Phase Partitioning in Convective Clouds: Observing and Modeling Studies

Description

Convective clouds are important to the energy and water cycle, but it is challenging to correctly simulate convective clouds in numerical models. Phase partitioning in the mixed-phase zone of convective clouds is critical in regarding cloud life cycle, precipitation efficiency, and cloud radiative properties; however, it is still not well understood. In this study, in situ measurements from two field campaigns (Mid-latitude Continental Convective Clouds Experiment and Ice in Clouds Experiment-Tropical), as well as model simulations with spectral bin microphysics (WRF and parcel model), are used to explore the phase partitioning in convective clouds, and help to improve the parameterizations in numerical models. Our recent analyses suggest: 1) fast ice generation controls the phase partitioning in convective clouds; 2) in different life stages, the phase partitioning in convective clouds significantly differs; 3) vertical velocity has a minor impact on liquid fraction in convective clouds compared to temperature and cloud life cycle; 4) WRF and parcel model simulations with default ice microphysics parameterizations underestimate the ice water fraction in developing convective clouds compared to observations; 5) with other ice-generation mechanisms included, e.g., drop freezing-splinter and droplet collisional freezing, the simulated phase partitioning in convective clouds is closer to observations.