Abstract
Abstract. Global positioning system scintillation and total electron content (TEC) data have been collected by ten specialized GPS Ionospheric Scintillation and TEC Monitors (GISTMs) of the Canadian High Arctic Ionospheric Network (CHAIN). The phase scintillation index σΦ is obtained from the phase of the L1 signal sampled at 50 Hz. Maps of phase scintillation occurrence as a function of the altitude-adjusted corrected geomagnetic (AACGM) latitude and magnetic local time (MLT) are computed for the period from 2008 to 2013. Enhanced phase scintillation is collocated with regions that are known as ionospheric signatures of the coupling between the solar wind and magnetosphere. The phase scintillation mainly occurs on the dayside in the cusp where ionospheric irregularities convect at high speed, in the nightside auroral oval where energetic particle precipitation causes field-aligned irregularities with steep electron density gradients and in the polar cap where electron density patches that are formed from a tongue of ionization. Dependences of scintillation occurrence on season, solar and geomagnetic activity, and the interplanetary magnetic field (IMF) orientation are investigated. The auroral phase scintillation shows semiannual variation with equinoctial maxima known to be associated with auroras, while in the cusp and polar cap the scintillation occurrence is highest in the autumn and winter months and lowest in summer. With rising solar and geomagnetic activity from the solar minimum to solar maximum, yearly maps of mean phase scintillation occurrence show gradual increase and expansion of enhanced scintillation regions both poleward and equatorward from the statistical auroral oval. The dependence of scintillation occurrence on the IMF orientation is dominated by increased scintillation in the cusp, expanded auroral oval and at subauroral latitudes for strongly southward IMF. In the polar cap, the IMF BY polarity controls dawn–dusk asymmetries in scintillation occurrence collocated with a tongue of ionization for southward IMF and with sun-aligned arcs for northward IMF. In investigating the shape of scintillation-causing irregularities, the distributions of scintillation occurrence as a function of "off-meridian" and "off-shell" angles that are computed for the receiver–satellite ray at the ionospheric pierce point are found to suggest predominantly field-aligned irregularities in the auroral oval and L-shell-aligned irregularities in the cusp.
Highlights
Space weather impacts the operation of modern technology that relies on global navigation satellite systems (GNSS) including GPS, GLONASS and Galileo, which have become indispensable in precise positioning and time keeping
The phase scintillation most frequently occurs on the dayside in the cusp, poleward of the cusp in the polar cap and in the nightside auroral oval, at its poleward edge associated with discrete auwww.ann-geophys.net/33/531/2015/
When the auroral oval expands as a result of southward interplanetary magnetic field (IMF) and ensuing geomagnetic activity, during impacts of coronal mass ejections and highspeed solar wind streams, phase scintillation increasingly occurs near the equatorward border of the post-midnight auroral oval where moderate-to-strong scintillation was previously shown to be collocated with intense return convection
Summary
Space weather impacts the operation of modern technology that relies on global navigation satellite systems (GNSS) including GPS, GLONASS and Galileo, which have become indispensable in precise positioning and time keeping. In a comprehensive study of space weather impact on the cusp and polar cap toward understanding plasma instabilities and scintillation in association with cusp flow channels and polar cap patches, Moen et al (2013) applied the GBSC method to investigate the multi-scale irregularity structures resulting from different physical processes that include flow shears and particle precipitation As these authors pointed out, the phase and amplitude scintillation are biased to different irregularity scale sizes from a few kilometers down to a few hundred meters, which are produced by different processes. The GNSS receiver tracking performance during severe scintillation conditions can be assessed by the analysis of receiver phase-locked-loop (PLL) jitter (Conker et al, 2003; Sreeja et al, 2011; Aquino and Sreeja, 2013, Prikryl et al, 2013a) Another method to mitigate the effect of ionospheric scintillation using TEC (total electron content) at 1 Hz was described by Tiwari and Strangeways (2015). In this paper we use phase scintillation index σ obtained by the Canadian High Arctic Ionospheric Network (CHAIN) to extend the initial phase scintillation climatology study (Prikryl et al, 2011a) over a period of 6 years, from 2008 to 2013
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