2011 SuperDARN Workshop
Making sense of SuperDARN elevation: Ionospheric diagnostics
P. Ponomarenko, J. Wiid, A. Koustov, and J.-P. St.-Maurice
University of Saskatchewan, saskatoon, SK, Canada
abstract. The elevation angle of HF signals contains information about ionospheric conditions affecting radio wave propagation. Unfortunately, this parameter has rarely been utilised in SuperDARN experiments due to the apparent bias attributed to some unaccounted-for phase offset. However, in the accompanying presentation we demonstrated that this effect, in fact, reflects the statistical variability of the phase measurements, and the majority of the elevation data can be trusted. Ray tracing modelling of the HF backscatter characteristics reveals the presence of two possible propagation modes related to Pedersen and low-angle rays. The first mode is characterised by very little variation in elevation with range and contains information about the refractive index (i.e. electron density) in the vicinity of the ionospheric maximum. Careful analysis of elevation data from the Rankin Inlet PolarDARN radar has shown that the Pederesen regime is regularly observed in daytime hours during the spring-summer-autumn months. Applying Snell?s law for the spherical geometry and the simplest form of the Appleton-Hartree equation to these data, we have attempted to reconstruct seasonal-diurnal variations of the maximum electron density near 70LAT.