arXiv subjects

Rahul Rathi

Publications and source records attributed to Rahul Rathi.

3 recordsLinked to original sources

arXiv2026

Role of E-F Coupling on Low-latitude Ingression of Mid-latitude MSTIDs over the Indian Subcontinent

This study provides the first observational evidence that E-F region electrodynamic coupling regulates the southernmost latitudinal extent of nighttime mid-latitude medium-scale traveling ionospheric disturbances (MSTIDs) over the Indian subcontinent. We have analyzed multiple MSTID events using total electron content (TEC) measurements from a dense network of dual-frequency GNSS receivers across India, GNSS radio occultation (RO) profiles, and ionosonde observations from New Delhi during May-July 2025, a high solar activity period. The lowest geographic latitude, at which MSTIDs wavefronts reached, varied between 17°N and 25°N. Their low-latitude extension showed no significant correlation with background TEC, but was positively correlated with the geomagnetically mapped southernmost latitude of sporadic-E (Es) layers identified from GNSS-RO measurements. These events occurred during high solar activity, when F-region MSTID growth is generally suppressed. Therefore, our results suggest that electrodynamic coupling with the underlying Es-layers is essential for sustaining MSTIDs and enabling their low-latitude penetration during solar maxima.

physics.space-ph↗

arXiv2026

Automatic Characterization of Mid-latitude Multiple Ionospheric Plasma Structures from All-sky Airglow Images using Deep Learning Technique

The F-region ionospheric plasma structures are propagating high and or low electron density regions in the Earth ionosphere. These plasma structures can be observed using ground based all-sky airglow imagers which can capture faint airglow emissions originating from the F-region of ionosphere. This study introduces a novel automatic method for determining the propagation parameters (horizontal velocity and orientation) of these multiple ionospheric plasma structures observed in O(1D) 630.0 nm all-sky airglow images from Hanle, India located in the mid-latitude region. We have used a deep learning-based segmentation model called YOLOv8 (You Only Look Once) to localize and BoT-SORT tracker to track individual mid-latitude ionospheric plasma structures. Three different automatic algorithms are used to characterize the observed plasma structures utilizing the segmented outputs from the YOLO model. Finally, an additional quality control step is introduced that filters the results from the three automatic algorithms and generates a flag to retain the most reliable estimate. The results of the proposed fully automated pipeline are systematically compared with a previously developed semi-automatic approach to assess the estimation efficacy. The automatic technique developed in this study is particularly valuable for all-sky airglow imaging systems having large datasets, where manual intervention or semi-automatic analysis is impractical.

physics.space-ph↗

arXiv2023

A comparison of the impacts of CMEs and CIRs on the Martian dayside and nightside ionospheric species

Measurements from the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft, orbiting Mars are used for investigating the impact of coronal mass ejections (CMEs) and corotating interaction regions (CIRs) on Martian ionospheric species. We have chosen 15 CME and 15 CIR events (2015-2020) at Mars from the existing catalogs. We have extensively analyzed the Martian dayside and nightside profiles of ionospheric species during each of the CME and CIR events. We have selected those orbit plasma density profiles which showed significant differences from the mean quiet-time profile during each event. The primary focus of this paper is to provide a comparative average scenario of the variation of Martian ionospheric species during CMEs and CIRs events. A significant difference can be observed in the profiles of the Martian dayside and nightside ionospheric species (O+, O2+, CO2+, NO+, C+, N+, & OH+) during CMEs and CIRs in comparison to mean quiet-time profile. The difference is more prominent on the nightside compared to the dayside ionosphere. During CIRs, the nightside ion density is nearly one order of magnitude less (above 250 km) in comparison to CMEs. The mean peak altitude and density of the lighter ions (O+, C+, N+, & OH+) were at lower altitudes during the CIRs compared to CMEs. Therefore, this study suggests that during the declining phase of solar cycle (SC 24), the impact of CIRs on the Martian ionospheric species is more prominent compared to CMEs.

physics.space-ph↗