GPS phase scintillation at high latitudes during geomagnetic storms of 7–17 March 2012 – Part 1: The North American sector

Abstract

Abstract. 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.

Climatology of GPS phase scintillation at northern high latitudes for the period from 2008 to 2013

“…As already stated for ICME days, this is a result of more frequent expansion of the auroral oval during intense auroral events that can include SAPS events and increased activity in the polar cap including the tongue of ionization (TOI) that is drawn from dense SED plasma producing patches of enhanced plasma density. In case studies, weak-to-moderate scintillation was found at sub-auroral latitudes, collocated with SAPS, and events of moderate-to-strong scintillation associated with TOI and polar patches were observed in the polar cap (Prikryl et al, 2013b(Prikryl et al, , 2015a.…”

“…This can be attributed to most intense events when auroral oval expanded further equatorward and SAPS/SED events occurred (Prikryl et al, 2013b(Prikryl et al, , 2015c, which is more often the case during ICME disturbances. On the other hand, CIR/HSSs are known to be permeated with high-amplitude solar wind Alfvén waves coupling to the dayside magnetopause and producing copious patches (Prikryl et al, 1999(Prikryl et al, , 2015a. Polar patches are the main cause of scintillation in the polar cap but also in the nightside auroral oval as they evolve into auroral blobs (Jin et al, 2014).…”

“…However, the energetic particles that cause aurora, discrete aurora in particular, produce maximum ionization at much lower heights. For mapping the scintillation caused by bright aurora, an IPP height of 110 km has been used (e.g., Prikryl et al, 2013bPrikryl et al, , 2015a fairly wide but the mapping at 110 km will significantly redistribute the IPPs in magnetic latitude and MLT when compared with mapping at 350 km. With a small number of receivers, the mapping at 110 km will result in some gaps in latitude coverage or reduced statistical samples due to small number of data points in grid cells between widely spaced receivers.…”

Ionospheric F-region response to the 26 September 2011 geomagnetic storm in the Antarctica American and Australian sectors

“…At high and middle latitudes, GPS phase scintillation observations have shown that ionospheric irregularities are primarily enhanced in the cusp in association with storm-enhanced plasma density (SED). A tongue of ionization (TOI) can be formed and broken into patches that are transported into the polar cap (e.g., Aarons et al, 2000;De Franceschi et al, 2008;Spogli et al, 2009Spogli et al, , 2013aPrikryl et al, 2011Prikryl et al, , 2015aPrikryl et al, , b, 2016Thomas et al, 2013;Horvarth and Lovell, 2015). In the auroral oval, GPS scintillation has been observed during energetic particle precipitation events (Skone et al, 2008;Kinrade et al, 2013;Prikryl et al, 2013aPrikryl et al, , b, 2016.…”

“…Most of the work done on specific geomagnetic storms refers to effects in the ionosphere at different sectors in the Northern Hemisphere (e.g., Yizengaw et al, 2005;De Franceschi et al, 2008;Spogli et al, 2009;Prikryl et al, 2011Prikryl et al, , 2015aPrikryl et al, , b, 2016Danilov, 2013;Thomas et al, 2013;Hovart and Lovell, 2015;and references therein) where there is a dense network of instrumentation for ionospheric studies. In contrast, in the Southern Hemisphere where the network of instrumentation is sparse, there is less work and most ionospheric studies have been done in the Australian and African sectors.…”