Variations in the Maximum Electron Density of the F<sub>2</sub> Layer (NmF<sub>2</sub>) over the Middle Latitude Station of Grahamstown, South Africa, during Solar Cycle 23

Ultraviolet (UV) and X-ray radiation are the primary causes of ionization that produce electron density in sufficient quantities to promote propagation satellite radio signals ionosphere. The densities suffer from spatio-temporal variations, this poses different degrees threats propagating through We aimed characterize maximum F<sub>2</sub> layer (N<sub>m</sub>F<sub>2</sub>) middle-latitude ionosphere over Grahamstown, South Africa (Geographic latitude: 33.30°S, Geographic longitude: 26.50°E; Geomagnetic Latitude: 33.92°S, Longitude: 89.37°E). mean N<sub>m</sub>F<sub>2</sub> data for solar cycle 23 (1998–2008) were used studies. grouped into high activity (HSA: 2000–2002), moderate (MSA: 1998–1999, 2003–2005), low (LSA: 2006–2008) years. variations characterized based on diurnal, seasonal, monthly, annual data. Also, correlation between sunspot number was investigated. Results diurnal seasonal revealed noontime bite-out observed during June solstice every year. However, it not other three seasons. Equinoctial asymmetry is show insignificant variations. with linear (exception: MSA, year 1999; HSA, years 2000–2001). results reveal under conditions annual, cycle, latitudinal 2005; negative (0.64)).