MMS Observations of Cross Scale Heating within the Kelvin-Helmholtz Instability

Abstract:

The magnetosphere heating problem is a long-standing question in space physics. Specific entropy increases up to two orders of magnitude across the magnetopause boundary, but reconnection alone cannot account for the necessary conversion of solar wind kinetic energy to the thermal energy of the magnetosphere. Some other physical process(es) must be at work, and based on the boundary layer thickness, must work across all plasma scales. The Kelvin-Helmholtz Instability (KHI) is a large-scale convective instability occurring regularly at the magnetopause that is known to trigger secondary processes on the ion scales. The KHI is thus a strong candidate to contribute to cross-scale heating. With the launch of the Magnetospheric Multiscale (MMS) mission, we are able to investigate the influence of KHI on the generation of smaller scale waves. We take advantage of MMS’s high spatial and temporal resolution to identify ion-cyclotron, lower-hybrid, and electron-cyclotron scale wave modes within the KHI and quantify their contribution to electron, ion and O+ heating across the magnetopause boundary. The contribution of KHI-associated heating processes is compared with heating during quiet boundary crossings when no KHI are present.