Salient Midlatitude Ionosphere‐Thermosphere Disturbances Associated With SAPS During a Minor but Geo‐Effective Storm at Deep Solar Minimum

Abstract

During a geomagnetic storm, intense injection of solar wind-magnetospheric energy and momentum into the coupled ionosphere-thermosphere (I-T) system occurs through enhanced electric fields, currents, and particle precipitation. These enhanced inputs are known to cause significant perturbations in the coupled I-T system (Buonsanto, 1999). In particular, dramatic and complicated local/global changes may occur in the I-T system in response to various chemical, dynamic, and electrodynamics driving processes, such as Joule heating, ion-drag forcing, and penetration electric field (Mendillo, 2006;Richmond & Lu, 2000). Moreover, besides the traditional concentration in storm effects within auroral/polar and equatorial regions, the midlatitude and subauroral ionosphere also experiences substantial dynamic structuring and increase in variability. These midlatitude I-T effects have been the subject of many recent community studies especially in the past decade as the observed response can exhibit far more storm-time dynamics than would be otherwise anticipated (e.g., Ferdousi et al., 2019;Raeder et al., 2016;Zhang et al., 2015). Furthermore, steep electron density gradients therein can pose detrimental effects on modern navigation and communication systems (e.g., Coster & Foster, 2007;Doherty et al., 2004). For these reasons, characterizing the storm-time midlatitude ionosphere and thermosphere perturbations and understanding the intrinsic mechanisms in triggering those perturbations are of considerable importance in frontier space weather research.Generally, midlatitude ionosphere-thermosphere responses to a geomagnetic storm are primarily determined by various ion-neutral coupling mechanisms and relevant electrodynamic processes. These include (a) Momentum transfer via ion drag: Strong ion convection in the storm-time auroral/subauroral region can

2022 Tonga Volcanic Eruption Induced Global Propagation of Ionospheric Disturbances via Lamb Waves

“…We use GNSS total electron content (TEC) products from 5,000+ worldwide GNSS (GPS, GLONASS, and Beidou) receivers, generated (Rideout and Coster, 2006;Vierinen et al, 2016) and provided via the Madrigal distributed data system developed at the Massachusetts Institute of Technology's Haystack Observatory. In order to detect ionospheric responses associated with the Tonga eruption, we calculated differential TEC using an approach that effectively removes the background ionospheric "trend", as used in many previous TID studies (Zhang et al, , 2019aLyons et al, 2019;Sheng et al, 2020;Aa et al, 2021;England et al, 2021). Zhang et al (2019a) provided more detailed discussions of this method.…”

Pronounced Suppression and X‐Pattern Merging of Equatorial Ionization Anomalies After the 2022 Tonga Volcano Eruption

“…Second, trans‐equatorial wind can transport the plasma either with or against the background ambipolar diffusion direction, sometimes causing an intensified/weak EIA crest in the winter/summer hemisphere during the morning‐time before an afternoon transition occurs (Dang et al., 2016 ; Huang et al., 2018 ; Lin et al., 2007 ). (c) Neutral composition effect : High‐latitude thermospheric composition (e.g., O/N 2 ) changes, especially during storm‐time periods, are carried by an equatorward wind surge to low‐latitudes, causing inhibited EIA crests in the recovery phase (e.g., Aa et al., 2021 ; Fuller‐Rowell et al., 1994 ; Sreeja et al., 2009 ). (d) Large‐scale waves from the lower atmosphere : Tides and planetary waves may cause prominent EIA longitudinal structures (e.g., wave‐4) and longer‐term (e.g., 6‐day or 16‐day) quasi‐periodic oscillations (e.g., Gan et al., 2020 ; Goncharenko et al., 2010 ; Immel et al., 2006 ; Yamazaki, 2018 ).…”

Space Weather Effects on the Earth’s Upper Atmosphere: Short Report on Ionospheric Storm Effects at Middle Latitudes

“…Present availability in global-scale observations, new models and new analysis methods may facilitate systematic studies. The results, in combination with the output of studies on the CMEs that dominate solar maximum, would complete our understanding of storm time ionospheric response throughout the solar cycle [61], and would significantly advance our prediction capabilities in case it is proven that different storm scenarios need to be addressed differently by ionospheric prediction models [47,62,63].…”