Longitudinal variations of ionospheric parameters near totality during the eclipse of December 14, 2020

On December 14, 2020, a total solar eclipse occurred whose shadow cone projected over part of South America. Its effect on critical ionospheric frequencies variability is analysed, considering two stations with similar geographical latitudes and a 95% obscuration percentage: Chillán (36.6°S, 72.0°W), in Chile, and Bahía Blanca (38.9°S, 62.2°W), in Argentina. A comparison of the ionospheric response to the eclipse is made with quiet time daily values and the IRI-2016 model. Results indicate that the greatest eclipse impacts are obtained in foE and foF1, with ∼31% and ∼40% of maximum reductions, respectively. Alternatively, weak disturbances are observed in the foF2 case (<20%). The recombination coefficients were calculated for the E- layer and F1-layer with values of α ∼10−9 cm3 s−1 and for F2-layer with values in β ∼10−4 s−1, similar to previous studies. Longitudinal differences between both ionospheric stations are very small for the F1-layer (∼11%), but a much larger variability is found at F2-layer critical frequencies (∼20%). These results suggest different plasma diffusion processes at high altitudes in the different locations that require further investigation in future studies.