Characteristics of Kelvin-Helmholtz Waves as Observed by the MMS from September 2015 to June 2017

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.