Ionospheric storm effects and equatorial plasma irregularities during the 17–18 March 2015 event

Abstract

The intense magnetic storm on 17–18 March 2015 caused large disturbances of the ionosphere. Based on the plasma density (Ni) observations performed by the Swarm fleet of satellites, the Gravity Recovery and Climate Experiment mission, and the Communications/Navigation Outage Forecasting System satellite, we characterize the storm‐related perturbations at low latitudes. All these satellites sampled the ionosphere in morning and evening time sectors where large modifications occurred. Modifications of plasma density are closely related to changes of the solar wind merging electric field (Em). We consider two mechanisms, prompt penetration electric field (PPEF) and disturbance dynamo electric field (DDEF), as the main cause for the Ni redistribution, but effects of meridional wind are also taken into account. At the start of the storm main phase, the PPEF is enhancing plasma density on the dayside and reducing it on the nightside. Later, DDEF takes over and causes the opposite reaction. Unexpectedly, there appears during the recovery phase a strong density enhancement in the morning/prenoon sector and a severe Ni reduction in the afternoon/evening sector, and we suggest a combined effect of vertical plasma drift, and meridional wind is responsible for these ionospheric storm effects. Different from earlier studies about this storm, we also investigate the influence of storm dynamics on the initiation of equatorial plasma irregularities (EPIs). Shortly after the start of the storm main phase, EPIs appear in the postsunset sector. As a response to a short‐lived decline of Em, EPI activity appears in the early morning sector. Following the second start of the main phase, EPIs are generated for a few hours in the late evening sector. However, for the rest of the storm main phase, no more EPIs are initiated for more than 12 h. Only after the onset of recovery phase does EPI activity start again in the postmidnight sector, lasting more than 7 h. This comprehensive view of ionospheric storm effects and plasma irregularities adds to our understanding of conditions that lead to ionospheric instabilities.

Observation of equatorial plasma bubbles by the airglow imager on ISS-IMAP

“…In the previous studies concerning EPBs in the recovery phase, the enhancement of the S4 index was observed during postmidnight period in the African and South American region in the 2015 St. Patrick's Day storm Carter et al 2016. In association with an intense storm, the density variations in the early morning were observed by the C/NOFS satellite (Zhou et al 2016). Comparing these previous studies, EPBs #13 and #14 were observed before midnight, which is the typical time zone for an EPB occurrence.…”

Geospace system responses to the St. Patrick's Day storms in 2013 and 2015

“…This Special Section achieved new insights into the storm time behavior of PPEF and disturbance dynamo electric field (DDEF) effects. Various observational studies deal with dynamical ionospheric changes at different geospace regimes, from subauroral to middle and low latitudes [ Hairston et al ., ; Huang et al ., ; Kalita et al , ; Kuai et al ., ; Zhou et al ., ; Zhang et al , ; etc]. Hairston et al [] provided a comprehensive view of the DMSP and C/NOFS measurements of the global evolution of plasma drifts (electric fields) during the March 2015 storm.…”

Plasma patches inside the polar cap and auroral oval: the impact on the spaceborne GPS receiver

“…The St. Patrick's Day storm was so far the largest storm occurring during the solar cycle 24 (minimum SYM-H value reached À234 nT). The ionospheric responses as well as the plasma irregularities and related scintillation at low latitudes have been discussed by previous studies (e.g., Astafyeva et al, 2015;Carter et al, 2016;Zhou et al, 2016). Focusing at high latitudes, Liu et al (2016) has compared the development of SED and TOI between measurements of global TEC map and model predictions.…”