Calibrating Liquid-Vapor and Ice-Vapor Supersaturation Relaxation Timescales in Mixed-Phase Clouds using SOCRATES Field Campaign Data

Mixed-phase clouds are ubiquitous but representing their unstable evolution and varied morphologies remains difficult for large-scale models. At the same time, representing the partitioning between liquid and ice in these clouds is essential to correctly computing climate sensitivities and radiative forcings. Climate models struggle to parameterize the microphysical processes relevant to maintaining supercooled water at large scales and must make many approximations for sub-gridscale processes such as diagnosing liquid-ice partitioning as a function of temperature or treating shallow boundary-layer and deep convective clouds separately. We use in-situ aircraft measurements from the Southern Ocean Clouds, Radiation and Aerosol Transport Experimental Study (SOCRATES) to constrain condensation/evaporation and sublimation/deposition timescales in a single-column model with a unified Eddy-Diffusivity Mass-Flux (EDMF) convective scheme and single-moment microphysics. We use this simple single-column setup to calibrate relaxation timescales for supersaturation over liquid and ice using observations of liquid and ice water content, dynamic/thermodynamic parameters, and particle size distributions. Next, we compare our calibrated timescales to observationally-implied timescales derived from first-principles. We assess the ability of our data-informed parameters to generalize in a unified scheme across the breadth of cloud morphologies presented in SOCRATES data. Finally we examine our calibrated timescale’s structures to assess implications for implementing data-informed methods in more robust, higher-moment microphysical schemes.