P. Aravindakshan et Kn. Iyer, DAY-TO-DAY VARIABILITY IN IONOSPHERIC ELECTRON-CONTENT, Journal of atmospheric and terrestrial physics, 55(11-12), 1993, pp. 1565-1573
Published values of ionospheric electron content (IEC) are used to stu
dy its day-to-day variability at a number of stations extending from e
quatorial to mid-latitudes in Indian and American sectors for high and
low solar activity years. It is seen that the variability is larger a
t night than by day, highest in February and November (D months) and l
owest in equinox (E) months. The solar activity dependence is such tha
t the variability is higher during high sunspot years than during low
sunspot years for mid- and subauroral latitudes while for low latitude
s this trend is reversed from 08 to 23 h local time. From a correlativ
e study of the variability in IEC vis-a-vis that in possible causative
factors such as solar 10.7 cm flux, magnetic activity, equatorial and
auroral electrojet, the relative contributions of the above factors t
o the variability in IEC at different locations are brought out. The s
patial correlation of TEC is also studied.