Transient Response of Polar‐Cusp Ionosphere to an Interplanetary Shock

Abstract

Geomagnetic field and plasma convection on Earth are strongly affected by interplanetary (IP) shocks and solar wind dynamic pressure pulses [P dyn ] (e.g., Boudouridis et al., 2007;Yue et al., 2010). After the IP shock hits the magnetosphere, the magnetopause moves inward, toward the Earth and the eastward magnetopause current intensifies rapidly as a result of this prompt compression (Araki, 1994). In consequence, the horizontal component of the geomagnetic field in low and mid-latitudes typically responds with an abrupt increase due to an enhanced eastward magnetopause current. This sudden increase in the horizontal component of the geomagnetic field on the dayside is referred to as an sudden impulse (SI) event with a precise onset time (Araki, 1994). In comparison with their clear stepwise signatures in the lower latitude regions, SI-associated geomagnetic disturbances at Abstract Interplanetary (IP) shock-driven sudden compression of the Earth's magnetosphere produces electromagnetic disturbances in the polar ionosphere. Several studies have examined the effects of IP shock on magnetosphere-ionosphere coupling systems using all-sky cameras and radars. In this study, we examine responses and drivers of the polar ionosphere following an IP shock compression on 16 June 2012. We observe the vertical drift and concurrent horizontal motion of the plasma. Observations from digisonde located at Antarctic Zhongshan station (ZHO) showed an ionospheric thick E region ionization and associated vertical downward plasma motion at F region. In addition, horizontal ionospheric convection reversals were observed on the Super Dual Auroral Radar Network ZHO and McMurdo radar observations. Findings suggest that the transient convective reversal breaks the original shear equilibrium, it is expected that the IP shock-induced electric field triggers an enhanced velocity shear mapping to the E region. The horizontal motion of the plasma was attributed to only the dusk-to-dawn electric field that existed during the preliminary phase of sudden impulse. We also found that ionospheric convection reversals were driven by a downward field-aligned current. The results of these observations reveal, for the first time, the immediate and direct cusp ionosphere response to the IP shock, which is critical for understanding the global response of the magnetosphere following an abrupt change in Interplanetory Magnetic Field (IMF) and solar wind conditions.Plain Language Summary On 16 June 2012, an interplanetary (IP) shock hit near-Earth space (geospace), resulting in enhanced plasma convection, auroral intensifications, and altering electric current systems in the high-and polar-latitude ionosphere. We present a case study characterizing the effect of IP shock-driven sudden impulse (SI) impact on geospace systems that changes vertical drift and horizontal convection observed by digital ionosonde and Super Dual Auroral Radar Network high-frequency radars. We found an SI-driven immediate vertical downward plasma motion, the sudden appearance of sp...

Substorm‐Time Ground dB/dt Variations Controlled by Interplanetary Shock Impact Angles: A Statistical Study

“…The strengths of IP shocks are frequently determined by means of solar wind parameters such as the ratio of downstream to upstream plasma densities and shock Mach numbers (Andréeová & Pr˘ech, 2007;Lugaz et al, 2016;Tsurutani & Lin, 1985). When IP shocks strike the Earth's magnetosphere, many geomagnetic perturbations are observed in the magnetosphere-ionosphere (MI) system, including magnetic field perturbations in geosynchronous orbit (Villante & Piersanti, 2011;, ultra-low frequency wave activity (C.-R. Zong et al, 2009), satellite orbital drag (Krauss et al, 2018;, ionospheric disturbances (Belakhovsky et al, 2017;Liu et al, 2023), and sudden impulse signatures observed by ground magnetometers around the world (Chao & Lepping, 1974;Russell et al, 1994;Smith et al, 2020). Therefore, understanding IP shock geoeffectiveness is of paramount importance in space weather investigations (Alves et al, 2011;Echer et al, 2004;Su et al, 2009).…”

Ionospheric Flow Vortex Induced by the Sudden Decrease in the Solar Wind Dynamic Pressure

“…Once generated, the TCVs propagate tailward away from local noon in the high‐latitude ionosphere with a speed of several km/s (Friis‐Christensen et al., 1988; Glassmeier et al., 1989; Lühr et al., 1996). The ionospheric flow vortices associated with TCVs have been observed by incoherent scatter radars (Lühr et al., 1996; Valladares et al., 1999) and Super Dual Auroral Radar Network (SuperDARN) radars (Kataoka et al., 2003; Liu et al., 2011, 2015, 2023; Lyatsky et al., 1999).…”