Small‐scale structure of the midlatitude storm enhanced density plume during the 17 March 2015 St. Patrick's Day storm

Abstract

Kilometer‐scale density irregularities in the ionosphere can cause ionospheric scintillation—a phenomenon that degrades space‐based navigation and communication signals. During strong geomagnetic storms, the midlatitude ionosphere is primed to produce these ∼1–10 km small‐scale irregularities along the steep gradients between midlatitude storm enhanced density (SED) plumes and the adjacent low‐density trough. The length scales of irregularities on the order of 1–10 km are determined from a combination of spatial, temporal, and frequency analyses using single‐station ground‐based Global Positioning System total electron content (TEC) combined with radar plasma velocity measurements. Kilometer‐scale irregularities are detected along the boundaries of the SED plume and depleted density trough during the 17 March 2015 geomagnetic storm, but not equatorward of the plume or within the plume itself. Analysis using the fast Fourier transform of high‐pass filtered slant TEC suggests that the kilometer‐scale irregularities formed near the poleward gradients of SED plumes can have similar intensity and length scales to those typically found in the aurora but are shown to be distinct phenomena in spacecraft electron precipitation measurements.

Geospace system responses to the St. Patrick's Day storms in 2013 and 2015

“…Heine et al . [] identified ∼1–10 km small‐scale ionospheric irregularities along the poleward edge of the Storm Enhanced Density (SED) plume. In northern Germany, the 17 March 2015 storm also led to the occurrence of E region ionospheric irregularities (50–80 km size) of narrow spectral width with both low and high Doppler speeds corresponding to different parts of the E region [ Chau and St.‐Maurice , ].…”

Global View of Ionospheric Disturbance Impacts on Kinematic GPS Positioning Solutions During the 2015 St. Patrick's Day Storm

“…We focus on the 17 March 2015 storm by analyzing 5,500 + globally distributed GNSS stations measurements. As the strongest geomagnetic storm of the 24th solar cycle so far, a considerable number of researchers have investigated the ionospheric disturbances associated with this storm, such as high-/middle-latitude plasma irregularities (e.g., Cherniak et al, 2015;Heine et al, 2017;Prikryl et al, 2016), EPBs (e.g., Carter et al, 2016;Zhou et al, 2016), LSTIDs (e.g., Yao et al, 2016;Zakharenkova et al, 2016), and other positive/negative storm effects (e.g., Astafyeva et al, 2015;Kuai et al, 2016). These studies have been carried out at both regional and global scales.…”

Features of Storm‐Induced Ionospheric Irregularities From Ground‐Based and Spaceborne GPS Observations During the 2015 St. Patrick's Day Storm

“…Over the North America region, formation and passage of the SED structure was observed with the use of the global ground‐based TEC maps and the Millstone Hill incoherent scatter radar (Liu et al, ; Zhang et al, ). Ionospheric irregularities associated with sharp plasma density gradients within and at the edges of the SED/TOI structures were clearly recognized in the ground‐based GPS measurements using both high‐resolution maps (Cherniak et al, ) and single station observations (Heine et al, ).…”