Ground?Based GNSS and C/NOFS Observations of Ionospheric Irregularities Over Africa: A Case Study of the 2013 St. Patrick’s Day Geomagnetic Storm

In this paper, the variations of ionospheric irregularities have been studied using C/NOFS, ground-based GNSS and magnetometer measurements in Africa during St. Patrick geomagnetic storm March 17, 2013. The latitudinal distribution was examined GNSS-ROTI maps covering longitude 25°–45°E. Longitudinal characteristics were also investigated along with equatorial plasma bubbles (EPBs) vertical drift velocity (Vz) from 12 to 21 results show postsunset 12°S–27°N stronger ones confined within 1°S–7°S 12°N–22°N prestorm period. observed pre-reversal enhancement (PRE) Vz varying 22.51–59.47 m/s between 20.26 20.86 LT corresponded occurrence EPBs. PRE greater than 40 nevertheless, supported long lasting depletions. During main phase, prompt penetration electric field enhanced thus, extended range 31°N. It induced a duration EPB 15°E several depletions over Eastern sector. recovery stormtime wind drove conspicuous asymmetry morphology anomaly. This reduction extent strength irregularities. Westward/eastward disturbance dynamo inhibited/triggered postsunset/postmidnight period on 18 difference accounted for longitudinal before storm. phase however, present (reduced) (Atlantic/Western) sectors. might related changes inferred anomaly shape.