Applying an S4 Scintillation Index to High Frequency Radar Pulses

Ionospheric scintillation is a fluctuation in the phase, amplitude, and/or angle of arrival of a radio-frequency signal that occurs as a result of the signal’s propagation through the ionosphere. In this work we have developed a methodology for computing an amplitude scintillation index (S4) for high frequency (HF; 3-30 MHz) radar pulses transmitted at 17.5 MHz by the Super Dual Auroral Radar Network (SuperDARN) system at Saskatoon. The pulses received by the Radio Receiver Instrument (RRI) on the Enhanced Polar Outflow Probe (e-POP) exhibit considerable amplitude fluctuations at times. Our preliminary results show that the S4 index of pulses with low signal-to-noise-ratio (SNR; low is defined as 0<SNR<10) is high in comparison to the other pulses. Furthermore, a comparison between our S4 calculations to those from GNSS systems show good agreement. In this presentation we will outline the details of the S4 computation, which are different from standard S4 calculations since the transmitted signal is made-up of pulses and not a continuous signal.