Evidence for the evolution and decay of an electrified medium scale traveling ionospheric disturbances during two consecutive substorms: First results

Rathi, Rahul and Sivakandan, M. and Chakrabarty, Dibyendu and Sunil Krishna, M.V. and Upadhayaya, Arun Kumar and Sarkhel, S. (2025) Evidence for the evolution and decay of an electrified medium scale traveling ionospheric disturbances during two consecutive substorms: First results. Advances in Space Research, 75 (6). pp. 4896-4909. ISSN 0273-1177

Abstract

Electrified Medium Scale Traveling Ionospheric Disturbances (EMSTIDs) is one of the prominent plasma structures that affect the propagation of high frequency radio waves. Overall, seasonal variation and propagation characteristics of the EMSTIDs are widely reported in literature. However, the effects of substorms on the formation and dissipation of the EMSTIDs are not well explored. In the present study, on a moderately geomagnetically active night of 26 October 2019 (Ap = 24), the airglow imager over Hanle (32.7°N, 78.9°E; Mlat. ∼ 24.1°N), India recorded the evolution and decay of an EMSTID in the O(1D) 630.0 nm airglow images in between 13.3 UT and 15.8 UT. In addition, during the same time, a steep rise and fall of the virtual base height of the ionospheric F-layer were also recorded by a nearby digisonde over New Delhi (28.70°N, 77.10°E; Mlat. ∼ 20.2°N). The most important aspect of the event was the occurrence of the two consecutive substorms in between 13.3 UT and 15.8 UT. To the best of our knowledge, this is the first of its kind study where we report the role of interplanetary electric field (IEF) and substorm induced electric fields on the evolution and decay of the EMSTID. Therefore, this investigation provides evidence that space weather induced prompt electric field perturbations can alter the state of the ionosphere already affected by EMSTID.