An Explanation for Arecibo Plasma Line Power Striations. Issue 2 (18th February 2021)

• Record Type: Journal Article
• Authors: Longley, William J.; Vierinen, Juha; Sulzer, Michael P.; Varney, Roger H.; Erickson, Philip J.; Perillat, Phil
• Is Part Of: Journal of geophysical research. Volume 126:Issue 2(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-02-18
• Subjects: Arecibo -- incoherent scatter -- landau and cyclotron damping -- plasma lines -- photoelectrons -- suprathermal electrons; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2020JA028734
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: Measurements of plasma lines by the Arecibo incoherent scatter radar are known to have sharp striations in power, varying with the plasma frequency and magnetic aspect angle of the radar beam. We explain these power striations as the manifestation of a suprathermal electron population with peaks in energy at approximately 15, 25, and 45 eV. These energies correspond to sharp features in the photoelectron energy spectra measured by rockets and spacecraft. A new theory is developed to predict the plasma line power for an arbitrary, magnetized suprathermal distribution. The magnetization terms in this theory are shown to contribute substantially to the enhancement of plasma line power through inverse Landau and cyclotron damping of the suprathermal peaks. The theory is applied as a forward model to measurements obtained at Arecibo for different magnetic field aspect angles, showing general agreement with the data. At large magnetic aspect angles the theory reproduces the upper‐hybrid instability which can cause 150 km echoes. The developed theory allows for the suprathermal distribution at a given altitude to be probed across a wide range of energies and pitch angles. Key Points: New theory is developed to calculate the enhancement of plasma line power by magnetized suprathermal electrons Measured plasma line power striations at Arecibo are generated by inverse Landau and cyclotron damping of suprathermal electron peaks At intermediate aspect angles plasma lines are strongly enhanced by n = 1 inverse cyclotron damping condition