SMILES observations of mesospheric ozone during the solar eclipse

Abstract

The Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) successfully observed vertical distributions of ozone (O[3]) concentration in the middle atmosphere during the annular solar eclipse that occurred on 15 January 2010. In the mesosphere, where the photochemical lifetime of O[3] is relatively short (approximately 100 s), altitude-dependent changes in O[3] concentration under reduced solar radiation and their temporal variations were clearly observed as a function of the eclipse obscuration. This study reports the vertical distributions of mesospheric O[3] during a solar eclipse event and analyzes theoretically the eclipse-induced changes. We show that simple analytical expressions for O[3] concentration, which assume that O[3] and O are in a photochemically steady state, can be used to describe the O[3] concentration under reduced solar radiation. The SMILES data obtained during the eclipse provide a unique opportunity to test our current understanding of mesospheric O[3] photochemistry.