loading page

3D simulation of an extreme SAID flow channel
  • +3
  • Joaquin Diaz Pena,
  • Matthew David Zettergren,
  • Joshua L. Semeter,
  • Yukitoshi (Toshi) Nishimura,
  • Michael Hirsch,
  • Brian Walsh
Joaquin Diaz Pena
Boston University

Corresponding Author:[email protected]

Author Profile
Matthew David Zettergren
Embry-Riddle Aeronautical University
Author Profile
Joshua L. Semeter
Boston University
Author Profile
Yukitoshi (Toshi) Nishimura
Boston University
Author Profile
Michael Hirsch
Boston University
Author Profile
Brian Walsh
Boston University
Author Profile

Abstract

Space-based observations of the signatures associated with STEVE show how this phenomenon might be closely related to an extreme version of a SAID channel. Measurements show high velocities ($>$4km/s), high temperatures ($>$4,000 K), and very large current density drivers (up to 1$\mu$A/m$^2$). This phenomena happens in a small range of latitudes, less than a degree, but with a large longitudinal span. In this study, we utilize the GEMINI model to simulate an extreme SAID/STEVE. We assume a FAC density coming from the magnetosphere as the main driver, allowing all other parameters to adjust accordingly. We have two main objectives with this work: show how an extreme SAID can have velocity values comparable or larger than the ones measured under STEVE, and to display the limitations and missing physics that arise due to the extreme values of temperature and velocity. Changes had to be made to GEMINI due to the extreme conditions, particularly some neutral-collision frequencies. The importance of the temperature threshold at which some collision frequencies go outside their respective bounds, as well as significance of the energies that would cause inelastic collisions and impact ionization are displayed and discussed. We illustrate complex structures and behaviors, emphasizing the importance of 3D simulations in capturing these phenomena. Longitudinal structure is emphasized, as the channel develops differently depending on MLT. However, these simulations should be viewed as approximations due to the limited observations available to constrain the model inputs and the assumptions made to achieve sensible results.
22 Mar 2024Submitted to ESS Open Archive
25 Mar 2024Published in ESS Open Archive