An updated model for O₂(a¹Δg) concentrations in the mesosphere and lower thermosphere and implications for remote sensing of ozone at 1.27 μm

An updated kinetic model for the calculation of daytime steady state O 2 (a 1 Δg) concentrations in the mesosphere and lower thermosphere is presented. In addition to the usual source from ozone photolysis in the Hartley band, energy transfer from O( 1 D) produced by photolysis of molecular oxygen in the Lyman alpha and Schumann‐Runge continuum spectral intervals is shown be a significant source of O 2 (a 1 Δg) as well. Numerous changes and additions to the basic O 2 (a 1 Δg) kinetic model have been included. These new sources and kinetic parameters imply that lower mesospheric ozone concentrations as inferred by near‐infrared emission techniques are to be decreased by as much as 10% while lower thermospheric ozone concentrations are to be increased by as much as 20%.