Solar quiet current response in the African sector due to a 2009 sudden stratospheric warming event

Abstract

We present solar quiet (Sq) variation of the horizontal (H) magnetic field intensity deduced from Magnetic Data Acquisition System (MAGDAS) records over Africa during an unusual strong and prolonged 2009 sudden stratospheric warming (SSW) event. A reduction in the SqH magnitude that enveloped the geomagnetic latitudes between 21.13°N (Fayum FYM) in Egypt and 39.51°S (Durban DRB) in South Africa was observed, while the stratospheric polar temperature was increasing and got strengthened when the stratospheric temperature reached its maximum. Another novel feature associated with the hemispheric reduction is the reversal in the north‐south asymmetry of the SqH, which is indicative of higher SqH magnitude in the Northern Hemisphere compared to the Southern Hemisphere during SSW peak phase. The reversal of the equatorial electrojet (EEJ) or the counter electrojet (CEJ) was observed after the polar stratospheric temperature reached its maximum. The effect of additional currents associated with CEJ was observed in the Southern Hemisphere at middle latitude. Similar changes were observed in the EEJ at the South America, Pacific Ocean, and Central Asia sectors. The effect of the SSW is largest in the South American sector and smallest in the Central Asian sector.

Deep Ionospheric Hole Created by Sudden Stratospheric Warming in the Nighttime Ionosphere

“…Enhancement in the westward perturbation that can be expected at low to middle latitudes according to numerical simulations (Liu et al, ), should further increase this downward drift. In addition, as magnetic declination varies with longitude, SSW‐induced perturbations to the zonal wind could contribute to significant longitudinal differences in ionospheric effects reported by multiple authors (Bolaji et al, ; Goncharenko et al, ; Maute et al, ; Vieira et al, ].…”

Lunar Tidal Modulation of Periodic Meridional Movement of Equatorial Ionization Anomaly Crest During Sudden Stratospheric Warming

“…The longitudinal dependence of these perturbations at the low-latitude ionosphere during SSW has also been demonstrated by satellite and ground-based measurements (Bolaji et al, 2016;Fejer et al, 2010;Goncharenko et al, 2013;Jonah et al, 2014;Liu et al, 2011;Paes et al, 2014). Using the ground-based magnetometer measurements in the America, Indian, and Pacific equatorial regions during 2002-2003SSW, Fejer et al (2010 showed that morning and afternoon current perturbations are strongest in American sector and weakest (particularly in the afternoon) in the Pacific sector.…”

“…Paes et al () pointed out that the EIA suppression is stronger than its intensification in the Brazilian sector during 2008–2009 and 2009–2010 SSW events, which is opposite to the observations over the Peruvian sector. Bolaji et al () observed a reduction in the S q H (solar quite variation of the horizontal magnetic field intensity) magnitude and a reversal in the EEJ in South Africa sector during 2009 SSW, which is largest in the South American sector and smallest in the Central Asian sector.…”

Variations of Mesospheric Neutral Winds and Tides Observed by a Meteor Radar Chain Over China During the 2013 Sudden Stratospheric Warming

“…The zonal and meridional winds in the mesospheric and lower thermospheric (MLT) region during wintertime are generally eastward and northward over the middle and low latitudes, respectively. However, the SSW can significantly affect the variations of dynamical structures in the MLT region (Chandran et al, 2013; Hoffmann et al, 2007; Ma et al, 2017; Wit et al, 2015) and even in the ionosphere (Bolaji et al, 2016; Owolabi et al, 2019; Siddiqui et al, 2015; Yamazaki et al, 2012). The neutral winds after the onset of SSW are observed to reverse to westward and southward (Chen et al, 2012; Dowdy et al, 2007; Lima et al, 2012; Sathishkumar & Sridharan, 2009; Wang & Alexander, 2009; Yuan et al, 2012).…”