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.
