electronsElectrons correlate with input variables even in ARMAX models that correct for autocorrelation and cycling [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.)
Database: GreenFILE
FullText Text:
  Availability: 0
Header DbId: 8gh
DbLabel: GreenFILE
An: 178071363
AccessLevel: 6
PubType: Academic Journal
PubTypeId: academicJournal
PreciseRelevancyScore: 0
IllustrationInfo
Items – Name: Title
  Label: Title
  Group: Ti
  Data: Comparing Influences of Solar Wind, ULF Waves, and Substorms on 20&#160;eV–2&#160;MeV Electron Flux (RBSP) Using ARMAX Models.
– Name: Author
  Label: Authors
  Group: Au
  Data: &lt;searchLink fieldCode=&quot;AR&quot; term=&quot;%22Simms%2C+L%2E+E%2E%22&quot;&gt;Simms, L. E.&lt;/searchLink&gt;&lt;relatesTo&gt;1,2&lt;/relatesTo&gt; (AUTHOR)&lt;i&gt; laurasim@umich.edu&lt;/i&gt;&lt;br /&gt;&lt;searchLink fieldCode=&quot;AR&quot; term=&quot;%22Ganushkina%2C+N%2E+Y%2E%22&quot;&gt;Ganushkina, N. Y.&lt;/searchLink&gt;&lt;relatesTo&gt;1,3&lt;/relatesTo&gt; (AUTHOR)&lt;br /&gt;&lt;searchLink fieldCode=&quot;AR&quot; term=&quot;%22Dubyagin%2C+S%2E%22&quot;&gt;Dubyagin, S.&lt;/searchLink&gt;&lt;relatesTo&gt;3&lt;/relatesTo&gt; (AUTHOR)
– Name: TitleSource
  Label: Source
  Group: Src
  Data: &lt;searchLink fieldCode=&quot;JN&quot; term=&quot;%22Journal+of+Geophysical+Research%2E+Space+Physics%22&quot;&gt;Journal of Geophysical Research. Space Physics&lt;/searchLink&gt;. Jun2024, Vol. 129 Issue 6, p1-18. 18p.
– Name: Subject
  Label: Subject Terms
  Group: Su
  Data: *&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Magnetic+storms%22&quot;&gt;Magnetic storms&lt;/searchLink&gt;&lt;br /&gt;&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Solar+wind%22&quot;&gt;Solar wind&lt;/searchLink&gt;&lt;br /&gt;&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Time+series+analysis%22&quot;&gt;Time series analysis&lt;/searchLink&gt;&lt;br /&gt;&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Electrons%22&quot;&gt;Electrons&lt;/searchLink&gt;&lt;br /&gt;&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Wind+pressure%22&quot;&gt;Wind pressure&lt;/searchLink&gt;&lt;br /&gt;&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Radiation+belts%22&quot;&gt;Radiation belts&lt;/searchLink&gt;
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: Electron fluxes (20 eV–2 MeV, RBSP‐A satellite) show reasonable simple correlation with a variety of parameters (solar wind, IMF, substorms, ultralow frequency (ULF) waves, geomagnetic indices) over L‐shells 2–6. Removing correlation‐inflating common cycles and trends (using autoregressive and moving average terms in an ARMAX analysis) results in a 10 times reduction in apparent association between drivers and electron flux, although many are still statistically significant (p &lt; 0.05). Corrected influences are highest in the 20 eV–1 keV and 1–2 MeV electrons, more modest in the midrange (2–40 keV). Solar wind velocity and pressure (but not number density), IMF magnitude (with lower influence of Bz), SME (a substorm measure), a ULF wave index, and geomagnetic indices Kp and SymH all show statistically significant associations with electron flux in the corrected individual ARMAX analyses. We postulate that only pressure, ULF waves, and substorms are direct drivers of electron flux and compare their influences in a combined analysis. SME is the strongest influence of these three, mainly in the eV and MeV electrons. ULF is most influential on the MeV electrons. Pressure shows a smaller positive influence and some indication of either magnetopause shadowing or simply compression on the eV electrons. While strictly predictive models may improve forecasting ability by including indirect driver and proxy parameters, and while these models may be made more parsimonious by choosing not to explicitly model time series behavior, our present analyses include time series variables in order to draw valid conclusions about the physical influences of exogenous parameters. Plain Language Summary: High levels of satellite‐damaging electrons (both high and low energy) in the radiation belts appear to be driven by substorms and ultralow frequency waves. There is a positive association between these variables and electron levels even when the cycling behavior of satellite‐derived data is corrected. Solar wind pressure, thought to reduce electron levels either temporarily (by compressing the magnetosphere below the level of the nominal L‐shell) or permanently (via magnetopause shadowing), shows only a small influence on lower energy electrons. Other solar wind and magnetosphere parameters do show correlations with electron levels even if autocorrelation and cycling behavior is accounted for, but these are not postulated to be direct drivers. Key Points: Substorms are the predominant driver of eV and MeV electron flux, with less influence on keV fluxUltralow frequency waves also influence MeV electronsElectrons correlate with input variables even in ARMAX models that correct for autocorrelation and cycling [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  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.)
PLink https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=8gh&AN=178071363
RecordInfo BibRecord:
  BibEntity:
    Identifiers:
      – Type: doi
        Value: 10.1029/2024JA032458
    Languages:
      – Code: eng
        Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 18
        StartPage: 1
    Subjects:
      – SubjectFull: Magnetic storms
        Type: general
      – SubjectFull: Solar wind
        Type: general
      – SubjectFull: Time series analysis
        Type: general
      – SubjectFull: Electrons
        Type: general
      – SubjectFull: Wind pressure
        Type: general
      – SubjectFull: Radiation belts
        Type: general
    Titles:
      – TitleFull: Comparing Influences of Solar Wind, ULF Waves, and Substorms on 20 eV–2 MeV Electron Flux (RBSP) Using ARMAX Models.
        Type: main
  BibRelationships:
    HasContributorRelationships:
      – PersonEntity:
          Name:
            NameFull: Simms, L. E.
      – PersonEntity:
          Name:
            NameFull: Ganushkina, N. Y.
      – PersonEntity:
          Name:
            NameFull: Dubyagin, S.
    IsPartOfRelationships:
      – BibEntity:
          Dates:
            – D: 01
              M: 06
              Text: Jun2024
              Type: published
              Y: 2024
          Identifiers:
            – Type: issn-print
              Value: 21699380
          Numbering:
            – Type: volume
              Value: 129
            – Type: issue
              Value: 6
          Titles:
            – TitleFull: Journal of Geophysical Research. Space Physics
              Type: main
ResultId 1