MMS/FEEPS Observations of Electron Microinjections Due to Kelvin‐Helmholtz Waves and Flux Transfer Events: A Case Study

Abstract

The Energetic Particle Detector (EPD) suite onboard the Magnetospheric Multiscale (MMS) spacecraft observes dispersive and repetitive fluxes of high‐energy (50–400 keV) electrons within the Pc5 frequency band (2–8 MHz) in the dusk to midnight region of Earth's magnetotail. These microinjections are a new phenomenon in this region of the magnetosphere, presently poorly understood, but clearly a new signature that remotely senses large‐scale magnetospheric boundary dynamics. It is therefore important to understand their properties and driver mechanisms. Here we have combined global magnetohydrodynamic simulations and particle tracing results with the MMS EPD Fly's Eye Energetic Particle Spectrometer (FEEPS) observations to investigate possible origins and source regions of the electron microinjections. Our simulation results suggest that the electron microinjections, observed in the dusk to premidnight sector, are associated with Kelvin‐Helmholtz waves (KHWs) and flux transfer events (FTEs). Energetic electrons launched from a limited range of locations near the postnoon dusk magnetopause and at times when KHWs and FTEs pass by that region have drift paths that connect with MMS and thus create time‐dependent microinjection electron signatures. Test‐particle tracing results in the magnetohydrodynamic fields also support the field‐aligned nature of electron microinjections observed by MMS. Though identifying the mechanism by which KHWs and FTEs might periodically inject electrons is beyond the scope of this work, our study does identify these duskside magnetopause boundary phenomena as likely agents of microinjection origins.

MMS SITL Ground Loop: Automating the Burst Data Selection Process

“…As an example of a science campaign, we build upon a recent MMS discovery of micro-injections at the dusk flank MP in conjunction with ULF wave activity ( Fennell et al, 2016 ). Simulations proposed that Kelvin-Helmholtz waves (KHWs) on the MP surface were the cause ( Kavosi et al, 2018 ). To gain more insight into this multi-scale process, one could create event classifiers for micro-injections ( Claudepierre et al, 2020 ), field line resonances, and KHWs.…”

Exospheric Neutral Hydrogen Density at the Nominal 10 RE Subsolar Point Deduced From XMM‐Newton X‐Ray Observations

“…This study uses OMNI solar wind and IMF data downloaded from https://omniweb.gsfc.nasa.gov (King & Papitashvili, ) as the model input. OpenGGCM can be used as a stand‐alone model (Raeder et al, ) or coupled with Rice Convection Model (Cramer et al, ), Coupled Thermosphere‐ Ionosphere Model (Connor et al, , ; Ferdousi & Raeder, ; Jensen et al, ; Oliveira & Raeder, ; Raeder et al, ), and a full particle tracing code (Connor et al, , ; Kavosi et al, ). Here, we used the stand‐alone version.…”

Soft X‐ray and ENA Imaging of the Earth's Dayside Magnetosphere

“…In this paper, we used the stand-alone OpenGGCM model. Details of OpenGGCM and its applications to the geospace environment can be found in Raeder et al (2001aRaeder et al ( , 2008, Connor et al (2012Connor et al ( , 2014Connor et al ( , 2015Connor et al ( , 2016, Oliveira and Raeder (2015), Ferdousi and Raeder (2016), Cramer et al (2017), Jensen et al (2017), Shi et al (2017), and Kavosi et al (2018).…”