Response to geomagnetic storm on 23–24 March 2023 long-lasting longitudinal variations of the global ionospheric TEC

Abstract

This study examines the global behavior of the ionospheric TEC anomalies, i.e. their structures and temporal variability, during the initial, main and recovery phase of the geomagnetic storm occurring on 23–24 March 2023. For this purpose the global vertical TEC maps, generated by the NASA JPL IGS Ionosphere center, have been used and the geomagnetically forced anomalies have been presented in 2D (longitude-modip latitude) and polar maps. The main peculiar features of the TEC response could be summarized as: (i) the TOI-like event observed at the SH midnight hours during the main storm phase, and (ii) a clear longitude asymmetry between the TEC response at low and middle latitudes of the western and eastern hemispheres was seen; while the long-lasting positive response was evident for a full day in the western hemisphere the negative response or almost the lack of response was a characteristic of the eastern part. The study presented possible explanations of the above mentioned basic type of TEC anomalies by using the GUVY [O/N2] ratio maps and geomagnetic data from eight magnetometric stations situated at low latitudes for the separation of the effect generated by the DDEF. An attempt was made the observed TEC response during different storm phases to be reproduced. The presented reconstructions described in almost perfect way the real TEC responses and the RMSE assessments provided clear evidence for this evaluation.