Abstract
AbstractA comparison tool has been developed by mapping the global GPS total electron content (TEC) and large coverage of ionospheric scintillations together on the geomagnetic latitude/magnetic local time coordinates. Using this tool, a comparison between large‐scale ionospheric irregularities and scintillations is pursued during a geomagnetic storm. Irregularities, such as storm enhanced density, middle‐latitude trough, and polar cap patches, are clearly identified from the TEC maps. At the edges of these irregularities, clear scintillations appeared but their behaviors were different. Phase scintillations (σφ) were almost always larger than amplitude scintillations (S4) at the edges of these irregularities, associated with bursty flows or flow reversals with large density gradients. An unexpected scintillation feature appeared inside the modeled auroral oval where S4 were much larger than σφ, most likely caused by particle precipitations around the exiting polar cap patches.
Highlights
The fluctuations in the spatial propagating radio wave signals are one of the first known effects of space weather, which is called scintillation [e.g., Hey et al, 1946]
We present a detailed comparison between the different irregularities and their associated scintillations and discuss the generated mechanisms by combining the observations of the global GPS total electron content (TEC) [Coster et al, 2003], scintillations measured by Canadian High Arctic Ionospheric Network (CHAIN) [Jayachandran et al, 2009], and the plasma flows observed by the SuperDARN radars [Greenwald et al, 1995; Chisham et al, 2007]
In order to make the comparison in large-scale areas, we have developed a tool to project both the GPS TEC and scintillations data at the Ionospheric Pierce Point (IPP) altitude of 350 km on a map of geomagnetic latitude (MLAT)/magnetic local time (MLT) grid in the northern polar ionosphere and generated a movie of the maps with 5 min resolution (e.g., Movies S1 and S2 in the supporting information)
Summary
The fluctuations in the spatial propagating radio wave signals (like their amplitude and phase) are one of the first known effects of space weather, which is called scintillation [e.g., Hey et al, 1946]. After formation, the polar cap patches move along the flow streamlines of the Dungey convection cycle [Dungey, 1961; Oksavik et al, 2010; Hosokawa et al, 2009; Zhang et al, 2013a, 2015] and transpolar evolution from the dayside to the nightside They have been found exiting the polar cap and entering the nightside auroral oval, in a manner modulated by the nightside reconnection rate, and evolving to dayside in the sunward return flow region [Zhang et al, 2013a, 2015]
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