Reply on RC1

Abstract. Organic aerosol (OA) viscosity and phase state govern multiphase diffusion and reactivity, yet systematic constraints across tropospheric temperature (T)–relative humidity (RH) space remain limited. We measured the viscosity of sucrose–H2O droplets (OA surrogate) over 273–303 K and ~20–90 % RH using bead-mobility and poke-and-flow methods, spanned ~9 orders of magnitude. A Vogel–Fulcher–Tammann fit with experimentally derived fragility (Df = 13) extended the parameterization to 230–310 K and 0–100 % RH. When coupled with zonal-mean tropospheric T–RH fields (2020–2024), the parameterization yielded global distributions of viscosity and organic-phase mixing time (τmix,org) for 200-nm particles: liquid states prevailed below ~2 km, semisolid regimes occupied ~2–9 km (latitude dependent), and near-glassy conditions emerged above ~9 km; τmix,org was