Comparative Analysis of the Primary Drivers of Plasma Sheet Electron Precipitation

Abstract Plasma sheet electron precipitation into Earth's atmosphere plays a key role in magnetosphere–ionosphere coupling at auroral latitudes. Such precipitation can be driven by four primary mechanisms that scatter equatorial electrons into the loss cone: resonant interactions with whistler‐mode waves, electron cyclotron harmonics (ECH), broadband electrostatic turbulence, and field‐line curvature scattering. Although each has been extensively examined, their relative occurrence rates and contributions remain poorly quantified. Using an extensive statistical data set from THEMIS (probe A) plasma and wave measurements, we compare the prevalence and characteristics of these four mechanisms. We show that broadband electrostatic turbulence and ECH are likely the dominant drivers of precipitation from the hot plasma sheet, whereas field‐line curvature scattering predominates in the pre‐substorm cold plasma sheet. We further examine the spatial scales of the associated precipitation patterns and characterize the representative electron spectra associated with different scattering mechanisms.