On the Storm-Time Character of Earth's Mid-Latitude Ionospheric Irregularities.

[摘要] During strong geomagnetic storms, the usual, horizontally uniform mid-latitude ionosphere can undergo a dramatic reconfiguration and become highly structured with the formation of Storm Enhanced Density (SED) plumes that were first observed in the North American sector, but have since been observed in all sectors at magnetic mid-latitudes. Along the steep gradients of these high density plumes and the low density plasmapause boundary, or trough, plasma instabilities can produce small-scale density variations, or irregularities. These small-scale density irregularities have the potential to interfere with the transmission of the radio waves used in space-based communication and navigation systems in a phenomenon known as scintillation. The societal impact from degradation in Global Navigation Satellite Systems (GNSS) (e.g., the Global Positioning System (GPS)) alone extends beyond the usual navigation application and into the systems’ use as a precise global time keeper — used to synchronize human activities ranging from high speed financial transactions, the power transmission grid, to the internet itself.Using spatial, temporal, and frequency analyses of ground-based GPS Total Electron Content (TEC), in combination with radar ion velocity measurements, the kilometer-scale irregularities responsible for High Frequency (HF) scintillation are detected and used to characterize the regions of the SED plume system in which they occur. The full scope of these observations, especially the determination of their vertical extent, will be greatly enhanced by the SCintillation and Ionospheric Occultation NanoSat (SCION) mission to perform space-based top-side, cross-track, and limb GPS radio occultations from two closely spaced (<5 km) spacecraft. Finally, a survey of twelve strong geomagnetic storms between 2012-2016 reveals correlations between the different regions of the SED plume system and the formation of small-scale irregularities at mid-latitudes.

[发布机构] University of Michigan

[效力级别] Small-scale ionospheric density irregularities

[关键词] Total Electron Content TEC;Small-scale ionospheric density irregularities;Storm Enhanced Density SED;SCION CubeSat;Mid-latitude scintillation;Aerospace Engineering;Atmospheric;Oceanic and Space Sciences;Engineering;Science;Atmospheric, Oceanic & Space Science