Thermospheric Neutral Winds as the Cause of Drift Shell Distortion in Earth's Inner Radiation Belt

Details

• Journal Title:
  Frontiers in Astronomy and Space Sciences
• Personal Author:
  Lejosne, Solène ; Fedrizzi, Mariangel ; Maruyama, Naomi ; Selesnick, Richard S.
• NOAA Program & Office:
  CIRES (Cooperative Institute for Research in Environmental Sciences) ; SWPC (Space Weather Prediction Center) ; NWS (National Weather Service)
• Description:
  Recent analysis of energetic electron measurements from the Magnetic Electron Ion Spectrometer instruments onboard the Van Allen Probes showed a local time variation of the equatorial electron intensity in the Earth’s inner radiation belt. The local time asymmetry was interpreted as evidence of drift shell distortion by a large-scale electric field. It was also demonstrated that the inclusion of a simple dawn-to-dusk electric field model improved the agreement between observations and theoretical expectations. Yet, exactly what drives this electric field was left unexplained. We combine in-situ field and particle observations, together with a physics-based coupled model, the Rice Convection Model (RCM) Coupled Thermosphere-Ionosphere-Plasmasphere-electrodynamics (CTIPe), to revisit the local time asymmetry of the equatorial electron intensity observed in the innermost radiation belt. The study is based on the dawn-dusk difference in equatorial electron intensity measured at L = 1.30 during the first 60 days of the year 2014. Analysis of measured equatorial electron intensity in the 150–400 keV energy range, in-situ DC electric field measurements and wind dynamo modeling outputs provide consistent estimates of the order of 6–8 kV for the average dawn-to-dusk electric potential variation. This suggests that the dynamo electric fields produced by tidal motion of upper atmospheric winds flowing across Earth’s magnetic field lines - the quiet time ionospheric wind dynamo - are the main drivers of the drift shell distortion in the Earth’s inner radiation belt.
• Keywords:
  Radiation Winds
• Source:
  Space Sci. 8:725800
• DOI:
  https://doi.org/10.3389/fspas.2021.725800
• Document Type:
  Journal Article
• Rights Information:
  CC BY
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha256:e594a24cb9c86b8afa2368ee2481badda95c8068405dd3eef4480157ec415fc6
• Download URL:
  https://repository.library.noaa.gov/view/noaa/45033/noaa_45033_DS1.pdf
• File Type:
  [PDF - 2.07 MB ]