Observation of daytime Pc3-4 ULF waves near the plasmapause using SuperDARN TIGER radar

SuperDARN radars are primarily designed to study large-scale long-period ionospheric plasma convection. However, these radars are also capable of monitoring much weaker and faster processes like ULF waves. Recently, we have shown that simple detrending together with utilization of sea/ground scatter echoes reveal on abundance of ULF waves in SuperDARN data. The basic radar sampling rate of 120 s limits ULF waves, which may be studied, to Pc4-5 frequency range. However, use of a special high time resolution mode shows regular appearance of band-limited daytime Pc3-4 waves. These waves are believed to be generated by ion-cyclotron instability in the reflected proton beams upstream of the Earth's bow-shock. Their propagation to the high-latitude ionosphere remains unclear. In this work we use SuperDARN TIGER radar (Tasmania) to investigate spatial characteristics of high-latitude daytime Pc3-4 waves in an attempt to clarify their propagation modes. Simultaneous ground magnetometer data were used for direct estimates of the ionosphere/ground transfer function in 10-100 mHz range, which was then compared with results of numerical and analytical modelling.