Spatio‐Temporal Evolution of Global Ionospheric Storm Drivers and Hemispherical Asymmetry During 17–18 March 2015 Geomagnetic Storm

Abstract

Excess energy and momentum deposition into the Earth's magnetosphere owing to the invasion of solar wind outbursts arising from active regions of the Sun causes major disturbances in the geomagnetic field referred to as geomagnetic storms (GMSs) (D'ujanga et al., 2013). The main drivers of GMSs are solar flares, coronal mass ejections (CMEs), and fast wind streams from coronal holes or their interplanetary remnants known as the interplanetary coronal mass ejections (Rawat et al., 2010;Richardson et al., 2006). The occurrence of GMSs is marked with a larger southward pointing interplanetary magnetic field (IMF), B z < −10 nT, that sustain for a period of time approximately longer than 3 h (Gonzalez & Tsurutani, 1987;Gonzalez et al., 1994). Southward B z is quite essential as it facilitates the transfer of energy, mass, and momentum from the solar wind into the Earth's magnetosphere through the magnetic reconnection with the northward directed geomagnetic field around Earth's magnetopause (Dungey, 1961).The state of the ionosphere at times of GMSs, commonly named ionospheric storms, describes variations of ionospheric parameters such as electron density, total electron content (TEC), or critical frequency (f o F 2 ) in response to geomagnetic storms. Based on the storm-induced alterations of the ionospheric parameters the ionospheric storms can be categorized as positive/negative corresponding to an increase/decrease in ionospheric parameters (

The Effect of Energy Deposition Hemispherical Asymmetry on Characteristics of LSTIDs During 17 March 2015 Geomagnetic Storm

“…The highest peak value reached was approximately 2,046 nT (13:55 UT). SYM‐H shows enhancement roughly from a value of 15–53 nT just on the onset of SSC and declines continuously from around 6:00 UT with different minima and registered the lowest value of −233 nT at 22:45 UT (Astafyeva et al., 2015; Terefe & Nigussie, 2021), which is also an indicator of the end of the main phase or the onset of the recovery phase.…”

“…As seen in Figure 2a, following the SSC Vsw jumped approximately from 425 km/s to above 500 km/s and it further increased to 600 km/s momentarily after the onset of the main phase, then it remains on average between 550 and 600 km/s throughout the recovery phase (Ramsingh et al, 2015;Terefe & Nigussie, 2021). During SSC the IMF Bz component was around 10 nT in the north direction and increased until it attained a value of 25 nT in the same north direction, then it abruptly decreased and reached a value of 18 nT.…”

“…(2016) incorporated the role of neutral wind in the hemispherical asymmetry. Additionally, Terefe and Nigussie (2021) reported the contribution of energy deposition imbalance between the two hemispheres as one of drivers of hemispherical asymmetry among others.…”

“…During the March 17–18, 2015 space weather event, hemispheric asymmetry observations are reported in the ionospheric storm (Astafyeva et al., 2015; Nava et al., 2016; Ngwira et al., 2019; Terefe & Nigussie, 2021). Astafyeva et al.…”

“…Astafyeva et al (2015) explained hemispherical asymmetries as a combined effect of thermospheric neutral composition alternation, the non-dipolar part of the geomagnetic field and the IMF BY component variations, whereas Nava et al (2016) incorporated the role of neutral wind in the hemispherical asymmetry. Additionally, Terefe and Nigussie (2021) reported the contribution of energy deposition imbalance between the two hemispheres as one of drivers of hemispherical asymmetry among others.…”