[P-EM14] Recent Advances in Ionosphere Observation and Modeling for Monitoring and Forecast

[PEM14-08] Temporal and spatial variation of GPS TEC and phase scintillation during substorms and auroral breakups

*Paul Prikryl^1,2、James M. Weygand³、Reza Ghoddousi-Fard⁴、P. Thayyil Jayachandran¹、David R. Themens¹、Anthony M. McCaffrey¹、Bharat S. R. Kunduri⁵、Emma Spanswick⁶、Yongliang Zhang⁷、Akira Sessai Yukimatu⁸ (1.Physics Dept. of University of New Brunswick, Canada、2.Geomagnetic Laboratory Natural Resources Canada、3.Earth Planetary and Space Sciences, University of California, USA、4.Canadian Geodetic Survey Natural Resources Canada 、5.Bradley Dept. of Electrical and Computer Engineering, Virginia Tech, USA、6.Dept. of Physics and Astronomy of University of Calgary, Canada、7.Johns Hopkins University Applied Physics Laboratory, USA、8.National Institute of Polar Research, Japan)

キーワード：Polar and auroral ionosphere (Ionospheric irregularities, Ionospheric currents, Energetic particles), Auroral substorms, GPS total electron content and phase scintillation

Ionospheric structure caused by precipitation of energetic particles can adversely affect the GPS signals resulting in phase scintillation and cycle slips (loss of lock). GPS phase scintillation has been found correlated with auroral emission intensity, particularly with rapid changes in auroral forms and their brightness [1,2,3]. Total electron content (TEC) enhancements that were observed during substorm expansion phase within the night side downward (R1) current appear to be associated with enhanced precipitating particle fluxes [4]. Such TEC enhancements cause phase scintillation, which is most intense just after substorm onsets and auroral breakups. Phase scintillation index is computed for sampling rate of 50 Hz by specialized GPS scintillation receivers from the Canadian High Arctic Ionospheric Network (CHAIN). A proxy scintillation index is obtained from dual frequency measurements of geodetic-quality GPS receivers sampling at 1 Hz, which include globally distributed receivers of RT-IGS network that are monitored by the Canadian Geodetic Survey in near-real-time. Temporal and spatial changes of TEC and phase scintillation are investigated in the context of equivalent ionospheric currents derived from ground magnetometer network using the spherical elementary current method [5,6]. The relation of phase scintillation with auroral emission observed by THEMIS all-sky imagers and the far-ultraviolet scanning imager SSUSI onboard the DMSP satellites is also examined. In general, GPS phase scintillation is mapped to regions of strong westward electrojet (upward R2 currents or the interface with downward R1 currents) and to the poleward edge of the eastward electrojet (upward R1 currents). Following substorm onsets and auroral breakups, strong phase scintillation associated with TEC enhancements are mapped mainly to the upward R2 current or the equatorward edge of the downward R1 current at or near the Harang discontinuity region [7].

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[4] Weygand J.M., et al., Abstract SA41B-3484, presented at 2018 AGU Fall Meeting
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