Geomagnetic Storm-time Ionospheric Response over Locations around the EIA and the Magnetic Equator

Abstract:

The major sources of disturbances, which impact the modern day sophisticated communication satellite systems and space-based navigational constellations, are the sudden outburst of plasma and radiation from the solar atmosphere. These outbursts can be categorized as the Coronal Mass Ejections (CMEs), the High Speed Solar Wind (HSSW) streams that emanate from a Coronal Hole (CH), the Co-rotating Interaction Regions (CIRs) and the Solar Flares, which causes space weather effects on the Earth in terms of perturbing the Magnetosphere-Ionosphere-Thermosphere (MIT) system. In order to clearly understand the effect of such solar disturbances which give rise to the geomagnetic storms and substorms, the present work highlights on an in-depth study of the impacts of weak-to-moderate (-30 nT ≤ Dst < -100 nT) and strong (Dst ≤ -100 nT) geomagnetic storms on the low-latitude ionization over the Indian subcontinent, during the declining phase of the last solar cycle. This study covers a large latitudinal extent from beyond the northern crest of the Equatorial Ionization Anomaly (EIA) to locations close to the magnetic equator by using the ionospheric Total Electron Content (TEC) derived from the Global Positioning System (GPS) receivers. The results show that even during the declining phase of a solar cycle, the storm-induced electrodynamics causes the diurnal maximum of the TEC to enhance to about 45 TECU over the quiet time ionization values, resulting in degradation of GNSS receiver performance used for precise navigation. This overall study brings forward the mechanisms for understanding how the MIT system changes during geomagnetic storm-time conditions over the Indian longitude sector.