Incoherent-Scatter Radar Observations of the Cusp

Abstract

With the establishment of the incoherent-scatter radar at Sondre Stromfjord, Greenland, ground-based observations of the dayside auroral oval are now being made. The initial experiments conducted were designed to identify the ionospheric manifestation of the polar cusp in terms of plasma convection and structure in plasma density and temperature. We have identified repeatable features of these parameters. Plasma convection within the field of view of the radar (70 to 80° Λ) is generally two-celled, its flow is parallel to the auroral oval, and shear reversals and rotational reversals are frequently observed on the dayside. The F region shows structures in both density and temperature that are associated with specific features of convection patterns. Along the shear reversal, we have observed enhancements in electron density and electron temperature. Other F-region density structures have been observed without a corresponding increase in electron temperature. These structures occur most frequently when there is a strong anti-sunward component in ion velocity and structures are generally aligned in the direction of the flow.