Coherent HF Radar System for the Study of Natural and Heater Induced Ionospheric Irregularities

The highly irregular polar ionosphere requires sophisticated sensing techniques to identify and monitor the ionospheric characteristics. This report describes the deployment of a new ionospheric sounder, the Digisonde Portable Sounder DPS, at Svalbard 78.2 deg N and discusses the first results obtained with this instrument. The most important new feature in the DPS, not available in the old Digisondes, is the capability of high precision incidence angle measurements and spectral characterization at up to 128 ranges. While Svalbard rotated from the polar cap at magnetic midnight through the reversal boundaries and the auroral oval to the cusp region, the DPS was able to monitor the different features of a highly stressed ionosphere. It is demonstrated that the DPS can characterize the behavior of the background ionosphere while simultaneously measuring the motion of irregular plasma structures. This capability can be applied to identify and track irregularities generated by high power HF transmitters as planned for HAARP HF Active Auroral Research Program experiments in Alaska. This report shows how the DPS identifies different plasma structures in a naturally stressed ionosphere within the field of view of the instrument which extends over several hundred kilometers in the ionosphere.