Characteristic of Sq current based on seasonal variation in different phases of solar cycle / Mohd Anuar N. ...[et al.]

The ionospheric current (Sq) variation is changeable
throughout a year. This study is aimed to examine the behavior of
Sq variation in different phases of the solar cycle. The horizontal
component has been used to measure the monthly diurnal
variation, Sq (H) and MSq (H) based on seasonal variation. The
magnetic data were extracted from magnetic data acquisition
system (MAGDAS) situated at Langkawi station (Geog. Lon.
99.68◦E, Geog. Lat. 6.30◦N), Malaysia. The data were collected in
2008 and 2012 to represent a different phase of the solar cycle. The
result of the numerical simulation indicates that the maximum
amplitude of Sq (H) values were 72.96 nT and 115.16 nT in
October 2008 and September 2012, respectively. Moreover, the Sq
(H) variation was generally low during night time and oscillated
between -21.54 nT and 5 nT for both years. The Sq (H) amplitude
was high at low latitude, specific to equatorial region due to the
superimposition of Sq and EEJ current. Furthermore, the active
CEJ occurred within 06:00 LT to 18:00 LT. The higher magnitude
of CEJ were -27.96 nT and -35.51 nT were observed in 2008 and
2012, respectively. Both maximum readings occurred in May
around 06:00 LT – 07:00 LT was due to the consequence of late
interchange process between nighttime westward current to
daytime eastward current flow. The seasonal mean variation
revealed the maximum of MSq (H) was 66.72 nT and 96.51 nT in
2008 and 2012, respectively. Both maxima values were peaked
during Equinox season resulting from the strong dynamo process
and great solar thermal heating with minimal loss rates other than,
during Equinox, the Sun exists right above the equator line.