arXiv subjects

Gopi K. Seemala

Publications and source records attributed to Gopi K. Seemala.

4 recordsLinked to original sources

arXiv2026

Interhemispheric differences in field-aligned currents, ground magnetic perturbations, and TEC during the geomagnetic storms of May and October 2024

This study investigates storm-to-storm variability and hemispheric differences in magnetosphere-ionosphere (MI) coupling during the extreme (G5) geomagnetic storm of May 10-11 and the severe (G4) storm of October 10-11, 2024. Global field-aligned current (FAC) patterns derived from the Active Magnetosphere and Planetary Dynamics Response Experiment (AMPERE), together with conjugate observations from ground-based magnetometers within the SuperMAG network and Global Positioning System (GPS)-derived total electron content (TEC), are analyzed to examine high-latitude electrodynamic and ionospheric responses in both hemispheres. The May event exhibits broad and relatively organized Region 1/Region 2 FAC systems encircling the polar caps across multiple local time sectors, accompanied by intervals of correspondence in conjugate magnetic perturbations and structured TEC enhancements with temporal offsets between hemispheres. In contrast, the October event shows more localized, asymmetric, and uneven FAC morphology with pronounced hemispheric and dawn-dusk asymmetries, together with greater divergence in conjugate magnetic responses and spatially heterogeneous TEC variability. These differences are consistent with enhanced mesoscale variability and asymmetric current closure under storm-time conditions. Overall, the results highlight that even under similarly strong solar wind driving, the coupled MI system can exhibit substantially different spatial organization and interhemispheric coupling, reflecting the combined influence of FAC morphology, ionospheric conductance, and local electrodynamic conditions.

physics.space-ph↗

arXiv2026

Predicting low-latitude ionospheric Total Electron Content (TEC) over the Indian sector under variable space weather conditions using solar wind parameters

Accurate prediction of ionospheric Total Electron Content (TEC) during geomagnetically disturbed conditions remains challenging, particularly when empirical models perform poorly during storms and neural network (NN) approaches rely explicitly on geomagnetic indices such as Kp/Ap or Dst/SYM-H. In this study, we develop an NN-based model to predict TEC variations over the Indian longitude sector without incorporating geomagnetic indices as inputs. The model is trained on the full-year (2024) Global Ionospheric Map (GIM) TEC dataset at a 15-minute cadence, together with solar wind parameters: Interplanetary Magnetic Field (IMF) $B_z$, velocity ($V_{sw}$), and density ($N_p$), along with the F10.7 cm solar radio flux. Seasonal and diurnal variability are represented using sinusoidal transformations of Day of Year (DOY) and hour of day (HOD). An optimized architecture with 96 hidden neurons yields strong training performance ($R^2$ $\sim$ 0.96, RMSE $\sim$ 5.4, and MAE $\sim$ 3.8 TECU). Independent predictions for the year 2025 demonstrate robust generalization under both quiet and geomagnetically active conditions. Quiet-time residuals are generally confined within $\pm$10 TECU, while during moderate and strong storm-time conditions, the model maintains comparable error bounds across most of the Indian region, despite not being trained on geomagnetic indices. The results indicate that solar wind parameters, combined with the F10.7 solar flux and cyclical temporal encoding, contain sufficient information to reproduce geomagnetic storm-time TEC variability. This study therefore demonstrates the applicability of the proposed approach for regional TEC prediction and ionospheric nowcasting, with potential applications in GNSS positioning, satellite navigation, radio communication systems, and the future development of operational ionospheric forecasting tools.

physics.space-ph↗

arXiv2025

Ionospheric responses over the Antarctic region to Intense Space Weather events: Plasma Convection vs. Auroral Precipitation

The present investigation is directed at exploring southern polar ionospheric responses to intense space weather events and their correlations with plasma convection and auroral precipitation. The main phases of six geomagnetic storms occurring in the year 2023 (ascending phase of the present solar cycle) are considered for this study. The ionospheric Total Electron Content (TEC) measurements derived from GPS receivers covering the Antarctic region are used for probing the electron density perturbations during these events. Auroral precipitation maps are shown to illustrate the locations of the GPS stations relative to particle precipitation. SuperDARN maps are shown to understand the effects of plasma convection over these locations. Correlation between the enhanced TEC observations with the auroral precipitation (R $\sim$ 0.31) and the plasma convection (R $\sim$ 0.88) reveals that the latter is more responsible for causing significant enhancements in the diurnal maximum values of TEC over the Antarctic region in comparison to the former. Therefore, this work shows correlation studies between two physical processes and ionospheric density enhancements over the under-explored south polar region under strong levels of geomagnetic activity during 2023.

physics.space-ph↗

arXiv2024

Influence of ICME-driven Magnetic Cloud-like and Sheath Region induced Geomagnetic Storms in causing anomalous responses of the Low-latitude Ionosphere: A Case Study

This work shows an anomalously enhanced response of the low-latitude ionosphere over the Indian sector under weak geomagnetic conditions (October 31, 2021) in comparison to a stronger event (November 04, 2021) under the influence of an Interplanetary Coronal Mass Ejection (ICME)-driven Magnetic Cloud (MC)-like and sheath regions respectively. The investigation is based on measurements of the Total Electron Content (TEC) from Ahmedabad (23.06$^\circ$N, 72.54$^\circ$E, geographic; dip angle: 35.20$^\circ$), a location near the northern crest of the Equatorial Ionization Anomaly (EIA) over the Indian region. During the weaker event, the observed TEC from the Geostationary Earth Orbit (GEO) satellites of Navigation with Indian Constellation (NavIC), showed diurnal maximum enhancements of about 20 TECU over quiet-time variations, as compared to the stronger event where no such enhancements are present. It is shown that storm intensity (SYM-H) or magnitude of the southward Interplanetary Magnetic Field (IMF) alone is unable to determine the ionospheric impacts of this space weather event. However, it is the non-fluctuating southward IMF and the corresponding penetration electric fields, for a sufficient interval of time, in tandem with the poleward neutral wind variations, that determines the strengthening of low-latitude electrodynamics of this anomalous event of October 31, 2021. Therefore, the present investigation highlights a case for further investigations of the important roles played by non-fluctuating penetration electric fields in determining a higher response of the low-latitude ionosphere even if the geomagnetic storm intensities are significantly low.

physics.space-ph↗