Effects of a mid-latitude solar eclipse on the thermosphere and ionosphere - a modelling study

Abstract

A modelling study is presented which investigates in-situ generated changes of the thermosphere and ionosphere during a solar eclipse. Neutral temperatures are expected to drop by up to 40°K at 240 km height in the totality footprint, with neutral winds of up to 26 m/s responding to the change of pressure. Both temperatures and winds are found to respond with a time lag of 30 min after the passing of the Moon's shadow. A gravity wave is generated in the neutral atmosphere and propagates into the opposite hemisphere at around 300 m/s. The combined effects of thermal cooling and downwelling lead to an overall increase in [O], while [N2] initially rises and then for several hours after the eclipse is below the 'steady state' level. An enhancement of [NmF2] is found and explained by the atmosphere's contraction during, and the reduced [O]/[N2] ratio after the eclipse.