A Survey of Plasma Waves Appearing Near Dayside Magnetopause Electron Diffusion Region Events

Abstract

One of the major unresolved questions regarding the magnetic reconnection phenomenon is how plasma waves impact the process. In 2015, the National Aeronautics and Space Administration launched the four‐satellite Magnetospheric Multiscale Mission to study magnetic reconnection, especially on the electron scale. Since launch, it has identified several wave modes below the electron plasma frequency that occur near the dayside reconnection X‐line. These include large‐amplitude parallel electrostatic waves, whistler mode waves, lower hybrid waves, and turbulence associated with a corrugated current structure. We survey 23 electron diffusion region events observed by Magnetospheric Multiscale Mission at the dayside magnetopause to help understand how these wave modes impact the reconnection process. Common wave modes are identified, as well as their typical location within the reconnection layer (e.g., electron diffusion region, ion diffusion region, separatrix, and inflow and outflow jets). We find that, with a few exceptions, electromagnetic whistlers are most commonly confined to the separatrices of the exhaust boundary. Lower hybrid waves are found on the magnetosphere side of the current layer and do not make it to the X‐line. The wave modes that typically occur closest to the dissipation region are the corrugated current structures and large‐amplitude parallel electrostatic waves.

The Occurrence and Prevalence of Time Domain Structures in the Kelvin-Helmholtz Instability at Different Positions Along the Earth’s Magnetospheric Flanks

“…All of this suggests that while TDS are seen throughout the KHI, there is a bias towards the portion of each period where magnetosphere-like plasma is present. This is consistent with observations of the reconnecting dayside magnetopause, where the bulk of the plasma wave activity occurred on the magnetospheric side of the current sheet (Wilder et al, 2019). It is also similar to the Ion Acoustic Waves (IAWs) observed in the KHI by (Wilder et al, 2020), which seemed to occur on the magnetospheric side of the "vortex" intervals, though in that case, the waves occurred closer to B Y 0, in a region referred to as the "turbulent mixing region.…”

Large Amplitude Electrostatic Proton Plasma Frequency Waves in the Magnetospheric Separatrix and Outflow Regions During Magnetic Reconnection

“…Plasma waves are often found in the vicinity of the magnetopause (e.g., Fairfield, 1976;Gurnett et al, 1979;LaBelle et al, 1987;Tang et al, 2019), and appear to be intimately connected to magnetic reconnection (Khotyaintsev et al, 2019), a fundamental plasma process where changes in magnetic field topology result in plasma mixing and explosive energy conversion from magnetic energy to kinetic and thermal energy (e.g., Birn & Priest, 2007). Though magnetic reconnection is a well-studied subject some fundamental aspects are still not understood, and studying wave dynamics might be crucial to fully understand the cause and effects of magnetic reconnection (Khotyaintsev et al, 2019;Wilder et al, 2019).The separatrix region is defined as the kinetic boundary separating the inflow and outflow regions of magnetic reconnection (Lindstedt et al, 2009). As such, it is characterized by recently reconnected magnetic field lines, complex distribution functions, and large parallel currents (Khotyaintsev et al, 2006) likely associated with kinetic Alfvén waves propagating away from the reconnection site (Dai, 2018;Dai et al, 2017;Huang et al, 2018).…”

Statistical Characteristics in the Spectrum of Whistler Waves Near the Diffusion Region of Dayside Magnetopause Reconnection

“…Near the X‐line of magnetopause reconnection, whistler waves have been observed in the vicinity of the electron diffusion region (EDR) (Burch et al., 2018; Cao et al., 2017; Tang et al., 2013). The most intense whistler waves are observed near the magnetosphere side separatrix region as revealed from Cluster observations (Graham et al., 2016) and recent MMS observations (J. Li et al., 2018; Le Contel et al., 2016; Khotyaintsev et al., 2020; Wilder et al., 2016, 2017, 2019; Yoo et al., 2018). Free energy for whistler waves in the magnetopause reconnection may originate from loss‐cone electron distributions (Graham et al., 2016), perpendicular temperature anisotropy (Tang et al., 2013), and electron beams (Khotyaintsev et al., 2020; Wilder et al., 2017).…”