Ionospheric storm occurrence over Grahamstown and Madimbo, South Africa for 1996-2011. The sunspot number and total number of geomagnetic storms are super-imposed (Matamba et al., (2015), Statistical analysis of the ionospheric response during geomagnetic storm conditions over South Africa using ionosonde and GPS data, Space Weather, 13, 536-547)
It is well established that the ionospheric response to geomagnetic induced processes depends on a number of factors including storm-time onset, season as well as geomagnetic/geographic region. To this effect, a number of physical mechanisms have been put forward for different ionospheric responses in different latitude regions. One understanding is not easily transferable from region to another and varies from storm to storm even within the same category. This study is statistically analysing ionospheric response over a long-term (more than one solar cycle) using satellite and ground-based data with an overall objective of categorising dominant mechanisms in different situations and latitude regions.