A model for the hydroxyl radical in the mesosphere during solar minimum

Abstract

Using particle fluxes from NOAA POES, atmospheric constituents from Aura MLS, and geomagnetic indices and solar wind parameters from CDAWeb, this study develops pre- dictive regression models for mesospheric hydroxyl radical (OH) variability at 62–78 km and 45–80° N during the 2007 - 2009 solar minimum period, with model development focused on 2008. Daily-mean data were processed and correlation analyses performed to identify dominant predictors. Both multiple linear and second-order polynomial regres- sion approaches were applied, and the polynomial models explained 66 – 77 % of OH variability, exceeding the performance of linear models. Validation with independent 2007 data showed high correlation coefficients (r = 0.72–0.79) and low mean-squared prediction errors (MSEP = 0.02–1.90), confirming model robust- ness. These results demonstrate that geomagnetic and solar wind parameters can reliably reproduce mesospheric OH variations linked to particle precipitation. Although the regres- sion coefficients were valid for the solar minimum period, the models provide a foundation for extending OH records beyond the Aura MLS era, supporting ongoing studies of ozone chemistry and climate–space weather interactions.