Peculiar features of the low‐latitude and midlatitude ionospheric response to the St. Patrick's Day geomagnetic storm of 17 March 2015

Abstract

The current study aims at investigating and identifying the ionospheric effects of the geomagnetic storm that occurred during 17–19 March 2015. Incidentally, with SYM‐H hitting a minimum of −232 nT, this was the strongest storm of the current solar cycle 24. The study investigates how the storm has affected the equatorial, low‐latitude, and midlatitude ionosphere in the American and the European sectors using available ground‐based ionosonde and GPS TEC (total electron content) data. The possible effects of prompt electric field penetration is observed in both sectors during the main phase of the storm. In the American sector, the coexistence of both positive and negative ionospheric storm phases are observed at low latitudes and midlatitudes to high latitudes, respectively. The positive storm phase is mainly due to the prompt penetration electric fields. The negative storm phase in the midlatitude region is a combined effect of disturbance dynamo electric fields, the equatorward shift of the midlatitude density trough, and the equatorward compression of the plasmapause in combination with chemical compositional changes. Strong negative ionospheric storm phase is observed in both ionosonde and TEC observations during the recovery phase which also shows a strong hemispherical asymmetry. Additionally, the variation of equatorial ionization anomaly as seen through the SWARM constellation plasma measurements across different longitudes has been discussed. We, also, take a look at the performance of the IRI Real‐Time Assimilative Mapping during this storm as an ionospheric space weather tool.

Suppression of ionospheric scintillation during St. Patrick’s Day geomagnetic super storm as observed over the anomaly crest region station Pingtung, Taiwan: A case study

“…As, the ionosphere itself is uplifted well above the path of the satellite, it measures such a small density which seems much smaller than the quiet time values. This particular SWARM observation (figure 2g) was also discussed in recent studies by Ram et al (2015) and Nayak et al (2016). Ram et al (2015) also suggested the presence of a strong eastward prompt penetration electric field in the Indian longitudes which was superposed on the pre reversal enhancement (PRE) electric field to lift the equatorial plasma to higher altitudes and the corresponding enhancement of the EIA.…”

“…As a result, it has garnered considerable interest in the scientific community. There have been a number of studies which investigated the ionospheric effects of this particular storm (Astafyeva et al, 2015;Cherniak et al, 2015;Kakad et al, 2016;Ramsingh et al, 2015;Nayak et al, 2016;Joshi et al, 2016;Nava et al, 2016;Ram et al, 2015). The study by Carter et al (2016) has studied the global variation of plasma bubble occurrence during the St. Patrick's Day storm.…”

Formation of ionospheric irregularities over Southeast Asia during the 2015 St. Patrick's Day storm

“…The green vertical short lines at the bottom of each plot mean that the ionogram is recorded but the trace is too poor to validate a reliable value of f o F 2 . Also, Nayak et al [2016] reported such hemispherical asymmetry but in the American and European sectors, suggesting that such asymmetry is a nonlocal effect related to the neutral wind circulation and to the equinoctial conditions [Fuller-Rowell et al, 1996;Goncharenko et al, 2007]. By comparing the response to the storm depicted by the two ionosondes, we remind the reader that the two ionosondes are is significantly smaller than the lower boundary limit defined by the mean minus the standard deviation.…”

Analysis of the global ionospheric disturbances of the March 2015 great storm

“…The March 2015 storm, triggered by CMEs, was the strongest storm in solar cycle 24 so far, and some studies on the ionosphere response of this storm have been made [e.g., Cherniak et al, 2015;Astafyeva et al, 2015;Liu et al, 2016aLiu et al, , 2016bZhong et al, 2016;Nayak et al, 2016]. Liu et al [2016a] studied the ionospheric stormenhanced density (SED) in the main phase and found that there was a SED in TEC but not in N m F 2 .…”