Solar-Driven Oxygen Photodissociation in the Schumann–Runge Continuum: A Parametric Study Based on Two Decades of TIMED/SEE Data

Accurate quantification of the absorption of far-ultraviolet (FUV) solar radiation in the Schumann–Runge continuum (126–175 nm) by molecular oxygen is fundamental to understanding processes in the middle and upper atmosphere. Atomic oxygen generated through O₂ photodissociation strongly influences the chemistry and thermal structure of the Earth’s mesosphere and lower thermosphere. Building on an earlier parameterization derived from UARS/SOLSTICE solar irradiance data, this study uses TIMED/SEE and SORCE/SOLSTICE observations covering the last two solar cycles to develop an improved parameterization of oxygen photolysis and energy deposition rates. Particular attention is given to variations associated with solar activity. The updated parameterization is designed for efficient application in multidimensional middle- and upper-atmosphere models.