Response of ionosphere over Korea and adjacent areas to 17 March 2015 geomagnetic storm

Abstract This study analyze and discuss the response of the ionosphere over Korea and adjacent areas (20–60°N in latitude, 110–160°E in longitude, and 80–1000 km in altitude) during geomagnetic quiet days and geomagnetic storm days (17–18 March 2015). Ionospheric Data Assimilation Four-Dimension (IDA4D) technique is used to assimilate measured data into IRI (International Reference Ionosphere) model. Assimilation 3D electron density was generated every 15 min, with slant total electron content (STEC) data from GPS, and NmF2 data from ionosonde as the ingested data into International Reference Ionosphere (IRI) model. Results show a pre-SSC (sudden storm commencement) and post-SSC enhancements of foF2 and equatorial ionization anomaly (EIA) vertical total electron content (VTEC) on 16th and 17th March, respectively. Furthermore, on 18 March, result shows a negative ionosphere response. Pre-SSC enhancement is observed in the nighttime and is caused by enhanced zonal electric field. During nighttime of 17 March the post-SSC enhancement of electron density is caused by LSTIDs. On daytime of 18 March westward DDEF and reduction of O/N 2 ratio cause depletion of foF2 and VTEC over the region. During nighttime of this day the negative storm is due to eastward disturbance dynamo electric field (DDEF).