Browsing by Author "Spanswick, E."

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    GPS phase scintillation and proxy index at high latitudes during a moderate geomagnetic storm
    Prikryl, P.; Ghoddousi-Fard, R.; Kunduri, B. S. R.; Thomas, E. G.; Coster, A. J.; Jayachandran, P. T.; Spanswick, E.; Danskin, D. W. (Copernicus Publications, 2013)
    The amplitude and phase scintillation indices are customarily obtained by specialised GPS Ionospheric Scintillation and TEC Monitors (GISTMs) from L1 signal recorded at the rate of 50 Hz. The scintillation indices S-4 and sigma(Phi) are stored in real time from an array of high-rate scintillation receivers of the Canadian High Arctic Ionospheric Network (CHAIN). Ionospheric phase scintillation was observed at high latitudes during a moderate geomagnetic storm (Dst = -61 nT) that was caused by a moderate solar wind plasma stream compounded with the impact of two coronal mass ejections. The most intense phase scintillation (sigma(Phi) similar to 1 rad) occurred in the cusp and the polar cap where it was co-located with a strong ionospheric convection, an extended tongue of ionisation and dense polar cap patches that were observed with ionosondes and HF radars. At sub-auroral latitudes, a sub-auroral polarisation stream that was observed by mid-latitude radars was associated with weak scintillation (defined arbitrarily as sigma(Phi) < 0.5 rad). In the auroral zone, moderate scintillation coincided with auroral breakups observed by an all-sky imager, a riometer and a magnetometer in Yellowknife. To overcome the limited geographic coverage by GISTMs other GNSS data sampled at 1 Hz can be used to obtain scintillation proxy indices. In this study, a phase scintillation proxy index (delta phase rate, DPR) is obtained from 1-Hz data from CHAIN and other GPS receivers. The 50-Hz and 1-Hz phase scintillation indices are correlated. The percentage occurrences of sigma(Phi) > 0.1 rad and DPR > 2mm s(-1), both mapped as a function of magnetic latitude and magnetic local time, are very similar.
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    GPS phase scintillation at high latitudes during geomagnetic storms of 7-17 March 2012-Part 1: The North American sector
    Prikryl, P.; Ghoddousi-Fard, R.; Thomas, E. G.; Ruohoniemi, J. Michael; Shepherd, Simon G.; Jayachandran, P. T.; Danskin, D. W.; Spanswick, E.; Zhang, Y.; Jiao, Y.; Morton, Y. T. (European Geosciences Union, 2015)
    The interval of geomagnetic storms of 7-17 March 2012 was selected at the Climate and Weather of the Sun-Earth System (CAWSES) II Workshop for group study of space weather effects during the ascending phase of solar cycle 24 (Tsurutani et al., 2014). The high-latitude ionospheric response to a series of storms is studied using arrays of GPS receivers, HF radars, ionosondes, riometers, magnetometers, and auroral imagers focusing on GPS phase scintillation. Four geomagnetic storms showed varied responses to solar wind conditions characterized by the interplanetary magnetic field (IMF) and solar wind dynamic pressure. As a function of magnetic latitude and magnetic local time, regions of enhanced scintillation are identified in the context of coupling processes between the solar wind and the magnetosphere-ionosphere system. Large southward IMF and high solar wind dynamic pressure resulted in the strongest scintillation in the nightside auroral oval. Scintillation occurrence was correlated with ground magnetic field perturbations and riometer absorption enhancements, and collocated with mapped auroral emission. During periods of southward IMF, scintillation was also collocated with ionospheric convection in the expanded dawn and dusk cells, with the antisunward convection in the polar cap and with a tongue of ionization fractured into patches. In contrast, large northward IMF combined with a strong solar wind dynamic pressure pulse was followed by scintillation caused by transpolar arcs in the polar cap.