The 2020 Patagonian solar eclipse from the point of view of the atmospheric electric field

Abstract

In this study, the response of atmospheric electrical and meteorological variables at three different sites of Argentina are studied during the total solar eclipse of December 14, 2020: Valcheta (100% darkening), Buenos Aires (73%) and El Leoncito (71%). The reduction in solar irradiance caused by the solar eclipse was expected to directly affect the near-surface electric field, known as the potential gradient (PG), through a reduction in turbulence and an increase in air conductivity. From the analysis of the observed meteorological parameters (temperature, relative humidity, and wind), no effects on the PG were observed that can be unequivocally attributed to this event based solely on boundary layer dynamics. The prevailing synoptic situation altered the response that the boundary layer could have given, namely, a clear drop in radiation, particularly at Valcheta, which was very close to a frontal zone and had occasional cloud coverage and reports of atmospheric suspended dust. PG measurements at Valcheta during the eclipse showed PG values several orders of magnitude higher and of opposite sign to the global daily mean fair weather (FW) PG curve and the local FW-PG curves calculated at CITEDEF (940 km away) and CASLEO (1200 km away). The PG values at Valcheta were shown to be more closely related to disturbed weather conditions than FW. On the contrary, at the other two locations studied, CITEDEF and CASLEO, further north and more distant from the frontal zone, the observed PG values on the day of the eclipse showed a higher consistency with the local daily mean FW-PG curves. A comparison between the FW-PG local curves at these two sites and the evolution of PG during the day of the eclipse, however, reveals a drop in PG values during the eclipse.