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

Abstract

AbstractKilometer‐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.