The Magnetospheric Multiscale (MMS) mission has presented a new opportunity to study the fine scale structures and phenomena of the Earth’s magnetosphere, including cross scale processes associated with the Kelvin-Helmholtz Instability (KHI), but such studies of the KHI and its secondary processes will require a database of MMS encounters with Kelvin-Helmholtz (KH) waves. Here we present an overview of 45 MMS observations of the KHI from September 2015 to March 2020. Growth rates and unstable solid angles for each of the 45 events were calculated using a new technique to automatically detect plasma regions on either side of the magnetopause boundary. There was no apparent correlation between solar wind conditions during the KHI and its growth rate and unstable solid angle, which is not surprising as KH waves were observed downstream of their source region. We note all KHI were observed for solar wind flow speeds between 295 km/s and 610 km/s, likely due to a filtering effect of the instability onset criteria and plasma compressibility. Two-dimensional Magnetohydrodynamic (2D MHD) simulations were compared with two of the observed MMS events. Comparison of the observations with the 2D MHD simulations indicates that the new region sorting method is reliable and robust. The ability to automatically detect separate plasma regions on either side of a moving boundary and determine the KHI growth rate may prove useful for future work identifying and studying secondary processes associated with the KHI.

High energy electrons observed in the magnetosheath must be accelerated by some mech- anism that is as yet undetermined. We present observations of high-energy electrons trapped in diamagnetic cavities as measured by Magnetospheric Multiscale from 2015-2018. The observations support the notion of local acceleration in the reconnection quasi-potential as many of events show particles with pitch angles that are increasingly closer to 90 de- grees with increasing energy. It is suggested that these particles can end up in the loss cone and be transported to the magnetosheath. We also characterize each diamagnetic cavity as formed due to low- or high-latitude reconnection based on prevailing solar wind conditions. The character of the ions in the diamagnetic cavity is only briefly mentioned as their properties warrant another stand-alone investigation.

Understanding the physical mechanisms responsible for the cross-scale energy transport and plasma heating from solar wind into the Earth’s magnetosphere is of fundamental importance for magnetospheric physics and for understanding these processes in other places in the universe with comparable plasma parameter ranges. This paper presents observations from Magnetosphere Multi-Scale (MMS) mission at the dawn-side high-latitude dayside boundary layer on 25th of February, 2016 between 18:55-20:05 UT. During this interval MMS encountered both inner and outer boundary layer with quasi-periodic low frequency fluctuations in all plasma and field parameters. The frequency analysis and growth rate calculations are consistent with the Kelvin-Helmholtz Instability (KHI). The intervals within low frequency wave structures contained several counter-streaming, low- (0-200 eV) and mid-energy (200 eV-2 keV) electrons in the loss cone and trapped energetic (70-600 keV) electrons in alternate intervals. Wave intervals also showed high energy populations of O+ ions, likely of ionospheric or ring current origin. The counter-streaming electron intervals were associated with a large-magnitude field-aligned Poynting fluxes. Burst mode data at the large Alfven velocity gradient revealed a strong correlation between counter streaming electrons, enhanced parallel electron temperatures, strong anti-field aligned wave Poynting fluxes, and wave activity from sub-proton cyclotron frequencies extending to electron cyclotron frequency. Waves were identified as Kinetic Alfven waves but their contribution to parallel electron heating was not sufficient to explain the > 100 eV electrons, and rapid non-adiabatic heating of the boundary layer as determined by the characteristic heating frequency, derived here for the first time.

The Magnetospheric Multiscale (MMS) mission has presented a new opportunity to study the fine scale structures and phenomena of Earth’s magnetosphere, including cross scale processes associated with the Kelvin-Helmholtz Instability (KHI). We present an overview of 19 MMS observations of the KHI from September 2015 to June 2017. Unitless growth rates and unstable solid angles for each of the 19 events were calculated using 5 techniques to automatically detect plasma regions on either side of the magnetopause boundary. There was no apparent correlation between solar wind conditions during the KHI and its growth rate and unstable solid angle, though we note no KHI were observed for solar wind flow speeds less than 300 km/s or greater than 600 km/s, likely due to a filtering effect of the instability onset criteria and plasma compressibility. Two-dimensional Magnetohydrodynamic (2D MHD) simulations were compared with two of the observed MMS events. Comparison of the observations with the 2D MHD simulations indicates that velocity dependent methods are the most consistent when calculating growth rate and unstable solid angle, but a combination of the velocity dependent and independent methods can be used to select KHI events in which the vortex has rolled over. This may prove useful for future work studying secondary processes associated with the KHI.

The solar wind plasma is a major plasma source for the Earth’s magnetosphere, which has a strong influence on the magnetotail plasma and field properties. The relative importance of different plasma entry mechanisms and pathways is largely determined by the solar wind conditions. Therefore, the spatial and temporal dependence of magnetotail plasma and field properties under different kinds of solar wind conditions is critically important for understanding the Earth’s magnetosphere. This study presents a statistical study of fundamental magnetotail plasma properties in a normalized reference frame by utilizing 12+ years of data from NASA’s Time History of Events and Macroscale Interactions during Substorms (THEMIS) -mission. These statistical maps are mostly in agreement with the MHD runs from the CCMC BATS-R-US model, but some features in the maps can be explained by kinetic particle physics, not present in the MHD. The results are also used to investigate the presence of any magnetotail plasma parameter asymmetries and their possible causes.

The Kelvin-Helmholtz instability (KHI) and its effects relating to the transfer of energy and mass from the solar wind into the magnetosphere remain an important focus of magnetospheric physics. One such effect is the generation of Pc4-Pc5 ultra low frequency (ULF) waves (periods of 45-600 s). On 3 July 2007 at $\sim$ 0500 magnetic local time (MLT) the Cluster space mission encountered Pc4 frequency Kelvin-Helmholtz waves (KHWs) at the magnetopause with signatures of persistent vortices. Such signatures included bipolar fluctuations of the magnetic field normal component associated with a total pressure increase and rapid change in density at the vortex edges, oscillations of magnetosheath and magnetospheric plasma populations, wave frequencies within the expected range of the fastest growing KH mode, and magnetopause conditions favorable to the onset of the KHI. The event occurred during a period of southward polarity of the interplanetary magnetic field. Most of the KHI vortices were associated with reconnection indicated by the Walén relation, the presence of deHoffman-Teller frames and field-aligned ion beams. Global magnetohydrodynamic (MHD) simulation of the event also resulted in KHWs at the magnetopause. The observed KHWs associated with reconnection coincided with recorded ULF waves at the ground whose properties suggest that they were driven by the KHWs. Such properties were the location of Cluster’s magnetic foot point, the Pc4 frequency, and the solar wind conditions.

The present paper demonstrates the first observations by the Magnetospheric Multiscale (MMS) mission of the counter-streaming energetic electrons and trapped energetic protons, localized in the magnetic field depressions between the mirror mode peaks, in the Earth’s dusk sector high-latitude magnetosphere. This region is characterized by high plasma beta, strong ion temperature anisotropy and intermediate plasma density between magnetospheric and magnetosheath plasma. We show that these plasma conditions are unstable for the drift mirror instability. The counter-streaming electron feature resembles those of the previously reported energetic electron microinjections, but without the energy-time dispersion signature. This suggests that MMS is passing through one of the potential microinjection source regions. The energetic ion data in the present study is mainly used to estimate the scale size of the mirror mode structures.