The total solar eclipse of December 14, 2020 in southern South America and its effects on atmospheric variables

Abstract

A total solar eclipse affected southern South America on December 14, 2020.Its occurrence close to the summer solstice in the Southern Hemisphere andaround noon brought almost ideal conditions to study the effects of the suddenreduction in incoming solar radiation on different atmospheric variables. Inter-estingly, the astronomical phenomenon moved over a region that at that timewas being affected by a cold front accompanied by significant cloudiness andcold air advection to the area. Therefore, the actual drop in surface temperatureover the umbra region resulted from a combination of the radiative effect (i.e.,the reduction in solar radiation due to the eclipse itself) and a circulation effectrelated to the injection of colder air. A quantification of both effects on the fulltemperature variation is provided, along with a discussion on the underlyingmechanisms and the related effects on surface winds derived from the cooling.Results show that temperature drops associated with total solar eclipses in areasfar away from the umbra can be as high as (or even higher than) those withinthe umbra, depending on the prevailing weather conditions.