Title: ” The investigation of travelling ionospheric disturbances under severe space and tropospheric weather condition”
Date: 15th September 2025 – Monday
Venue: Smart classroom
Zoom link: https://usp-fj.zoom.us/j/88152817362?pwd=7OqX9j2Yb9uf2qkPI3yKsKlnCjj4uv.1
Abstract for Oral Examination
The Investigation of Travelling Ionospheric Disturbances under Severe Space and Tropospheric Weather Conditions
Traveling Ionospheric Disturbances (TIDs) are among the most significant manifestations of space weather and its impact on atmosphere–ionosphere coupling. Their impacts span a wide range of applications: from degrading GNSS accuracy, which provides a range of services such as positioning, timing, navigation, mapping, public safety, surveillance, geographic surveys, time standards, and weather. Despite decades of research, the TIDs characteristics, especially their scale sizes, propagation directions, and sources, remain poorly understood, particularly when generated by extreme geophysical events. A particular motivation stemmed from the limited observational coverage of the South Pacific and Australasian regions, where both ionosonde and GNSS data can provide untapped insights into TIDs morphology. My thesis presents a novel integration of High Frequency Interferometry (HF-Int) and a newly developed Total Electron Content (TEC) perturbation method to detect and characterize TIDs during selected extreme geophysical events (Geomagnetic storms, Earthquakes, Volcanic eruptions, and Tropical Cyclones). Large-scale TIDs were detected over the Australian region during moderate, intense, and super intense geomagnetic storms. Their propagation characteristics derived from HF-Int showed a significant increase in detections that co-occurred with storm phases. These characteristics had periods of ~100 min with velocities ranging from ~500–1500 m/s. During super intense and intense storms, the structures observed over Australia originated from higher latitudes and could be associated with storm-induced auroral heating. Moderate storms produced auroral TIDs in global observations but did not necessarily propagate to large distances. Consequently, the TIDs were not strongly discernible in the Australian region. The propagation characteristics showed a wide spectrum with periods that ranged from ~44 – 85 min and velocities from ~400 – 1000 m/s, having both equatorward and poleward propagating events over the Australian sector. Beyond geomagnetic storms, large-scale TIDs were identified during the 2011 Tohoku earthquake and the 2022 Tonga–Hunga Ha’apai volcanic eruption, where strong atmospheric gravity waves propagated thousands of kilometers and were visible over Australia and New Zealand. The category 5 tropical cyclone Winston that occurred in 2016 showed a negative phase ionospheric response and perturbations consistent with TIDs. Overall, this study demonstrated the advantages of integrating HF-Int with advanced TEC perturbation analysis to systematically investigate TIDs during geomagnetic storms and severe natural hazards, highlighting new observational evidence of propagational anisotropy and regional-scale TIDs evolution.
Biodata:
Amol Kishore is an Assistant Lecturer in Physics at the University of the South Pacific, where he teaches undergraduate courses and is completing a PhD in Atmospheric Physics and Space Weather. His research explores the impacts of space weather phenomena such as geomagnetic storms associated with coronal mass ejections and Earthquakes, Volcanic Eruptions, and Tropical Cyclones, to which the South Pacific Region is highly vulnerable. With several international publications, conference presentations, and recognition, including the USP Gold Medal in Physics and the URSI Young Scientist Award, he brings strong academic and research expertise with significant contributions to the Physics discipline and School (STEMP). He is an active member of the Union of Radio Science International (URSI), and the Worldwide Lightning Location Network.
