The Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES)
successfully observed vertical distributions of ozone (O3) concentration in
the middle atmosphere during the annular solar eclipse that occurred on 15
January 2010. In the mesosphere, where the photochemical lifetime of O3 is
relatively short (ca. 100 s), altitude-dependent changes in O3 concentration
under reduced solar radiation and their temporal variations were clearly
observed as a function of the eclipse obscuration. This study reports for
the first time the vertical distributions of mesospheric O3 during a solar
eclipse event, and analyzes theoretically the eclipse-induced changes. We
show that simple analytical expressions for O3 concentration, which assume
that O3 and O are in a photochemically steady state, can be used to describe
the O3 concentration under reduced solar radiation. The SMILES data obtained
during the eclipse provide a unique opportunity to test our current
understanding of mesospheric O3 photochemistry.