The ionospheric responses to the total solar eclipse on 2 July 2019 over low latitudes in southern South America are presented. Ionosonde observations were used within the totality path at La Serena (LS: 29.9°S, 71.3°W) and at Tucumán (TU: 26.9°S, 65.4°W) and Jicamarca (JI: 12.0°S, 76.8°W), with 85% and 52% obscuration, respectively. Total electron content (TEC) estimations over the South American continent were analyzed. The ionospheric impact of the eclipse was simulated using the Sheffield University Plasmasphere‐Ionosphere Model (SUPIM) at the Instituto Nacional de Pesquisas Espaciais (INPE). The significant variability of the diurnal variations of the various ionospheric characteristics over equatorial and low latitudes on geomagnetically quiet days makes it difficult to unambiguously determine the ionospheric responses to the eclipse. Nonetheless, some specific issues can be derived, mainly using simulation results. The E and F1 layer critical frequencies and densities below 200 km are found to consistently depend on decreasing solar radiation. However, the F1 layer stratification observed at both TU and LS cannot be related to the eclipse or other processes. The F2 layer does not follow the changes in direct solar radiation during the eclipse. The SUPIM‐INPE‐modeled F region critical frequency and TEC are overestimated before the eclipse at LS and particularly at TU. However, these overestimations are within the observed large day‐to‐day variability. When an artificial prereversal enhancement is added, the simulations during the eclipse better reproduce the observations at JI, are qualitatively better for LS, and are out of phase for TU. The simulations are consistent with conjugate location effects.

We present the first prediction of the ionospheric response to the 14 December 2020 solar eclipse using the SUPIM‐INPE model. Simulations are made for all known ionosonde stations for which solar obscuration is significant. The found response is similar to that previously reported for other eclipses, but it also shows a modification of the equatorial fountain transport that will impact the low latitudes after the event. In addition to the large reduction of electron concentration along the totality path (~4.5 TECu, ~22%), a significant electron and oxygen ion temperature cooling is observed (up to ~400 K) followed by lasting temperature increases. Changes of up to ~1.5 TECu (~5%) are also expected at the conjugate hemisphere. These predictions may serve as a reference for eventual ionospheric measurements of multiple instruments and are leading to a better understanding of the ionospheric response to solar eclipses.

Context. In this study, we apply a novel heuristic core-strahlo (CS) model to analyze solar wind electrons. This model reproduces the behavior of a core-halo-strahl representation by employing solely two subpopulations: a bi-Maxwellian core and a modified Kappa distribution that introduces skewness. This modification effectively represents halo and strahl electrons within a single skew distribution. Aims. This work aims to demonstrate that the CS model can be utilized to model observations beyond theoretical contexts. The CS model can reproduce the main features of electron velocity distribution functions (eVDFs) in the solar wind–thermal core, enhanced tails, and skewness–with the advantage that a single parameter controls the asymmetry. Methods. We implemented a comprehensive statistical analysis of solar wind electrons at 1 AU using the electron and solar wind plasma moments on board the NASA Wind SWE/VEIS instrument. This work uses a sophisticated algorithm developed to analyze and characterize separately the core and strahlo populations. We limited our effective energy from 10 eV to 3 keV and fit the eVDFs measurements observed by the WIND satellite to the CS model. Results. Our experimental analysis show good agreement with existing models of solar wind electrons, including those that account for core, halo, and strahl components, as the resulting values fall within the expected order of magnitude. The CS model not only achieves results comparable to previous studies, but also offers the added capability of accounting for heat flux and the asymmetry of the electron velocity distribution through the δ parameter, which enhances our understanding of solar wind electron dynamics. Further, we confirm that the kappa parameter (κ) is independent of the skewness parameter (δ), consistent with previous theoretical studies’ findings. Conclusions. This work serves as an initial practical application of the CS model. We extend its relevance beyond theoretical contexts to the study of observational data. This novel approach not only highlights the specific dynamics of solar wind electrons but also provides insights into their behavior. Specifically, as the strahl relaxes, the halo becomes more enhanced.

This study presents the first coordinated observations of atmospheric electric field (AEF) and ionospheric plasma drifts during the partial solar eclipses of 2 July 2019 and 14 October 2023, observed near the magnetic equator in Lima, Peru. AEF was measured using a field mill, while ionospheric drifts were obtained from radar observations at the Jicamarca Radio Observatory and local magnetometers. The two events displayed contrasting electrodynamic responses: in 2019, AEF variations were ambiguous due to meteorological fluctuations, while in 2023, clearer weather conditions revealed distinct decreases in both surface AEF and ionospheric vertical drift near maximum obscuration. These results demonstrate the variable nature of eclipse-time electrodynamics and demonstrate that simultaneous measurements of AEF and ionospheric electric field are crucial for elucidating the mechanisms of vertical coupling between atmospheric layers. Such coordinated observations provide preliminary insight into how solar and terrestrial drivers jointly modulate the near-surface electric environment, contributing to a more comprehensive understanding of atmosphere–ionosphere interactions in low-latitude regions.