The Super Dual Auroral Radar Network (SuperDARN) of HF coherent radars has been originally designed to monitor echoes, and thus study physical processes, from within the auroral oval, the area with the most frequent occurrence of discrete auroras. Monitoring of higher latitudes, the so-called polar cap (including the magnetic Poles areas), was anticipated because of over-the-horizon nature of the radars, but this capability was considered to be a value-added feature. Recently (2006 and 2008), two new radars at Rankin Inlet and Inuvik (Canada) were installed by the University of Saskatchewan radar group to be able to monitor HF echoes from within the polar cap directly. In this Thesis, two aspects of the Rankin Inlet (RKN) radar observations are investigated. First, occurrence of ionospheric echoes is studied. Assessment of the echo occurrence rate is performed and the rate is compared with observations of concurrently operating Saskatoon and Halley (Southern hemisphere) SuperDARN radars. It is shown that the RKN overall occurrence rates (within the optimal area of detection) are ~20% which is well above the rates for the Saskatoon (~6%) and Halley (~1%) radars. The rates are somewhat smaller in the early morning (02-05 MLT) and postnoon (15-20 MLT) hours of magnetic local time. Seasonally, the rates are smaller for summer with significant drop near the magnetic noon. Secondly, an event of the RKN radar monitoring of a polar cap arc, progressing through the radar field of view, is presented. F region echoes are shown to be stronger in the arcs wake, and they are broader on both its sides. Arc-related sheared plasma flows were demonstrated by considering the radar velocity measurements. Occasional occurrence of strong shears away from the arc was noticed, and it was related to the onset of a second, sub-visual arc, emerging from the auroral oval and intruding the polar cap. The data presented demonstrate the usefulness of the RKN observations of the high-latitude arcs whose mechanism of formation is presently unclear. An attempt has been made to discern magnetic signatures of the polar cap arc. Magnetic perturbations were found to be very weak and not easily interpreted.

The Super Dual Auroral Radar Network (SuperDARN) of HF coherent radars has been originally designed to monitor echoes, and thus study physical processes, from within the auroral oval, the area with the most frequent occurrence of discrete auroras. Monitoring of higher latitudes, the so-called polar cap (including the magnetic Poles areas), was anticipated because of over-the-horizon nature of the radars, but this capability was considered to be a value-added feature. Recently (2006 and 2008), two new radars at Rankin Inlet and Inuvik (Canada) were installed by the University of Saskatchewan radar group to be able to monitor HF echoes from within the polar cap directly. In this Thesis, two aspects of the Rankin Inlet (RKN) radar observations are investigated. First, occurrence of ionospheric echoes is studied. Assessment of the echo occurrence rate is performed and the rate is compared with observations of concurrently operating Saskatoon and Halley (Southern hemisphere) SuperDARN radars. It is shown that the RKN overall occurrence rates (within the optimal area of detection) are ~20% which is well above the rates for the Saskatoon (~6%) and Halley (~1%) radars. The rates are somewhat smaller in the early morning (02-05 MLT) and postnoon (15-20 MLT) hours of magnetic local time. Seasonally, the rates are smaller for summer with significant drop near the magnetic noon. Secondly, an event of the RKN radar monitoring of a polar cap arc, progressing through the radar field of view, is presented. F region echoes are shown to be stronger in the arcs wake, and they are broader on both its sides. Arc-related sheared plasma flows were demonstrated by considering the radar velocity measurements. Occasional occurrence of strong shears away from the arc was noticed, and it was related to the onset of a second, sub-visual arc, emerging from the auroral oval and intruding the polar cap. The data presented demonstrate the usefulness of the RKN observations of the high-latitude arcs whose mechanism of formation is presently unclear. An attempt has been made to discern magnetic signatures of the polar cap arc. Magnetic perturbations were found to be very weak and not easily interpreted.