Significant Mid‐ and Low‐Latitude Ionospheric Disturbances Characterized by Dynamic EIA, EPBs, and SED Variations During the 13–14 March 2022 Geomagnetic Storm

Abstract

This work investigates mid‐ and low‐latitude ionospheric disturbances over the American sector during a moderate but geo‐effective geomagnetic storm on 13–14 March 2022 (π‐Day storm), using ground‐based Global Navigation Satellite System total electron content data, ionosonde observations, and space‐borne measurements from the Global‐scale Observations of Limb and Disk (GOLD), Swarm, the Defense Meteorological Satellite Program (DMSP), and the Ionospheric Connection Explorer (ICON) satellites. Our results show that this modest but geo‐effective storm created a number of large ionospheric disturbances, especially the dynamic multi‐scale electron density gradient features in the storm main phase as follows: (a) The low‐latitude equatorial ionization anomaly (EIA) exhibited a dramatic storm‐time deformation and reformation, where the EIA crests evolved into a bright equatorial band for 1–2 hr and then quickly separated back into the typical double‐crest structure with a broad crest width and deep equatorial trough. (b) Strong equatorial plasma bubbles (EPBs) occurred with an abnormally high latitude/altitude extension, reaching the geomagnetic latitude of ∼30°, corresponding to an Apex height of 2,600 km above the dip equator. (c) The midlatitude ionosphere experienced a conspicuous storm‐enhanced density (SED) plume structure associated with the subauroral polarization stream (SAPS). This SED/SAPS feature showed an unusual temporal variation that intensified and diminished twice. These distinct mid‐ and low‐latitude ionospheric disturbances could be attributed to the storm‐time electrodynamic effect of electric field perturbation, along with contributions from neutral dynamics and thermospheric composition change.

The Short‐Periodic Response of Equatorial Electrojet to the Temporal Variations of IMF Bz During Geomagnetic Quiet Time

“…As introduced before, the daytime EEJ is related to the zonal electric field (e.g., Bulusu et al., 2018). It is well‐known that at equatorial latitudes, two crests of electron density (Ne) are fully developed due to daytime eastward electric field (e.g., Aa et al., 2023; Zhang & Wang, 2022). An upward E × B drift could be generated upon the eastward electric field, resulting in the formation of EIA.…”

Multiple Longitude Sector Storm‐Enhanced Density (SED) and Long‐Lasting Subauroral Polarization Stream (SAPS) During the 26–28 February 2023 Geomagnetic Storm

“…There are three potential stormtime mechanisms that could be responsible for the observed SED over North America during a negative ionospheric storm in the storm recovery phase: (a) Zonal plasma flux transportation via long-lasting SAPS: As shown in Figure 3, the observed SED was associated with the presence of intense SAPS flow of 1.5-2.0 km/s near dusk, and there is furthermore a considerable subauroral peak of sunward ion flux larger than its poleward and equtorward counterparts, overlapping with the SAPS channel near the SED base region. This indicates that plume material could be transported sunward from later local times around the SAPS region, contributing to higher densities in the SED plume (Aa et al, 2023;Foster et al, 2007Foster et al, , 2021. Also, Lu et al (2020) suggests that the enhanced ion drift at SAPS region reinforces the needed plasma density gradient for maintaining the plume-like structure.…”

“…The conditions would also trigger strong prompt penetration electric fields (PPEF) associated with such a significant IMF southward excursion. Both PPEF and expanded convection/SAPS are favorable to the formation of SED plumes as described in the Introduction: the former enhances the plasma density mainly via the increased upward component of E × B drift raising plasma to a higher altitude with lower recombination rate (Heelis et al, 2009), while the latter facilitates the establishment of flow stagnation in the midlatitude ionosphere relative to the solar inertial frame, transporting plasma sunward via horizontal advection (Aa et al, 2023;Foster et al, 2007;.…”

Impacts of the Sudden Stratospheric Warming on Equatorial Plasma Bubbles: Suppression of EPBs and Quasi-6-Day Oscillations

“…The GOLD instrument is a UV imaging spectrograph that operates from the geostationary orbit at a longitude of 47.5 • W, which observes airglow emissions of Earth within the wavelength range of 134 to 160 nm through the disk, limb, and stellar occultation technique [89,90]. In the evening, the disk measurements of the OI 135.6 nm emission by the GOLD instrument offer continuous and crucial information on the low-latitude and equatorial ionosphere from West Africa to South America, which is particularly valuable for revealing the two-dimensional spatial morphology of EPBs, e.g., [57,88,[91][92][93][94]. To characterize the day-to-day variation in EPBs, Aa et al [88] has developed a new GOLD Bubble Index capable of quantifying the intensity of the bubbles in two dimensions on any given night within the field-of-view of GOLD measurements.…”