F region ionosphere effects on the mapping accuracy of SuperDARN HF radar echoes

Abstract

Structured particle precipitation in the cusp is an important source for the generation of F region ionospheric irregularities. The equatorward boundaries of broad Doppler spectral width in Super Dual Auroral Radar Network (SuperDARN) data and the concurrent OI 630.0 nm auroral emission are good empirical proxies for the dayside open‐closed field line boundary. However, SuperDARN currently employs a simple virtual model to determine the location of its echoes, instead of a direct calculation of the radio wave path. The varying ionospheric conditions could influence the final mapping accuracy of SuperDARN echoes. A statistical comparison of the offsets between the SuperDARN Finland radar spectral width boundary (SWB) and the OI 630.0 nm auroral emission boundary (AEB) from a meridian‐scanning photometer (MSP) on Svalbard is performed in this paper. By restricting the location of the 630.0 nm data to be near local zenith where the MSP has the highest spatial resolution, the optical mapping errors were significantly reduced. The variation of the SWB‐AEB offset confirms that there is a close relationship between the mapping accuracy of the HF radar echoes and solar activity. The asymmetric variation of the SWB‐AEB offset versus magnetic local time suggests that the intake of high‐density solar extreme ultraviolet ionized plasma from postnoon at subauroral latitudes could result in a stronger refraction of the HF radar signals in the noon sector, while changing the HF radar operating frequency also has a refraction effect that contributes to the final location of the HF radar echoes.

Dynamic properties of throat aurora revealed by simultaneous ground and satellite observations

“…In this study only channel A data are used. With a distance to the first range gate of 180 km and 75 sampled range gates at each beam (each range gate is 45 km long), range gates 40–45 typically correspond to the location of Ny‐Ålesund, depending on propagation conditions [e.g., Chen et al ., , ; Yeoman et al ., ]. This is due to the fact that SuperDARN currently employs a simple virtual model, i.e., assuming a fixed scattering height, to determine the location of its echoes, instead of a direct calculation of the ray path.…”

“…This is due to the fact that SuperDARN currently employs a simple virtual model, i.e., assuming a fixed scattering height, to determine the location of its echoes, instead of a direct calculation of the ray path. A recent statistical observation [ Chen et al ., ] of the SuperDARN Finland radar spectral width boundary, transferring from narrow to broad, showed that the location of radar echoes near Svalbard is, on average, overestimated by ~2° (~1°) latitude in the poleward direction during solar maxima (solar minima). This is consistent with the theoretical analysis of Chisham et al .…”

Space weather impact on radio device operation

“…As HF radio waves propagate, the emergence of additional ionospheric layers leads to the emergence of additional propagation paths [Tsunoda et al, 2016], and, as a result, complicates matching of the radar range (group delay of a signal) and azimuth to real positions of scattering objects or directions to them [Reinisch et al, 1997;Chen et al, 2016;Warrington et al, 2016]. The frequency dependence of propagation paths causes strong phase distortions, thus making the detection of complex signals over long paths even more difficult.…”

Space weather impact on radio device operation

“…При распространении КВ-радиоволн возникно-вение дополнительных ионосферных слоев приво-дит к возникновению дополнительных траекторий распространения и, как след-ствие, к усложнению привязки радиолокационной дальности (групповой задержки сигнала) и азимута к реальным положениям рассеивающих объектов или направлениям на них [Reinisch et al, 1997;Chen et al, 2016;Warrington et al, 2016]. Зависимость траекторий распростране-ния от частоты приводит к сильным фазовым иска-жениям сигнала, что дополнительно усложняет де-тектирование сложных сигналов на дальних трассах.…”