Explicit IMF B_y‐Dependence in Geomagnetic Activity: Quantifying Ionospheric Electrodynamics

Abstract

The physical mechanism of the explicit B y -effect has so far remained poorly understood. It is well known that IMF B y plays important roles in several magnetospheric and ionospheric dynamics. For example, IMF B y affects the geometry of the dayside reconnection (Park et al., 2006;Sonnerup, 1974;Trattner et al., 2012) and exerts magnetic stress on opened field lines, leading to dawn-dusk asymmetries in magnetospheric

Effect of Interplanetary Magnetic Field on Hemispheric Asymmetry in Ionospheric Horizontal and Field‐Aligned Currents During Different Seasons

“…Regarding the explicit IMF B E y effect in a given hemisphere, our results are in agreement with several other previous studies (e.g., Holappa & Mursula, 2018;Holappa et al, 2020Holappa et al, , 2021Laundal et al, 2018;Ohma et al, 2021;Smith et al, 2017, references therein). Using satellite measurements, Smith et al (2017) E y effect on the high latitude ionospheric currents is not yet known.…”

“…Using FAC measurements from AMPERE, Holappa et al. (2021) found stronger R1 and R2 FACs for B than for B in the NH winter, and for B than for B in the SH winter for the same level of solar wind driving. Ohma et al.…”

“…They found larger CPCP in the NH than in the SH during IMF B  E y in the NH (B  E y in the SH) under neutral tilt (equinoxes). Previous studies have reported the effect of IMF B E y on the geomagnetic activity and fluxes of high energy electron precipitation and (e.g., Holappa & Mursula, 2018;Holappa et al, 2020Holappa et al, , 2021 and substorm occurrence rates (e.g., Liou et al, 2020;Ohma et al, 2021, and references therein). Holappa and Mursula (2018) and Holappa et al (2021) 2020) of a B  E y preference were due to the choice of substorm list used.…”

“…Previous studies have reported the effect of IMF B E y on the geomagnetic activity and fluxes of high energy electron precipitation and (e.g., Holappa & Mursula, 2018;Holappa et al, 2020Holappa et al, , 2021 and substorm occurrence rates (e.g., Liou et al, 2020;Ohma et al, 2021, and references therein). Holappa and Mursula (2018) and Holappa et al (2021) 2020) of a B  E y preference were due to the choice of substorm list used. Hemispheric asymmetry in auroral current systems has been reported in several previous studies (Coxon et al, 2016;Green et al, 2009;Huang et al, 2017;Laundal et al, 2016;Milan et al, 2017;Smith et al, 2017;Workayehu et al, 2019Workayehu et al, , 2020.…”

The Magnitude of IMF By Influences the Magnetotail Response to Solar Wind Forcing

“…Liou et al, 2001;Liou & Newell, 2010;Østgaard et al, 2011). Recent studies have also shown that auroral electrojets (Friis-Christensen et al, 2017;Holappa & Mursula, 2018;Holappa et al, 2021;Smith et al, 2017), auroral oval size (Reistad et al, 2020), energetic electron precipitation (Holappa et al, 2020) and substorm occurrence frequency (Ohma et al, 2021) respond differently to solar wind forcing, depending on the sign of IMF 𝐴𝐴 𝐴𝐴𝑦𝑦 and the dipole tilt angle (or season). For a fixed value of 𝐴𝐴 Φ𝐷𝐷 , the above parameters are greater for 𝐴𝐴 𝐴𝐴𝑦𝑦 > 0 than for 𝐴𝐴 𝐴𝐴𝑦𝑦 < 0 during negative dipole tilt (NH winter and SH summer).…”