GNSS positioning accuracy over Nigeria during geomagnetic storm of 24-27 October 2011 and 7-10 October 2012

138-146<span style="font-size:11.0pt;mso-bidi-font-size: 10.0pt;font-family:" times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";="" letter-spacing:-.1pt;mso-ansi-language:en-gb;mso-fareast-language:en-us;="" mso-bidi-language:ar-sa"="" lang="EN-GB">The present work investigates the positioning error of five Nigeria GNSS network stations during the geomagnetic storm of 24-27 October 2011, a sudden storm commencement (SSC) with disturbance storm time (Dst) minimum of -134 nT; and 7-10 October 2012, a gradual storm commencement (GSC) with Dst minimum -105 nT. Satellite data were obtained from Nigeria GNSS network stations and Dst values were obtained from World Data Center (WDC) for Geomagnetism Kyoto, Japan while the quiet period was selected with Ap index of zero (0) and one (1) for the two storms, respectively from the same World Data Center. RTKLIB (version 2.4.2), a GNSS analysis software, was used to determine the positioning of the stations during the selected storm period and quiet period and the results were analyzed using MATLAB. This investigation revealed that during the selected storm period, the positioning error of the stations increase; though the two storms do not show the same characteristics on GNSS positioning. The GSC of 7-10 October 2012 showed a latitudinal effect, which may be as a result of local variation in the electron density and enhancement of ionospheric irregularity during the storm. This was not clearly depicted in the SSC of 24–27 October 2011.