Using a comprehensive database of ~5300 ground‐based Global Navigation Satellite Systems (GNSS) stations we have investigated large‐scale traveling ionospheric disturbances (LSTIDs) during 17–18 March 2015 (St. Patrick's Day storm). For the first time, the high‐resolution, two‐dimensional maps of the total electron content perturbation were made using not only GPS but also GLONASS measurements. Several LSTIDs originated from the auroral regions in the Northern and Southern Hemispheres were observed simultaneously over Europe, North America, and South America. This storm is considered as a two‐step main phase storm. During the first main phase LSTIDs propagated over the whole daytime European region and over high latitudes of North America. During the second main phase we report (1) intense LSTIDs propagated equatorward in North America and Europe, (2) convergence of several LSTIDs originated from the opposite hemispheres in the interference zone over geomagnetic equator in South America, and (3) “super” LSTIDs with the wavefront length of more than 10,000 km observed simultaneously in North America and Europe. LSTIDs observed in three sectors had wavelength of ~1200–2500 km and wave periods of ~50–80 min. During the recovery phase on the background of the negative ionospheric storm developed over North America we detect signatures of the stream‐like structures elongated within the latitudinal range of 29°N–42°N across the U.S. These structures persisted through the nighttime to the early morning from 04 UT to 13 UT on 18 March 2015, and they were associated with the subauroral polarization stream‐induced nighttime ionospheric flows.

We report first results on the study of the high-latitude ionospheric irregularities observed in worldwide GPS data during the St. Patrick's Day geomagnetic storm (17 March 2015). Multisite GPS observations from more than 2500 ground-based GPS stations were used to analyze the dynamics of the ionospheric irregularities in the Northern and Southern Hemispheres. The most intense ionospheric irregularities lasted for more than 24 h starting at 07 UT of 17 March. This period correlates well with an increase of the auroral Hemispheric Power index. We find hemispheric asymmetries in the intensity and spatial structure of the ionospheric irregularities. Over North America, the ionospheric irregularities zone expanded equatorward below~45°N geographic latitude. Additionally, the strong midlatitude and high-latitude GPS phase irregularities in the auroral oval were found to be related to the formation of storm enhanced density and deepening of the main ionospheric trough through upper atmosphere ionization by energetic particle precipitation. Significant increases in the intensity of the irregularities within the polar cap region of both hemispheres were associated with the formation and evolution of the storm enhanced density/tongue of ionization structures and polar patches.

Ionospheric plasma bubbles of equatorial origin have never been registered at midlatitudes in Europe. During the 22–23 June 2015 geomagnetic storm the prompt penetration electric fields caused the occurrence of plasma bite‐outs in the postsunset sector over low latitudes of Western Africa and large‐scale plasma bubbles extended toward Europe. For the first time, using multisite GPS and Global Navigation Satellite System observations (~1500 stations), the super plasma bubble signatures were registered in Europe. They were observed more than 8 h (20–04 UT) and covered a broad area within 30°–40°N and 20°W–10°E. These unique results were confirmed by measurements on board Swarm and DMSP satellites and ground‐based absolute total electron content observations. Occurrence of the super plasma bubbles in Europe affected Global Navigation Satellite Systems measurements over a number of stations in Spain, Portugal, southern France, and Italy and led to performance degradation of the European Geostationary Navigation Overlay Service.

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