<p>In this work Total Electron Content (TEC) during the moderate geomagnetic storm of 27 February 2014 over the Iberian Peninsula and Northern Africa is analysed. The data used are coming from GNSS derived TEC and ROTI from several receiver stations from Spain, Portugal and Morocco. Maps of TEC are developed to study its evolution before, during and some days after the main phase of the storm. This study shows that before the storm, i.e. during quiet geomagnetic conditions, a northern crest of the Equatorial Ionosphere Anomaly (EIA) is located in Western North Africa with low gradients and values of TEC. During the main period of the storm, this northern crest of the EIA is also located in the Western North Africa with larger gradients that affect the southern part of the Iberian Peninsula. These gradients are present both in latitude and longitude. They are observed exclusively over this region but not seen in the rest of Southern Europe. In addition, increased values of ROTI from GNSS stations located in Southern Spain are also found during the storm, but not observed northwards and eastwards of that region. Since the Iberian Peninsula is located in a mid-latitude area not expected to be influenced by the EIA, these findings seem to indicate that the Southern part of the Peninsula could be influenced by the EIA during disturbed geomagnetic conditions.</p>
Studies on the irregularities of the ionosphere during disturbed geomagnetic conditions are fundamental to understanding the complex dynamics taking place in the upper atmosphere. In this work, different data sources are used to study the ionosphere effects of two moderate geomagnetic storms, 26–27 February 2014 and 17–18 September 2021, over the Iberian Peninsula. Data are obtained from digital ionosondes in Spain, Italy and Greece; the Global Navigation Satellite System (GNSS) derived Total Electron Content (TEC) and Rate Of TEC Index (ROTI) from several receiver stations in Spain, Portugal and Morocco; and the UPC Quarter-of-an-hour time resolution Rapid GIM (UQRG), vertical TEC global ionosphere maps (GIMs), produced at 15 min intervals by the Universitat Politecnica de Catalunya (UPC, Spain). This analysis showed that, during the two moderate storms, spread-F and high values of ROTI, indicating the presence of irregularities, are found in a very localized area (Southern Iberian Peninsula and northwest Africa) and local times (night-time). However, no irregularities are found eastwards and northwards of the location indicated. We propose some possible explanations for these observations for both the storms, one of them related to the position of the Equatorial Ionosphere Anomaly (EIA) and the other one attributed to the Perkins’ instabilities.
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