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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-today 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.

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