Space Weather observations and HF transmissions around the 2021 autumn equinox

Continuing the study of the influence of Space Weather conditions on radio communications in Mexico accomplished for 17 days of the spring of 2020, results of a longer campaign and around autumn of 2021 are analyzed in this paper. The length of the study and the number and variety of people collaborating in its development turn this new experiment into a remarkable event of citizen science. While the Space Weather conditions of the study in 2020 corresponded to an early stage of the Cycle 25 characterized by a very low level of solar activity, in the 77 days of the new observation period, 8 M class and 1 X class Solar Flares and 17 Coronal Mass Ejections took place. In addition, Coronal Holes were present in 50 days. This significant activity originated 2 G1, 1 G2 and 2 G3 geomagnetic storms and increased the scientific interest of the survey. This article includes a short explanation of the main solar phenomena affecting Space Weather and their presence in the survey followed by the description of the main variations of radio signals recorded by radio ham operators of the National Emergency Network in Mexico, at 7.120 MHz (40 m band) and 3.720 MHz (80 m band) frequencies. According to the records, the first band seems to present better response to propagation conditions than the second one during the experiment period, but a larger amount of observations are necessary to confirm this result.