EISCAT Svalbard Radar observations of ionospheric plasma dynamics in relation to dayside auroral transients

The first EISCAT Svalbard Radar (ESR) and ground optical campaign was carried out in January 1998 to cover a variety of dayside auroral activities in the 1000-1400 magnetic local time sector. The current paper focuses on 1 hour of combined radar, meridian scanning photometer, and ground magnetometer observations near the cusp convection throat on January 23, 1998. The radar was pointing north, at a fixed elevation of 45 degrees, in the scan plane of the photometer. Several plasma dynamical features were revealed by this simplest possible convection mode of the ESR, such as spontaneous movement of the cusp inflow region and cusp-related ionization blobs pushing through the ambient incompressible plasma. Multiple morning discrete arcs were found to be aligned with convection streamlines equatorward of the flow reversal, while plasma in the polar cap inflow region streamed perpendicularly across the optical cusp boundary, as earlier anticipated.