Statistical Associations among C-Class Solar Flares, Ionospheric TEC, Plasma Temperatures, and Solar-Activity Indices (January-March 2025)
Ashish Kumar Meena *
Department of Physics, SR University, Warangal, Telangana, India.
*Author to whom correspondence should be addressed.
Abstract
Aims: To characterise the distributions and pairwise associations among C-class solar-flare magnitude, duration, ion temperature (Ti), electron temperature (Te), total electron content (TEC), solar zenith angle (SZA), sunspot number (SSN), and 10.7 cm solar radio flux (F10.7) in an author-compiled January-March 2025 dataset, while distinguishing descriptive covariance from event-centred ionospheric flare responses.
Study Design: Exploratory descriptive observational analysis of co-tabulated solar and ionospheric variables.
Place and Duration of Study: Public space-weather records compiled for 1 January to 18 March 2025, a 77-calendar-day interval; 75 days are represented in the retained source compilation.
Methodology: The dataset contains 624 C-class flares. Flare magnitude and duration were summarised together with Ti, Te, absolute TEC, SZA, SSN, and F10.7. Pearson coefficients were used descriptively. Correlations involving TEC used 623 records because one TEC entry was missing; analyses not involving TEC used 624 records. Repeated same-day solar-index values mean that event-level coefficients are flare-record-weighted rather than day-independent estimates. Product-level metadata on station, altitude, geographical coordinates, and retrieval for TEC/Ti/Te, as well as the terrestrial reference location used for SZA, were not retained; therefore, no causal or p-value-based inference is made.
Results: Mean flare magnitude was C3.87 and mean duration was 19.9 min. Flare magnitude showed its largest positive descriptive association with F10.7 (r = 0.331), followed by SZA (r = 0.227) and SSN (r = 0.146), whereas its association with absolute TEC was negligible (r = 0.032). Mean Ti and Te were 1168 K and 1694 K, respectively, with a mean Ti/Te ratio of approximately 0.70.
Conclusion: The results characterise association patterns within the retained dataset during an active interval of Solar Cycle 25. The near-zero magnitude-TEC correlation concerns absolute TEC and does not establish an absence of C-class flare effects. Event-centred analysis requires traceable high-cadence ionospheric measurements, explicit spatial and geomagnetic controls, and recoverable product provenance.
Keywords: C-class solar flares, total electron content, ion temperature, electron temperature, F10.7, solar zenith angle, ionosphere, space weather